nitrate reduction VIII (dissimilatory)

MetaCyc:PWY0-1352

Nitrate reduction VIII in E. coli couples NADH oxidation to menaquinone reduction by NDH-I and menaquinol oxidation to nitrate reduction by NarGHI (nitrate reductase A) or NarZYV (nitrate reductase Z). These are two composite biological events linked by a recyclable quinone pool. Nitrite is the terminal product within this boundary: downstream ammonification, denitrification, nitrate assimilation, ATP synthesis and nitrate transport are adjacent processes, not additional steps. Nar catalysis faces the cytoplasm; the separate Nap system is periplasmic. The old background description of NrfA as hexaheme is not adopted as a structural claim about this route. (MetaCyc:PWY0-1352; EcoCyc:NITRATREDUCTA-CPLX; EcoCyc:NITRATREDUCTZ-CPLX; EcoCyc:PWY0-1352.) The complete native LEFT-TO-RIGHT donor event is a menaquinone + NADH(in) + 5 H+(in) → a menaquinol + NAD+(in) + 4 H+(out). The acceptor event is a menaquinol + nitrate(in) + 2 H+(in) → a menaquinone + nitrite(in) + water(in) + 2 H+(out). All non-proton coefficients are one. The two events retain all thirteen native side occurrences; quinone-class sides have no explicit compartment. CCO-IN and CCO-OUT are generic membrane sides, interpreted here in the E. coli inner-membrane context as cytoplasmic and periplasmic sides. (MetaCyc:RXN0-5388; MetaCyc:RXN0-3501.) Five constituent contexts preserve nineteen side occurrences: transport of 4 H+ from in to out; inner-side menaquinone + 2 H+ + 2 electrons → menaquinol; NAD+ + H+(in) + 2 electrons → NADH; nitrate + 2 H+(in) + 2 electrons → nitrite + water; and outer-side menaquinone + 2 H+ + 2 electrons → menaquinol. The NAD+ reduction is reversed in the donor composite, and the outer-side quinone reduction is reversed in the acceptor composite. These contexts are not five extra forward steps. Their literal electron symbols remain literal source content, without invented chemical identifiers. (MetaCyc:RXN-13519; MetaCyc:RXN0-5254; MetaCyc:RXN0-5248; MetaCyc:RXN0-5242; MetaCyc:TRANS-RXN0-234.) RHEA:29100 and RHEA:29136 are the oriented, transport-aware source projections of the two composites. They preserve the five-in/four-out donor proton terms and two-in/two-out acceptor terms. Their whole Polymer resources 9537 and 9539 are generic menaquinone and menaquinol with repeat index n; neither an underlying ChEBI class nor a fixed MK8 molecule replaces those resources. Rhea does not assign every non-proton participant a compartment, so native localization is not silently copied into the Rhea projection. Alternative ubiquinone or non-transport equations are comparative annotations, not substitute route identities. (RHEA:29100; RHEA:29136; MetaCyc:RXN0-5388; MetaCyc:RXN0-3501.) The native pathway account reports a whole-chain H+/electron value of three and represents NDH-I with four outward protons per NADH, followed by the Nar redox-loop contribution. These are source-attributed coupling conventions, not a universal ratio newly measured here. The same account explicitly discusses a lower NDH-I value of three protons per two electrons; newer NDH-I preparations report condition-dependent relative coupling. Scalar protons consumed by quinone/nitrate chemistry must be distinguished from translocated charge, and model stoichiometry must be distinguished from a calibrated assay. (MetaCyc:PWY0-1352; EcoCyc:PWY0-1352; EcoCyc:NADH-DHI-CPLX; PMID:27118783; PMID:34308841.) NDH-I is the energy-conserving donor shown by this pathway. E. coli also contains non-pumping NDH-II, and native genetic and expression accounts do not establish that NDH-I is the preferred donor during nitrate respiration: they report preference for NDH-II in that setting, whereas NDH-I is important for fumarate and DMSO respiration. Nitrate induction of nuo is NarL-dependent. Both expression and flux depend on growth conditions; the reported aerobic electrophoretic association of NDH-I with NDH-II does not establish a fixed functional heteroassembly. (MetaCyc:PWY0-1352; EcoCyc:PWY0-1352; EcoCyc:NADH-DHI-CPLX; UniProtKB:P00393; UniProtKB:P0AF28.) Quinone abundance and respiratory competence are distinct. The native nitrate account records increased menaquinone and reduced ubiquinone after anaerobic growth with nitrate, yet demethylmenaquinone can be the major pool constituent. A DMK-only strain failed to grow with nitrate, and the historical NADH-linked membrane assay did not support replacing its required quinone context with menaquinone alone. NarA can accept menaquinol and ubiquinol, but menadiol/duroquinol analogue kinetics and mixed-pool reconstitutions do not prove that every quinone species is interchangeable. The generic menaquinone route remains a source-defined capability, not an assertion of exclusive physiological flux. (MetaCyc:PWY0-1352; EcoCyc:PWY0-1352; EcoCyc:NITRATREDUCTA-CPLX; PMID:195602; PMID:1444716; PMID:27118783.) The NAD couple is an electron-donor context rather than a fixed in vivo redox voltage: the native NAD half-reaction cites a cellular effective potential near −280 mV under its stated assumptions. The nitrate/nitrite half-reaction also appears in reverse nitrite-oxidation contexts in other organisms. Those thermodynamic and comparative annotations do not reverse the two E. coli composites or add a nitrite-oxidizer pathway. (MetaCyc:RXN0-5248; MetaCyc:RXN0-5242.) Reference NDH-I has thirteen E. coli polypeptides because NuoC and NuoD are fused. NuoE/F/G form the electron-input module, NuoB/CD/I connect it to the membrane arm, and NuoA/H/J/K/L/M/N occupy the membrane arm. The native assembly explicitly nests the six-protein peripheral complex beneath the seven membrane subunits. Detergent-isolated EFG, BCDI and AHJKLMN fragments are informative preparations, not autonomous versions of the complete NADH-to-menaquinone event. Deamino-NADH activity can distinguish NDH-I in specified strains; it is not a new physiological substrate assigned to the route. (EcoCyc:NADH-DHI-CPLX; EcoCyc:CPLX0-3361; EcoCyc:NUOB-MONOMER; EcoCyc:NUOC-MONOMER; EcoCyc:NUOE-MONOMER; EcoCyc:NUOF-MONOMER; EcoCyc:NUOG-MONOMER; EcoCyc:NUOI-MONOMER; PMID:34308841.) The peripheral redox inventory contains FMN and nine Fe–S clusters: NuoF carries FMN and N3; NuoE carries N1a; NuoG carries N1b, N4, N5 and N7; NuoI carries N6a and N6b; and NuoB carries terminal cluster N2. N1a and N7 lie outside the main NADH-to-quinone chain. N7 has a structural-stability role in the native account. Historical N4/N5 and NuoG/NuoI spectral assignments were revised; modern names should not be projected backward without qualification. Table 2 of the nanodisc paper omits N5 in its NuoG cell, whereas Table 5 and the body preserve the complete nine-cluster inventory. (EcoCyc:NUOB-MONOMER; EcoCyc:NUOG-MONOMER; EcoCyc:NUOI-MONOMER; PMID:34308841; UniProtKB:P33602; UniProtKB:P0AFD6.) The resolved quinone-headgroup site is near N2 in a NuoB/NuoD crevice, within a larger membrane-accessible cavity to which NuoH contributes. Earlier NuoM-centered site proposals, two-site redox-potential assignments and multiple semiquinone signals remain method-dependent interpretations. The native account also describes electron-transfer rates measured by different kinetic approaches; those estimates need not describe the same limiting transition. Neither these observations nor the cofactor-free NuoCD scaffold establish the old proposed proton channel in NuoCD. (EcoCyc:NUOC-MONOMER; EcoCyc:NUOH-MONOMER; EcoCyc:NADH-DHI-CPLX; PMID:34308841.) In the nanodisc structural study, BL21FS was a BL21-AI derivative with a genomic N-terminal Twin-Strep/TEV-site NuoF modification; editing plasmids were cured, and the scaffold plasmid expressed MSP2N2 rather than the nuo operon. Cells were grown microaerobically in LB, not as a nitrate-chain assay. DDM purification and nanodisc reconstitution used E. coli lipids, while the separate LMNG preparation had different assay-buffer conditions. Focused refinements reached 2.1 Å for the peripheral arm and 3.7 Å for the membrane arm; the entire complex was not resolved at 2.1 Å. (EcoCyc:NADH-DHI-CPLX; PMID:34308841.) That study measured NADH reduction of Q1 and decylubiquinone, not menaquinone turnover or proton transport. Nanodisc maximal rates of 2.2 ± 0.2 and 5 ± 1 μmol NADH/min/mg fell to 0.4 ± 0.1 and 0.3 with 20 μM piericidin A; the DQ nanodisc assay included 0.003% LMNG. Separate LMNG rates were 11 ± 3 and 28 ± 2, falling to 1.6 ± 0.3 and 4.7 ± 0.5. Lack of a sealed proton compartment precluded a pumping measurement, and differences in analogue solubility and assay conditions preclude interpreting rate increases as better coupling. (PMID:34308841.) The nanodisc structures show arm rotation, a solvent-open Q-cavity and local NuoM TMH8 heterogeneity. The authors interpret the observed conformations as uncoupled; whether they represent a biological resting state or preparation effects remains unsettled. Missing NuoH TMH1 density is interpreted as mobility, not a deletion. Their proposed sealed-cavity antiport mechanism and net-four-proton calculation are models; the Appendix uses explicit equilibrium assumptions and mitochondrial parameter values. The observed hydration gap does not rule out transient paths in unobserved states, and the authors discuss deletion counterevidence rather than resolving it experimentally. (PMID:34308841.) In the separate quinone-intermediate study, LMNG-solubilized E. coli complex with His-tagged NuoF was assayed with decylubiquinone. The delayed activity of NuoH D213G was associated with a 305-nm signal interpreted as a quinol anion, not as direct identification of a menaquinone-bound intermediate. A missing semiquinone signal in the uncoupled detergent preparation does not establish that semiquinones never occur. Piericidin was a 10 mM stock used at 10 μM final concentration; the remaining activity near 60% must not be rewritten as 60% inhibition. The upper/lower Q-site and one-stroke coupling scheme is an interpretation. (EcoCyc:NADH-DHI-CPLX; PMID:34026733.) The related NuoH/NuoL disease-model study separates a stable NuoH D213G complex from the strongly assembly-impaired NuoL V259A variant. In BW25113 Δndh with the chromosomal nuo replacement and pBADnuoHis, V259A retained about 3% membrane NADH-oxidation activity and approximately half the ferricyanide activity; extraction did not recover a stable complete enzyme. D213G retained about 72% membrane oxidation and about 46% purified DQ activity with quinol reoxidation, with a roughly one-minute lag. Pre-reducing the quinone pool did not remove that lag, supporting an interpretation involving Q reduction rather than solely QH2 release. (EcoCyc:NUOH-MONOMER; PMID:34135385.) D213G proteoliposomes retained coupled pumping at lower rates, with about 60% of NADH sites accessible. The paper infers unchanged stoichiometry; it does not calibrate an absolute H+/electron ratio. Figure 6/Results specify 130 μM NADH for the ACMA comparison whereas the Methods give 200 μM; the oxonol assay uses another condition. These panels must remain separate. E. coli D213G and V259A model human ND1 D199G and ND5 V253A; the human multi-residue genotype cited elsewhere is not an additional bacterial construct assayed here. The proposed proton-wave or water-chain explanation remains mechanistic inference. (PMID:34135385; PMID:34026733.) NuoE N1a and NuoF FMN participate in proposed protection against electron leakage. The native record reports very tight binding of oxidized FMN and weaker binding of reduced FMN, and links the NADH/NAD+ ratio to ROS formation. In the full N1a study, Aquifex NuoEF structures and E. coli mutations are distinct evidence streams: the Aquifex NuoF construct has a C-terminal His tag, whereas the E. coli whole-complex preparations use His-tagged NuoF. A reduction-dependent peptide switch limiting NAD+ release is a model, and the later E. coli nanodisc carbonyl orientation disagrees with that structural explanation without directly disproving all ROS observations. (EcoCyc:NADH-DHI-CPLX; EcoCyc:NUOE-MONOMER; PMID:31186428; PMID:34308841.) For E. coli NuoE G135D, the N1a study reports low NADH:DQ activity and strong dependence on whether the ferricyanide assay is initiated with NADH or with ferricyanide; product inhibition is not interchangeable with loss of protein stability. G135S is less disruptive. Its Table 2 gives ROS rates of 90, 66 and 11 nmol/min/mg for reference, G135S and G135D, with 116 for V96P/N142M. The corresponding relative values are 2.7%, 2.5%, 2.2% and 4.3%; the prose phrase about a 160% increase should not replace those actual denominators. Figure 6 and Table 2 also use different NADH concentrations. These are quinone-analogue/ROS assays, not measurements of nitrate-chain flux. (PMID:31186428.) Native and reviewed UniProt accounts describe NuoF E95Q as altering FMN potential, hydride transfer and ROS, while mutations of N3 ligands impair electron transfer. NuoF E183 substitutions were used to change NADPH utilization: the evolved E183A and other substitutions cannot establish NADPH as the reference pathway donor, and the A/G subset has a different ROS phenotype from some other variants. NuoE C97A, the V96P/N142M potential-shift construct and the reported +1 frameshift reporter likewise concern particular molecules or reporters, not alterations to the reference subunit sequence. Exact canonical variant objects remain in the coverage ledger. (EcoCyc:NUOE-MONOMER; EcoCyc:NUOF-MONOMER; UniProtKB:P31979; UniProtKB:P0AFD1; PMID:31186428.) The native NuoB account ties N2-associated acidic residues and Tyr114/Tyr139 to redox-linked protonation and activity. Its double-tyrosine mutant retained limited activity, whereas other acidic-residue replacements had much stronger effects. NuoCD has separable assembly and quinone-site roles: NuoD histidine/arginine substitutions, NuoC acidic-residue substitutions and attempts to separate the fused protein did not produce one uniform phenotype. Those are database-attributed mutant/FTIR findings, not new functional tests in the nanodisc paper. The NuoB–NuoI and NuoA–NuoJ crosslink responses to NADH provide additional construct-specific conformational evidence. (EcoCyc:NUOB-MONOMER; EcoCyc:NUOC-MONOMER; EcoCyc:NUOI-MONOMER; EcoCyc:NUOA-MONOMER; EcoCyc:NUOJ-MONOMER; UniProtKB:P0AFC7; UniProtKB:P33599.) Topology and assembly annotations place NuoA in three membrane helices with a cytoplasmic C terminus, NuoH in eight, NuoJ in five and NuoK in three. Source-attributed NuoA D79/E81 effects and NuoH cytoplasmic-loop substitutions concern assembly/coupling; a change in NuoH E36 affects quinone kinetics in its own assay. The NuoJ V65G growth defect was especially strong with malate, while Y59F was motivated by a human ND6 analogy. Such condition-dependent observations do not make every null mutant universally growth-defective or convert a human disease substitution into an E. coli clinical phenotype. (EcoCyc:NUOA-MONOMER; EcoCyc:NUOH-MONOMER; EcoCyc:NUOJ-MONOMER; EcoCyc:NUOK-MONOMER; UniProtKB:P0AFC3; UniProtKB:P0AFD4; UniProtKB:P0AFE0; UniProtKB:P0AFE4.) NuoK insertion and function depend on its membrane context. Native and UniProt annotations describe SecYEG/YidC involvement, strong E36A/Q impairment, more residual activity for E72 substitutions, and rescue of E72Q by the specific I39D second mutation. Deleting two or more C-terminal residues affects assembly/activity; the particular RR25–26 replacement is another tested construct. These entries support source-qualified sequence-function context, not a general rule that every conservative charge replacement or truncation abolishes proton transport. (EcoCyc:NUOK-MONOMER; UniProtKB:P0AFE4.) NuoI carries the N6a/N6b connection between the electron-input and terminal modules, and its conserved cysteine/acidic-residue mutant and deletion phenotypes concern both assembly and electron conduction. NuoG is essential for a functional input arm, while its off-path N7 cluster contributes to stability. Reported solvent-tolerance effects in crp/cyaA backgrounds and stress-induced mutagenesis associations of selected nuo genes are adjacent phenotypes; they do not add solvent resistance or mutation production as chemical steps of nitrate reduction. (EcoCyc:NUOG-MONOMER; EcoCyc:NUOI-MONOMER; EcoCyc:NUOC-MONOMER; EcoCyc:NUOH-MONOMER; EcoCyc:NUOJ-MONOMER; EcoCyc:NUOK-MONOMER; EcoCyc:NUOL-MONOMER; UniProtKB:P0AFD6; UniProtKB:P33602.) NuoL, NuoM and NuoN have antiporter-like membrane architectures, each represented with fourteen helices in modern accounts. The long NuoL amphipathic helix was proposed as a mechanical piston, but constraints at named positions that preserved activity favor a stabilizing clamp interpretation over obligatory large piston motion. NuoM helix positioning, charged-residue replacements and one-turn rescue experiments constrain local architecture; historical His-tag/topology experiments around helices X/XI should remain distinct from modern whole-complex structural topology. (EcoCyc:NUOL-MONOMER; EcoCyc:NUOM-MONOMER; EcoCyc:NUON-MONOMER; PMID:34308841; UniProtKB:P33607; UniProtKB:P0AFE8; UniProtKB:P0AFF0.) Partial NuoL deletions and C-terminal truncations gave different assembly and coupling outcomes across preparations. Some ΔNuoL material also lacked NuoM, and inactive or contaminating populations complicate a simple assignment of a fixed proton count to one subunit. D563 substitutions, assembly-impaired V259A and the separate NuoL/NDH knockout backgrounds are not interchangeable constructs. Heterologous complementation of Bacillus MrpA and sodium transport by a truncated NuoL fragment do not establish sodium pumping by intact E. coli NDH-I. The EP432 sodium-pump report and ANN003 proton-pump results remain strain/assay-specific disagreements. (EcoCyc:NADH-DHI-CPLX; EcoCyc:NUOL-MONOMER; PMID:27118783; PMID:34135385; PMID:34308841.) The NuoL coupling study purified MC4100 enzyme with nine histidines before NuoE and compared E144Q, D178N, D303A/N, H334Q and D400A/E/N. Reconstitution into double-knockout membranes used an ndh deletion plus NuoG N1b-ligand substitutions, named C36A/C47A/C50A/C69A in the paper; those coordinates are not silently converted to the current UniProt sequence numbering. ACMA initial rates were measured after 150 μM NADH. Figures 1 and 5 specify 20 μM DQ, whereas the generic Methods do not; endogenous membrane enzymes and mixed quinone pools remain part of this preparation. (PMID:27118783.) In that preparation, pumping was nearly absent without Mg2+ and greatest around 10–20 mM; D400A was an exception to the claim that oxidation changes little with magnesium. At 2 μM ZnCl2, reference pumping fell by 24% without a significant reference oxidation change, but several NuoL mutants also showed inhibited oxidation. At 15 μM EIPA, reference pumping remained at 60.8%, while D178N lacked the same inhibitory pumping response and Table II shows other oxidation exceptions. The Figure 4 caption unit and a Discussion D178A spelling conflict with the body/table and actual D178N construct. These data warrant assay-qualified ion/inhibitor edges, not universal selective binding or inhibition of every mutant. (PMID:27118783.) The same work compared MK-rich and UQ-rich membranes, each still a mixed pool with the predominant quinone only about 2.5-fold enriched. The reference mean MK-rich/UQ-rich coupling efficiency was 54.9%; D178N and other variants differed. This is a relative ACMA-rate/oxidation ratio, not a calibrated absolute two-proton event or a purified generic-menaquinone-to-nitrate chain. Quinol-feedback explanations, some oxidase controls and other data-not-shown observations retain their reported status rather than becoming independent measurements. (PMID:27118783.) NuoN K395H, K158-region interactions and heterologous MrpD complementation support specific antiporter-like roles under their reported conditions. A full-length C-terminal His/HA-tagged NuoN study used its own chromosomal deletion and showed altered inhibitor sensitivity with K158C/H224K. Molecular dynamics proposing NuoN/NuoK hydration is a simulation, not an observed proton trajectory. An older NuoN-null report found normal LB growth but poor acetate growth, whereas other nuo-null series report defects in rich medium; genotype and culture differences are retained. NuoN–NuoM crosslink loss of activity and NuoL-helix constraints that preserve activity are different interventions. (EcoCyc:NADH-DHI-CPLX; EcoCyc:NUON-MONOMER; UniProtKB:P0AFF0; PMID:12718520.) Many native subunit records report reduced NADH oxidation, proton transport or growth after the corresponding deletion. These observations establish requirements in particular strains and assays, not autonomous activity of each subunit or identical viability effects in every medium. The combined ndh/nuoE defect is distinct from a single nuo lesion. Native NuoCD–flagellar-protein interactions and stress-mutagenesis associations are retained as adjacent phenotypes in the evidence ledger without fabricating a direct flagellar or mutagenesis pathway edge. (EcoCyc:NUOA-MONOMER; EcoCyc:NUOB-MONOMER; EcoCyc:NUOC-MONOMER; EcoCyc:NUOE-MONOMER; EcoCyc:NUOF-MONOMER; EcoCyc:NUOG-MONOMER; EcoCyc:NUOH-MONOMER; EcoCyc:NUOJ-MONOMER; EcoCyc:NUOK-MONOMER; EcoCyc:NUOL-MONOMER; EcoCyc:NUOM-MONOMER; UniProtKB:P33599.) Purified NDH-I responds to detergent and lipid composition, and the native account describes Fe–S assembly pathways, tellurite-associated cluster damage and a bound divalent metal initially assigned tentatively. In the nanodisc study a NuoG density was assigned to calcium in a preparation containing 2 mM calcium, with a proposed stabilizing role. This does not establish calcium as an obligatory physiological catalytic cofactor. Stationary-phase fitness, C4-dicarboxylate-dependent regulation of the nuo operon and oxygen/nitrate/fumarate regulation are conditional cellular contexts; phylogenomic arguments about ancient ancestry are evolutionary inference rather than direct mechanism in this record. (EcoCyc:NADH-DHI-CPLX; PMID:34308841.) The 2022 persistence study concerns allele-specific antibiotic tolerance, not a cryo-EM structure or general antibiotic resistance. Chromosomal restoration reversed the phenotype, whereas complete nuo disruption did not reproduce it. In its strain list, SX43 NuoL A294D and SX2513 NuoM F356C/NuoN G402R must remain distinct from UTI89-derived NuoM F356C or S414R and NuoN L79R or G402D clones. MIC, uptake, ATP, growth phase, carbon source and pH responses were examined separately; decreased drug uptake and early ATP depletion did not explain the reported phenotype as a universal mechanism. (EcoCyc:NADH-DHI-CPLX; PMID:35087069.) Crucially, the purified-complex constructs in that study were His6-NuoF pBADnuo versions with NuoL A294D, NuoM S414R or NuoN G402R. The cellular NuoM F356C result cannot be relabeled as a biochemical measurement of the purified S414R enzyme. The preparations used the BW25113 Δnuo Δndh background, DDM and E. coli polar lipids; reconstitution efficiency was about 21%, NADH accessibility about 75%, and empty-liposome activity about 15%. With 60 μM DQ and 100 μM NADH at pH 6, relative pumping losses of approximately 50–75% do not establish an absolute four-proton wild-type stoichiometry. (PMID:35087069.) Stationary-phase acidification and shifts in carbon metabolism contribute to the persistence interpretation; RpoS and ppGpp were not sufficient single explanations. Inverted-vesicle assays without supplied DQ can include other respiratory activities, and the paper’s ethylamine wording conflicts with methylamine in a figure/Methods context. Structural mapping used existing models, not a new experimental structure, and the SpoT fusion assay is an engineered interaction context. The supplemental strain and primer spreadsheets have been inspected separately from the acquired but uninspected supplemental PDF. (PMID:35087069.) NarA transfers electrons from membrane quinol through NarI b hemes and NarH Fe–S centers to the cytoplasmic NarG molybdenum site, where nitrate becomes nitrite. NarG contains the Mo-bis(molybdopterin guanine dinucleotide) cofactor and FS0; NarH contains FS4 [3Fe–4S] plus FS1/FS2/FS3 [4Fe–4S]. NarI has two b hemes within a five-helix membrane anchor. This cofactor relay supports the composite redox-loop event, not reduction of nitrate by every isolated subunit. (EcoCyc:NITRATREDUCTA-CPLX; EcoCyc:NARH-MONOMER; EcoCyc:NARI-MONOMER; UniProtKB:P09152; UniProtKB:P11349; UniProtKB:P11350.) Modern NarG structures and reviewed annotations assign the FS0 ligands H50/C54/C58/C93, while an older mutagenesis abstract interpreted H50 differently and denied its direct Fe–S binding role. The disagreement is retained as historical interpretation rather than resolved by transferring an old mutation phenotype into a modern ligation statement. NarI heme ligands H56/H205 and H66/H187 are distinct bH/bL assignments; the native first helix and C-terminal region have dimerization and NarGH-contact roles. Exact ligand and mutation annotations remain tied to their reference sequences and evidence codes. (EcoCyc:NARG-MONOMER; UniProtKB:P09152; UniProtKB:P11350; PMID:9585550.) The native NarA assembly has coefficient two for each NarG/H/I, consistent with a dimer of heterotrimers in that representation. The structural literature distinguishes soluble NarGH from membrane NarGHI and inhibitor-bound structures, and the native account treats an in vivo dimer as probable rather than demonstrated in every condition. The inspected PDB 1Q16 deposition contains a heterotrimeric deposited assembly and software-proposed higher assemblies; that provenance cannot be collapsed into a single universally measured hexameric stoichiometry. (EcoCyc:NITRATREDUCTA-CPLX; DOI:10.2210/pdb1q16/pdb.) NarJ is a maturation chaperone, contacting an N-terminal NarG region and supporting cofactor assembly; it is not an additional subunit of mature NarGHI. Soluble NarGH preparations can reduce nitrate with artificial benzylviologen, which does not establish an intact membrane quinol reaction. NarW is the corresponding NRZ maturation factor by reviewed homology annotation and remains outside the mature NarZYV component set. (EcoCyc:NITRATREDUCTA-CPLX; EcoCyc:NARG-MONOMER; EcoCyc:NITRATREDUCTZ-CPLX; UniProtKB:P0AF26; UniProtKB:P19317.) NRZ assembly stoichiometry remains a genuine source conflict. The native complex explicitly lists one NarZ, one NarY and one NarV and describes a heterotrimer by homology. Reviewed NarZ instead describes an alpha/beta/gamma 1:1:2 composition, while NarY and NarV describe a dimer of heterotrimers by similarity. The graph retains native coefficient-one membership as a source-qualified claim, without declaring a reconciled fixed solution stoichiometry. NarY Fe–S centers, NarV b hemes and NarZ molybdenum-site functions are predominantly homology-based assignments, not three new directly measured NRZ structures. (EcoCyc:NARV-MONOMER; EcoCyc:NARY-MONOMER; EcoCyc:NARZ-MONOMER; EcoCyc:NITRATREDUCTZ-CPLX; UniProtKB:P19319; UniProtKB:P19318; UniProtKB:P0AF32.) NarA expression increases with nitrate under anaerobic control, whereas NRZ has low aerobic activity and additional stationary-phase regulation. Calling NRZ wholly independent of nitrate or oxygen would overstate the sources: the multicopy/constitutive observations coexist with Fnr repression under anaerobic conditions, slight nitrate induction and RpoS-dependent stationary-phase induction with residual expression. A role during the aerobic-to-anaerobic transition is a hypothesis. The cited narG/napF competition study addresses those systems and cannot alone establish an NRZ expression mechanism. (MetaCyc:PWY0-1352; EcoCyc:PWY0-1352; EcoCyc:NITRATREDUCTA-CPLX; EcoCyc:NITRATREDUCTZ-CPLX; UniProtKB:P0AF28; UniProtKB:P0A9E5; UniProtKB:P13445.) Native regulation records attribute NarA inhibition to azide, hydrogen cyanide, stigmatellin and 2-heptyl-4-hydroxyquinoline N-oxide; only the azide record explicitly calls the mechanism competitive. NRZ records list potassium cyanide, azide, p-chloromercuribenzoate and the same quinoline inhibitor. These are located database assay annotations with primary access limits, not proof of inhibition at every concentration in growing cells. Exact structures distinguish N3− from hydrogen azide and the p-chloromercuribenzoate anion from its acid; the native stale chemical cross-references do not override whole structural identity. (EcoCyc:REG0-6957; EcoCyc:REG0-9191; EcoCyc:REG0-9192; EcoCyc:REG0-9193; EcoCyc:REG0-12133; EcoCyc:REG0-12134; EcoCyc:REG0-12135; EcoCyc:REG0-12136.) NarA and NRZ also have source-attributed tellurite-reduction activities. In the inspected primary abstract, both reductases were implicated by membrane activity bands and loss in a double mutant, but tellurite hypersensitivity was observed aerobically; an additional soluble anaerobic activity accompanied the absence of anaerobic hypersensitivity. Native accounts include other overexpression and reduction interpretations, including uncertainty about direct versus multistep conversion. These alternative activities do not alter the nitrate-to-nitrite route or establish universal tellurite resistance. (EcoCyc:NITRATREDUCTA-CPLX; EcoCyc:NITRATREDUCTZ-CPLX; PMID:9141681.) The frozen PathBank PW002092 diagram contains both donor and acceptor events, but its nitrate-reductase controller combines NarG/H/I, NarZ/Y/V, the NarJ/W maturation factors and periplasmic NapA/B into one object. That mixed set is rejected as a physical assembly. Its NDH-I object has the thirteen Nuo polypeptides, but labels every one as inner-membrane located without distinguishing the peripheral arm. NapA/NapB remain comparative sources, not route components. The three other archived candidate members inspected during preflight concern different pathways and do not supply nitrate-route chemistry. (PathBank:SMP0002104; MetaCyc:PWY0-1352; UniProtKB:P33937; UniProtKB:P0ABL3.) Evidence depth is explicit. Full main-body readings underpin the 34026733, 34308841, 35087069, 27118783, 31186428 and 34135385 assessments; the nanodisc peer-review letters and replies are kept separate from the final article. Other statements are attributed to inspected native/UniProt annotations or to specifically inspected indexed abstracts, with unavailable papers and uninspected supplements recorded as limits. The 259-entry bibliographic index is not a claim to have read 259 papers. Older mutant, kinetic and topology claims remain source-qualified where primary details were unavailable, and the complete source-to-claim ledger preserves them for independent review. (MetaCyc:PWY0-1352; EcoCyc:NADH-DHI-CPLX.) Historical proton-translocation papers do not all establish the modern topology or an identical stoichiometry. The 1975 spheroplast abstract inferred an outside-facing nitrate/azide site; that historical interpretation conflicts with the cytoplasmic NarG site in later structures. The atebrin experiment establishes energy-dependent membrane responses without specifying a universal four-proton NDH-I event. The 1996 oxygen/DMSO-pulse comparison supports at least 1.5 H+/electron for NDH-I under its conditions, whereas the 2012 three-H+/two-electron argument is mitochondrial thermodynamic inference. Neither is silently recast as a direct generic-MK/nitrate measurement. (PMID:5996; PMID:776172; PMID:8892824; PMID:22392981; PMID:12910261.) The NarA inhibitor and analogue studies resolve additional conditional distinctions. The inspected HOQNO abstract reports different potentiometric shifts of bL and bH, whereas stigmatellin shifts bL without a detectable bH effect; neither altered the NarH [3Fe–4S] potential in that comparison. Isolated NarI(ΔGH) and H56R constructs differ from intact reference NarGHI. The menadiol/duroquinol study used membranes with overexpressed enzyme and Fe–S-deficient beta-subunit mutants: loss of a high-potential center abolished menadiol activity while leaving duroquinol activity, and loss of a lower-potential center reduced both. Analogue specificity and mutant losses are not universal polymer-carrier kinetics. (PMID:10504245; PMID:9428711; PMID:15615728.) Direct NRZ purification and later annotation must also remain distinct. The inspected 1990 abstract describes a narGHI-deleted strain carrying multicopy NRZ genes, a roughly230kDa purified complex, thirteen iron and twelve labile sulfur atoms per molecule, and molybdopterin-cofactor reconstitution. These measurements do not by themselves reconcile the conflicting native and UniProt subunit stoichiometries. Its Fnr repression/slight nitrate response also differs in experimental setting from the later growth-phase work: RpoS dependence was especially strong in minimal medium, yet residual stationary-phase induction occurred without rpoS. No single word such as constitutive captures all these conditions. (PMID:2139607; PMID:3311749; PMID:10564515.)

Pathway type

energy metabolism

Organism scope

• Escherichia coli NCBITaxon:562

Read the source YAML

Components and activities

Mechanistic edges

References

• MetaCyc:RXN0-5388 MetaCyc:RXN0-5388: MetaCyc:RXN0-5388 (source version: Whole issuing Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:PROTON MetaCyc:PROTON: H+ (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:NAD MetaCyc:NAD: NAD+ (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:NADH MetaCyc:NADH: NADH (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:RXN0-3501 MetaCyc:RXN0-3501: MetaCyc:RXN0-3501 (source version: Whole issuing Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:NITRITE MetaCyc:NITRITE: nitrite (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:WATER MetaCyc:WATER: H2O (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:NITRATE MetaCyc:NITRATE: nitrate (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• RHEA:29100 a menaquinone + NADH + 5 H(+)(in) => a menaquinol + NAD(+) + 4 H(+)(out) (source version: Whole Rhea RDF release 142, oriented transport reaction and complete whole participant/Polymer objects.)
• RHEA:29136 a menaquinol + nitrate + 2 H(+)(in) => a menaquinone + nitrite + H2O + 2 H(+)(out) (source version: Whole Rhea RDF release 142, oriented transport reaction and complete whole participant/Polymer objects.)
• MetaCyc:PWY0-1352 MetaCyc:PWY0-1352: nitrate reduction VIII (dissimilatory) (source version: Whole issuing Pathway XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:ENZRXN0-6540 EcoCyc:ENZRXN0-6540: NADH:menaquinone oxidoreductase (H+-transporting) (source version: Whole issuing Enzymatic-Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NITRATREDUCTA-ENZRXN EcoCyc:NITRATREDUCTA-ENZRXN: menaquinol:nitrate oxidoreductase (source version: Whole issuing Enzymatic-Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NITRATREDUCTZ-ENZRXN EcoCyc:NITRATREDUCTZ-ENZRXN: nitrate reductase (source version: Whole issuing Enzymatic-Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NADH-DHI-CPLX EcoCyc:NADH-DHI-CPLX: NADH:quinone oxidoreductase I (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOA-MONOMER EcoCyc:NUOA-MONOMER: NADH:quinone oxidoreductase subunit A (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOH-MONOMER EcoCyc:NUOH-MONOMER: NADH:quinone oxidoreductase subunit H (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOJ-MONOMER EcoCyc:NUOJ-MONOMER: NADH:quinone oxidoreductase subunit J (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOK-MONOMER EcoCyc:NUOK-MONOMER: NADH:quinone oxidoreductase subunit K (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOL-MONOMER EcoCyc:NUOL-MONOMER: NADH:quinone oxidoreductase subunit L (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOM-MONOMER EcoCyc:NUOM-MONOMER: NADH:quinone oxidoreductase subunit M (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUON-MONOMER EcoCyc:NUON-MONOMER: NADH:quinone oxidoreductase subunit N (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:CPLX0-3361 EcoCyc:CPLX0-3361: NADH:quinone oxidoreductase I, peripheral arm (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOB-MONOMER EcoCyc:NUOB-MONOMER: NADH:quinone oxidoreductase subunit B (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOC-MONOMER EcoCyc:NUOC-MONOMER: NADH:quinone oxidoreductase subunit CD (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOE-MONOMER EcoCyc:NUOE-MONOMER: NADH:quinone oxidoreductase subunit E (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOF-MONOMER EcoCyc:NUOF-MONOMER: NADH:quinone oxidoreductase subunit F (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOG-MONOMER EcoCyc:NUOG-MONOMER: NADH:quinone oxidoreductase subunit G (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NUOI-MONOMER EcoCyc:NUOI-MONOMER: NADH:quinone oxidoreductase subunit I (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NITRATREDUCTA-CPLX EcoCyc:NITRATREDUCTA-CPLX: nitrate reductase A (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NARG-MONOMER EcoCyc:NARG-MONOMER: nitrate reductase A subunit α (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NARH-MONOMER EcoCyc:NARH-MONOMER: nitrate reductase A subunit β (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NARI-MONOMER EcoCyc:NARI-MONOMER: nitrate reductase A subunit γ (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NITRATREDUCTZ-CPLX EcoCyc:NITRATREDUCTZ-CPLX: nitrate reductase Z (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NARY-MONOMER EcoCyc:NARY-MONOMER: nitrate reductase Z subunit β (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NARZ-MONOMER EcoCyc:NARZ-MONOMER: nitrate reductase Z subunit α (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:NARV-MONOMER EcoCyc:NARV-MONOMER: nitrate reductase Z subunit γ (source version: Whole issuing Protein XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• UniProtKB:P09152 Respiratory nitrate reductase 1 alpha chain (source version: Whole reviewed UniProt entry version 228; original evidence codes retained. )
• UniProtKB:P11349 Respiratory nitrate reductase 1 beta chain (source version: Whole reviewed UniProt entry version 216; original evidence codes retained. )
• UniProtKB:P19319 Respiratory nitrate reductase 2 alpha chain (source version: Whole reviewed UniProt entry version 197; original evidence codes retained. )
• UniProtKB:P19318 Respiratory nitrate reductase 2 beta chain (source version: Whole reviewed UniProt entry version 190; original evidence codes retained. )
• UniProtKB:P0AFD1 NADH-quinone oxidoreductase subunit E (source version: Whole reviewed UniProt entry version 151; original evidence codes retained. )
• UniProtKB:P31979 NADH-quinone oxidoreductase subunit F (source version: Whole reviewed UniProt entry version 181; original evidence codes retained. )
• UniProtKB:P33602 NADH-quinone oxidoreductase subunit G (source version: Whole reviewed UniProt entry version 213; original evidence codes retained. )
• UniProtKB:P0AFD6 NADH-quinone oxidoreductase subunit I (source version: Whole reviewed UniProt entry version 146; original evidence codes retained. )
• UniProtKB:P0AFC7 NADH-quinone oxidoreductase subunit B (source version: Whole reviewed UniProt entry version 141; original evidence codes retained. )
• UniProtKB:P11350 Respiratory nitrate reductase 1 gamma chain (source version: Whole reviewed UniProt entry version 205; original evidence codes retained. )
• UniProtKB:P0AF32 Respiratory nitrate reductase 2 gamma chain (source version: Whole reviewed UniProt entry version 131; original evidence codes retained. )
• MetaCyc:CPD-15873 MetaCyc:CPD-15873: bis(guanylyl molybdopterin) cofactor (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• UniProtKB:P0AF26 Nitrate reductase molybdenum cofactor assembly chaperone NarJ (source version: Whole reviewed UniProt entry version 126; original evidence codes retained. )
• UniProtKB:P19317 Probable nitrate reductase molybdenum cofactor assembly chaperone NarW (source version: Whole reviewed UniProt entry version 165; original evidence codes retained. )
• UniProtKB:P0AF28 Nitrate/nitrite response regulator protein NarL (source version: Whole reviewed UniProt entry version 145; original evidence codes retained. results[primaryAccession=P0AF28])
• EcoCyc:REG0-6957 EcoCyc:REG0-6957: EcoCyc:REG0-6957 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:CPD-2841 EcoCyc:CPD-2841: azide (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:REG0-9191 EcoCyc:REG0-9191: EcoCyc:REG0-9191 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:REG0-9192 EcoCyc:REG0-9192: EcoCyc:REG0-9192 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:CPD0-1686 EcoCyc:CPD0-1686: stigmatellin (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:REG0-9193 EcoCyc:REG0-9193: EcoCyc:REG0-9193 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:CPD-7975 EcoCyc:CPD-7975: 2-heptyl-4-hydroxyquinoline N-oxide (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:REG0-12133 EcoCyc:REG0-12133: EcoCyc:REG0-12133 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:REG0-12134 EcoCyc:REG0-12134: EcoCyc:REG0-12134 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:REG0-12135 EcoCyc:REG0-12135: EcoCyc:REG0-12135 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:CPD-29 EcoCyc:CPD-29: p-chloromercuribenzoate (source version: Whole issuing Compound XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• EcoCyc:REG0-12136 EcoCyc:REG0-12136: EcoCyc:REG0-12136 (source version: Whole issuing Regulation XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• PMID:27118783 Roles of subunit NuoL in the proton pumping coupling mechanism of NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli. (source version: Complete main scientific body inspected; separate source/construct ledger records supplements and peer-review limits.)
• PMID:34308841 Structure of Escherichia coli respiratory complex I reconstituted into lipid nanodiscs reveals an uncoupled conformation. (source version: Complete main scientific body inspected; separate source/construct ledger records supplements and peer-review limits.)
• EcoCyc:PWY0-1352 EcoCyc:PWY0-1352: nitrate reduction VIII (dissimilatory) (source version: Whole issuing Pathway XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:RXN-13519 MetaCyc:RXN-13519: vectoral H+ export (source version: Whole issuing Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:RXN0-5254 MetaCyc:RXN0-5254: MetaCyc:RXN0-5254 (source version: Whole issuing Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:RXN0-5248 MetaCyc:RXN0-5248: MetaCyc:RXN0-5248 (source version: Whole issuing Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:RXN0-5242 MetaCyc:RXN0-5242: MetaCyc:RXN0-5242 (source version: Whole issuing Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• MetaCyc:TRANS-RXN0-234 MetaCyc:TRANS-RXN0-234: MetaCyc:TRANS-RXN0-234 (source version: Whole issuing Reaction XML, PGDB 27.0, retrieved 2026-10-12. Native annotations inspected; cited papers not all read.)
• UniProtKB:P00393 Type II NADH:quinone oxidoreductase (source version: Whole reviewed UniProt entry version 194; original evidence codes retained. results[primaryAccession=P00393])
• PMID:195602 Role of quinones in electron transport to oxygen and nitrate in Escherichia coli. Studies with a ubiA- menA- double quinone mutant. (source version: Indexed metadata/abstract only in this authoring phase; inherited bounded readings separately attributed, no complete-paper claim.)
• PMID:1444716 An Escherichia coli mutant containing only demethylmenaquinone, but no menaquinone: effects on fumarate, dimethylsulfoxide, trimethylamine N-oxide and nitrate respiration. (source version: Indexed metadata/abstract only in this authoring phase; inherited bounded readings separately attributed, no complete-paper claim.)
• PMID:34026733 A Quinol Anion as Catalytic Intermediate Coupling Proton Translocation With Electron Transfer in E. coli Respiratory Complex I. (source version: Complete main scientific body inspected; separate source/construct ledger records supplements and peer-review limits.)
• PMID:34135385 Biochemical consequences of two clinically relevant ND-gene mutations in Escherichia coli respiratory complex I. (source version: Complete main scientific body inspected; separate source/construct ledger records supplements and peer-review limits.)
• PMID:31186428 A mechanism to prevent production of reactive oxygen species by Escherichia coli respiratory complex I. (source version: Complete main scientific body inspected; separate source/construct ledger records supplements and peer-review limits.)
• UniProtKB:P33599 NADH-quinone oxidoreductase subunit C/D (source version: Whole reviewed UniProt entry version 204; original evidence codes retained. )
• UniProtKB:P0AFC3 NADH-quinone oxidoreductase subunit A (source version: Whole reviewed UniProt entry version 134; original evidence codes retained. )
• UniProtKB:P0AFD4 NADH-quinone oxidoreductase subunit H (source version: Whole reviewed UniProt entry version 139; original evidence codes retained. )
• UniProtKB:P0AFE0 NADH-quinone oxidoreductase subunit J (source version: Whole reviewed UniProt entry version 130; original evidence codes retained. )
• UniProtKB:P0AFE4 NADH-quinone oxidoreductase subunit K (source version: Whole reviewed UniProt entry version 136; original evidence codes retained. )
• UniProtKB:P33607 NADH-quinone oxidoreductase subunit L (source version: Whole reviewed UniProt entry version 168; original evidence codes retained. )
• UniProtKB:P0AFE8 NADH-quinone oxidoreductase subunit M (source version: Whole reviewed UniProt entry version 133; original evidence codes retained. )
• UniProtKB:P0AFF0 NADH-quinone oxidoreductase subunit N (source version: Whole reviewed UniProt entry version 132; original evidence codes retained. )
• PMID:12718520 Mutagenesis of subunit N of the Escherichia coli complex I. Identification of the initiation codon and the sensitivity of mutants to decylubiquinone. (source version: Indexed metadata/abstract only in this authoring phase; inherited bounded readings separately attributed, no complete-paper claim.)
• PMID:35087069 Mutations in respiratory complex I promote antibiotic persistence through alterations in intracellular acidity and protein synthesis. (source version: Complete main scientific body inspected; separate source/construct ledger records supplements and peer-review limits.)
• PMID:9585550 Molybdenum cofactor properties and [Fe-S] cluster coordination in Escherichia coli nitrate reductase A: investigation by site-directed mutagenesis of the conserved his-50 residue in the NarG subunit. (source version: Indexed metadata/abstract only in this authoring phase; inherited bounded readings separately attributed, no complete-paper claim.)
• UniProtKB:P0A9E5 Fumarate and nitrate reduction regulatory protein (source version: Whole reviewed UniProt entry version 145; original evidence codes retained. results[primaryAccession=P0A9E5])
• UniProtKB:P13445 RNA polymerase sigma factor RpoS (source version: Whole reviewed UniProt entry version 208; original evidence codes retained. results[primaryAccession=P13445])
• UniProtKB:P33937 Periplasmic nitrate reductase (source version: Whole reviewed UniProt entry version 208; original evidence codes retained. )
• UniProtKB:P0ABL3 Periplasmic nitrate reductase, electron transfer subunit (source version: Whole reviewed UniProt entry version 133; original evidence codes retained. )
• PMID:9141681 Tellurite reductase activity of nitrate reductase is responsible for the basal resistance of Escherichia coli to tellurite. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PathBank:SMP0002104 Frozen PW002092 / SMP0002104 Nitrate Reduction VIII BioPAX diagram (source version: Whole frozen BioPAX member; parent archive and complete object projection retained. Not accepted as an exact physical assembly.)
• DOI:10.2210/pdb1q16/pdb PDB1Q16: respiratory nitrate reductase A structural deposition (source version: Whole deposited mmCIF and selected issuing metadata inspected during accepted eligibility review; deposition assembly/host context distinguished from physiological assembly and journal full-methods access.)
• PMID:5996 Proton translocation and the respiratory nitrate reductase of Escherichia coli. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:776172 Functional anaerobic electron transport linked to the reduction of nitrate and fumarate in membranes from Escherichia coli as demonstrated by quenching of atebrin fluorescence. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:8892824 H+/e- stoichiometry for NADH dehydrogenase I and dimethyl sulfoxide reductase in anaerobically grown Escherichia coli cells. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:22392981 Stoichiometry of proton translocation by respiratory complex I and its mechanistic implications. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:12910261 Insights into the respiratory electron transfer pathway from the structure of nitrate reductase A. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:10504245 The hemes of Escherichia coli nitrate reductase A (NarGHI): potentiometric effects of inhibitor binding to narI. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:9428711 Kinetics of membrane-bound nitrate reductase A from Escherichia coli with analogues of physiological electron donors--different reaction sites for menadiol and duroquinol. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:15615728 Structural and biochemical characterization of a quinol binding site of Escherichia coli nitrate reductase A. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:2139607 Purification and further characterization of the second nitrate reductase of Escherichia coli K12. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:3311749 Biochemical and immunological evidence for a second nitrate reductase in Escherichia coli K12. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)
• PMID:10564515 Expression of the Escherichia coli NRZ nitrate reductase is highly growth phase dependent and is controlled by RpoS, the alternative vegetative sigma factor. (source version: Indexed abstract inspected in this author phase; no complete-paper claim. Any inherited fuller access is separately attributed.)