tetrahydromonapterin biosynthesis

MetaCyc:PWY0-1433

An explicitly incomplete mechanism for the established tetrahydromonapterin biosynthetic pathway in Escherichia coli K-12, with pathway and assembly identities grounded to MG1655. The FolE homodecamer forms dihydroneopterin triphosphate from GTP, and the FolX homooctamer epimerizes it to dihydromonapterin triphosphate. Separately, FolM reduces unphosphorylated dihydromonapterin using NADPH. The intervening dephosphorylation mechanism and catalyst remain unresolved in the inspected evidence: the source's hypothetical net reaction is not asserted here, and no connecting edge bridges these modules. This is a pathway-existence claim, not a complete biochemical reconstruction. Rhea and primary enzyme studies ground the chemistry independently of the erroneous dihydromethysticin intermediate in PathBank. Characterization of K-12 proteins, genetic complementation, and purified-enzyme assays have distinct scopes. Folate/queuosine branches, FolB alternatives, downstream Pseudomonas hydroxylation and pterin recycling are excluded; native physiological use of tetrahydromonapterin in E. coli is not assigned.

Pathway type

pterin biosynthesis

Organism scope

Escherichia coli K-12 NCBITaxon:83333

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Pathway network

20 nodes · 24 asserted directed edges

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Chemical / cofactor
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Pathway
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Components and activities

Declared biological components and source reaction directions
Node	Kind or role	Source direction
Escherichia coli K-12 `NCBITaxon:83333`	taxon
GTP(4-) `CHEBI:37565`	small molecule
water `CHEBI:15377`	small molecule
7,8-dihydroneopterin 3'-triphosphate(4-) `CHEBI:58462`	small molecule
formate `CHEBI:15740`	small molecule
hydron `CHEBI:15378`	small molecule
7,8-dihydromonapterin 3-triphosphate(4-) `CHEBI:61186`	small molecule
7,8-dihydromonapterin `CHEBI:71175`	small molecule
NADPH(4-) `CHEBI:57783`	small molecule
tetrahydromonapterin `CHEBI:71177`	small molecule
NADP(3-) `CHEBI:58349`	small molecule
zinc(2+) `CHEBI:29105`	cofactor
GTP cyclohydrolase 1 `UniProtKB:P0A6T5`	protein
Dihydroneopterin triphosphate 2'-epimerase `UniProtKB:P0AC19`	protein
Dihydromonapterin reductase `UniProtKB:P0AFS3`	protein
GTP cyclohydrolase 1 `MetaCyc:FOLE-CPLX`	complex
dihydroneopterin triphosphate 2'-epimerase `MetaCyc:FOLXTET-CPLX`	complex
FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	molecular activity	left to right
FolX-dependent epimerization to dihydromonapterin triphosphate `RHEA:28347`	molecular activity	left to right
FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	molecular activity	left to right

Mechanistic edges

Mechanistic edges and their cited evidence
Subject	Predicate and description	Object	Evidence
GTP(4-) `CHEBI:37565`	consumes Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	RHEA:17473 Source assertion: RHEA:17474 substrates 17473_L contains1 Participant_17473_compound_6355, whose compound is CHEBI:37565. Source location `http://rdf.rhea-db.org/17474 rh:substrates; http://rdf.rhea-db.org/17473_L rh:contains1 http://rdf.rhea-db.org/Participant_17473_compound_6355; rh:compound/rh:accession`
water `CHEBI:15377`	consumes Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	RHEA:17473 Source assertion: RHEA:17474 substrates 17473_L contains1 Participant_17473_compound_1283, whose compound is CHEBI:15377. Source location `http://rdf.rhea-db.org/17474 rh:substrates; http://rdf.rhea-db.org/17473_L rh:contains1 http://rdf.rhea-db.org/Participant_17473_compound_1283; rh:compound/rh:accession`
FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	produces Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	7,8-dihydroneopterin 3'-triphosphate(4-) `CHEBI:58462`	RHEA:17473 Source assertion: RHEA:17474 products 17473_R contains1 Participant_17473_compound_2443, whose compound is CHEBI:58462. Source location `http://rdf.rhea-db.org/17474 rh:products; http://rdf.rhea-db.org/17473_R rh:contains1 http://rdf.rhea-db.org/Participant_17473_compound_2443; rh:compound/rh:accession`
FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	produces Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	formate `CHEBI:15740`	RHEA:17473 Source assertion: RHEA:17474 products 17473_R contains1 Participant_17473_compound_3001, whose compound is CHEBI:15740. Source location `http://rdf.rhea-db.org/17474 rh:products; http://rdf.rhea-db.org/17473_R rh:contains1 http://rdf.rhea-db.org/Participant_17473_compound_3001; rh:compound/rh:accession`
FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	produces Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	hydron `CHEBI:15378`	RHEA:17473 Source assertion: RHEA:17474 products 17473_R contains1 Participant_17473_compound_3249, whose compound is CHEBI:15378. Source location `http://rdf.rhea-db.org/17474 rh:products; http://rdf.rhea-db.org/17473_R rh:contains1 http://rdf.rhea-db.org/Participant_17473_compound_3249; rh:compound/rh:accession`
7,8-dihydroneopterin 3'-triphosphate(4-) `CHEBI:58462`	consumes Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form. FolX is reversible experimentally; this record selects its monapterin-forming direction.	FolX-dependent epimerization to dihydromonapterin triphosphate `RHEA:28347`	RHEA:28346 Source assertion: RHEA:28347 substrates 28346_L contains1 Participant_28346_compound_2443, whose compound is CHEBI:58462. Source location `http://rdf.rhea-db.org/28347 rh:substrates; http://rdf.rhea-db.org/28346_L rh:contains1 http://rdf.rhea-db.org/Participant_28346_compound_2443; rh:compound/rh:accession`
FolX-dependent epimerization to dihydromonapterin triphosphate `RHEA:28347`	produces Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form. FolX is reversible experimentally; this record selects its monapterin-forming direction.	7,8-dihydromonapterin 3-triphosphate(4-) `CHEBI:61186`	RHEA:28346 Source assertion: RHEA:28347 products 28346_R contains1 Participant_28346_compound_6431, whose compound is CHEBI:61186. Source location `http://rdf.rhea-db.org/28347 rh:products; http://rdf.rhea-db.org/28346_R rh:contains1 http://rdf.rhea-db.org/Participant_28346_compound_6431; rh:compound/rh:accession`
7,8-dihydromonapterin `CHEBI:71175`	consumes Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	RHEA:34847 Source assertion: RHEA:34848 substrates 34847_L contains1 Participant_34847_compound_7636, whose compound is CHEBI:71175. Source location `http://rdf.rhea-db.org/34848 rh:substrates; http://rdf.rhea-db.org/34847_L rh:contains1 http://rdf.rhea-db.org/Participant_34847_compound_7636; rh:compound/rh:accession`
NADPH(4-) `CHEBI:57783`	consumes Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	RHEA:34847 Source assertion: RHEA:34848 substrates 34847_L contains1 Participant_34847_compound_3438, whose compound is CHEBI:57783. Source location `http://rdf.rhea-db.org/34848 rh:substrates; http://rdf.rhea-db.org/34847_L rh:contains1 http://rdf.rhea-db.org/Participant_34847_compound_3438; rh:compound/rh:accession`
hydron `CHEBI:15378`	consumes Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	RHEA:34847 Source assertion: RHEA:34848 substrates 34847_L contains1 Participant_34847_compound_3249, whose compound is CHEBI:15378. Source location `http://rdf.rhea-db.org/34848 rh:substrates; http://rdf.rhea-db.org/34847_L rh:contains1 http://rdf.rhea-db.org/Participant_34847_compound_3249; rh:compound/rh:accession`
FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	produces Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	tetrahydromonapterin `CHEBI:71177`	RHEA:34847 Source assertion: RHEA:34848 products 34847_R contains1 Participant_34847_compound_7637, whose compound is CHEBI:71177. Source location `http://rdf.rhea-db.org/34848 rh:products; http://rdf.rhea-db.org/34847_R rh:contains1 http://rdf.rhea-db.org/Participant_34847_compound_7637; rh:compound/rh:accession`
FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	produces Coefficient 1 in the selected biosynthetic Rhea direction; exact source charge and stereochemical form.	NADP(3-) `CHEBI:58349`	RHEA:34847 Source assertion: RHEA:34848 products 34847_R contains1 Participant_34847_compound_5188, whose compound is CHEBI:58349. Source location `http://rdf.rhea-db.org/34848 rh:products; http://rdf.rhea-db.org/34847_R rh:contains1 http://rdf.rhea-db.org/Participant_34847_compound_5188; rh:compound/rh:accession`
GTP cyclohydrolase 1 `MetaCyc:FOLE-CPLX`	catalyzes The experimentally characterized FolE homodecamer catalyzes GTP cyclohydrolase I chemistry. The reviewed catalytic cross-reference has no explicit experimental ECO tag; primary enzyme evidence is cited separately.	FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	MetaCyc:FOLE-CPLX Source assertion: FOLE-CPLX catalyzes GTP-CYCLOHYDRO-I-ENZRXN, whose reaction is GTP-CYCLOHYDRO-I-RXN. Source location `Protein[@frameid="FOLE-CPLX"]/catalyzes/Enzymatic-Reaction/reaction` UniProtKB:P0A6T5 Source assertion: The reviewed catalytic-activity comment assigns the GTP cyclohydrolase I equation and RHEA:17473. Source location `comments[0].reaction; reactionCrossReferences[Rhea]` PMID:11087827 Source assertion: Purified recombinant E. coli GTP cyclohydrolase I showed activity and active-site zinc in the crystallographic and biochemical analysis. Source location `PMC17616, Results and Discussion, Crystallographic Analysis of eGTP-CH-I Purified in the Absence of Chelating Agents`
dihydroneopterin triphosphate 2'-epimerase `MetaCyc:FOLXTET-CPLX`	catalyzes FolX catalyzes reversible epimerization at side-chain carbon 2′; its monapterin-forming direction is selected here. The catalytic species is the experimentally supported octamer.	FolX-dependent epimerization to dihydromonapterin triphosphate `RHEA:28347`	MetaCyc:FOLXTET-CPLX Source assertion: FOLXTET-CPLX catalyzes H2NTPEPIM-ENZRXN and H2NTPEPIM-RXN. Source location `Protein[@frameid="FOLXTET-CPLX"]/catalyzes/Enzymatic-Reaction/reaction` UniProtKB:P0AC19 Source assertion: CATALYTIC ACTIVITY assigns RHEA:28346, with experimental evidence from PMID 9182560 and 9651328. Source evidence code: ECO:0000269. Source location `comments[1].reaction; reactionCrossReferences; evidences` PMID:9651328 Source assertion: Recombinant FolX catalyzes carbon 2′ epimerization of dihydroneopterin and dihydromonapterin triphosphates; FolX forms a homooctamer. Source location `Europe PMC core result[id=9651328].abstractText`
Dihydromonapterin reductase `UniProtKB:P0AFS3`	catalyzes Purified FolM reduces dihydromonapterin with NADPH. The primary assay used 100 µM NADPH, 50 µM pterin, 10 mM beta-mercaptoethanol and 100 mM potassium phosphate pH 6 at 22–23°C. This does not establish the upstream dephosphorylation step or a quinonoid-recycling role.	FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	UniProtKB:P0AFS3 Source assertion: The dihydromonapterin catalytic-activity comment assigns RHEA:34847 and cites PMID 19897652 as experimental evidence. Source evidence code: ECO:0000269. Source location `comments[2].reaction; reactionCrossReferences; evidences` PMID:19897652 NADH could not replace NADPH as the cofactor. Source location `PMC2805310, Results, Recombinant FolM has high H2-MPt reductase activity` PMID:19897652 Source assertion: Purified FolM reduces dihydromonapterin; no activity above rearrangement-derived background was detected with quinonoid dihydromonapterin. Source location `PMC2805310, Materials and Methods (FolM assays); Results/Fig.4`
GTP cyclohydrolase 1 `UniProtKB:P0A6T5`	part_of 10 identical FolE subunits form the homodecamer.	GTP cyclohydrolase 1 `MetaCyc:FOLE-CPLX`	MetaCyc:FOLE-CPLX Source assertion: FOLE-CPLX has component GTP-CYCLOHYDRO-I-MONOMER with coefficient 10. Source location `Protein[@frameid="FOLE-CPLX"]/component` MetaCyc:GTP-CYCLOHYDRO-I-MONOMER Source assertion: GTP-CYCLOHYDRO-I-MONOMER has a UNIPROT unification cross-reference to P0A6T5. Source location `Protein[@frameid="GTP-CYCLOHYDRO-I-MONOMER"]/dblink[dblink-db="UNIPROT"]` PMID:12297008 Source assertion: Biochemical reconstitution and size-exclusion experiments support a pentamer of five dimers. Source location `Europe PMC core result[id=12297008].abstractText`
Dihydroneopterin triphosphate 2'-epimerase `UniProtKB:P0AC19`	part_of 8 identical FolX subunits form the homooctamer; the 1997 hydrodynamic hexamer estimate is superseded by 1998 biochemical and 1999 structural evidence.	dihydroneopterin triphosphate 2'-epimerase `MetaCyc:FOLXTET-CPLX`	MetaCyc:FOLXTET-CPLX Source assertion: FOLXTET-CPLX has component H2NTPEPIM-MONOMER with coefficient 8. Source location `Protein[@frameid="FOLXTET-CPLX"]/component` MetaCyc:H2NTPEPIM-MONOMER Source assertion: H2NTPEPIM-MONOMER has a UNIPROT unification cross-reference to P0AC19. Source location `Protein[@frameid="H2NTPEPIM-MONOMER"]/dblink[dblink-db="UNIPROT"]` PMID:10378270 Source assertion: The 2.9 Å crystal structure shows a torus-shaped D4-symmetric homooctamer formed by two head-to-head tetramers. Source location `Europe PMC core result[id=10378270].abstractText` PMID:9182560 Source assertion: The 1997 study inferred a probable homohexamer from apparent molecular masses 82.6 kDa (native) and 13.7 kDa (subunit); this is a conflicting historical estimate, not the selected assembly. Source location `Europe PMC core result[id=9182560].abstractText`
GTP cyclohydrolase 1 `MetaCyc:FOLE-CPLX`	has_cofactor Catalytically essential zinc is bound at each FolE active site; the E. coli study measured 0.9 ± 0.1 zinc ions per subunit. This is enzyme-bound cofactor evidence, not merely a metal added to assay buffer.	zinc(2+) `CHEBI:29105`	PMID:11087827 Source assertion: Chemical analysis of the E. coli protein measured 0.9 ± 0.1 zinc ions per subunit, and the structure localized the bound metal to the active site. Source location `PMC17616, Results and Discussion, Crystallographic Analysis of eGTP-CH-I Purified in the Absence of Chelating Agents` UniProtKB:P0A6T5 Source assertion: Binding-site features identify Zn(2+) with ChEBI:CHEBI:29105; the features do not supply an explicit ECO tag. Source location `features[type="Binding site"].ligand.id`
FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	part_of A supported reaction module in the native pathway. Membership does not assert that the omitted dephosphorylation has been mechanistically resolved.	`MetaCyc:PWY0-1433`	MetaCyc:PWY0-1433 Source assertion: PWY0-1433 explicitly lists GTP-CYCLOHYDRO-I-RXN as a pathway reaction. Source location `Pathway[@frameid="PWY0-1433"]/reaction-list` MetaCyc:GTP-CYCLOHYDRO-I-RXN Source assertion: GTP-CYCLOHYDRO-I-RXN has a Rhea unification cross-reference to 17473. Source location `Reaction[@frameid="GTP-CYCLOHYDRO-I-RXN"]/dblink[dblink-db="RHEA"]` RHEA:17473 Source assertion: Master RHEA:17473 has directional reaction RHEA:17474. Source location `http://rdf.rhea-db.org/17473 rh:directionalReaction`
FolX-dependent epimerization to dihydromonapterin triphosphate `RHEA:28347`	part_of A supported reaction module in the native pathway. Membership does not assert that the omitted dephosphorylation has been mechanistically resolved.	`MetaCyc:PWY0-1433`	MetaCyc:PWY0-1433 Source assertion: PWY0-1433 explicitly lists H2NTPEPIM-RXN as a pathway reaction. Source location `Pathway[@frameid="PWY0-1433"]/reaction-list` MetaCyc:H2NTPEPIM-RXN Source assertion: H2NTPEPIM-RXN has a Rhea unification cross-reference to 28349. Source location `Reaction[@frameid="H2NTPEPIM-RXN"]/dblink[dblink-db="RHEA"]` RHEA:28346 Source assertion: Master RHEA:28346 has directional reaction RHEA:28347 and bidirectional reaction RHEA:28349, the latter being the native MetaCyc cross-reference. Source location `http://rdf.rhea-db.org/28346 rh:directionalReaction; rh:bidirectionalReaction`
FolM-dependent NADPH reduction of dihydromonapterin `RHEA:34848`	part_of A supported reaction module in the native pathway. Membership does not assert that the omitted dephosphorylation has been mechanistically resolved.	`MetaCyc:PWY0-1433`	MetaCyc:PWY0-1433 Source assertion: PWY0-1433 explicitly lists RXN0-6367 as a pathway reaction. Source location `Pathway[@frameid="PWY0-1433"]/reaction-list` MetaCyc:RXN0-6367 Source assertion: RXN0-6367 has a Rhea unification cross-reference to 34847. Source location `Reaction[@frameid="RXN0-6367"]/dblink[dblink-db="RHEA"]` RHEA:34847 Source assertion: Master RHEA:34847 has directional reaction RHEA:34848. Source location `http://rdf.rhea-db.org/34847 rh:directionalReaction`
FolE-dependent formation of dihydroneopterin triphosphate `RHEA:17474`	provides_input_for FolE produces the exact dihydroneopterin-triphosphate form consumed by FolX. This connects only these two experimentally supported reactions; no edge connects FolX to FolM.	FolX-dependent epimerization to dihydromonapterin triphosphate `RHEA:28347`	RHEA:17473 Source assertion: RHEA:17474 produces CHEBI:58462. Source location `http://rdf.rhea-db.org/17474 rh:products; rh:contains1/rh:compound/rh:accession` RHEA:28346 Source assertion: RHEA:28347 consumes CHEBI:58462. Source location `http://rdf.rhea-db.org/28347 rh:substrates; rh:contains1/rh:compound/rh:accession`
Dihydroneopterin triphosphate 2'-epimerase `UniProtKB:P0AC19`	enables Genetic evidence supports the role of folX in the established pathway; it neither identifies the intervening phosphatase nor proves its net phosphate-release stoichiometry.	`MetaCyc:PWY0-1433`	PMID:19897652 Source assertion: Deleting folX abolished heterologous PhhA/PhhB rescue of tyrosine auxotrophy in E. coli K-12 JP2255, and plasmid expression of the deleted gene restored rescue. Source location `PMC2805310, Methods (E. coli deletions); Results/Fig.3D`
Dihydromonapterin reductase `UniProtKB:P0AFS3`	enables Genetic evidence supports the role of folM in the established pathway; it neither identifies the intervening phosphatase nor proves its net phosphate-release stoichiometry.	`MetaCyc:PWY0-1433`	PMID:19897652 Source assertion: Deleting folM abolished heterologous PhhA/PhhB rescue of tyrosine auxotrophy in E. coli K-12 JP2255, and plasmid expression of the deleted gene restored rescue. Source location `PMC2805310, Methods (E. coli deletions); Results/Fig.3D`

References

MetaCyc:PWY0-1433 MetaCyc PWY0-1433 native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
MetaCyc:FOLE-CPLX MetaCyc FOLE-CPLX native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
MetaCyc:FOLXTET-CPLX MetaCyc FOLXTET-CPLX native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
MetaCyc:GTP-CYCLOHYDRO-I-MONOMER MetaCyc GTP-CYCLOHYDRO-I-MONOMER native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
MetaCyc:H2NTPEPIM-MONOMER MetaCyc H2NTPEPIM-MONOMER native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
MetaCyc:GTP-CYCLOHYDRO-I-RXN MetaCyc GTP-CYCLOHYDRO-I-RXN native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
MetaCyc:H2NTPEPIM-RXN MetaCyc H2NTPEPIM-RXN native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
MetaCyc:RXN0-6367 MetaCyc RXN0-6367 native Pathway Tools object (source version: MetaCyc 22.5; public getxml export accessed 2026-10-10; digest covers exact XML response)
RHEA:17473 RHEA:17473 and biosynthetic direction RHEA:17474 (source version: Rhea 142, 2026-09-02; digest covers complete compressed official RDF)
RHEA:28346 RHEA:28346 and biosynthetic direction RHEA:28347 (source version: Rhea 142, 2026-09-02; digest covers complete compressed official RDF)
RHEA:34847 RHEA:34847 and biosynthetic direction RHEA:34848 (source version: Rhea 142, 2026-09-02; digest covers complete compressed official RDF)
UniProtKB:P0A6T5 GTP cyclohydrolase 1 — reviewed UniProtKB record (source version: UniProt 2026_03; entry version 153; sequence version 2; accessed 2026-10-10)
UniProtKB:P0AC19 Dihydroneopterin triphosphate 2'-epimerase — reviewed UniProtKB record (source version: UniProt 2026_03; entry version 135; sequence version 2; accessed 2026-10-10)
UniProtKB:P0AFS3 Dihydromonapterin reductase — reviewed UniProtKB record (source version: UniProt 2026_03; entry version 131; sequence version 1; accessed 2026-10-10)
PMID:11087827 Zinc plays a key role in human and bacterial GTP cyclohydrolase I. (source version: Full primary HTML; exact response digest; DOI 10.1073/pnas.240463497; accessed 2026-10-10)
PMID:12297008 Biochemical characterization of oligomerization of Escherichia coli GTP cyclohydrolase I. (source version: Primary abstract in Europe PMC core; digest covers complete 5-paper JSON response, not the individual PubMed page; DOI 10.5483/bmbrep.2002.35.3.255; accessed 2026-10-10)
PMID:9651328 Biosynthesis of pteridines in Escherichia coli. Structural and mechanistic similarity of dihydroneopterin-triphosphate epimerase and dihydroneopterin aldolase. (source version: Primary abstract in Europe PMC core; digest covers complete 5-paper JSON response, not the individual PubMed page; DOI 10.1074/jbc.273.28.17418; accessed 2026-10-10)
PMID:10378270 Crystal structure of 7,8-dihydroneopterin triphosphate epimerase. (source version: Primary abstract in Europe PMC core; digest covers complete 5-paper JSON response, not the individual PubMed page; DOI 10.1016/s0969-2126(99)80067-7; accessed 2026-10-10)
PMID:9182560 Purification, cloning, and functional expression of dihydroneopterin triphosphate 2'-epimerase from Escherichia coli. (source version: Primary abstract in Europe PMC core; digest covers complete 5-paper JSON response, not the individual PubMed page; DOI 10.1074/jbc.272.24.15323; accessed 2026-10-10)
PMID:19897652 FolX and FolM are essential for tetrahydromonapterin synthesis in Escherichia coli and Pseudomonas aeruginosa. (source version: Full primary HTML; exact response digest; DOI 10.1128/jb.01198-09; accessed 2026-10-10)

Curation history

2026-10-10T22:35:07Z codex
- CREATE — Add supported tetrahydromonapterin biosynthesis modules with an explicit mechanistic gap
  Ground MetaCyc:PWY0-1433, FolE and FolX assemblies, FolM reduction, zinc cofactor and exact Rhea chemistry independently. Full primary evidence establishes the pathway and distinguishes MG1655 pterin profiling from JP2255 complementation. Preserve conflicting historical FolX assembly estimates. The intervening dephosphorylation remains unresolved after later-literature inspection; omit its hypothetical net reaction and any invented connecting edge while explaining the gap in the maintained record. Reject the native PathBank dihydromethysticin intermediate. Research receipts preserve the complete source and exclusion ledger.
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