pyochelin II
CHEBI:67185 EXACT REVIEWED
What these status tags mean
Curation status describes a workflow state. SEEDED means the record entered through the source-seeding workflow; it does not imply that no later curation occurred. PROPOSED marks an addition awaiting review; REVIEWED records curator sign-off on identity, structure, filing class and producer claims; DEPRECATED retains a superseded or out-of-scope record. These are workflow decisions, not independently verified human review. Agent-assisted contributions may appear in the record history.
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A pyochelin that has S-stereochemistry at the thioaminal centre; the diastereoisomer with R-stereochemistry at this centre is pyochelin I. Pseudomonas aeruginosa produces a mixture of pyochelin I (major) and pyochelin I (minor) via condensation of salicylic acid and two molecules of cysteine. The enantiomeric compounds, enant-pyochelin I and II, are produced by Pseudomonas fluorescens.
Structure
| Standard InChIKey | NYBZAGXTZXPYND-NRUUGDAUSA-N |
|---|---|
| SMILES | [H][C@]1([C@]2([H])SC[C@@H](C(=O)O)N2C)CSC(c2ccccc2O)=N1 |
| Stereochemistry | fully defined |
Filing pathway
Alkaloids — computed by NPClassifier npclassifier.gnps2.org@2026-10-30, which is why it is pinned rather than recomputed. The gene cluster's asserted class is nrps, from MIBiG.
Producer organisms 1
A claim that this taxon makes the compound. The basis says what the evidence addressed — a knockout and a database assertion are not the same claim.
| Taxon | Basis | Cluster | Evidence |
|---|---|---|---|
| Pseudomonas aeruginosa PAO1 Strain: PAO1 NCBITaxon:208964 |
BGC_CHARACTERIZED | mibig:BGC0000412 | PMID:9846750
|
Occurrences 0
None cited.
Biosynthetic gene clusters 1
| Accession | Host | Locus evidence | Genome |
|---|---|---|---|
| mibig:BGC0000412 | Pseudomonas aeruginosa PAO1 NCBITaxon:208964 |
CLUSTER_DEMONSTRATED | genbank:AF074705.2 |
A locus claim and a taxon claim are different questions. Heterologous expression settles the first and leaves the second where the isolation report left it.
Biosynthesis curated
Written by a curator with claim-level evidence on each step; not derived from a source. This is what the rest of the record exists to support.
| Step | Enzyme | Reaction | Substrate → product | Evidence |
|---|---|---|---|---|
| 1 | PchA (isochorismate synthase), PchB (isochorismate pyruvate-lyase), and PchD (salicyl-AMP ligase) | CHEBI:17333 → CHEBI:16914 | PMID:8982005 | |
| 2 | PchE (NRPS), PchF (NRPS with methyltransferase and thioesterase domains), and PchG (thiazoline reductase) | CHEBI:16914 + CHEBI:17561 + CHEBI:15414 → CHEBI:67185 | PMID:11467965 |
Step 1: Conversion of chorismic acid to salicylic acid by PchA/PchB and ATP-dependent adenylation to salicyl-AMP by PchD for loading onto the PchE NRPS.
Step 2: NRPS condensation and cyclodehydration of salicylate with two L-cysteine residues, NADPH-dependent thiazoline reduction by PchG, SAM-dependent N-methylation by PchF, and thioesterase release to yield pyochelin II.
Mechanism & Biosynthesis Overview
Causal graph — bioactivity 12 nodes, 11 edges
NRPS-directed biosynthesis of phenolate-thiazoline-thiazolidine metallophore pyochelin II by the pchDCBA/pchEFGHI cluster (BGC0000412) in Pseudomonas aeruginosa and chelation of Fe(III), CMM cations Ga(III), Co(II), Ni(II), VO(2+), and Cu(II)/Zn(II)/Mo(VI).
| Subject | Predicate | Object | Notes | Evidence |
|---|---|---|---|---|
| salicylic acid | substrate_of | pchDCBA/pchEFGHI biosynthetic gene cluster (BGC0000412) | Salicylic acid is activated by PchD to initiate pyochelin assembly. | PMID:10555976
|
| L-cysteine | substrate_of | pchDCBA/pchEFGHI biosynthetic gene cluster (BGC0000412) | Two L-cysteine residues are condensed and heterocyclized by PchE and PchF into the thiazoline and N-methylthiazolidine rings. | PMID:10555976
|
| pchDCBA/pchEFGHI biosynthetic gene cluster (BGC0000412) | synthesizes | pyochelin II | PchDEFG synthesize the diastereomeric mixture of pyochelin I and pyochelin II. | PMID:11467965
|
| pyochelin II | chelates | iron(3+) | Forms 2:1 [Fe(Pch)(HPch)] complex (Kf ~ 2 x 10^28 M^-2). | PMID:22261733
|
| iron(3+) | enables | siderophore transport | Transported across the Pseudomonas aeruginosa outer membrane by TonB-dependent receptor FptA. | PMID:16139844
|
| pyochelin II | chelates | gallium(3+) | [CMM] Forms 2:1 Ga(III)-pyochelin complex recognized and transported by FptA. | PMID:19329644
|
| pyochelin II | chelates | cobalt(2+) | [CMM] Chelates Co(II) and mediates lower-rate FptA-dependent cobalt uptake. | PMID:19329644
|
| pyochelin II | chelates | nickel(2+) | [CMM] Chelates Ni(II) and mediates lower-rate FptA-dependent nickel uptake. | PMID:19329644
|
| pyochelin II | chelates | oxidovanadium(2+) | [CMM] Coordinates oxidovanadium(2+) in solution (binds FptA without active nutrition). | PMID:19329644
|
| pyochelin II | chelates | copper(2+) | Coordinates Cu(II) in 2:1 stoichiometry in solution. | PMID:22261733
|
| pyochelin II | chelates | zinc(2+) | Coordinates Zn(II) in 2:1 stoichiometry in solution. | PMID:22261733
|
Every edge carries its own citation; an uncited edge is refused by the corpus tests.
Molecular targets 8
| Target | Target organism | Measurement | Evidence |
|---|---|---|---|
| iron(3+) OTHER BINDS Primary physiological ferric ion chelation via tetradentate phenolate, thiazoline-N, thiazolidine-N, and carboxylate coordination (forming 2:1 [Fe(Pch)(HPch)] complexes, Kf ~ 2 x 10^28 M^-2) transported via the FptA outer membrane receptor. |
PMID:11467965 |
||
| gallium(3+) OTHER BINDS [Critical Mineral & Material (CMM)] Chelation of trivalent gallium(3+) in solution; Ga(III)-pyochelin binds FptA and mediates gallium uptake into Pseudomonas aeruginosa. |
PMID:19329644
|
||
| cobalt(2+) OTHER BINDS [Critical Mineral & Material (CMM)] Chelation of divalent cobalt(2+) in solution; Co(II)-pyochelin binds the FptA outer membrane receptor and promotes measurable Co(II) accumulation in Pseudomonas aeruginosa, though at lower efficiency than Fe(III). |
PMID:19329644
|
||
| nickel(2+) OTHER BINDS [Critical Mineral & Material (CMM)] Chelation of divalent nickel(2+) in solution; Ni(II)-pyochelin binds FptA and promotes measurable Ni(II) uptake in Pseudomonas aeruginosa at lower efficiency than Fe(III). |
PMID:19329644
|
||
| oxidovanadium(2+) OTHER BINDS [Critical Mineral & Material (CMM)] Coordination of vanadyl / oxidovanadium(2+) in solution (1:2 complex, measured in vitro; binds FptA without supporting physiological iron nutrition). |
PMID:19329644
|
||
| copper(2+) OTHER BINDS Coordination of divalent copper(2+) in solution (2:1 ligand:metal stoichiometry, log beta ~ 25.0, measured in vitro; binds FptA with limited intracellular transport). |
PMID:22261733 |
||
| zinc(2+) OTHER BINDS Coordination of divalent zinc(2+) in solution (2:1 ligand:metal stoichiometry, log beta ~ 23.0, measured in vitro; binds FptA without active transport). |
PMID:22261733 |
||
| molybdenum(6+) OTHER BINDS In vitro complexation of molybdate / molybdenum(6+) in aqueous solution. |
PMID:19329644
|
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Provenance
| Source concept | Source | Version |
|---|---|---|
| CHEBI:67185 | CHEBI | 3-star |
This page is generated from data/natural_products/alkaloids/pyochelin-ii.yaml, which is generated from the committed inventories. Neither is edited by hand.