fabZ

UniProt ID: Q88MG9
Organism: Pseudomonas putida (strain ATCC 47054 / DSM 6125 / CFBP 8728 / NCIMB 11950 / KT2440)
Review Status: DRAFT
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Gene Description

FabZ is the broad-chain-range cytoplasmic (3R)-hydroxyacyl-ACP dehydratase of Pseudomonas putida KT2440. It converts hydroxyacyl-ACP intermediates to trans-2-enoyl-ACP during type-II fatty-acid elongation and helps partition hydroxyacyl-ACP pools between phospholipid/fatty-acid synthesis and lipid A precursor production.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005737 cytoplasm
IEA
GO_REF:0000120 		ACCEPT
Summary: Correct localization from the reviewed UniProt record.
Reason: Reviewed UniProt places FabZ in the cytoplasm.
Supporting Evidence:
file:PSEPK/fabZ/fabZ-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
GO:0006633 fatty acid biosynthetic process
IEA
GO_REF:0000120 		ACCEPT
Summary: Correct core pathway assignment.
Reason: FabZ dehydrates FAS-II hydroxyacyl-ACP intermediates.
Supporting Evidence:
file:PSEPK/fabZ/fabZ-uniprot.txt
the dehydration of short chain beta-hydroxyacyl-ACPs and long chain
GO:0009245 lipid A biosynthetic process
IEA
GO_REF:0000104 		KEEP AS NON CORE
Summary: Valid secondary pathway assignment for hydroxyacyl-ACP pool control.
Reason: FabZ activity affects the hydroxyacyl-ACP substrates used in lipid A biosynthesis, but its central catalytic role is the general FAS-II dehydration reaction.
GO:0016836 hydro-lyase activity
IEA
GO_REF:0000120 		MARK AS OVER ANNOTATED
Summary: Correct parent activity but redundant with the ACP-specific term.
Reason: The substrate-specific (3R)-hydroxyacyl-ACP dehydratase term is available.
GO:0019171 (3R)-hydroxyacyl-[acyl-carrier-protein] dehydratase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Exact core molecular function for FabZ.
Reason: Reviewed UniProt records dehydration to a trans-2-enoyl-ACP product.
Supporting Evidence:
file:PSEPK/fabZ/fabZ-uniprot.txt
Reaction=a (3R)-hydroxyacyl-[ACP] = a (2E)-enoyl-[ACP] + H2O;

Core Functions

Dehydrates (3R)-hydroxyacyl-ACP intermediates to trans-2-enoyl-ACP during type-II fatty-acid elongation.

Molecular Function:
(3R)-hydroxyacyl-[acyl-carrier-protein] dehydratase activity
Directly Involved In:
fatty acid biosynthetic process
Cellular Locations:
cytoplasm
Supporting Evidence:
  • file:PSEPK/fabZ/fabZ-uniprot.txt
    Reaction=a (3R)-hydroxyacyl-[ACP] = a (2E)-enoyl-[ACP] + H2O;
  • file:PSEPK/fabZ/fabZ-deep-research-openscientist.md
    FabZ (Q88MG9, PP_1602) is the (3R)-hydroxyacyl-[acyl-carrier-protein] dehydratase (EC 4.2.1.59) that catalyzes the third, dehydration step of every elongation cycle in the bacterial type II fatty acid synthase (FAS-II) system of *Pseudomonas putida* KT2440.

References

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Suggested Questions for Experts

Q: How does FabZ substrate use partition hydroxyacyl-ACP between membrane fatty acids and lipid A?

Suggested Experiments

Experiment: Quantify acyl-ACP and lipid A species after graded FabZ depletion and compare rescue by FabA.

Deep Research

OpenScientist

(fabZ-deep-research-openscientist.md)

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📚 Additional Documentation

Notes

(fabZ-notes.md)

fabZ curation notes

  • Reviewed UniProt accession Q88MG9 records the general FabZ reaction
    [file:PSEPK/fabZ/fabZ-uniprot.txt,
    "Reaction=a (3R)-hydroxyacyl-[ACP] = a (2E)-enoyl-[ACP] + H2O;"].
  • The exact ACP dehydratase term, fatty-acid biosynthesis, and cytoplasmic
    localization are accepted; generic hydro-lyase activity is replaced by the
    exact term.
  • Lipid A biosynthesis is retained as a non-core consequence of FabZ control
    over hydroxyacyl-ACP pools rather than treated as the enzyme's principal
    pathway.

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