accA

UniProt ID: Q88MG4
Organism: Pseudomonas putida (strain ATCC 47054 / DSM 6125 / CFBP 8728 / NCIMB 11950 / KT2440)
Review Status: DRAFT
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Gene Description

AccA is the alpha subunit of the carboxyltransferase component of heteromeric acetyl-CoA carboxylase in Pseudomonas putida KT2440. Together with AccD, it transfers the carboxyl group from carboxybiotinyl-AccB to acetyl-CoA, producing malonyl-CoA for de novo fatty-acid synthesis.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0003989 acetyl-CoA carboxylase activity
IEA
GO_REF:0000002 		MARK AS OVER ANNOTATED
Summary: Correct complex-level function, but not independently enabled by AccA.
Reason: AccA is one carboxyltransferase subunit of heteromeric ACC. The complete reaction requires AccB, AccC, AccA, and AccD, so the core function uses contribution semantics.
Supporting Evidence:
file:PSEPK/accA/accA-uniprot.txt
Component of the acetyl coenzyme A carboxylase (ACC) complex.
file:PSEPK/accA/accA-deep-research-openscientist.md
transfers the carboxyl group from carboxybiotin to acetyl-CoA to make malonyl-CoA
GO:0005737 cytoplasm
IEA
GO_REF:0000120 		ACCEPT
Summary: Correct experimentally expected localization.
Reason: The reviewed UniProt record places AccA in the cytoplasm.
Supporting Evidence:
file:PSEPK/accA/accA-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
GO:0006633 fatty acid biosynthetic process
IEA
GO_REF:0000002 		ACCEPT
Summary: Correct downstream process assignment for malonyl-CoA production.
Reason: ACC supplies the committed two-carbon donor for fatty-acid synthesis.
Supporting Evidence:
file:PSEPK/accA/accA-uniprot.txt
PATHWAY: Lipid metabolism; malonyl-CoA biosynthesis;
GO:0009317 acetyl-CoA carboxylase complex
IEA
GO_REF:0000002 		ACCEPT
Summary: Correct complex membership for the AccA alpha subunit.
Reason: Reviewed UniProt describes the heteromeric AccABCD complex.
Supporting Evidence:
file:PSEPK/accA/accA-uniprot.txt
Acetyl-CoA carboxylase is a heterohexamer composed of biotin
GO:0016743 carboxyl- or carbamoyltransferase activity
IEA
GO_REF:0000120 		MARK AS OVER ANNOTATED
Summary: Correct reaction class but overstates activity of isolated AccA.
Reason: AccA contributes the alpha component of the AccA/AccD carboxyltransferase; neither subunit alone enables the complete transfer.
Supporting Evidence:
file:PSEPK/accA/accA-uniprot.txt
ACCase subunit alpha
GO:0016874 ligase activity
IEA
GO_REF:0000002 		REMOVE
Summary: Incorrect standalone reaction-class assignment for the AccA subunit.
Reason: The isolated AccA catalytic half-reaction is a carboxyltransferase reaction (EC 2.1.3.15), not a ligase reaction. Ligase classification applies to the ATP-coupled overall ACC reaction.
Supporting Evidence:
file:PSEPK/accA/accA-uniprot.txt
EC=2.1.3.15
GO:2001295 malonyl-CoA biosynthetic process
IEA
GO_REF:0000120 		ACCEPT
Summary: Correct direct process annotation for the ACC carboxyltransferase subunit.
Reason: UniProt assigns AccA to the single malonyl-CoA-from-acetyl-CoA step.
Supporting Evidence:
file:PSEPK/accA/accA-uniprot.txt
acetyl-CoA: step 1/1.

Core Functions

Alpha carboxyltransferase subunit that contributes to transfer of the AccB-bound carboxyl group to acetyl-CoA in heteromeric ACC.

Directly Involved In:
malonyl-CoA biosynthetic process fatty acid biosynthetic process
Cellular Locations:
cytoplasm
In Complex:
acetyl-CoA carboxylase complex
Supporting Evidence:
  • file:PSEPK/accA/accA-uniprot.txt
    Component of the acetyl coenzyme A carboxylase (ACC) complex.
  • file:PSEPK/accA/accA-deep-research-openscientist.md
    transfers the carboxyl group from carboxybiotin to acetyl-CoA to make malonyl-CoA

References

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Suggested Questions for Experts

Q: What controls AccA/AccD carboxyltransferase assembly in KT2440?

Suggested Experiments

Experiment: Reconstitute AccA/AccD with AccB and AccC and quantify complex assembly and malonyl-CoA production across subunit stoichiometries.

Deep Research

OpenScientist

(accA-deep-research-openscientist.md)

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📚 Additional Documentation

Notes

(accA-notes.md)

accA curation notes

  • Reviewed UniProt accession Q88MG4 identifies AccA as the alpha
    carboxyltransferase subunit of heteromeric acetyl-CoA carboxylase
    [file:PSEPK/accA/accA-uniprot.txt,
    "Component of the acetyl coenzyme A carboxylase (ACC) complex."].
  • Whole-complex acetyl-CoA carboxylase activity and the carboxyltransferase
    reaction are modeled with contribution semantics because AccA does not act
    independently of AccD and the other ACC subunits.
  • Generic ligase activity is removed: AccA's half-reaction is EC 2.1.3.15,
    while ATP-dependent ligase classification belongs to the complete ACC
    reaction.

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