AcnB is a [4Fe-4S]-dependent aconitate hydratase of Pseudomonas putida KT2440. It reversibly isomerizes citrate and isocitrate in the tricarboxylic-acid cycle and also catalyzes the interconversion of 2-methyl-cis-aconitate and 2-methylisocitrate in propionate catabolism through the methylcitrate cycle.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003730 mRNA 3'-UTR binding | IEA GO_REF:0000117 | MARK AS OVER ANNOTATED | Summary: ARBA machine-learning prediction of an RNA-binding moonlighting function, not supported by organism-specific evidence. Reason: This electronic ARBA prediction transfers an apo-aconitase moonlighting function demonstrated in other bacteria. No transcript-binding or post-transcriptional-regulation evidence was found for Q88KF1 in P. putida, so the term should not be treated as established for this target. Supporting Evidence: file:PSEPK/acnB/acnB-deep-research-openscientist.md Whether *P. putida* AcnB binds specific transcripts, and which ones, has not been established |
| GO:0003994 aconitate hydratase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Core catalytic activity of AcnB, well supported by family/EC assignment and organism-specific pathway placement. Reason: Q88KF1 belongs to the aconitase/IPM-isomerase family, and UniProt assigns the citrate-isocitrate reaction and EC 4.2.1.3. This is a core molecular function. Supporting Evidence: file:PSEPK/acnB/acnB-uniprot.txt Reaction=citrate = D-threo-isocitrate; |
| GO:0005829 cytosol | IEA GO_REF:0000120 | ACCEPT | Summary: AcnB is a soluble enzyme of the TCA/methylcitrate central metabolic network, best inferred to act in the cytosol. Reason: AcnB is a soluble central-metabolic enzyme with no secretion or membrane role. The InterPro-derived cytosol assignment is consistent with its substrates and conserved bacterial aconitase function. |
| GO:0006099 tricarboxylic acid cycle | IEA GO_REF:0000120 | ACCEPT | Summary: AcnB catalyzes the aconitase step of the TCA cycle; a core biological process for this enzyme. Reason: The citrate-isocitrate aconitase reaction is a defining TCA-cycle step, and UniProt explicitly places Q88KF1 in this pathway. Supporting Evidence: file:PSEPK/acnB/acnB-uniprot.txt PATHWAY: Carbohydrate metabolism; tricarboxylic acid cycle; isocitrate |
| GO:0047456 2-methylisocitrate dehydratase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Methylcitrate-cycle dehydratase activity (EC 4.2.1.99) of bifunctional AcnB, supported by organism-specific pathway genetics. Reason: UniProt assigns EC 4.2.1.99 to Q88KF1. Biochemical reconstitution with the Salmonella ortholog shows that AcnB catalyzes conversion of 2-methyl-cis-aconitate to 2-methylisocitrate. Supporting Evidence: PMID:11294638 homogeneous AcnB protein of S. enterica also had strong aconitase activity and catalyzed the conversion of 2-methyl-cis-aconitate into 2-methylisocitrate file:PSEPK/acnB/acnB-deep-research-openscientist.md AcnB catalyzes the hydration of **2-methyl-*cis*-aconitate to 2-methylisocitrate** (EC 4.2.1.99) |
| GO:0051539 4 iron, 4 sulfur cluster binding | IEA GO_REF:0000120 | ACCEPT | Summary: AcnB requires a catalytic [4Fe-4S] cluster, an essential cofactor of aconitase-family enzymes. Reason: A catalytic [4Fe-4S] cluster is a defining mechanistic feature of aconitases, and UniProt assigns one cluster per Q88KF1 subunit. Supporting Evidence: file:PSEPK/acnB/acnB-uniprot.txt Name=[4Fe-4S] cluster; |
| GO:0019543 propionate catabolic process | IC file:PSEPK/acnB/acnB-uniprot.txt | NEW | Summary: Process annotation for AcnB's role in propionate catabolism. Reason: UniProt places Q88KF1 in propanoate degradation, and the accepted 2-methylisocitrate dehydratase activity is the aconitase step of the methylcitrate cycle. Supporting Evidence: file:PSEPK/acnB/acnB-uniprot.txt PATHWAY: Organic acid metabolism; propanoate degradation. |
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