FadA (PP_2137; Q88L01) is the inferred beta subunit of the cytoplasmic FadBA fatty-acid oxidation complex in Pseudomonas putida KT2440. It catalyzes thiolytic cleavage of a 3-oxoacyl-CoA with coenzyme A to form acetyl-CoA and an acyl-CoA shortened by two carbons. Native transposon fitness supports fatty-acid utilization, especially longer substrates, while exact enzyme specificity and complex stoichiometry remain comparative assignments.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003988 acetyl-CoA C-acyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: FadA catalyses the thiolytic step of each beta-oxidation turn. Reason: HAMAP rule MF_01620 types Q88L01 as FadA, and the E. coli FadA orthologue has this activity experimentally. This is a conserved catalytic assignment, not a direct purified KT2440 thiolase assay or a guarantee of complete terminal C4 processing. Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt HAMAP; MF_01620; FadA; 1. file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; file:ECOLI/fadA/fadA-uniprot.txt Catalyzes the final step of fatty acid oxidation in which acetyl-CoA is released and the CoA ester of a fatty acid two carbons shorter is formed. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: FadA is cytoplasmic. Reason: Rule-assigned location, matching the soluble-fraction recovery of the E. coli thiolase and complex. Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm PMID:334745 acyl-CoA dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase, enoyl-CoA hydratase, and 3-ketoacyl-CoA thiolase activities that utilized both C4 and C16 acyl-CoA substrates were isolated from the soluble fraction. |
| GO:0006631 fatty acid metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: Broad fatty acid metabolism term. Reason: The broad claim is correct; refine it to the supported specific activity or process already represented in this review. The replacement reflects the FadA/FadB curated rule and homolog evidence, with KT2440 fitness supporting pathway participation rather than directly measuring all isolated reactions. Proposed replacements: fatty acid beta-oxidation Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt Catalyzes the final step of fatty acid oxidation in which acetyl-CoA is released and the CoA ester of a fatty acid two carbons shorter is formed. |
| GO:0006635 fatty acid beta-oxidation | IEA GO_REF:0000120 | ACCEPT | Summary: FadA catalyses the final thiolytic step of each beta-oxidation turn. Reason: HAMAP assigns the terminal thiolytic reaction, and primary KT2440 fitness identifies PP_2137 involvement in fatty-acid utilization, strongest on C8+ substrates under those conditions. Native fitness supports pathway work but does not determine purified-enzyme chain-length limits or prove that every substrate is completely degraded to acetyl-CoA. Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt Catalyzes the final step of fatty acid oxidation in which acetyl-CoA is released and the CoA ester of a fatty acid two carbons shorter is formed. file:ECOLI/fadA/fadA-uniprot.txt Catalyzes the final step of fatty acid oxidation in which acetyl-CoA is released and the CoA ester of a fatty acid two carbons shorter is formed. file:PSEPK/fadB/fadB-source-analysis/primary-scope.md primary long-chain thiolase appears to be the fadA homolog PP_2137 |
| GO:0010124 phenylacetate catabolic process | IEA GO_REF:0000118 | UNDECIDED | Summary: Phenylacetate-pathway participation is not established or excluded for this FadA thiolase. Reason: Q88L01 is a HAMAP FadA/SF11 protein with supported native fatty-acid-catabolic function. The propagated phenylacetate claim is questionable across the broad thiolase family, but a dedicated PaaJ route does not by itself prove that FadA cannot contribute. Moreover, the previous argument identified PP_3280 as the dedicated PaaJ, while full primary32826213 names PP_3275; the frozen PP_3280 symbol/domain record therefore cannot serve as decisive target-exclusion evidence. No exact target loss or negative phenylacetate assay is established. Retain uncertainty pending locus/phylogeny/functional resolution rather than infer loss from the donor count. Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt PANTHER; PTHR43853:SF11; 3-KETOACYL-COA THIOLASE FADA; 1. file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt HAMAP; MF_01620; FadA; 1. file:PSEPK/fadB/fadB-source-analysis/primary-scope.md the primary identifies paaJ as PP_3275 |
| GO:0016042 lipid catabolic process | IEA GO_REF:0000120 | MODIFY | Summary: Broad lipid catabolism term. Reason: The broad claim is correct; refine it to the supported specific activity or process already represented in this review. The replacement reflects the FadA/FadB curated rule and homolog evidence, with KT2440 fitness supporting pathway participation rather than directly measuring all isolated reactions. Proposed replacements: fatty acid beta-oxidation Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt Catalyzes the final step of fatty acid oxidation in which acetyl-CoA is released and the CoA ester of a fatty acid two carbons shorter is formed. |
| GO:0016746 acyltransferase activity | IEA GO_REF:0000002 | MODIFY | Summary: Generic acyltransferase activity. Reason: The broad claim is correct; refine it to the supported specific activity or process already represented in this review. The replacement reflects the FadA/FadB curated rule and homolog evidence, with KT2440 fitness supporting pathway participation rather than directly measuring all isolated reactions. Proposed replacements: acetyl-CoA C-acyltransferase activity Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; |
| GO:0016747 acyltransferase activity, transferring groups other than amino-acyl groups | IEA GO_REF:0000002 | MODIFY | Summary: Generic acyltransferase (non-aminoacyl) parent. Reason: The broad claim is correct; refine it to the supported specific activity or process already represented in this review. The replacement reflects the FadA/FadB curated rule and homolog evidence, with KT2440 fitness supporting pathway participation rather than directly measuring all isolated reactions. Proposed replacements: acetyl-CoA C-acyltransferase activity Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; |
| GO:0036125 fatty acid beta-oxidation multienzyme complex | ISS file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt | NEW | Summary: FadA is inferred to be the beta subunit of the matched KT2440 FadBA complex. Reason: Preserve the historical ISS proposal. The curated HAMAP subunit assignment, conserved FadA/FadB architecture and independent native PP_2136/PP_2137 fitness support the compatible assembly inference. This is structural participation, not a new assertion made merely because FadB carries a complex annotation. Purified E. coli complex evidence is comparative; neither target stoichiometry nor arbitrary mixed-species compatibility has been measured. Supporting Evidence: file:PSEPK/fadA__Q88L01/fadA__Q88L01-uniprot.txt Heterotetramer of two alpha chains (FadB) and two beta chains (FadA). PMID:368024 Evidence is presented in support of the proposed association of all five enzyme activities with one protein which apparently is composed of two types of subunits and which can exist in several aggregated forms. |
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Download this section (compressed HTML)Q: Which chain lengths are preferentially processed by the FadBA complex relative to other KT2440 thiolase paralogs?
Suggested experts: Pseudomonas fatty acid metabolism experts
Experiment: Compare fatty-acid growth and acyl-CoA intermediate profiles for fadA and pathway-specific thiolase deletions, with complementation by Q88L01.
Type: comparative genetics and targeted acyl-CoA metabolomics
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