PA5384 is an alpha/beta-hydrolase fold-3 protein of the 'GDXG' lipolytic enzyme (hormone-sensitive lipase-like) family, encoded as the last gene of the carnitine catabolism operon (caiX-cdhCAB-PA5384, PA5388-PA5384) of Pseudomonas aeruginosa PAO1. It is an L-enantiomer-specific short-chain acylcarnitine hydrolase that cleaves acetyl- and butyrylcarnitine to carnitine and the corresponding short-chain fatty acid, and it is required for growth on these acylcarnitines. The released carnitine is catabolised by the Cdh enzymes to glycine betaine, which serves as an osmoprotectant and an inducer of the phospholipase C gene plcH. PA5384 is not required for growth on carnitine itself.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016787 hydrolase activity | IEA GO_REF:0000120 | TOO GENERAL | Summary: Combined IEA hydrolase activity from the AB_hydrolase_3 domain (IPR013094). Reason: True, but GO:0047619 acylcarnitine hydrolase activity, accepted in this review, is an is_a descendant of GO:0016787. Supporting Evidence: PMID:23524670 we have characterized PA5384 as an l-enantiomer-specific short-chain acylcarnitine hydrolase |
| GO:0034338 short-chain carboxylesterase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA short-chain carboxylesterase activity from PTN000546472, seeded by E. coli Aes and three M. tuberculosis GDXG esterases (LipI, LipN, NlhH). Reason: Hydrolysis of acetyl- and butyrylcarnitine is the hydrolysis of a carboxylic ester whose acyl chain has fewer than eight carbons, so the reaction PA5384 performs falls within the GO:0034338 definition, and the seeds are characterised short-chain esterases of the same family. The two terms are not linked by is_a in GO, so this row is not redundant with GO:0047619; it is the family-level description of the same activity. Supporting Evidence: PMID:23524670 required for growth and hydrolysis of acetyl- and butyrylcarnitine to carnitine and the respective short-chain fatty acid |
| GO:0047619 acylcarnitine hydrolase activity | IDA PMID:23524670 Characterization of Pseudomonas aeruginosa growth on O-acylc... | ACCEPT | Summary: PseudoCAP IDA acylcarnitine hydrolase activity; one of 16 seeds of the PTN009058710 hydrolase activity IBD. Reason: The abstract states that PA5384 was characterised as an L-enantiomer-specific short-chain acylcarnitine hydrolase; enantiomer specificity implies an enzyme assay rather than only a growth phenotype. Full text was not available to check the assay format, but the claim is the paper's central finding and is consistent with the family and the operon context. Supporting Evidence: PMID:23524670 we have characterized PA5384 as an l-enantiomer-specific short-chain acylcarnitine hydrolase |
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Download this section (compressed HTML)Q: Which enzyme hydrolyses medium- and long-chain acylcarnitines in P. aeruginosa, given that PA5384 is specific for short chains while C10-C16 acylcarnitines still support growth?
Experiment: Determine steady-state kinetics of purified PA5384 across C2-C16 acylcarnitines and mutate the predicted catalytic serine (GDXG motif) to confirm the active site.
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