PA3859 encodes an intracellular carboxylesterase of Pseudomonas aeruginosa PAO1, a 24-kDa monomeric alpha/beta-hydrolase of the phospholipase/carboxylesterase (AB hydrolase 2, LYPLA1/2-like) family with the GXSXG serine-hydrolase motif. The native enzyme, purified from P. aeruginosa and identified by its N-terminal sequence, and the recombinant protein hydrolyse p-nitrophenyl acetate and other acetylated substrates, prefer short-chain acyl esters, and are inhibited by PMSF but not EDTA; optimal activity is at pH 9.0 and 55 degrees C. Its physiological substrate is not known.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016787 hydrolase activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: Generic hydrolase activity from the phospholipase/carboxylesterase InterPro entry. Reason: Entailed by the accepted carboxylic ester hydrolase activity. |
| GO:0052689 carboxylic ester hydrolase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Carboxylic ester hydrolase activity by IBA from PTN004181029 (6 seeds, including human LYPLA1 O75608 and LYPLA2 O95372, rat Lypla1 and E. coli P76561). Reason: The node term is the broad activity shared by the LYPLA-like esterase clade, whose seeds are characterised acyl-protein thioesterases, lysophospholipases and carboxylesterases; the general ester-hydrolase term is appropriate for a clade with varied substrates. Q9HXE7 in WITH/FROM reflects its own IDA. Supporting Evidence: PMID:15717224 Homology-based database searches clearly revealed the presence of the consensus GXSXG signature motif that is present in the serine-dependent acylhydrolase protein family. |
| GO:0052689 carboxylic ester hydrolase activity | IDA PMID:15717224 Isolation, characterization, and heterologous expression of ... | ACCEPT | Summary: PseudoCAP IDA, one of six seeds of the PTN004181029 IBD. The native enzyme was purified from PAO1, assigned to PA3859 by N-terminal sequencing, and the recombinant protein was purified and assayed. Reason: Abstract only, but the abstract states the purification, gene assignment and kinetics outright, so the activity is directly shown for this gene product. Seed verdict SOUND. GO:0034338 short-chain carboxylesterase activity was considered, but the preference rests on artificial p-nitrophenyl esters and the natural substrate is unknown, so the general ester hydrolase term is as precise as the evidence allows. Supporting Evidence: PMID:15717224 The corresponding gene PA3859 was identified in the P. aeruginosa PAO1 genome as the only gene encoding for a protein with this N-terminus. PMID:15717224 Native enzyme preparations typically showed a Michaelis constant (K(m)) and V(max) of 0.43 mM and 12,500 U mg(-1), respectively, using p-nitrophenyl acetate as substrate. |
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Download this section (compressed HTML)Q: Is PA3859, like its human LYPLA1/LYPLA2 relatives, a depalmitoylase or lysophospholipase in vivo, or a short-chain esterase acting on another cellular substrate?
Experiment: Screen purified PA3859 against lysophospholipids, acylated peptides and acyl-ACP/acyl-CoA thioesters, and profile the lipidome of a PA3859 deletion mutant.
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