Accession check: the reviewed entry for PA5112 is O33407 (ESTA_PSEAE, 646 aa).
Q9HUP2, which appears in the WITH/FROM of the carboxylic ester hydrolase IBA, is
a different protein: PA4921, an unreviewed GDSL lipase/acylhydrolase (PANTHER
PTHR45648) that is the second seed of that IBD through a PseudoCAP IDA choline
esterase row (PMID:22192836). Checked by UniProt REST and QuickGO, 2026-10-28.
No deep-research provider was available; the notes below come from my own
reading of the cached abstracts (all key EstA papers are abstract-only in the
cache; PMC full text of PMID:17631636 was requested via the PubMed MCP but came
back empty) and of the UniProt record.
Rhamnolipid synthesis is performed by RhlA (HAA synthesis from
beta-hydroxyacyl-ACP), RhlB and RhlC (rhamnosyltransferases), which act at the
cytoplasm/inner membrane. EstA is a surface-exposed outer-membrane esterase that
has negligible activity on acyl-CoA and triacylglycerols. No paper identifies a
rhamnolipid intermediate as an EstA substrate. The requirement of EstA is
therefore a necessity phenotype of unknown mechanism (possibly membrane
remodelling, release of rhamnolipid, or signalling), not participation in a
biosynthetic step. Swimming, twitching and swarming are all lost in the mutant;
these disparate motility systems (flagellar, type IV pilus) point to a
pleiotropic, likely rhamnolipid/surface-mediated effect, not to EstA acting in
the flagellar machinery.
| PTN node | node term | n_seeds | leaf IBAs | seed annotation (term, evidence, PMID) | verdict | rationale |
|---|---|---|---|---|---|---|
| PTN005219546 | GO:0052689 carboxylic ester hydrolase activity | 2 (O33407, Q9HUP2/PA4921) | 960 (51 taxa) | GO:0052689 IMP PMID:17631636 (PseudoCAP); also GO:0106435 IDA PMID:20931591 (UniProt) | SOUND | Active-site S38A variant is inactive; esterase activity of purified/surface EstA measured in 1999, 2007 and 2010 papers, KM for pNP-butyrate known; GDSL/SGNH catalytic triad conserved and structurally resolved. IBD is appropriate for a family of GDSL esterases. On EstA itself the term is correct but general (GO:0106435 carboxylesterase activity is supported). |
| PTN005219546 | GO:0008610 lipid biosynthetic process | 1 (O33407, sole seed) | 960 (51 taxa) | GO:0008610 IMP PMID:17631636 (UniProt) and GO:0009247 glycolipid biosynthetic process IMP PMID:17631636 (PseudoCAP) | INDIRECT-PHENOTYPE | Both seed rows rest on the estA deletion lacking rhamnolipid. EstA is an outer-membrane, surface-exposed esterase with no activity on acyl-CoA; the biosynthetic steps are catalysed by RhlA/RhlB/RhlC; UniProt itself states the role is unclear. A necessity phenotype is not participation. The IBD therefore projects an unsupported biosynthetic process to 960 GDSL autotransporter esterases in 51 taxa; it should be withdrawn. |
Note: strictly the GO:0008610 seed row was assigned by UniProt; the PseudoCAP row
(GO:0009247) is a descendant term from the same paper and also supports the
node. Both are recorded as source defects (UNIPROT and PSEUDOCAP), and the IBD
is recorded as a GO_CENTRAL defect.
Other PseudoCAP rows (not seeds):
- GO:0044010 single-species biofilm formation IMP: phenotype, kept as non-core
(widely accepted GO practice for bacterial biofilm IMP), no defect.
- GO:0071973 flagellum-dependent cell motility IMP: over-annotation; twitching
(pilus) is lost too, so the term asserts a mechanism that is not shown.
- GO:0071978 swarming IDA PMID:20360178: the evidence is an overexpression
phenotype, which GO codes as IMP, not IDA; also indirect.