PA2078 (Q9I237) notes
Review session 2026-11-05 (PseudoCAP IBA-seed protocol, tier 2)
Fetched with just fetch-gene PSEAE Q9I237 --alias PA2078; accession matches the worklist.
Unreviewed entry. No deep-research provider; PubMed eutils and Europe PMC searches failed
during the session. Literature from the PseudoCAP seed paper (PMID:24980978, abstract only)
and the 2015 full-text follow-up (PMID:26154497, cached with ai-gene-review fetch-pmid).
Reviewed together with PA2077 (see genes/PSEAE/PA2077/PA2077-notes.md).
Literature
- PMID:24980978
- PMID:26154497: PA2078 has two CXXCH heme motifs, but mutating either heme site or the
putative P450-like cysteine does not affect activity PMID:26154497. Periplasmic (signal peptide 1-23, PhoA fusion). Co-expression
with PA2077 relieves PA2077 toxicity PMID:26154497.
- 10-H(P)OME and 7,10-DiHOME are isomers (both C18H34O4), so the 7,10-DS reaction is formally an
intramolecular hydroxyl transfer (cf. GO:0052879, the fungal 8-hydroperoxide 8S-isomerase).
Annotation decisions
- GO:0031408 oxylipin biosynthetic process (IMP, IBA): ACCEPT (catalyses the second step).
- NEW GO:0050486 intramolecular hydroxytransferase activity (IMP, PMID:24980978): parent of the
analogous fungal hydroperoxide isomerase term; a specific term is proposed.
- GO:0004130 cytochrome-c peroxidase activity (IBA): MARK_AS_OVER_ANNOTATED (as PA2077; the
hemes are not needed for the known activity).
- GO:0009055 electron transfer activity (IEA): MARK_AS_OVER_ANNOTATED.
- GO:0020037 heme binding (IEA): KEEP_AS_NON_CORE (CXXCH motifs present; hemes dispensable for
activity).
- GO:0098869 cellular oxidant detoxification (IEA from GO:0004130): MARK_AS_OVER_ANNOTATED. PA2078
does remove a toxic hydroperoxide, but the row rests on the untested peroxidase activity and the
detoxification role is the authors' interpretation.
- NEW GO:0042597 periplasmic space (IC).
- Action counts: ACCEPT 2, KEEP_AS_NON_CORE 1, MARK_AS_OVER_ANNOTATED 3, NEW 2.
PseudoCAP IBA-seed assessment
| PTN node |
node term |
n_seeds |
leaf IBAs |
seed annotation (term, evidence, PMID) |
verdict |
rationale |
other seeds |
IBD stands without this seed? |
| PTN002826263 |
GO:0031408 oxylipin biosynthetic process |
2 |
7 (3 taxa) |
GO:0031408, IMP, PMID:24980978 |
SOUND |
Mutant cannot release 7,10-DiHOME; complementation shows PA2078 converts 10-H(P)OME to 7,10-DiHOME, the second step. |
PA2077 (Q9I238; PseudoCAP IMP, SOUND) |
Yes on the seeds, but the node term does not suit the clade |
The node-level GO_CENTRAL defect (term placed above the PA2077/PA2078 in-paralog duplication, so
it reaches PA0007, PA1941, Bradyrhizobium and Rhodopirellula proteins with no evidence) is
recorded once, on the PA2077 IBA row (genes/PSEAE/PA2077/PA2077-ai-review.yaml, PROBABLE). No
PSEUDOCAP defects.