speE2 (PA4774, Q9HV34) review notes

No deep-research provider was available. Sources: UniProt record (Q9HV34,
HAMAP MF_00198), cached PMID:22155771 (abstract only; PMC full text body not
returned by the PubMed MCP). speC (PA ornithine decarboxylase) was reviewed
earlier; it sits on a different PANTHER node (PTN000159726), so there is no
shared node to coordinate.

Function

Spermidine synthase (EC 2.5.1.16): putrescine + decarboxy-AdoMet -> spermidine
[file:PSEAE/speE2/speE2-uniprot.txt "Catalyzes the irreversible transfer of a
propylamine group from the amino donor S-adenosylmethioninamine (decarboxy-AdoMet)
to putrescine (1,4-diaminobutane) to yield spermidine"].
PA4774 mutant makes no surface spermidine; restored by complementation; surface
spermidine stabilises the OM PMID:22155771.

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?
PTN000168372	GO:0006596 polyamine biosynthetic process	2	120 (56 taxa)	GO:0008295 spermidine biosynthetic process, IMP, PMID:22155771 (PseudoCAP)	SOUND	SpeE2 is the spermidine synthase, so the mutant's loss of spermidine coincides with its own catalytic step (participation). The broad BP node term suits an aminopropyltransferase clade; the seed's GO:0008295 is a descendant.	S. solfataricus SpeE (Q9UXE4), a multifunctional aminopropyltransferase	Yes; Q9UXE4 is experimentally characterised. No GO_CENTRAL defect for the GO:0006596 BP IBD.

Separate issue: the GO:0010487 MF IBD at the same node over-propagates

PTN000168372 also carries a thermospermine synthase activity (GO:0010487) MF IBD,
seeded by Q9UXE4 and Arabidopsis ACL5 (AT5G19530, a dedicated thermospermine
synthase). This is NOT a PseudoCAP-seeded row, but it propagates a GO:0010487 IBA
onto SpeE2, which is a putrescine aminopropyltransferase (spermidine synthase) by
HAMAP curation, not a thermospermine synthase. I MODIFY the GO:0010487 IBA on
SpeE2 to GO:0004766 spermidine synthase activity (the enzyme's curated activity,
already present by IEA) and raise a PROBABLE resource: GO_CENTRAL defect that the
thermospermine-synthase MF IBD should sit on the thermospermine-synthase sub-clade
rather than the whole-family node. Full enzymatic characterisation of SpeE2 would
confirm whether it has any thermospermine side activity.

PseudoCAP defects from this gene: none. GO_CENTRAL defects: 1 (PTN000168372
GO:0010487 over-propagation, PROBABLE).