PP_0312

Summary: Appropriate molecular function for an ETF alpha subunit.

Reason: Combined automated annotation (GO_REF:0000120) from the InterPro IPR001308 ETF alpha/FixB family mapping and PANTHER node PTN002249443. The ETF alpha/FixB family assignment (InterPro, Pfam ETF_alpha, PANTHER PTHR43153) and the conserved placement beside DgcAB support electron transfer as the intrinsic function: ETF is an electron carrier between flavoprotein dehydrogenases and respiratory acceptors (PMID:8962055), and the 65.5%-identical Chromohalobacter ortholog EtfA is genetically required for dimethylglycine degradation (PMID:32631860). This is family-level and orthology inference without a KT2440 assay. The UniProt SIMILARITY line rests only on an ARBA rule and is not cited. As in the human ETFA review, core_functions records the activity as contributes_to_molecular_function because it belongs to the heterodimer; the GOA term itself is correct.

Summary: TreeGrafter pathway transfer from a PAINT IBD seeded by human ETFA; the dimethylglycine-locus ETF paralog is not supported in this specific acyl-CoA dehydrogenase partnership, though it is not shown to be excluded from it.

Reason: TreeGrafter IEA (GO_REF:0000118): Q88R22 is grafted to PTN002249443 and inherits the GO:0033539 IBD that PAINT placed on PTN000097951 in PTHR43153, seeded only by human ETFA (P13804) with no taxon constraint in the family PAINT file. GO defines the term as beta-oxidation in which "the initial step of each oxidation cycle, which converts an acyl-CoA to a trans-2-enoyl-CoA, is catalyzed by acyl-CoA dehydrogenase", so it names a specific donor partnership. Reading the phylogeny: KT2440 has two ETF alpha genes, PP_0312 and PP_4201, both placed in PTHR43153:SF1, but they belong to different paralog groups. PP_4201 is 62.1% identical to the human seed, whereas PP_0312 is 33.1% identical to human ETFA and 65.5% identical to the Chromohalobacter dgc-locus EtfA (file:PSEPK/PP_0312/PP_0312-bioinformatics/RESULTS.md). The matching PAINT IBD in the beta family PTHR21294 (PTN000480319) is restricted to Eukaryota, so PAINT itself does not assert this process for bacterial ETF beta subunits, including the partner PP_0313. The locus evidence points to a different donor: PP_0312 sits downstream of dgcA-dgcB, and the orthologous four-gene locus is genetically required for dimethylglycine degradation in Chromohalobacter (PMID:32631860). That is positive evidence for a different assignment, but not evidence that PP_0312 cannot act in beta-oxidation. ETFs can serve several dehydrogenases, and no KT2440 test with an acyl-CoA dehydrogenase has been reported. The row therefore attributes more pathway membership than the evidence supports without being demonstrably false. It is marked over-annotated rather than removed, as recorded in the TreeGrafter re-review (projects/TREEGRAFTER/rereview-2026-09-24/batch-02.yaml).

Summary: FAD binding is a conserved property of ETF alpha subunits.

Reason: Combined automated annotation (GO_REF:0000120) from the InterPro IPR001308 mapping and the PANTHER node. PP_0312 has the ETF alpha C-terminal domain (InterPro IPR014731, Pfam ETF_alpha), which in the human ETF structure holds most of the single FAD (PMID:8962055). Its Chromohalobacter ortholog carries Swiss-Prot FAD-binding residues by similarity. FAD binding has not been measured for PP_0312; the claim rests on conserved domain architecture.