hal3 (SPAC15E1.04, UniProt Q9UTI7) notes

Fetch: just fetch-gene SCHPO hal3 failed (no UniProt ID found for "hal3"; UniProt names the entry "Probable thymidylate synthase" with ORF name only). Fetched with -u Q9UTI7; uniprot file confirmed TYSY_SCHPO, AC Q9UTI7.

Evidence

• Fusion protein: N-terminal Hal3-like (HFCD flavoprotein) half + C-terminal thymidylate synthase half PMID:23962284; [UniProt:Q9UTI7 "In the N-terminal section; belongs to the HFCD (homo-"].
• PPCDC: PMID:23962284. Contrast S. cerevisiae, where PPCDC is the Cab3 + Sis2/Vhs3 heterotrimer (see genes/yeast/CAB3, SIS2 reviews).
• TS: PMID:23962284. S. pombe has no separate TS gene; hal3 is the TS.
• Ppz inhibition (moonlighting, modest, in vitro): PMID:23962284.
• Essential, not processed: PMID:23962284.
• Localization: cytoplasm/cytosol from ORFeome screen PMID:16823372.

Decisions

• Core: GO:0004633 (CoA biosynthesis, cytosol) and GO:0004799 (dTMP biosynthesis, cytosol).
• Protein phosphatase inhibitor IDA kept non-core. FMN binding IDA kept non-core (cofactor of PPCDC).
• Mitochondrion IBA (human TYMS / plant DHFR-TS seeded) marked over-annotated, as in genes/yeast/CDC21.
• Comparison with S. cerevisiae: the budding-yeast PPCDC subunits (CAB3, SIS2) have no molecular_function in core_functions because neither is active alone (contributes_to); hal3 is a complete monogenic PPCDC so enables GO:0004633 is appropriate. This is an S. pombe-specific difference, consistent with the module's homo-oligomeric PPCDC variant.
• PomBase GO-CAM 678073a900002636: hal3 enables GO:0004633 in cytosol (IDA PMID:23962284) - agrees. The model does not include the TS activity (out of scope for that model).