dfrP

Summary: Core enzymatic function. DfrP contains a conserved DHFR domain (IPR001796) and catalyzes the NADPH-dependent reduction of DHF to THF (EC 1.5.1.3). Well-supported by sequence homology and domain architecture.

Summary: DHFR activity is central to one-carbon metabolism by regenerating THF, which carries one-carbon units for nucleotide and amino acid biosynthesis. Appropriate annotation.

Summary: True but too general. The more specific term GO:0004146 (dihydrofolate reductase activity) is already annotated and should be preferred.

Reason: Redundant with GO:0004146 which provides the specific oxidoreductase activity. The general oxidoreductase term adds no additional information. Retired because absent from GOA as of the 2026-07-27 QuickGO release (GOA refresh 2026-09-29); the review is kept for provenance. TOO_GENERAL rather than REMOVE: dihydrofolate reductase activity, kept in this review, entails this term, so the claim is true but less informative.

Summary: Appropriate biological process annotation. DHFR directly metabolizes dihydrofolate by reducing it to tetrahydrofolate.

Reason: The statement is re-asserted as a NEW annotation below, because no current GOA row carries it. Retired because absent from GOA as of the 2026-07-27 QuickGO release (GOA refresh 2026-09-29); the review is kept for provenance.

Summary: Core biological process. DfrP directly catalyzes the final step in THF biosynthesis - the reduction of 7,8-dihydrofolate to 5,6,7,8-tetrahydrofolate. This is not merely modulation of a host process; the phage-encoded enzyme directly performs the biosynthetic reaction. THF is essential for thymidylate synthesis (DNA precursor), purine synthesis, and amino acid biosynthesis. The phage carries this gene as an auxiliary metabolic gene to ensure robust THF production during viral DNA replication, forming a complete folate cycle together with its thymidylate synthase (thyA) gene.

Reason: The same term is still present via InterPro2GO (GO_REF:0000002). Retired because absent from GOA as of the 2026-07-27 QuickGO release (GOA refresh 2026-09-29); the review is kept for provenance.

Summary: Appropriate broader process annotation. DHFR is a key enzyme in folate metabolism, converting oxidized folate (DHF) back to the reduced active form (THF).

Reason: While correct, this is a broader parental process. The more specific GO:0046452 (dihydrofolate metabolic process) and GO:0046654 (tetrahydrofolate biosynthetic process) better capture the direct function. Retired because absent from GOA as of the 2026-07-27 QuickGO release (GOA refresh 2026-09-29); the review is kept for provenance.

Summary: DHFR uses NADPH as the electron donor/cofactor. The domain contains conserved NADP-binding motifs. Appropriate MF annotation.

Summary: DfrP is predicted to localize to the host cell cytoplasm where folate metabolism occurs. As a viral enzyme expressed during phage infection, GO guidelines specify using 'host cell cytoplasm' (GO:0030430) rather than generic 'cytoplasm' for viral proteins. Cytoplasmic localization is expected by analogy to other DHFR enzymes (no signal peptide or transmembrane domains).

Summary: True but too general; the specific dihydrofolate reductase activity (GO:0004146) is already accepted. Same term as the retired GO_REF:0000043 keyword row, now delivered through the GO_REF:0000120 merge (KW-0560 + UniRule UR000414346).

Reason: Redundant with GO:0004146; kept consistent with the earlier review of the keyword-derived row for the same term. TOO_GENERAL rather than REMOVE: dihydrofolate reductase activity, kept in this review, entails this term, so the claim is true but less informative.

Summary: Core biological process. DfrP catalyzes the final step of THF biosynthesis, the NADPH-dependent reduction of 7,8-dihydrofolate to 5,6,7,8-tetrahydrofolate. This is the same term that was previously supplied via GO_REF:0000120 (now retired); in the current GOA release it comes from InterPro2GO on the DHFR domain entries.

Summary: DfrP carries out the chemistry on dihydrofolate itself, reducing 7,8-dihydrofolate to 5,6,7,8-tetrahydrofolate with NADPH, so it participates in dihydrofolate metabolism rather than merely being required for it. This statement was previously supplied by TreeGrafter (GO_REF:0000118, PTN000167324, now retired). Its replacement in GOA, tetrahydrofolate biosynthetic process (GO:0046654), is a sibling under folic acid-containing compound metabolic process (GO:0006760), not an ancestor, so without this NEW the DHF-side statement is lost.

Reason: The dihydrofolate reductase activity (GO:0004146) is accepted. Comparator check (interpro/panther/PTHR48069/PTHR48069-paint.tsv) shows that the PAINT IBD for this term sits on the family root node PTN000167322, seeded by rat Dhfr (RGD:2500), yeast DFR1 (SGD:S000005762) and human DHFR (P00374). Descendants such as E. coli folA (P0ABQ4, same subfamily PTHR48069:SF3 as dfrP) and mouse Dhfr carry it by IBA, and dfrP's former TreeGrafter graft node PTN000167324 descends from it. Asserted by similarity because TreeGrafter no longer propagates to this viral sequence.