CYP79F1 (BUS1 / SPS / SUPERSHOOT; dihomomethionine N-hydroxylase) - Arabidopsis thaliana - review notes

UniProt: Q949U1 · At1g16410 · EC 1.14.14.42 · Taxon 3702
Context: entry step of aliphatic glucosinolate core structure formation
(modules/aliphatic_glucosinolate_myrosinase_defense.yaml, annoton cyp79f_activity).
No falcon deep-research file was present at review time.

Core function

• ER-anchored P450 converting chain-elongated methionines to aldoximes (two
  N-hydroxylations, then dehydration/decarboxylation).
  PMID:11133994
• Substrate range mono- to hexahomomethionine; short-chain (di-/tri-) preferred (Km ~34-37 uM
  vs ~200 uM for tetra/penta per UniProt from PMID:12609033).
  PMID:12609033
• Genetics: null mutant lacks short-chain aliphatic GSLs; long-chain GSLs increase (substrates
  undergo more elongation cycles). Double cyp79f1 cyp79f2 abolishes aliphatic GSLs.
  PMID:11226190
  PMID:15194821

Localization

• ER: N-terminal 62 aa-GFP fusion co-localizes with ER-GFP.
  PMID:11226190
• Chloroplast (AtSubP ISM) contradicted -> REMOVE. Nucleus (HDA, PMID:28887381 fractionation)
  -> MARK_AS_OVER_ANNOTATED (likely ER/nuclear envelope co-fractionation).

Pleiotropic phenotypes (not core)

• bushy/supershoot: loss of apical dominance, crinkled leaves, retarded vasculature; linked to
  altered auxin/IAN/indole-GSL or cytokinin levels -> indirect consequence of the metabolic block.
  PMID:11226190
  PMID:15194821
  No development/branching GO terms are proposed.

Regulation

• Induced by MeJA PMID:12529537; repressed after aphid feeding PMID:23144921 and by
  lepidopteran oral secretions PMID:40546745 -> IEP response to insect kept as non-core.

Decisions

• GO:0120526 homomethionine N-monooxygenase activity (IEA, Rhea/EC) -> ACCEPT (core MF)
• GO:0016709 IDA (PMID:12609033) -> MODIFY to GO:0120526
• GO:0016709 IBA -> MODIFY to GO:0016712 (P450 reductase = flavoprotein donor; GO:0120526 is_a GO:0016712)
• GO:0019761 IBA/IMP -> ACCEPT; ER (IBA/IDA), ER membrane, membrane -> ACCEPT
• monooxygenase, 0016705, heme, iron -> KEEP_AS_NON_CORE
• chloroplast ISM -> REMOVE; nucleus HDA -> MARK_AS_OVER_ANNOTATED; response to insect IEP x2 -> KEEP_AS_NON_CORE
• GO note: no "aliphatic glucosinolate biosynthetic process" term exists; GO:0033506 (from homomethionine)
  and CYP79F1-specific MF terms GO:0103096-8 are obsolete; GO:0120526 is the live replacement.

Module-member evidence audit — 2026-10-25

Reviewed every original row (17) and core function using review/annotation-reviewer instructions, current cached primary publications and the existing research. Preserved all source annotation fields and all pre-existing proposed rows. Attempted defaultFalcon withPerplexity-lite fallback concurrently with normal publication caching; Falcon authentication failed and fallback returnedHTTP401 insufficient_quota. No provider report was fabricated. These plant targets do not require bacterial FEBA retrieval.

Live QuickGO GO:0120526 defines an L-polyhomomethionine substrate class (RHEA51972), despite the shorter homomethionine label. It covers the mono-to-hexa range directly assayed in PMID12609033; the two same-term donor-class rows now have the same substrate-specific replacement. Broad oxidation/membrane terms are refined; heme/iron is intrinsic catalytic chemistry. The nucleus HDA is unresolved, not dismissed as contamination. The developmental phenotype is not assigned a uniquely proven substrate-accumulation mechanism.

Broad and substrate-specific terms were assessed consistently across evidence codes. No NEW rows were added. Previously proposed rows were evaluated for direct participation rather than filled from pathway adjacency. Experimental cohort calls whose protein-level data were not verified were left UNDECIDED; full-text availability alone was not treated as proof of a target-specific assay. Original sources and provider reports were not hand-edited.

2026-10-26 — PR #5550 source-level correction

Revisited review findings 1–3 against the actual publication cache and the primary sources. Removed generic source-unresolved boilerplate where the assay design is adjudicable. Restored relevant verbatim biochemical and localization evidence; did not restore label-only CHAIN features, unrelated introductory statements, or quotations that no longer support the revised claim. Existing source annotation fields were preserved.

Read PMID:28887381 full text, especially "Identification of True Membrane-associated Proteins" and Fig. 7: washed microsomes and sucrose gradients distinguish membrane association but do not separate organelles; named compartments are imported from SUBAcon/GFP knowledge. The paper states "no organelle fell in a single cluster". Mark the specific compartment claim as over-annotated while preserving proteomic detection. This applies projects/ORGANELLES.md at the actual resolution of the assay.