CYP79F1 (BUS1/SPS/SUPERSHOOT; dihomomethionine N-hydroxylase) is an endoplasmic reticulum membrane-anchored cytochrome P450 monooxygenase that catalyzes the entry step of core structure formation in methionine-derived (aliphatic) glucosinolate biosynthesis. Using O2 and electrons from NADPH-cytochrome P450 reductase, it performs two successive N-hydroxylations of chain-elongated methionine homologues, followed by dehydration and decarboxylation, to yield the corresponding omega-(methylthio)alkanaldoximes (EC 1.14.14.42). CYP79F1 has a broad chain-length range, converting mono- to hexahomomethionine, but is the main or only enzyme for the short-chain homologues (di- and trihomomethionine) that give rise to the predominant leaf glucosinolates 4-methylthiobutyl and 4-methylsulfinylbutyl glucosinolate; its tandem paralog CYP79F2 is restricted to long-chain substrates. CYP79F1 is expressed in vascular tissue of cotyledons, leaves, stems and siliques and is induced by methyl jasmonate. Null mutants lack short-chain aliphatic glucosinolates and, together with cyp79f2, abolish aliphatic glucosinolate synthesis. The striking bushy/supershoot phenotype of cyp79f1 mutants (loss of apical dominance, shoot overproliferation, altered auxin/cytokinin levels) accompanies altered glucosinolate and hormone metabolism; these phenotypes do not make CYP79F1 a dedicated developmental regulator.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004497 monooxygenase activity | IEA GO_REF:0000002 | MODIFY | Summary: The demonstrated activity is homomethionine N-monooxygenase. Reason: Recombinant-enzyme substrate/product measurements support GO:0120526, already asserted in this review. Use the same target-specific replacement across evidence types. Electron delivery is through the P450 reductase/flavoprotein system; correcting the direct NAD(P)H-donor wording is a reaction-class correction where applicable. Proposed replacements: homomethionine N-monooxygenase activity Supporting Evidence: PMID:11133994 Our data provide the first evidence that a cytochrome P450 catalyzes the N-hydroxylation of chain-elongated methionine homologues to the corresponding aldoximes in the biosynthesis of aliphatic glucosinolates. |
| GO:0005506 iron ion binding | IEA GO_REF:0000002 | ACCEPT | Summary: Heme iron is the catalytic cofactor of this P450 monooxygenase. Reason: Heme/iron binding supports the established P450 oxygenation chemistry. It is an intrinsic catalytic feature, not a peripheral process or an additional independent core activity. Supporting Evidence: file:ARATH/CYP79F1/CYP79F1-uniprot.txt Name=heme; Xref=ChEBI:CHEBI:30413; Evidence={ECO:0000250}; |
| GO:0005634 nucleus | HDA PMID:28887381 Global Analysis of Membrane-associated Protein Oligomerizati... | MARK AS OVER ANNOTATED | Summary: The microsome experiment does not independently establish nucleus localization. Reason: Full-text inspection of PMID:28887381 shows that washed microsomes were profiled by chromatography and sucrose gradients, while subcellular labels were taken from SUBAcon and prior GFP data. The authors explicitly report that no organelle occupied a single gradient cluster. Detection or membrane association is meaningful, but assigning CYP79F1 specifically to nucleus exceeds the spatial resolution of this experiment. This is not a claim that the detected protein is absent or that all additional localization is impossible; the unsupported compartment assignment, rather than the proteomic observation, is marked as over-annotated. Supporting Evidence: PMID:28887381 The proteins with known localizations had scattered distributions across the entire gradient and no organelle fell in a single cluster. PMID:28887381 We used SUBAcon localization predictions to analyze oligomerization as a function of subcellular localization (Fig. 7C). |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of ER localization across plant P450s; CYP79F1 (AT1G16410) itself is among the experimental donors, which is expected and not circular. Consistent with direct GFP-fusion evidence. Reason: Plant CYP79 and related P450s are ER-anchored; CYP79F1 ER localization is experimentally confirmed. Supporting Evidence: PMID:11226190 Comparison of the fluorescence patterns between the controls and the fusion proteins revealed that the GFP fusions of CYP79F1 and CYP79F2 were both located in the ER |
| GO:0005783 endoplasmic reticulum | IDA PMID:11226190 Bus, a bushy Arabidopsis CYP79F1 knockout mutant with abolis... | ACCEPT | Summary: The N-terminal 62 residues of CYP79F1 (signal/anchor region) fused to GFP co-localized with an ER-targeted GFP control, showing ER targeting. Reason: Direct experimental localization consistent with the ER-anchored P450 topology. Supporting Evidence: PMID:11226190 The first 62 amino acids of either CYP79F1 or CYP79F2 (named N-CYP79F1 and N-CYP79F2), which include the motifs mentioned above ( Figure 3 ), were fused to green fluorescent protein (GFP). PMID:11226190 Comparison of the fluorescence patterns between the controls and the fusion proteins revealed that the GFP fusions of CYP79F1 and CYP79F2 were both located in the ER |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (ER membrane, single-pass). Consistent with the N-terminal membrane anchor and the GFP evidence; this is the most precise location for the enzyme. Reason: Correct and appropriately specific location for a microsomal P450. Supporting Evidence: PMID:11226190 a stretch of hydrophobic amino acids constituting the transmembrane helix, which anchors the protein in the ER |
| GO:0009507 chloroplast | ISM GO_REF:0000122 | REMOVE | Summary: AtSubP sequence-based prediction. Contradicted by the experimentally demonstrated ER targeting of the CYP79F1 N-terminus; the N-terminal hydrophobic segment is an ER signal-anchor, not a plastid transit peptide. Reason: Computational prediction contradicted by direct localization evidence and by the known topology of plant microsomal P450s. Supporting Evidence: PMID:11226190 Comparison of the fluorescence patterns between the controls and the fusion proteins revealed that the GFP fusions of CYP79F1 and CYP79F2 were both located in the ER |
| GO:0009625 response to insect | IEP PMID:23144921 Water stress and aphid feeding differentially influence meta... | KEEP AS NON CORE | Summary: CYP79F1 transcript levels decreased after aphid infestation (Myzus persicae and Brevicoryne brassicae) in a metabolite/transcript profiling study. This is an expression response, not a demonstration that CYP79F1 executes a response process. Reason: Valid expression-pattern observation, and aliphatic glucosinolates are anti-herbivore defence compounds, but the gene's function is biosynthetic; the insect response is a regulatory context, so it is kept as non-core. Supporting Evidence: PMID:23144921 transcript levels of biosynthetic genes MAM1, CYP79F1, CYP83A1, and UGT74C1 decreased after infestation with either aphid species |
| GO:0009625 response to insect | IEP PMID:40546745 Impact of Lepidopteran Oral Secretions on the Transcriptome ... | KEEP AS NON CORE | Summary: Lepidopteran (Spodoptera littoralis, Pieris brassicae) oral secretions applied to wounds suppressed expression of aliphatic glucosinolate biosynthetic genes including CYP79F1 (qPCR-validated). Expression response only. Reason: Transcriptional downregulation by insect-derived elicitors is a regulatory context of the biosynthetic gene, not evidence that CYP79F1 performs a step of a response process; retained as non-core. Supporting Evidence: PMID:40546745 Strikingly, OS of both caterpillars suppressed the basal expression of MYC4, MYB28, and MYB29 and most genes responsible for aliphatic GS biosynthesis (Figure 6A), three of which were further validated by qPCR (Figure 6B). PMID:40546745 Expression level of MYB28 (At5g61420), CYP79F1 (At1g16410), and CYP79F2 (At1g16400) 3 h after treatment |
| GO:0016020 membrane | IBA GO_REF:0000033 | MODIFY | Summary: CYP79F is anchored in the endoplasmic reticulum membrane. Reason: Refine generic membrane to the supported ER membrane location already present in this review; GFP-fusion localization and microsomal P450 topology support this assignment. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN001210282 UNRESOLVED Proximate PAINT node traced from the original annotation. Its full ancestral assertion history has not been reconstructed in this audit; the target-specific assessment is grounded in the primary evidence explained in review.reason, not donor counts or self-inclusion. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: PMID:11226190 a stretch of hydrophobic amino acids constituting the transmembrane helix, which anchors the protein in the ER |
| GO:0016705 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen | IEA GO_REF:0000002 | MODIFY | Summary: The demonstrated activity is homomethionine N-monooxygenase. Reason: Recombinant-enzyme substrate/product measurements support GO:0120526, already asserted in this review. Use the same target-specific replacement across evidence types. Electron delivery is through the P450 reductase/flavoprotein system; correcting the direct NAD(P)H-donor wording is a reaction-class correction where applicable. Proposed replacements: homomethionine N-monooxygenase activity Supporting Evidence: PMID:11133994 We report that cytochrome P450 CYP79F1 catalyzes aldoxime formation in the biosynthesis of aliphatic glucosinolates in Arabidopsis thaliana. |
| GO:0016709 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, NAD(P)H as one donor, and incorporation of one atom of oxygen | IBA GO_REF:0000033 | MODIFY | Summary: The demonstrated activity is homomethionine N-monooxygenase. Reason: Recombinant-enzyme substrate/product measurements support GO:0120526, already asserted in this review. Use the same target-specific replacement across evidence types. Electron delivery is through the P450 reductase/flavoprotein system; correcting the direct NAD(P)H-donor wording is a reaction-class correction where applicable. Propagation Review Root cause: TERM SCOPING PROBLEM Sources checked: PANTHER:PTN001210282 · PTN001210282 SUPPORTS TRANSFER The P450 monooxygenase function at this node is sound and CYP79F1 is inside the clade; only the electron-donor branch of the asserted term (NAD(P)H rather than flavoprotein reductase) is mis-scoped for microsomal P450s. Proposed replacements: homomethionine N-monooxygenase activity Supporting Evidence: file:ARATH/CYP79F1/CYP79F1-uniprot.txt Reaction=L-dihomomethionine + 2 reduced [NADPH--hemoprotein reductase] PMID:12609033 Using recombinant CYP79F1 and CYP79F2 expressed in Escherichia coli and Saccharomyces cerevisiae, respectively, we show that CYP79F1 metabolizes mono- to hexahomomethionine, resulting in both short- and long-chain aliphatic glucosinolates. |
| GO:0016709 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, NAD(P)H as one donor, and incorporation of one atom of oxygen | IDA PMID:12609033 CYP79F1 and CYP79F2 have distinct functions in the biosynthe... | MODIFY | Summary: The demonstrated activity is homomethionine N-monooxygenase. Reason: Recombinant-enzyme substrate/product measurements support GO:0120526, already asserted in this review. Use the same target-specific replacement across evidence types. Electron delivery is through the P450 reductase/flavoprotein system; correcting the direct NAD(P)H-donor wording is a reaction-class correction where applicable. Proposed replacements: homomethionine N-monooxygenase activity Supporting Evidence: PMID:12609033 Using recombinant CYP79F1 and CYP79F2 expressed in Escherichia coli and Saccharomyces cerevisiae, respectively, we show that CYP79F1 metabolizes mono- to hexahomomethionine, resulting in both short- and long-chain aliphatic glucosinolates. |
| GO:0019761 glucosinolate biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT node for the CYP79F clade (CYP79F1 and CYP79F2 as donors). CYP79F1 catalyzes the first committed step of aliphatic glucosinolate core structure formation. Reason: Core process with direct biochemical and genetic support on the target itself; the node placement within the Brassicales-specific CYP79F clade is sound. Supporting Evidence: PMID:11133994 We report that cytochrome P450 CYP79F1 catalyzes aldoxime formation in the biosynthesis of aliphatic glucosinolates in Arabidopsis thaliana. |
| GO:0019761 glucosinolate biosynthetic process | IMP PMID:12609033 CYP79F1 and CYP79F2 have distinct functions in the biosynthe... | ACCEPT | Summary: A transposon-tagged cyp79f1 knockout completely lacks short-chain aliphatic glucosinolates; together with the enzyme assays this shows CYP79F1 catalyzes a step of glucosinolate biosynthesis. Reason: Mutant phenotype plus demonstrated catalytic activity on the pathway intermediate establish direct participation (the enzyme performs the aldoxime-forming step). Supporting Evidence: PMID:12609033 A transposon-tagged CYP79F1 knockout mutant completely lacks short-chain aliphatic glucosinolates, but has an increased level of long-chain aliphatic glucosinolates, especially in leaves and seeds. PMID:15194821 Our analysis shows that aliphatic glucosinolate biosynthesis is completely abolished in the double-knockout plants, providing genetic proof for the proposed biochemical functions of these genes. |
| GO:0020037 heme binding | IEA GO_REF:0000002 | ACCEPT | Summary: Heme iron is the catalytic cofactor of this P450 monooxygenase. Reason: Heme/iron binding supports the established P450 oxygenation chemistry. It is an intrinsic catalytic feature, not a peripheral process or an additional independent core activity. Supporting Evidence: file:ARATH/CYP79F1/CYP79F1-uniprot.txt Name=heme; Xref=ChEBI:CHEBI:30413; Evidence={ECO:0000250}; |
| GO:0120526 homomethionine N-monooxygenase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Rhea/EC-based mapping of the experimentally characterized UniProt catalytic activities (EC 1.14.14.42) to the specific GO term. This is the core molecular function: conversion of chain-elongated methionines (preferentially di- and trihomomethionine) to omega-methylthioalkanaldoximes. Reason: Directly supported by recombinant-enzyme assays with defined substrates and products and by kinetic data. Supporting Evidence: PMID:11133994 Using recombinant CYP79F1 functionally expressed in Escherichia coli, we show that both dihomomethionine and trihomomethionine are metabolized by CYP79F1 resulting in the formation of 5-methylthiopentanaldoxime and 6-methylthiohexanaldoxime, respectively. PMID:12609033 we show that CYP79F1 metabolizes mono- to hexahomomethionine, resulting in both short- and long-chain aliphatic glucosinolates. |
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Download this section (compressed HTML)Q: What structural features of the CYP79F1 substrate pocket allow it to accept short-chain (di-/trihomomethionine) homologues that CYP79F2 cannot, and do these residues predict chain-length specificity of CYP79F orthologs in Brassica and Camelina oilseeds?
Q: Is the cyp79f1 bushy/supershoot phenotype caused by accumulating short-chain methionine homologues, by diversion of flux to indole glucosinolates and auxin, or by altered cytokinin homeostasis?
Experiment: Swap candidate substrate-recognition-site residues between CYP79F1 and CYP79F2, express in yeast with ATR1, and measure kinetics on mono- to hexahomomethionine.
Hypothesis: A small set of active-site residues determines CYP79F1 versus CYP79F2 chain-length specificity.
Type: site-directed mutagenesis and enzyme kinetics
Experiment: Combine cyp79f1 with mutants blocking chain elongation (e.g. bcat4 or mam1) and test whether shoot branching and hormone levels revert to wild type.
Hypothesis: Accumulation of unconverted chain-elongated methionines drives the bushy phenotype.
Type: genetic epistasis
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