A0A0E0SMA3 · ERG6B_GIBZE

Function

function

Sterol 24-C-methyltransferase; part of the third module of ergosterol biosynthesis pathway that includes the late steps of the pathway (By similarity).
ERG6A and ERG6B methylate lanosterol at C-24 to produce eburicol (By similarity).
The third module or late pathway involves the ergosterol synthesis itself through consecutive reactions that mainly occur in the endoplasmic reticulum (ER) membrane. Firstly, the squalene synthase ERG9 catalyzes the condensation of 2 farnesyl pyrophosphate moieties to form squalene, which is the precursor of all steroids. Squalene synthase is crucial for balancing the incorporation of farnesyl diphosphate (FPP) into sterol and nonsterol isoprene synthesis. Secondly, squalene is converted into lanosterol by the consecutive action of the squalene epoxidase ERG1 and the lanosterol synthase ERG7. Then, the delta24-sterol C-methyltransferase ERG6 methylates lanosterol at C-24 to produce eburicol. Eburicol is the substrate of the sterol 14-alpha demethylase encoded by CYP51A, CYP51B and CYP51C, to yield 4,4,24-trimethyl ergosta-8,14,2428-trienol. CYP51B encodes the enzyme primarily responsible for sterol 14-alpha-demethylation, and plays an essential role in ascospore formation. CYP51A encodes an additional sterol 14-alpha-demethylase, induced on ergosterol depletion and responsible for the intrinsic variation in azole sensitivity. The third CYP51 isoform, CYP51C, does not encode a sterol 14-alpha-demethylase, but is required for full virulence on host wheat ears. The C-14 reductase ERG24 then reduces the C14=C15 double bond which leads to 4,4-dimethylfecosterol. A sequence of further demethylations at C-4, involving the C-4 demethylation complex containing the C-4 methylsterol oxidases ERG25, the sterol-4-alpha-carboxylate 3-dehydrogenase ERG26 and the 3-keto-steroid reductase ERG27, leads to the production of fecosterol via 4-methylfecosterol. ERG28 has a role as a scaffold to help anchor ERG25, ERG26 and ERG27 to the endoplasmic reticulum. The C-8 sterol isomerase ERG2 then catalyzes the reaction which results in unsaturation at C-7 in the B ring of sterols and thus converts fecosterol to episterol. The sterol-C5-desaturases ERG3A and ERG3BB then catalyze the introduction of a C-5 double bond in the B ring to produce 5-dehydroepisterol. The C-22 sterol desaturases ERG5A and ERG5B further convert 5-dehydroepisterol into ergosta-5,7,22,2428-tetraen-3beta-ol by forming the C-2223 double bond in the sterol side chain. Finally, ergosta-5,7,22,2428-tetraen-3beta-ol is substrate of the C-2428 sterol reductase ERG4 to produce ergosterol (Probable).

Miscellaneous

In Fusarium, the biosynthesis pathway of the sterol precursors leading to the prevalent sterol ergosterol differs from yeast. The ringsystem of lanosterol in S.cerevisiae is firstly demethylised in three enzymatic steps leading to the intermediate zymosterol and secondly a methyl group is added to zymosterol by the sterol 24-C-methyltransferase to form fecosterol. In Fusarium, lanosterol is firstly transmethylated by the sterol 24-C-methyltransferase leading to the intermediate eburicol and secondly demethylated in three steps to form fecosterol.

Catalytic activity

Pathway

Steroid metabolism; ergosterol biosynthesis.

GO annotations

AspectTerm
Cellular Componentendoplasmic reticulum
Molecular Functionsterol 24-C-methyltransferase activity
Biological Processergosterol biosynthetic process
Biological Processmethylation

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Sterol 24-C-methyltransferase ERG6B
  • EC number
  • Short names
    SCMT
    ; SMT
  • Alternative names
    • Delta(24)-sterol C-methyltransferase ERG6B
    • Ergosterol biosynthesis protein 6B

Gene names

    • Name
      ERG6B
    • ORF names
      FG05740, FGRAMPH1_01T18649

Organism names

Accessions

  • Primary accession
    A0A0E0SMA3

Proteomes

Organism-specific databases

Subcellular Location

PTM/Processing

Features

Showing features for chain.

TypeIDPosition(s)Description
ChainPRO_00004543681-380Sterol 24-C-methyltransferase ERG6B

Expression

Induction

Expression is increased in the absence of the C-2428 sterol reductase ERG4 (PubMed:22947191).
Expression is positively regulated by the FgSR transcription factor that targets gene promoters containing 2 conserved CGAA repeat sequences (PubMed:30874562).

Interaction

Protein-protein interaction databases

Family & Domains

Sequence similarities

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    380
  • Mass (Da)
    42,727
  • Last updated
    2016-04-13 v1
  • Checksum
    0595F7289DBA5892
MPTTELISYDEAQNSAFDNVLHGKSKESRGGMRAMMNKDNKAHAAAVDEYFQFFDNKKAEDEVEAVRQERTDNYASLTRQYYNLATDLYEYGWSQSFHFCRFAYGESFDRAIARHEHYLAHNIGIKPGMKVLDVGCGVGGPAREIVKFTGAHVTGLNINEYQVGRAGIYAEKEGLSDKLKFVQGDFMKMPFPDNSFDAVYAIEATVHAPSLEGVYSEIRRVLKPGGIFGVYEWLMTDIYDNDDLEQRRIRLDIELGDGIAQMFKIDHGLSAIKAAGFELLHHEDLAATDDGTAPWYWPLDSDMRYAQNLSDLLTVFRMNKWGRLVMHNLIGVLEACSIAPKGTRKTADGLAKGADALVEGGKRKLFTPMYLMVGKKPEKI

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
HG970334
EMBL· GenBank· DDBJ
CEF87566.1
EMBL· GenBank· DDBJ
Genomic DNA

Similar Proteins

Disclaimer

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