M2XHE6 · AVFA_DOTSN

Function

function

Averufin oxidase A; part of the fragmented gene cluster that mediates the biosynthesis of dothistromin (DOTH), a polyketide toxin very similar in structure to the aflatoxin precursor, versicolorin B (PubMed:12039746, PubMed:17683963, PubMed:22069571, PubMed:23207690, PubMed:23448391).
The first step of the pathway is the conversion of acetate to norsolorinic acid (NOR) and requires the fatty acid synthase subunits hexA and hexB, as well as the polyketide synthase pksA (PubMed:16649078, PubMed:23207690).
PksA combines a hexanoyl starter unit and 7 malonyl-CoA extender units to synthesize the precursor NOR (By similarity).
The hexanoyl starter unit is provided to the acyl-carrier protein (ACP) domain by the fungal fatty acid synthase hexA/hexB (By similarity).
The second step is the conversion of NOR to averantin (AVN) and requires the norsolorinic acid ketoreductase nor1, which catalyzes the dehydration of norsolorinic acid to form (1'S)-averantin (PubMed:23207690).
The cytochrome P450 monooxygenase avnA then catalyzes the hydroxylation of AVN to 5'hydroxyaverantin (HAVN) (PubMed:23207690).
The next step is performed by adhA that transforms HAVN to averufin (AVF) (PubMed:23207690).
Averufin might then be converted to hydroxyversicolorone by cypX and avfA (PubMed:23207690).
Hydroxyversicolorone is further converted versiconal hemiacetal acetate (VHA) by moxY (PubMed:23207690).
VHA is then the substrate for the versiconal hemiacetal acetate esterase est1 to yield versiconal (VAL) (PubMed:23207690).
Versicolorin B synthase vbsA then converts VAL to versicolorin B (VERB) by closing the bisfuran ring (PubMed:16649078, PubMed:23207690).
Then, the activity of the versicolorin B desaturase verB leads to versicolorin A (VERA) (PubMed:23207690).
DotB, a predicted chloroperoxidase, may perform epoxidation of the A-ring of VERA (PubMed:23207690).
Alternatively, a cytochrome P450, such as cypX or avnA could catalyze this step (PubMed:23207690).
It is also possible that another, uncharacterized, cytochrome P450 enzyme is responsible for this step (PubMed:23207690).
Opening of the epoxide could potentially be achieved by the epoxide hydrolase epoA (PubMed:23207690).
However, epoA seems not to be required for DOTH biosynthesis, but other epoxide hydrolases may have the ability to complement this hydrolysis (PubMed:23207690).
Alternatively, opening of the epoxide ring could be achieved non-enzymatically (PubMed:23207690).
The next step is the deoxygenation of ring A to yield the 5,8-dihydroxyanthraquinone which is most likely catalyzed by the NADPH dehydrogenase encoded by ver1 (PubMed:23207690).
The last stages of DOTH biosynthesis are proposed to involve hydroxylation of the bisfuran (PubMed:23207690).
OrdB and norB might have oxidative roles here (PubMed:23207690).
An alternative possibility is that cytochrome P450 monoogenases such as avnA and cypX might perform these steps in addition to previously proposed steps (PubMed:23207690).

Pathway

Mycotoxin biosynthesis.

GO annotations

AspectTerm
Molecular Functionoxidoreductase activity

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Averufin oxidase A
  • EC number
  • Alternative names
    • Dothistromin biosynthesis protein avfA

Gene names

    • Name
      avfA
    • ORF names
      DOTSEDRAFT_75546

Organism names

Accessions

  • Primary accession
    M2XHE6

Proteomes

PTM/Processing

Features

Showing features for signal, chain, glycosylation.

TypeIDPosition(s)Description
Signal1-23
ChainPRO_000044346624-284Averufin oxidase A
Glycosylation62N-linked (GlcNAc...) asparagine
Glycosylation86N-linked (GlcNAc...) asparagine
Glycosylation190N-linked (GlcNAc...) asparagine

Keywords

PTM databases

Expression

Induction

Expression is positively regulated by the dothistromin-specific transcription factor aflR (PubMed:23207690).
Dothistromin biosynthetic proteins are co-regulated, showing a high level of expression at ealy exponential phase with a subsequent decline in older cultures (PubMed:17683963).

Interaction

Protein-protein interaction databases

Family & Domains

Sequence similarities

Belongs to the avfA family.

Keywords

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Sequence processing
    The displayed sequence is further processed into a mature form.
  • Length
    284
  • Mass (Da)
    30,716
  • Last updated
    2013-05-01 v1
  • Checksum
    A3F5B919AFFB7C24
MPTYALLGATGATGSAILRCLLASPPPDLDLNILVRSKQKLLKSFPTLTTTISPRIHIIQGNSTDTIALQQCLEDASVAFMCVADNASNKGVSLTADTVTAIVTTLGMLRKLHGSAYNAPTILQLRSASLNPKLSCQVPRLVYNIVSFCLHYSHLDIVKACEHYEAAAAKGLLSYIYVDPPTIHDAFGPNRTGHKLISCKPDVCDKQETALSYADLGAGFVEIASRKEDFLNQPVGVTATGKAKETWGVLAGFLFDGAKGRARAWWEEERPMSKPQNLFLYCGM

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
KB446546
EMBL· GenBank· DDBJ
EME38862.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

Disclaimer

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