| IED ID | IndEnz0010001731 |
| Enzyme Type ID | esterase001731 |
| Protein Name |
Versicolorin B synthase EC 4.2.1.143 5'-oxoaverantin cyclase EC 4.2.1.142 Dothistromin biosynthesis protein vbsA |
| Gene Name | vbsA |
| Organism | Dothistroma septosporum (Red band needle blight fungus) (Mycosphaerella pini) |
| Taxonomic Lineage | cellular organisms Eukaryota Opisthokonta Fungi Dikarya Ascomycota saccharomyceta Pezizomycotina leotiomyceta dothideomyceta Dothideomycetes Dothideomycetidae Mycosphaerellales Mycosphaerellaceae Dothistroma Dothistroma septosporum (Red band needle blight fungus) (Mycosphaerella pini) |
| Enzyme Sequence | MALSTILTAAAMPVAGLFAFAQQSSAFFDQIPVLGSMLNSPVGTYDAQAAQMDGRIQARDLLSSHFGPVGWPHQSFDYVIVGGGTAGLAMAKRLSEEEGNSVALIEAGGFYEMDAGNATEVPMYLFNYFFDNGYMKNPLFDWYQYTEPQEGLHNREMFYMQGKTLGGSTARGAMLYHRGSKGAYQKWADEVGDDSYTWEKWLPHFQRGIKFSGPNTNPRPANATAVNDDKAWSASGGPVHVAYPYLTNAISSWVDKALDSFGFSNVQGFSNGVLLGKSYITHTINPFTRRRETASSSYLREALVESNNLNIYIRTLAKKVLFDENKKANAVEVQTDGFKWKIEAKKEVILSAGVMRSPQLLMVSGIGPKETLEKLDIPVLSDRPGVGQNMQDTIILGPTNPIRVESHSQLLGGKDTLPRSIDDYNNHRTGLLTNPGQDFFAFEKHAEEGPGSLSKETAADIDANFPADWPTYSFIALDDTFVPQFNGKNYFSMSAALMTTFSRGYVSINSTDTLDNPIVDPKWLSDPRDQEMAVAAFRRCRQFTQHEILQDVIDGEELLPGKKYQTDDEVLGYIAETSDAYYAGVGTAAMGKKDDPKAVLDSKARVLGVQGLRVVDASSFPFAIDGQPMGTVYALAEKIAADIIAGN |
| Enzyme Length | 647 |
| Uniprot Accession Number | A4UHS8 |
| Absorption | |
| Active Site | |
| Activity Regulation | |
| Binding Site | BINDING 617; /note=FAD; via amide nitrogen; /evidence=ECO:0000250|UniProtKB:E4QP00 |
| Calcium Binding | |
| catalytic Activity | CATALYTIC ACTIVITY: Reaction=(2S-3S)-versiconal hemiacetal = H2O + versicolorin B; Xref=Rhea:RHEA:33859, ChEBI:CHEBI:15377, ChEBI:CHEBI:77950, ChEBI:CHEBI:77951; EC=4.2.1.143; Evidence={ECO:0000250|UniProtKB:Q12062}; CATALYTIC ACTIVITY: Reaction=(S)-5'-oxoaverantin + H(+) = (1'S,5'S)-averufin + H2O; Xref=Rhea:RHEA:35671, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:71537, ChEBI:CHEBI:77933; EC=4.2.1.142; Evidence={ECO:0000250|UniProtKB:Q12062}; |
| DNA Binding | |
| EC Number | 4.2.1.143; 4.2.1.142 |
| Enzyme Function | FUNCTION: Versicolorin B synthase; 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). {ECO:0000250|UniProtKB:Q12062, ECO:0000269|PubMed:12039746, ECO:0000269|PubMed:16649078, ECO:0000303|PubMed:22069571, ECO:0000305|PubMed:17683963, ECO:0000305|PubMed:23207690, ECO:0000305|PubMed:23448391}. |
| Temperature Dependency | |
| PH Dependency | |
| Pathway | PATHWAY: Mycotoxin biosynthesis. {ECO:0000303|PubMed:22069571, ECO:0000305|PubMed:23207690}. |
| nucleotide Binding | NP_BIND 85..86; /note=FAD; /evidence=ECO:0000250|UniProtKB:E4QP00; NP_BIND 106..107; /note=FAD; /evidence=ECO:0000250|UniProtKB:E4QP00; NP_BIND 172..175; /note=FAD; /evidence=ECO:0000250|UniProtKB:E4QP00; NP_BIND 628..629; /note=FAD; /evidence=ECO:0000250|UniProtKB:E4QP00 |
| Features | Binding site (1); Chain (1); Glycosylation (3); Nucleotide binding (4); Signal peptide (1) |
| Keywords | Cytoplasm;FAD;Flavoprotein;Glycoprotein;Lyase;Signal |
| Interact With | |
| Induction | INDUCTION: Expression is positively regulated by the dothistromin-specific transcription factors aflR and aflJ (PubMed:23207690, PubMed:25986547). 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, PubMed:18262779). {ECO:0000269|PubMed:17683963, ECO:0000269|PubMed:18262779, ECO:0000269|PubMed:23207690, ECO:0000269|PubMed:25986547}. |
| Subcellular Location | SUBCELLULAR LOCATION: Cytoplasm, cytosol {ECO:0000250|UniProtKB:Q12062}. |
| Modified Residue | |
| Post Translational Modification | |
| Signal Peptide | SIGNAL 1..26; /evidence=ECO:0000255 |
| Structure 3D | |
| Cross Reference PDB | - |
| Mapped Pubmed ID | - |
| Motif | |
| Gene Encoded By | |
| Mass | 70,966 |
| Kinetics | |
| Metal Binding | |
| Rhea ID | RHEA:33859; RHEA:35671 |
| Cross Reference Brenda |