| IED ID | IndEnz0010000719 |
| Enzyme Type ID | esterase000719 |
| Protein Name |
Fatty acid synthase alpha subunit hexA EC 2.3.1.86 Includes: 3-oxoacyl- acyl-carrier-protein reductase EC 1.1.1.100 Beta-ketoacyl reductase ; 3-oxoacyl- acyl-carrier-protein synthase EC 2.3.1.41 Dothistromin biosynthesis protein hexA Fragment |
| Gene Name | hexA |
| 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 | AAAWMLNGCLQVMDSRTIPANRNADNVDPALQTATHLCFPTRPVRVQDVRAFILTSFGFGQKGGQVVGVAPKYFFATLDEEVYKDYSVRVTKRSKTADRAYAKALMSNAIVKVQDHSPYEQEDQSRIFMDPLSRITEDAETGSYHFDTKDIRNVADVKARLTRLVRGERLNARPDAASGLAQAARSAQAWIEKQTGGRSSVDTSTVGIDLVDLSAFSAHENETFIERNFTEQEKAFAKQSLDQKMAFASRWAAKEAVFKCLHTQTKGAGAAMKDIEIVKSDNAPQGQAGRKAGLEDIQLSISHGEDCLIAVAIGIAGNGPAKYTL |
| Enzyme Length | 325 |
| Uniprot Accession Number | A7TUG9 |
| Absorption | |
| Active Site | |
| Activity Regulation | |
| Binding Site | |
| Calcium Binding | |
| catalytic Activity | CATALYTIC ACTIVITY: Reaction=acetyl-CoA + 2n H(+) + n malonyl-CoA + 2n NADPH = a long-chain fatty acyl-CoA + n CO2 + n CoA + H2O + 2n NADP(+); Xref=Rhea:RHEA:22896, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:16526, ChEBI:CHEBI:57287, ChEBI:CHEBI:57288, ChEBI:CHEBI:57384, ChEBI:CHEBI:57783, ChEBI:CHEBI:58349, ChEBI:CHEBI:83139; EC=2.3.1.86; Evidence={ECO:0000250|UniProtKB:P19097}; CATALYTIC ACTIVITY: Reaction=a fatty acyl-[ACP] + H(+) + malonyl-[ACP] = a 3-oxoacyl-[ACP] + CO2 + holo-[ACP]; Xref=Rhea:RHEA:22836, Rhea:RHEA-COMP:9623, Rhea:RHEA-COMP:9685, Rhea:RHEA-COMP:9916, Rhea:RHEA-COMP:14125, ChEBI:CHEBI:15378, ChEBI:CHEBI:16526, ChEBI:CHEBI:64479, ChEBI:CHEBI:78449, ChEBI:CHEBI:78776, ChEBI:CHEBI:138651; EC=2.3.1.41; Evidence={ECO:0000255|PROSITE-ProRule:PRU10022}; CATALYTIC ACTIVITY: Reaction=a (3R)-hydroxyacyl-[ACP] + NADP(+) = a 3-oxoacyl-[ACP] + H(+) + NADPH; Xref=Rhea:RHEA:17397, Rhea:RHEA-COMP:9916, Rhea:RHEA-COMP:9945, ChEBI:CHEBI:15378, ChEBI:CHEBI:57783, ChEBI:CHEBI:58349, ChEBI:CHEBI:78776, ChEBI:CHEBI:78827; EC=1.1.1.100; Evidence={ECO:0000250|UniProtKB:P19097}; |
| DNA Binding | |
| EC Number | 2.3.1.86; 1.1.1.100; 2.3.1.41 |
| Enzyme Function | FUNCTION: Fatty acid synthase alpha subunit; 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:Q12437, 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 | |
| Features | Chain (1); Metal binding (2); Non-terminal residue (1); Region (4) |
| Keywords | Fatty acid biosynthesis;Fatty acid metabolism;Lipid biosynthesis;Lipid metabolism;Magnesium;Metal-binding;Multifunctional enzyme;NADP;Oxidoreductase;Phosphopantetheine;Phosphoprotein;Transferase |
| Interact With | |
| Induction | INDUCTION: Expression is positively regulated by the dothistromin-specific transcription factors aflR and aflJ (PubMed:23207690, PubMed:25986547). {ECO:0000269|PubMed:23207690, ECO:0000269|PubMed:25986547}. |
| Subcellular Location | |
| Modified Residue | |
| Post Translational Modification | PTM: 4'-phosphopantetheine is transferred from CoA to a specific serine of the acyl carrier domain by the C-terminal PPT domain. This modification is essential for activity because fatty acids are bound in thioester linkage to the sulfhydryl of the prosthetic group. {ECO:0000305}. |
| Signal Peptide | |
| Structure 3D | |
| Cross Reference PDB | - |
| Mapped Pubmed ID | - |
| Motif | |
| Gene Encoded By | |
| Mass | 35,522 |
| Kinetics | |
| Metal Binding | METAL 209; /note=Magnesium; /evidence=ECO:0000250|UniProtKB:P19097; METAL 302; /note=Magnesium; /evidence=ECO:0000250|UniProtKB:P19097 |
| Rhea ID | RHEA:22896; RHEA:22836; RHEA:17397 |
| Cross Reference Brenda |