title: Identification of a novel sesquiterpene biosynthetic machinery involved in astellolide biosynthesis.
abstract: Esterified drimane-type sesquiterpene lactones such as astellolides display various biological activities and are widely produced by plants and fungi. Given their low homology to known sesquiterpene cyclases, the genes responsible for their biosynthesis have not been uncovered yet. Here, we identified the astellolide gene cluster from Aspergillus oryzae and discovered a novel sesquiterpene biosynthetic machinery consisting of AstC, AstI, and AstK. All these enzymes are annotated as haloacid dehalogenase-like hydrolases, whereas AstC also contains a DxDTT motif conserved in class II diterpene cyclases. Based on enzyme reaction analyses, we found that AstC catalysed the protonation-initiated cyclisation of farnesyl pyrophosphate into drimanyl pyrophosphate. This was successively dephosphorylated by AstI and AstK to produce drim-8-ene-11-ol. Moreover, we also identified and characterised a unique non-ribosomal peptide synthetase, AstA, responsible for esterifying aryl acids to drimane-type sesquiterpene lactones. In this study, we highlight a new biosynthetic route for producing sesquiterpene and its esterified derivative. Our findings shed light on the identification of novel sesquiterpenes via genome mining.
authors.affiliation: Noda Institute for Scientific Research, 399 Noda, Noda, Chiba 278-0037, Japan.
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Shinohara
authors.affiliation: Chemical Biology Research Group, RIKEN CSRS, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Chemical Biology Research Group, RIKEN CSRS, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Osada
authors.affiliation: Noda Institute for Scientific Research, 399 Noda, Noda, Chiba 278-0037, Japan.
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Koyama
mesh_terms: D020816:Amino Acid Motifs; D001236:Aspergillus oryzae / Q000201:enzymology / Q000235:genetics*; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D005800:Genes, Fungal; D009682:Magnetic Resonance Spectroscopy; D005810:Multigene Family; D020411:Oligonucleotide Array Sequence Analysis; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000378:metabolism; D012717:Sesquiterpenes / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D012717:Sesquiterpenes; D010744:Phosphoric Monoester Hydrolases