title: Cloning of the gene cluster responsible for biosynthesis of KS-505a (longestin), a unique tetraterpenoid.
abstract: KS-505a (longestin), produced by Streptomyces argenteolus, has a unique structure that consists of a tetraterpene (C40) skeleton, to which a 2-O-methylglucuronic acid and an o-succinyl benzoate moiety are attached. It is a novel inhibitor of calmodulin-dependent cyclic-nucleotide phosphodiesterase, which is representative of a potent anti-amnesia drug. As a first step to understanding the biosynthetic machinery of this unique and pharmaceutically useful compound, we cloned a KS505a biosynthetic gene cluster. First we searched for a gene encoding octaprenyl diphosphates, which yielded a C40 precursor by PCR, and four candidate genes were obtained. Among these, one was confirmed to have the expected enzyme activity by recombinant enzyme assay. On the basis of an analysis of the flanking regions of the gene, a putative KS-505a biosynthetic gene cluster consisting of 24 ORFs was judged perhaps to be present on a 28-kb DNA fragment. A gene disruption experiment was also employed to confirm that the cluster indeed participated in KS-505a biosynthesis. This is believed to be the first report detailing the gene cluster of a cyclized tetraterpenoid.
authors: Biotechnology Research Center, Toyama Prefectural University, Toyama, Japan.
authors: Yutaka
authors: Y
authors: Hayashi
authors: Hiroyasu
authors: H
authors: Onaka
authors: Nobuya
authors: N
authors: Itoh
authors: Haruo
authors: H
authors: Seto
authors: Tohru
authors: T
authors: Dairi
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000378:metabolism; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1 / Q000235:genetics / Q000378:metabolism; D008757:Methylglucosides / Q000096:biosynthesis*; D005810:Multigene Family; D016366:Open Reading Frames; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*; D013729:Terpenes / Q000378:metabolism*
chemical_list: D008757:Methylglucosides; D013729:Terpenes; C074362:longestin; D019883:Alkyl and Aryl Transferases; C048987:octaprenyl pyrophosphate synthetase; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1