title: Epoxide hydrolase Lsd19 for polyether formation in the biosynthesis of lasalocid A: direct experimental evidence on polyene-polyepoxide hypothesis in polyether biosynthesis.
abstract: Polyether metabolites are an important class of natural products. Although their biosynthesis, especially construction of polyether skeletons, attracted organic chemists for many years, no experimental data on the enzymatic polyether formation has been obtained. In this study, a putative epoxide hydrolase gene lsd19 found on the biosynthetic gene cluster of an ionophore polyether lasalocid was cloned and successfully overexpressed in Escherichia coli. Using the purified Lsd19, a proposed substrate, bisepoxyprelasalocid, and its synthesized analogue were successfully converted into lasalocid A and its derivative via a 6-endo-tet cyclization mode. On the other hand, treatment of the bisepoxide with trichloroacetic acid gave isolasalocid A via a 5-exo-tet cyclization mode. Therefore, the enzymatic conversion observed in this study unambiguously showed that the bisepoxyprelasalocid is an intermediate of the lasalocid biosynthesis and that Lsd19 catalyzes the sequential cyclic ether formations involving an energetically disfavored 6-endo-tet cyclization. This is the first example of the enzymatic epoxide-opening reactions leading to a polyether natural product.
authors: Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors: Yoshihiro
authors: Y
authors: Shichijo
authors: Akira
authors: A
authors: Migita
authors: Hiroki
authors: H
authors: Oguri
authors: Mami
authors: M
authors: Watanabe
authors: Tetsuo
authors: T
authors: Tokiwano
authors: Kenji
authors: K
authors: Watanabe
authors: Hideaki
authors: H
authors: Oikawa
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis; D003001:Cloning, Molecular; D003500:Cyclization; D004851:Epoxide Hydrolases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004852:Epoxy Compounds / Q000138:chemical synthesis / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D004987:Ethers / Q000138:chemical synthesis / Q000378:metabolism; D007476:Ionophores / Q000378:metabolism; D007832:Lasalocid / Q000096:biosynthesis*; D011108:Polymers / Q000138:chemical synthesis; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004852:Epoxy Compounds; D004987:Ethers; D007476:Ionophores; D011108:Polymers; D004851:Epoxide Hydrolases; D007832:Lasalocid