title: Allosteric regulation of epoxide opening cascades by a pair of epoxide hydrolases in monensin biosynthesis.
abstract: Multistep catalysis of epoxide hydrolase/cyclase in the epoxide opening cascade is an intriguing issue in polyether biosynthesis. A pair of structurally homologous epoxide hydrolases was found in gene clusters of ionophore polyethers. In the epoxide opening reactions with MonBI and MonBII involved in monensin biosynthesis, we found that MonBII and catalytically inactive MonBI mutant catalyzed two-step reactions of bisepoxide substrate analogue to afford bicyclic product although MonBII alone catalyzed only the first cyclization. The X-ray crystal structure of MonBI dimers suggested the importance of the KSD motif in MonBI/MonBI interaction, which was further supported by gel filtration chromatography of wild-type MonBI and mutant MonBI. The involvement of the KSD motif in heterodimer formation was confirmed by in vitro assay. Direct evidence of MonBI/MonBII interaction was obtained by native mass spectrometry. Its dissociation constant was determined as 2.21 × 10(-5) M by surface plasmon resonance. Our results suggested the involvement of an allosteric regulation mechanism by MonBI/MonBII interaction in monensin skeletal construction.
authors: Division of Chemistry, Graduate School of Science and ‡Faculty of Pharmaceutical Sciences, Hokkaido University , Sapporo 060-0810, Japan.
authors: Atsushi
authors: A
authors: Minami
authors: Toyoyuki
authors: T
authors: Ose
authors: Kyohei
authors: K
authors: Sato
authors: Azusa
authors: A
authors: Oikawa
authors: Kimiko
authors: K
authors: Kuroki
authors: Katsumi
authors: K
authors: Maenaka
authors: Hiroki
authors: H
authors: Oguri
authors: Hideaki
authors: H
authors: Oikawa
mesh_terms: D000494:Allosteric Regulation; D018360:Crystallography, X-Ray; D004851:Epoxide Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008985:Monensin / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D011487:Protein Conformation; D055503:Protein Multimerization; D013302:Streptomyces / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D008985:Monensin; D004851:Epoxide Hydrolases