title: Crystal structures of halohydrin hydrogen-halide-lyases from Corynebacterium sp. N-1074.
abstract: Halohydrin hydrogen-halide-lyase (H-Lyase) is a bacterial enzyme that is involved in the degradation of halohydrins. This enzyme catalyzes the intramolecular nucleophilic displacement of a halogen by a vicinal hydroxyl group in halohydrins to produce the corresponding epoxides. The epoxide products are subsequently hydrolyzed by an epoxide hydrolase, yielding the corresponding 1, 2-diol. Until now, six different H-Lyases have been studied. These H-Lyases are grouped into three subtypes (A, B, and C) based on amino acid sequence similarities and exhibit different enantioselectivity. Corynebacterium sp. strain N-1074 has two different isozymes of H-Lyase, HheA (A-type) and HheB (B-type). We have determined their crystal structures to elucidate the differences in enantioselectivity among them. All three groups share a similar structure, including catalytic sites. The lack of enantioselectivity of HheA seems to be due to the relatively wide size of the substrate tunnel compared to that of other H-Lyases. Among the B-type H-Lyases, HheB shows relatively high enantioselectivity compared to that of HheBGP1 . This difference seems to be due to amino acid replacements at the active site tunnel. The binding mode of 1, 3-dicyano-2-propanol at the catalytic site in the crystal structure of the HheB-DiCN complex suggests that the product should be (R)-epichlorohydrin, which agrees with the enantioselectivity of HheB. Comparison with the structure of HheC provides a clue for the difference in their enantioselectivity.
authors.affiliation: Yokohama Research Laboratories, Mitsubishi Rayon Co. Ltd., Yokohama, Kanagawa, 230-0053, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Watanabe
authors.affiliation: Yokohama Research Laboratories, Mitsubishi Rayon Co. Ltd., Yokohama, Kanagawa, 230-0053, Japan.
authors.forename: Fujio
authors.initials: F
authors.lastname: Yu
authors.affiliation: Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588, Japan.
authors.forename: Akashi
authors.initials: A
authors.lastname: Ohtaki
authors.affiliation: Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Yamanaka
authors.affiliation: Instrumentation Analysis Center, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Noguchi
authors.affiliation: Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yohda
authors.affiliation: Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588, Japan.|Department of Life Science, Faculty and Graduate School of Engineering and Resource Science, Akita University, Akita City, Akita, 010-8502, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Odaka
mesh_terms: D020134:Catalytic Domain; D003352:Corynebacterium / Q000201:enzymology*; D018360:Crystallography, X-Ray; D004811:Epichlorohydrin / Q000378:metabolism; D008190:Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009570:Nitriles / Q000737:chemistry / Q000378:metabolism; D020005:Propanols / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D013237:Stereoisomerism
chemical_list: C000622431:1,3-dicyano-2-propanol; D009570:Nitriles; D020005:Propanols; D004811:Epichlorohydrin; D008190:Lyases; C066813:haloalcohol hydrogen-halide lyase
keywords: NAD(P)H-dependent short-chain dehydrogenases/reductase; Rossmann fold; crystal structure; enantioselectivity; halohydrin; lyase