title: Crystallographic and mutational analyses of cystathionine β-synthase in the H2S-synthetic gene cluster in Lactobacillus plantarum.
abstract: Cystathionine β-synthase (CBS) catalyzes the formation of l-cystathionine from l-serine and l-homocysteine. The resulting l-cystathionine is decomposed into l-cysteine, ammonia, and α-ketobutylic acid by cystathionine γ-lyase (CGL). This reverse transsulfuration pathway, which is catalyzed by both enzymes, mainly occurs in eukaryotic cells. The eukaryotic CBS and CGL have recently been recognized as major physiological enzymes for the generation of hydrogen sulfide (H2S). In some bacteria, including the plant-derived lactic acid bacterium Lactobacillus plantarum, the CBS- and CGL-encoding genes form a cluster in their genomes. Inactivation of these enzymes has been reported to suppress H2S production in bacteria; interestingly, it has been shown that H2S suppression increases their susceptibility to various antibiotics. In the present study, we characterized the enzymatic properties of the L. plantarum CBS, whose amino acid sequence displays a similarity with those of O-acetyl-l-serine sulfhydrylase (OASS) that catalyzes the generation of l-cysteine from O-acetyl-l-serine (l-OAS) and H2S. The L. plantarum CBS shows l-OAS- and l-cysteine-dependent CBS activities together with OASS activity. Especially, it catalyzes the formation of H2S in the presence of l-cysteine and l-homocysteine, together with the formation of l-cystathionine. The high affinity toward l-cysteine as a first substrate and tendency to use l-homocysteine as a second substrate might be associated with its enzymatic ability to generate H2S. Crystallographic and mutational analyses of CBS indicate that the Ala70 and Glu223 residues at the substrate binding pocket are important for the H2S-generating activity.
authors.affiliation: Graduate School of Biomedical and Health Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Matoba
authors.affiliation: Graduate School of Biomedical and Health Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: Graduate School of Biomedical and Health Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Hisae
authors.initials: H
authors.lastname: Izuhara-Kihara
authors.affiliation: Graduate School of Biomedical and Health Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Noda
authors.affiliation: Graduate School of Biomedical and Health Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Sugiyama
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003540:Cystathionine / Q000378:metabolism; D003541:Cystathionine beta-Synthase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006862:Hydrogen Sulfide / Q000737:chemistry / Q000378:metabolism; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism; D048191:Lactiplantibacillus plantarum / Q000201:enzymology / Q000235:genetics; D005810:Multigene Family; D020125:Mutation, Missense
chemical_list: D001426:Bacterial Proteins; D003540:Cystathionine; D006867:Hydrolases; C463961:homocysteinase; D003541:Cystathionine beta-Synthase; D006862:Hydrogen Sulfide
keywords: Lactobacillus plantarum; amino acid; crystal structure; cystathionine β-synthase; hydrogen sulfide