title: Novel substrate specificity of glutathione synthesis enzymes from Streptococcus agalactiae and Clostridium acetobutylicum.
abstract: Glutathione (GSH) is synthesized by gamma-glutamylcysteine synthetase (gamma-GCS) and glutathione synthetase (GS) in living organisms. Recently, bifunctional fusion protein, termed gamma-GCS-GS catalyzing both gamma-GCS and GS reactions from gram-positive firmicutes Streptococcus agalactiae, has been reported. We revealed that in the gamma-GCS activity, S. agalactiae gamma-GCS-GS had different substrate specificities from those of Escherichia coli gamma-GCS. Furthermore, S. agalactiae gamma-GCS-GS synthesized several kinds of gamma-glutamyltripeptide, gamma-Glu-X(aa)-Gly, from free three amino acids. In Clostridium acetobutylicum, the genes encoding gamma-GCS and putative GS were found to be immediately adjacent by BLAST search, and had amino acid sequence homology with S. agalactiae gamma-GCS-GS, respectively. We confirmed that the proteins expressed from each gene showed gamma-GCS and GS activity, respectively. C. acetobutylicum GS had broad substrate specificities and synthesized several kinds of gamma-glutamyltripeptide, gamma-Glu-Cys-X(aa). Whereas the substrate specificities of gamma-GCS domain protein and GS domain protein of S. agalactiae gamma-GCS-GS were the same as those of S. agalactiae gamma-GCS-GS.
authors.affiliation: Department of Applied Chemistry, School of Science and Engineering, Waseda University, Ohkubo 3-4-1, Tokyo 169-8555, Japan. kkino@waseda.jp
authors.forename: Kuniki
authors.initials: K
authors.lastname: Kino
authors.forename: Shoko
authors.initials: S
authors.lastname: Kuratsu
authors.forename: Atsushi
authors.initials: A
authors.lastname: Noguchi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kokubo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakazawa
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Arai
authors.forename: Makoto
authors.initials: M
authors.lastname: Yagasaki
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Kirimura
mesh_terms: D046969:Clostridium acetobutylicum / Q000145:classification / Q000201:enzymology*; D004789:Enzyme Activation; D005978:Glutathione / Q000737:chemistry*; D005981:Glutathione Synthase / Q000737:chemistry*; D013045:Species Specificity; D013292:Streptococcus agalactiae / Q000145:classification / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D005981:Glutathione Synthase; D005978:Glutathione