Novel substrate specificity of glutathione synthesis enzymes from Streptococcus agalactiae and Clostridium acetobutylicum.
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.
Kino
Kuniki
K
Department of Applied Chemistry, School of Science and Engineering, Waseda University, Ohkubo 3-4-1, Tokyo 169-8555, Japan. kkino@waseda.jp
Kuratsu
Shoko
S
Noguchi
Atsushi
A
Kokubo
Masahiro
M
Nakazawa
Yuji
Y
Arai
Toshinobu
T
Yagasaki
Makoto
M
Kirimura
Kohtaro
K
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
D005981:Glutathione Synthase; D005978:Glutathione