Novel substrate specificity of glutathione synthesis enzymes from Streptococcus agalactiae and Clostridium acetobutylicum

• Published in: Biochemical and biophysical research communications Vol. 352; no. 2; pp. 351 - 359
• Main Authors: Kino, Kuniki, Kuratsu, Shoko, Noguchi, Atsushi, Kokubo, Masahiro, Nakazawa, Yuji, Arai, Toshinobu, Yagasaki, Makoto, Kirimura, Kohtaro
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.01.2007
• Subjects: 60 APPLIED LIFE SCIENCES; AMINO ACID SEQUENCE; AMINO ACIDS; BIOSYNTHESIS; CLOSTRIDIUM ACETOBUTYLICUM; Clostridium acetobutylicum - classification; Clostridium acetobutylicum - enzymology; Enzyme Activation; ESCHERICHIA COLI; Firmicutes; GENES; GLUTATHIONE; Glutathione - chemistry; Glutathione Synthase - chemistry; Glutathione synthetase; LIGASES; Species Specificity; SPECIFICITY; STREPTOCOCCUS; Streptococcus agalactiae; Streptococcus agalactiae - classification; Streptococcus agalactiae - enzymology; Substrate Specificity; SUBSTRATES; γ-Glutamylcysteine synthetase; γ-Glutamylpeptide; Clostridium acetobutylicum; γ-Glutamylcysteine synthetase; γ-Glutamylpeptide; Streptococcus agalactiae; Glutathione; Glutathione synthetase
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2006.11.016

Glutathione (GSH) is synthesized by γ-glutamylcysteine synthetase (γ-GCS) and glutathione synthetase (GS) in living organisms. Recently, bifunctional fusion protein, termed γ-GCS–GS catalyzing both γ-GCS and GS reactions from gram-positive firmicutes Streptococcus agalactiae, has been reported. We revealed that in the γ-GCS activity, S. agalactiae γ-GCS–GS had different substrate specificities from those of Escherichia coli γ-GCS. Furthermore, S. agalactiae γ-GCS–GS synthesized several kinds of γ-glutamyltripeptide, γ-Glu-Xaa-Gly, from free three amino acids. In Clostridium acetobutylicum, the genes encoding γ-GCS and putative GS were found to be immediately adjacent by BLAST search, and had amino acid sequence homology with S. agalactiae γ-GCS–GS, respectively. We confirmed that the proteins expressed from each gene showed γ-GCS and GS activity, respectively. C. acetobutylicum GS had broad substrate specificities and synthesized several kinds of γ-glutamyltripeptide, γ-Glu-Cys-Xaa. Whereas the substrate specificities of γ-GCS domain protein and GS domain protein of S. agalactiae γ-GCS–GS were the same as those of S. agalactiae γ-GCS–GS.