The gshB gene in the cyanobacterium Synechococcus sp. PCC 7942 encodes a functional glutathione synthetase

Noriko Okumura; Kazumori Masamoto; Hajime Wada

doi:10.1099/00221287-143-9-2883

Volume 143, Issue 9

Research Article

Free

The gshB gene in the cyanobacterium Synechococcus sp. PCC 7942 encodes a functional glutathione synthetase

Noriko Okumura¹, Kazumori Masamoto¹ and Hajime Wada²
View Affiliations Hide Affiliations

Affiliations: ¹ Biological Laboratory, Faculty of Education, Kumamoto University, Kurokami, Kumamoto 860, Japan ² Department of Biology, Faculty of Science, Kyushu University, Fukuoka 810, Japan
Author for correspondence: Hajime Wada. Tel: +81 92 726 4761. Fax: +81 92 726 4644. e-mail: [email protected]
Published: 01 September 1997 https://doi.org/10.1099/00221287-143-9-2883

Abstract

Summary: The gene homologous to glutathione synthetase of Escherichia coli was inactivated in the cyanobacterium Synechococcus sp. PCC 7942. The region of genomic DNA including the mutation site was isolated from the mutant by plasmid rescue and the native gene of the wild-type was cloned from a genomic DNA library of the wild-type using the flanking DNA as a probe. The wild-type gene, designated gshB, encodes a polypeptide of 323 amino acids with a molecular mass of 35 kDa. The deduced amino acid sequence resembles glutathione synthetases of bacteria, but not those of higher organisms. When gshB was overexpressed in E. coli, glutathione synthetase activity was increased markedly in the E. coli extract. In addition, the Synechococcus sp. PCC 7942 gshB mutants had lost their ability to synthesize glutathione. These findings demonstrate that the gshB gene of Synechococcus sp. PCC 7942 is a structural gene for glutathione synthetase and is involved in the biosynthesis of glutathione.