Characterization of Rhizobium tropici CIAT899 gshB promoter

MUGLIA, C. I.; AGUILAR, O. M.

Iguazú, Misiones, Argentina

Congreso; XL Reunión Anual SOCIEDAD ARGENTINA DE INVESTIGACIÓN BIOQUÍMICA Y BIOLOGÍA MOLECULAR; 2004

SOCIEDAD ARGENTINA DE INVESTIGACIÓN BIOQUÍMICA Y BIOLOGÍA MOLECULAR

The tripeptide glutathione is ubiquitous among most organisms studied, being the most abundant low molecular weight thiol found in most cells. Many functions have been attributed to this compound, which include participation in sulphur metabolism, maintenance of cell redox state, disulfide bond formation, detoxification, and stress protection. We have previously obtained a R. tropici mutant in gshB gene - which codifies for glutathione synthetase, the first enzyme in glutathione biosynthesis- which is sensitive to acid, oxidative and saline stress. We have shown that transcription of gshB transiently increases in response to an acid shift, in addition a putative promoter upstream from the start of transcription of this gene was identified, by sequence analysis. This putative promoter sequence was found to show similarity to that of rhizobial recA promoters, which suggests that gshB could be part of rhizobial general SOS response. Further analysis of this upstream sequence by using gene fusions confirmed that it displays transcriptional promoter activity that indeed responds to an acidic environment.