Role for the cyanobacterial HtpG in protection from oxidative stress.
The heat shock protein HtpG, which is a homolog of HSP90, is essential for basal and acquired thermotolerances in cyanobacteria. Recently we demonstrated that HtpG was involved in the acclimation to low temperatures in cyanobacteria. In this study, we elucidated a role of HtpG in the cyanobacterium Synechococcus sp. PCC 7942, in the acclimation to oxidative stress that was caused by high irradiance and/or methyl viologen. The inactivation of the htpG gene resulted in a decrease in the survival rate and an increase in the photoinhibition of photosystem II when cells in a liquid medium were incubated under high light conditions. The htpG mutant was highly sensitive to methyl viologen when it was grown on an agar plate. High irradiance and/or methyl viologen greatly increased the expression of the htpG gene as well as the groEL gene in the wild-type strain. Taken together, our results suggest that HtpG may play a role by itself or with other molecular chaperones in the acclimation to oxidative stress.
Hossain
Md Motarab
MM
Department of Biochemistry and Molecular Biology, Saitama University, Saitama 338-8570, Japan.
Nakamoto
Hitoshi
H
D001426:Bacterial Proteins; D018834:Chaperonin 60 / Q000096:biosynthesis; D003080:Cold Temperature; D000458:Cyanobacteria / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis / Q000502:physiology*; D008027:Light; D009154:Mutation; D018384:Oxidative Stress; D010269:Paraquat / Q000378:metabolism
D001426:Bacterial Proteins; D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; C066720:HtpG protein, bacteria; C063842:dnaK protein, E coli; D010269:Paraquat