Abstract
Small heat shock proteins (Hsps), which have been detected in all the domains are a group of proteins having molecular masses ranging from 15 to 42 kDa. Small Hsps can suppress aggregation of heat-denatured proteins. We have already shown that methyl viologen induces the small Hsp HspA in the cyanobacterium Synechocystis sp. PCC 6803. In order to elucidate a role of small Hsp under oxidative stress, we analyzed the phenotype of an hspA knockout mutant of Synechocystis sp. PCC 6803.
The hspA mutant grew more slowly and its viability was lost more rapidly in the presence of 5 μM methyl viologen, as compared with the wild type. Photosynthetic pigments such as chlorophyll and phycocyanins were lost more rapidly in the mutant than the wild type after the addition of methyl viologen. These results indicate that small Hsp plays a role under oxidative stress.
