Tobacco mitochondrial small heat shock protein NtHSP24.6 adopts a dimeric configuration and has a broad range of substrates

Abstract

There is a broad range of different small heat shock proteins (sHSPs) that have diverse structural and functional characteristics. To better understand the functional role of mitochondrial sHSP, NtHSP24.6 was expressed in Escherichia coli with a hexahistidine tag and purified. The protein was analyzed by non-denaturing PAGE, chemical cross-linking and size exclusion chromatography and the H6NtHSP24.6 protein was found to form a dimer in solution. The in vitro functional analysis of H6NtHSP24.6 using firefly luciferase and citrate synthase demonstrated that this protein displays typical molecular chaperone activity. When cell lysates of E. coli were heated after the addition of H6NtHSP24.6, a broad range of proteins from 10 to 160 kD in size remained in the soluble state. These results suggest that NtHSP24.6 forms a dimer and can function as a molecular chaperone to protect a diverse range of proteins from thermal aggregation.