Protective function of the recombinant Oshsp18.0-CII protein, a class II small heat shock protein of rice, in Escherichia coli.

All plants synthesize multiple families of small heat shock proteins (sHSP). A cDNA clone, Oshsp18.0-CII, encoding an 18.0 kDa class II sHSP was isolated from rice previously. The function of the rice class II sHSP was studied by overproduction of the Oshsp18.0-CII fusion protein in transformed Escherichia coli cells. The results suggest that heterologous expression of the Oshsp18.0-CII fusion protein increases thermotolerance of E. coli cells in vivo and provided thermoprotection to E. coli soluble proteins in vitro. The survival rate of Oshsp 18.0-CII fusion protein-accumulating cells treated at 50°C for 1 h was almost 1000- fold higher than that of the control cells transformed with pET32a expression vector. Overproduction of the Oshsp18.0-CII fusion protein in E. coli also confers tolerance of E. coli cells to ultraviolet (UV) irradiation. The post-UV survival of the Oshsp18.0-CII fusion protein-accumulating cells is about 7.29-fold over that of the control cells transformed with pET32a expression vector when exposed to 1700 μJ of UV. There is almost no post-UV survival (≦0.4%) in the untransformed cells after exposing to 900 μJ UV light. [ABSTRACT FROM AUTHOR]