Abstract
Five polypeptides in the soluble fraction of chloroplasts and three polypeptides in the thylakoid membranes in chloroplasts from green spores of the fern Osmunda japonica decreased during spore germination. The 22-kDa protein in thylakoid membranes almost completely disappeared during germination over 48 h. We had purified the 22-kDa protein and analyzed the cDNA encoding the protein. A computer search of the protein database revealed similar features between the 22-kDa protein and the LEA 3 homolog of Deinococcus radiodurans. In this study, we have examined effects of this 22-kDa protein on UV-tolerance in Escherichia coli. A cDNA encoding the mature 22-kDa protein with a His-Flag was wxpressed in E. coli BL21(DE3)pLysS. The transformed cells produced the 22-kDa protein regardless of the presence of IPTG and showed a higher survival rate against UV-irradiation. This may suggest that the 22-kDa protein has the DNA repair capability.
