Detection and analysis of DNA-binding proteins from the radioresistant bacterium Deinococcus radiodurans

Deinococcus radiodurans (D. radiodurans) possesses a prominent ability to repair DNA injury induced by various DNA-damaging agents including mitomycin C, ultraviolet light and ionizing radiation. In order to demonstrate the effect of DNA-binding proteins (DBPs) on the radioresistance of D. Radiodurans, the DBPs were detected from the bacteria and the amino-acid (aa) sequences of some DBPs were analysed. The chromosomal DNA labelled with Digoxin (DIG) was used as probe. The protein extract was prepared by ultrasonication the bacteria cells and centrifuging at 4 degree C. South-western blotting was employed for detecting DBPs. the results indicated that eight kinds of DBPs were detected from the wild type D. radiodurans, the molecular weights of them are 122, 93, 33, 29, 16, 15, 14 and 12 kDa respectively. The expression levels of 93 kDa and 33 kDa DBPs from wild type KR1 were changed with different culture media and different culture time. The results of N-terminal aa sequence analysis showed that these two DBPs were not homologous as compared with other known proteins according to FASTA and BLAST libraries, i.e. they were two novel proteins. It could be concluded that Dbp and their aa sequences of D. radiodurans were very different from that of other bacteria. It was suggested that DBPs, especially 93 kDa and 33 kDa DBPs, might be closely related with the radioresistance of D. radiodurans