RESUMO
In order to examine radiation-induced proteins in an extremely radio-resistant bacterium, it became possible to perform comparative proteomic analysis on radio-resistance Bacillus megaterium WHO as a wild-type strain for the first time. Variation in cellular proteins profiles of the Bacillus megaterium WHO after 5 KGy gamma -irradiation were analyzed by two-dimensional poly acryl amide gel electrophoresis and silver staining. Although many spots were decreased in density, our primary focus was on the induced spots. The expression level of 48 protein spots showed significant increase under radiation stress. Of these spots, 45 were identified with MALDI TOF-TOF [peptide mass fingerprinting using matrix-assisted laser desorption/ionization time of flight mass spectrometry] after tryptic in-gel digestion. These proteins exhibited various interesting cellular functions including: [i] transcription [ii] translation [iii] signal transduction [iv] carbohydrate transport and metabolism [v] energy production and conversion [vi] nucleotide transport and metabolism [vii] posttranslational modification, protein turnover and chaperones [viii] DNA replication, recombination and repair [ix] bacterial general stress response and [iix] different and some still unknown functions. The appearance of four spots [24, 27, 30 and 36] in response to gamma -irradiation was the distinct result of present study. These proteins appear to mediate processes related to ionizing radiation resistance and clearly demonstrate that Bacillus megaterium WHO, significantly has mechanisms contribute to the ionizing radiation resistance