Document Type: Research Paper
Biology Department, Faculty of Science, University of Zanjan, P.O. Box 313, Zanjan, I.R. Iran.
Departments of Biophysics and Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14155-111, Tehran, I.R. Iran.
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 wildtype
strain for the first time. Variation in cellular proteins profiles of the Bacillus megaterium WHO after 5
KGy γ-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 γ-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.