Insights in the spore resistance to low and high LET particle radiation: the interplay of DNA repair mechanisms

摘要

Based on their unique resistance to various space parameters, spores of Bacillus subtilis are one of the model systems used for astrobiological research to effects of the galactic cosmic radiation. The role of various DNA repair mechanisms [non-homologous end joining (NHEJ), homologous recombination (HR), spore photoproduct lyase (SP lyase) and DNA polymerase I] and major small, acid-soluble spore proteins (α/β-type SASP) in B. subtilis spore resistance to accelerated heavy ions (Helium, Argon and Iron; in a linear energy transfer (LET) range of 2 to 200 keV/um) and X-rays has been studied. These results indicate that NHEJ provides an efficient pathway during spore germination for repair of DNA double-strand breaks induced by HZE particles. In addition, the loss of the α/β-type SASP leads to a significant radiosensitivity to ionizing radiation, implicating the essential function of these spore proteins as pro-tectants of spore DNA to ionizing radiation and heavy particle damage.