title: Resistance of Bacillus subtilis spore DNA to lethal ionizing radiation damage relies primarily on spore core components and DNA repair, with minor effects of oxygen radical detoxification.
abstract: The roles of various core components, including α/β/γ-type small acid-soluble spore proteins (SASP), dipicolinic acid (DPA), core water content, and DNA repair by apurinic/apyrimidinic (AP) endonucleases or nonhomologous end joining (NHEJ), in Bacillus subtilis spore resistance to different types of ionizing radiation including X rays, protons, and high-energy charged iron ions have been studied. Spores deficient in DNA repair by NHEJ or AP endonucleases, the oxidative stress response, or protection by major α/β-type SASP, DPA, and decreased core water content were significantly more sensitive to ionizing radiation than wild-type spores, with highest sensitivity to high-energy-charged iron ions. DNA repair via NHEJ and AP endonucleases appears to be the most important mechanism for spore resistance to ionizing radiation, whereas oxygen radical detoxification via the MrgA-mediated oxidative stress response or KatX catalase activity plays only a very minor role. Synergistic radioprotective effects of α/β-type but not γ-type SASP were also identified, indicating that α/β-type SASP's binding to spore DNA is important in preventing DNA damage due to reactive oxygen species generated by ionizing radiation.
authors.affiliation: German Aerospace Center (DLR e.V.), Institute of Aerospace Medicine, Radiation Biology Department, Cologne, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Moeller
authors.forename: Marina
authors.initials: M
authors.lastname: Raguse
authors.forename: Günther
authors.initials: G
authors.lastname: Reitz
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okayasu
authors.forename: Zuofeng
authors.initials: Z
authors.lastname: Li
authors.forename: Stuart
authors.initials: S
authors.lastname: Klein
authors.forename: Peter
authors.initials: P
authors.lastname: Setlow
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Nicholson
mesh_terms: D001412:Bacillus subtilis / Q000528:radiation effects*; D001426:Bacterial Proteins / Q000378:metabolism; D004260:DNA Repair; D004269:DNA, Bacterial / Q000528:radiation effects*; D010848:Picolinic Acids / Q000378:metabolism; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species / Q000378:metabolism; D013171:Spores, Bacterial / Q000528:radiation effects*; D014867:Water / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D010848:Picolinic Acids; D017382:Reactive Oxygen Species; C030069:spore-specific proteins, Bacillus; D014867:Water; C004860:dipicolinic acid