| Title | A Major Role for Non-Enzymatic Antioxidant Processes in the Radioresistance of Halobacterium salinarum. |
| Publication Type | Journal Article |
| Year of Publication | 2011 |
| Authors | Robinson, Courtney K., Webb Kim, Kaur Amardeep, Jaruga Pawel, Dizdaroglu Miral, Baliga Nitin S., Place Allen, and Diruggiero Jocelyne |
| Journal | Journal of bacteriology |
| Date Published | 2011 Jan 28 |
| ISSN | 1098-5530 |
| Abstract | Oxidative stress occurs when the generation of reactive oxygen species (ROS) exceeds the capacity of the cell's endogenous systems to neutralize them. Our analyses of the cellular damage and oxidative stress responses of the archaeon Halobacterium salinarum exposed to ionizing radiation (IR) revealed a critical role played by non-enzymatic antioxidant processes in the resistance of H. salinarum to IR. ROS scavenging enzymes were essential for resistance to chemical oxidants, yet those enzymes were not necessary for H. salinarum resistance to IR. We found that protein-free cell extracts from H. salinarum provided a high level of protection for protein activity against IR, in vitro, but did not protect DNA significantly. When compared with cell extracts of radiation sensitive bacteria, H. salinarum extracts were enriched in manganese, amino acids, and peptides supporting an essential role in ROS scavenging for those small molecules, in vivo. With regard to chemical oxidants, we showed that the damage caused by γ-irradiation was mechanistically different than that produced by hydrogen peroxide or by the superoxide-generating redox-cycling drug paraquat. The data presented support the idea that IR resistance is most likely achieved by a "metabolic route" with a combination of tightly coordinated physiological processes. |
