Abstract
The model Archaeon Halobacterium sp. NRC-1 is an extreme halophile known for its resistance to multiple stressors, including electron-beam and ultraviolet radiation. It is a well-developed system with a completely sequenced genome and extensive post-genomic tools for the study of a variety of biological processes. To further understand the mechanisms of Halobacterium's, radiation resistance, we previously reported the selection for multiple independent highly resistant mutants using repeated exposure to high doses of 18-20 MeV electrons using a medical S-band Linac. Molecular analysis of the transcriptional profile of several of these mutants revealed a single common change: upregulation of the rfa3 operon. These genes encode proteins homologous to the subunits of eukaryotic Replication Protein A (RPA), a DNA binding protein with major roles in DNA replication, recombination, and repair. This operon has also been implicated in a somewhat lesser role in resistance of wild type Halobacterium to ultraviolet radiation, suggesting common mechanisms for resistance. To further understand the mechanism of radiation resistance in the mutant strains, we measured the survival after exposure to both electron-beam and ultraviolet radiation, UV-A, B, and C All mutant strains showed increased resistance to electrons when compared with the parent. However, the mutant strains do not display increased UV resistance, and in one case is more sensitive than the parent strain. Thus, the protective role of increased RPA expression within a cell may be specific to the DNA damage caused by the different physical effects induced by high energy electron-beam radiation.
Original language | English (US) |
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Pages (from-to) | 993-996 |
Number of pages | 4 |
Journal | AIP Conference Proceedings |
Volume | 1099 |
DOIs | |
State | Published - 2009 |
Externally published | Yes |
Event | 20th International Conference on the Application of Accelerators in Research and Industry, CAARI 2008 - Fort Worth, TX, United States Duration: Aug 10 2008 → Aug 15 2008 |
Keywords
- DNA damage
- Extremophile
- Radiation resistance
ASJC Scopus subject areas
- General Physics and Astronomy