Extremely radiation-resistant mutants of a halophilic archaeon with increased single-stranded DNA-binding protein (RPA) gene expression

DeVeaux, L. C. and Muller, J. A. and Smith, J. and Petrisko, Jill E. and Wells, D. P. and DasSarma, S. (2007) Extremely radiation-resistant mutants of a halophilic archaeon with increased single-stranded DNA-binding protein (RPA) gene expression. Radiation Research, 168 (4). pp. 507-514. ISSN 0033-7587


Extremely halophilic archaea are highly resistant to multiple stressors, including radiation, desiccation and salinity. To study the basis of stress resistance and determine the maximum tolerance to ionizing radiation, we exposed cultures of the model halophile Halobacterium sp. NRC-1 to four cycles of irradiation with high doses of 18-20 MeV electrons. Two independently obtained mutants displayed an LD50 > 11 kGy, which is higher than the LD50 of the extremely radiation-resistant bacterium Deinococcus radiodurans. Whole-genome transcriptome analysis comparing the mutants to the parental wild-type strain revealed up-regulation of an operon containing two single-stranded DNA-binding protein (RPA) genes, VNG2160 (rfa3) and VNG2162, and a third gene of unknown function, VNG2163. The putative transcription start site for the rfa3 operon was mapped ∼40 bp upstream of the ATG start codon, and a classical TATA-box motif was found centered about 25 bp further upstream. We propose that RPA facilitates DNA repair machinery and/or protects repair intermediates to maximize the ionizing radiation resistance of this archaeon.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to paper due to publisher copyright restrictions.
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 26 Mar 2010 07:03
Last Modified: 02 Jul 2013 23:43
Uncontrolled Keywords: protein rfa3; single stranded DNA binding protein; unclassified drug; replication protein A, Archaea; Bacteria (microorganisms); Deinococcus radiodurans; Halobacterium sp. NRC-1, Base Sequence; DNA Repair; Gene Expression Regulation
Fields of Research : 06 Biological Sciences > 0605 Microbiology > 060501 Bacteriology
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970106 Expanding Knowledge in the Biological Sciences
Identification Number or DOI: 10.1667/RR0935.1
URI: http://eprints.usq.edu.au/id/eprint/7200

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