title: Biochemical characterization of RecA variants that contribute to extreme resistance to ionizing radiation.
abstract: Among strains of Escherichia coli that have evolved to survive extreme exposure to ionizing radiation, mutations in the recA gene are prominent and contribute substantially to the acquired phenotype. Changes at amino acid residue 276, D276A and D276N, occur repeatedly and in separate evolved populations. RecA D276A and RecA D276N exhibit unique adaptations to an environment that can require the repair of hundreds of double strand breaks. These two RecA protein variants (a) exhibit a faster rate of filament nucleation on DNA, as well as a slower extension under at least some conditions, leading potentially to a distribution of the protein among a higher number of shorter filaments, (b) promote DNA strand exchange more efficiently in the context of a shorter filament, and (c) are markedly less inhibited by ADP. These adaptations potentially allow RecA protein to address larger numbers of double strand DNA breaks in an environment where ADP concentrations are higher due to a compromised cellular metabolism.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, United States.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Piechura
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Tzu-Ling
authors.initials: TL
authors.lastname: Tseng
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Hsin-Fang
authors.initials: HF
authors.lastname: Hsu
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, United States.
authors.forename: Rose T
authors.initials: RT
authors.lastname: Byrne
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States.
authors.forename: Tricia A
authors.initials: TA
authors.lastname: Windgassen
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, United States.
authors.forename: Sindhu
authors.initials: S
authors.lastname: Chitteni-Pattu
authors.affiliation: Department of Biological Sciences, Louisiana State University and A & M College, Baton Rouge, LA 70803, United States.
authors.forename: John R
authors.initials: JR
authors.lastname: Battista
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Hung-Wen
authors.initials: HW
authors.lastname: Li
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, United States. Electronic address: cox@biochem.wisc.edu.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Cox
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D011836:Radiation Tolerance / Q000235:genetics*; D011839:Radiation, Ionizing; D011938:Rec A Recombinases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D059767:Recombinational DNA Repair / Q000235:genetics* / Q000502:physiology
chemical_list: D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011938:Rec A Recombinases
keywords: DNA repair; Double strand break repair; Evolution; Radiation resistance; RecA protein