Drosophila Rrp1 complements E. coli xth nfo mutants: protection against both oxidative and alkylation-induced DNA damage.
Drosophila Rrp1 protein has four tightly associated enzymatic activities: DNA strand transfer, ssDNA renaturation, dsDNA 3'-exonuclease and apurinic/apyrimidinic (AP) endonuclease. The carboxy-terminal region of Rrp1 is homologous to Escherichia coli exonuclease III and several eukaryotic AP endonucleases. All members of this protein family cleave abasic sites. Rrp1 protein was expressed under the control of the E. coli RNA polymerase tac promoter (pRrp1-tac) in two repair deficient E. coli strains (BW528 and LG101) lacking both exonuclease III (xth) and endonuclease IV (nfo). Rrp1 confers resistance to killing by oxidative, antitumor and alkylating agents that damage DNA (hydrogen peroxide, t-butylhydroperoxide, bleomycin, methyl methanesulfonate, and mitomycin C). Complementation of the repair deficiency by Rrp1 provides up to a two log increase in survival and requires the C-terminal nuclease region of Rrp1, but not its N-terminal region. The AP endonuclease activity in extracts from the repair deficient strain LG101 is increased up to 12-fold when the strain contains pRrp1-tac. These results indicate that pRrp1-tac directs the synthesis of active enzyme, and that the nuclease activities of Rrp1 are likely to be the cause of the increased resistance to DNA damage of the mutant cells.
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Laboratory of Genetics D3-04, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
Huang
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Sander
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D000478:Alkylation; D000818:Animals; D004249:DNA Damage; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D005816:Genetic Complementation Test; D009154:Mutation; D009713:Nucleotidyltransferases / Q000235:genetics* / Q000378:metabolism; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic
D029721:Drosophila Proteins; D029968:Escherichia coli Proteins; D009713:Nucleotidyltransferases; C061900:Rrp1 protein, Drosophila; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase