Differential suppressor effects of the ssb-1 and ssb-113 alleles on uvrD mutator of Escherichia coli in DNA repair and mutagenesis.
We have constructed double mutants carrying either ssb-1 or ssb-113 alleles, which encode temperature-sensitive single strand DNA binding proteins (SSB), and the uvrD::Tn5 allele causing deficiency in DNA helicase II, and have examined sensitivity to ultraviolet light (UV), recombination and spontaneous as well as UV-induced mutagenesis. We have found in a recA+ background that (i) none of the ssb uvrD double mutants was more sensitive to UV than either single mutant; (ii) the ssb-1 allele partially suppressed the strong UV sensitivity of uvrD::Tn5 mutants; (iii) in the recA730 background with constitutive SOS expression, the ssb-1 and ssb-113 alleles suppressed the strong UV-sensitivity caused by the uvrD::Tn5 mutation; (iv) in ssb-113 mutants, the level of recombination was reduced only 10-fold but 100-fold in ssb-1 mutants, showing that there was no correlation between the DNA repair deficiency and the recombination deficiency; (v) the hyper-recombination phenotype of the uvrD::Tn5 mutant was suppressed by the addition of either the ssb-1 or the ssb-113 allele; (vi) no addition of the spontaneous mutator effects promoted by the uvrD::Tn5 and the ssb-113 alleles was observed. These results suggest a possible functional interaction between SSB and Helicase II in DNA repair and mutagenesis.
Quiñones
A
A
Wissenschaftsbereich Genetik, Martin-Luther-Universität Halle-Wittenberg, DDR-Halle/Saale.
Piechocki
R
R
D000251:Adenosine Triphosphatases / Q000235:genetics; D000483:Alleles; D004265:DNA Helicases; D004260:DNA Repair; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000528:radiation effects; D029968:Escherichia coli Proteins; D009154:Mutation; D010641:Phenotype; D013489:Suppression, Genetic; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D000251:Adenosine Triphosphatases; C506746:UvrD protein, E coli; D004265:DNA Helicases