Mutational alteration of Bacillus subtilis DNA polymerase 3 to hydroxyphenylazopyrimidine resistance: polymerase 3 is necessary for DNA replication |
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Authors: | N R Cozzarelli R L Low |
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Affiliation: | 1. Department of Biochemistry, University of Chicago, Chicago, Illinois 60637 USA;2. Department of Biophysics, University of Chicago, Chicago, Illinois 60637 USA |
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Abstract: | A spontaneous mutant of resistant to killing by two hydroxyphenylazopyrimidines has been isolated. The DNA polymerase III of this mutant is resistant to inhibition by these drugs. The Ki for 6-(p-hydroxyphenylazo)-uracil (HPUra) is 20 μM, about 40 times higher than the Ki of the wild-type enzyme. The mutant and wild-type polymerases behave similarly during purification, are sensitive to N-ethylmaleimide and to 0.1 M KCl, and have the same Km for dGTP (0.5 μM). The HPUra inhibition of both enzymes is attenuated competitively by dGTP. We conclude that polymerase III is the target for hydroxyphenylazopyrimidines , and since the drugs specifically inhibit replicative DNA synthesis, polymerase III is necessary for DNA replication. |
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