SELECTION OF BACTERIOPHAGE-T4 ANTIMUTATOR DNA-POLYMERASES - A LINK BETWEEN PROOFREADING AND SENSITIVITY TO PHOSPHONOACETIC ACID

During DNA replication, DNA polymerases alternate between DNA synthesi s and proofreading the newly synthesized DNA. In order to understand t he molecular details of how DNA polymerases determine the balance betw een polymerase and proofreading activities, it would be useful to have mutants which switch between the two activities either more or less f requently. Antimutator DNA polymerases switch more frequently and thus have more opportunity for proofreading. We have observed that mutant DNA polymerases which proofread less frequently have a mutator phenoty pe and are inhibited by the pyrophosphate analogue phosphonoacetic aci d. Sensitivity to phosphonoacetic acid can be used to isolate second-s ite suppressor mutations. These suppressor mutations encode amino acid substitutions which produce antimutator DNA polymerases.