Examination of the role of DNA polymerase proofreading in the mutator effect of miscoding tRNAs.

ABSTRACT: We previously described Escherichia coli mutator tRNAs that insert glycine in place of aspartic acid and postulated that the elevated mutation rate results from generating a mutator polymerase. We suggested that the proofreading subunit of polymerase III, epsilon, is a likely target for the aspartic acid-to-glycine change that leads to a lowered fidelity of replication, since the altered epsilon subunits resulting from this substitution (approximately 1% of the time) are sufficient to create a mutator effect, based on several observations of mutD alleles. In the present work, we extended the study of specific mutD alleles and constructed 16 altered mutD genes by replacing each aspartic acid codon, in series, with a glycine codon in the dnaQ gene that encodes epsilon. We show that three of

SUBMITTER: Slupska MM 

PROVIDER: S-EPMC107632 | biostudies-literature | 1998 Nov

REPOSITORIES: biostudies-literature