Title: Reversion of Frameshift Mutations by Mutator Genes in <i>Escherichia coli</i>
Abstract: The Escherichia coli mutator genes mutU4, mutS3 , and mut-25 (a possible allele of mutL ), previously known to induce transitional base changes, increased significantly the frequencies of reversion of lacZ frameshift mutations. mutT1 , previously shown to induce only the transversion of adenine-thymine to cytosine-guanine, had no effect on the reversion of lacZ frameshift mutations. With mutator genes other than mutT1 , small increases were found in the frequencies of reversion of trpA frameshift mutations.