Transient mutators: a semiquantitative analysis of the influence of translation and transcription errors on mutation rates.
A population of bacteria growing in a nonlimiting medium includes mutator bacteria and transient mutators defined as wild-type bacteria which, due to occasional transcription or translation errors, display a mutator phenotype. A semiquantitative theoretical analysis of the steady-state composition of an Escherichia coli population suggests that true strong genotypic mutators produce about 3 x 10(-3) of the single mutations arising in the population, while transient mutators produce at least 10% of the single mutations and more than 95% of the simultaneous double mutations. Numbers of mismatch repair proteins inherited by the offspring, proportions of lethal mutations and mortality rates are among the main parameters that influence the steady-state composition of the population. These results have implications for the experimental manipulation of mutation rates and the evolutionary fixation of frequent but nearly neutral mutations (e.g., synonymous codon substitutions).
Ninio
J
J
Institut Jacques Monod, Paris, France.
D001419:Bacteria / Q000235:genetics*; D004260:DNA Repair; D004261:DNA Replication; D005838:Genotype; D016296:Mutagenesis; D010641:Phenotype; D014176:Protein Biosynthesis; D014158:Transcription, Genetic