Molecular handles on adaptive mutation.
In one experimental system, several handles on the molecular mechanism of apparent adaptive mutation have emerged. The system is reversion of a lac frameshift mutation in Escherichia coli. The molecular handles include a requirement for homologous recombination; the implication of DNA double-strand breaks as a molecular intermediate; a unique sequence spectrum of -1 deletions in mononucleotide repeats which implies polymerase errors, and also implies a failure of postsynthesis mismatch repair on those errors; and the involvement of sexual functions at some stage of the process. These molecular handles are revealing an unexpected new mechanism of mutagenesis.
Rosenberg
S M
SM
Department of Biochemistry, University of Alberta, Edmonton, Canada.
Harris
R S
RS
Torkelson
J
J
D003227:Conjugation, Genetic; D004249:DNA Damage; D004260:DNA Repair; D004926:Escherichia coli / Q000235:genetics*; D016368:Frameshift Mutation; D007763:Lac Operon / Q000235:genetics; D010957:Plasmids; D011995:Recombination, Genetic; D013489:Suppression, Genetic