Evidence that F plasmid transfer replication underlies apparent adaptive mutation.
An Escherichia coli K12 strain, FC40, has been used extensively in the analysis of adaptive mutability. This strain carries a revertible mutant lac allele on an F plasmid and accumulates Lac+ (lactose utilizing) revertants, but not unselected mutants, when placed on selective medium. These adaptive mutations are a subset of spontaneous types and their formation depends on the RecABC functions. Data presented here suggest that this phenomenon depends on transfer functions of the F factor. Fertility inhibition eliminates RecA-dependent adaptive reversion. Thus, "adaptive" revertants may form during replication from the transfer origin, whereas loci in the nonreplicating chromosome show little mutation.
Galitski
T
T
Department of Biology, University of Utah, Salt Lake City 84112, USA.
Roth
J R
JR
D000222:Adaptation, Physiological / Q000235:genetics*; D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics; D003470:Culture Media; D004261:DNA Replication; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins; D005144:F Factor; D016368:Frameshift Mutation; D007763:Lac Operon; D056968:Lac Repressors; D007785:Lactose / Q000378:metabolism; D009154:Mutation; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics
D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli; D012097:Repressor Proteins; D011938:Rec A Recombinases; D007785:Lactose