Mechanism for induction of adaptive mutations in Escherichia coli.
When bacterial cells are subjected to a strong selective pressure it often induces specific mutations. Here a model is considered in which errors are introduced at random in one of the strands of the DNA molecule: a nick in one of the strands can initiate strand displacement rendering a region of the chromosome single-stranded. Upon conversion back to double-stranded DNA there is a certain probability of introducing errors creating a heteroduplex. If an error results in the production of an mRNA molecule encoding a product which provides a selective advantage, growth will be stimulated and the mutation can be immortalized by chromosomal replication. Otherwise, the error can be corrected by the DNA 'proof-reading' enzymes.
Department of Microbiology, Technical University of Denmark, Copenhagen.
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D000222:Adaptation, Physiological; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D008745:Methylation; D008958:Models, Molecular; D009154:Mutation; D012333:RNA, Messenger / Q000096:biosynthesis
D004269:DNA, Bacterial; D012333:RNA, Messenger; D004259:DNA-Directed DNA Polymerase