The effect of genomic position on reversion of a lac frameshift mutation (lacIZ33) during non-lethal selection (adaptive mutation).

摘要: Summary In a system described by Cairns and Foster, starva- tion of particular leaky lac mutant (lacIZ33) in the presence lactose appears to direct mutation non-growing cells sites that allow growth (adaptive mutation). This behaviour requires operon be located on an F¢ plasmid. position effect was investigated placing at many genome Salmonella enterica (Typhimurium; LT2) testing reversion behaviour. Genomic did not affect during non-selective growth. When any 550 chromosomal sites, starvation caused little or no enhancement reversion. 28 strains with Salmonella's conjugative plasmid (pSLT), selection enhanced strongly, just as seen for 46 strains, inserted within small chromo- somal duplication, stimulated RecA- dependent partial simple amplification (about 8¥) region. The is important because it allows more frequent gene duplication amplification. These events are central under they increase number replicating alleles each devel- oping revertant clone.