PMID:10359804
| Citation |
Rosche, WA and Foster, PL (1999) The role of transient hypermutators in adaptive mutation in Escherichia coli. Proc. Natl. Acad. Sci. U.S.A. 96:6862-7 |
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| Abstract |
Microbial populations under nonlethal selection can give rise to mutations that relieve the selective pressure, a phenomenon that has come to be called "adaptive mutation." One explanation for adaptive mutation is that a small proportion of the cells experience a period of transient hypermutation, and that these hypermutators account for the mutations that appear. The experiments reported here investigated the contribution that hypermutators make to the mutations occurring in a Lac- strain of Escherichia coli during selection for lactose utilization. A broad mutational screen, loss of motility, was used to compare the frequency of nonselected mutations in starved Lac- cells, in Lac+ revertants, and in Lac+ revertants carrying yet another nonselected mutation. These frequencies allowed us to calculate that the hypermutating subpopulation makes up approximately 0.06% of the population and that its mutation rate is elevated approximately 200-fold. From these numbers we conclude that the hypermutators are responsible for nearly all multiple mutations but produce only approximately 10% of the adaptive Lac+ mutations. |
| Links | |
| Keywords |
Escherichia coli/genetics; Gene Expression Regulation, Bacterial; Genome, Bacterial; Lac Operon; Mutation |
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