Open AccessMutation rate is reduced by increased dosage of mutL gene in Escherichia coli K‐12
Author(s) -
Galán JuanCarlos,
Turrientes MaríaCarmen,
Baquero MaríaRosario,
RodríguezAlcayna Manuel,
MartínezAmado Jorge,
Martínez JoséLuis,
Baquero Fernando
Publication year - 2007
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2007.00902.x
Subject(s) - biology , escherichia coli , mutation , genetics , mutation rate , gene , microbiology and biotechnology , gene dosage , point mutation , gene expression
A variable but substantial proportion of wild Escherichia coli isolates present consistently lower mutation frequencies than that found in the ensemble of strains. The genetic mechanisms responsible for the hypo‐mutation phenotype are much less known than those involved in hyper‐mutation. Changes in E. coli mutation frequencies derived from the gene‐copy effect of mutS , mutL , mutH , uvrD , mutT , mutY , mutM , mutA , dnaE , dnaQ , and rpoS are explored. When present in a very high copy number (∼300 copies cell −1 ), mutL , mutH , and mutA gene copies yielded ≥twofold decrease in mutation rates determined by Luria–Delbrück fluctuation tests. Nevertheless, when the copy number was not such high (∼15 copies cell −1 ), only mutL results in a consistent twofold decrease in the mutation rate. This reduction seems to be independent from the RecA background, phase of growth, or from the presence of proficient MutS. An increase in mutL gene copies was also able to partially compensate the hypermutator phenotype of a mutS ‐defective E. coli derivative.