The frequency of mutators in populations of Escherichia coli.
Owing to occasional spontaneous mutations in genes encoding DNA repair, any population of a reasonable size is expected to harbor a sub-population of genetic mutators. Using a genetically modified strain of Escherichia coli K-12, we have estimated the frequency of mutators to be about 3x10(-5). By and large, this corresponds to a mutation rate from non-mutators to mutators of 5x10(-6) per bacterium per generation. Using a mutS&Colon;Tn10 derivative as representative for mutators, we estimated the increase in mutation rates in mutators to be 19- to 82-fold, depending on the test-mutation under consideration. The load associated with this increase in mutation rate resulted in a growth inhibition of 1%. From these data, we estimated that the rate of detrimental mutations in the non-mutators to be 2x10(-4)-8x10(-4). The situations where adaptive mutations may result in an increase in the frequency of mutators are discussed.
Boe
L
L
Department of Microbiology, Technical University of Denmark, DK-2800, Lyngby, Denmark.
Danielsen
M
M
Knudsen
S
S
Petersen
J B
JB
Maymann
J
J
Jensen
P R
PR
D000251:Adenosine Triphosphatases; D001426:Bacterial Proteins / Q000235:genetics*; D002455:Cell Division / Q000235:genetics; D003470:Culture Media; D004260:DNA Repair / Q000235:genetics; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005787:Gene Frequency; D005828:Genetics, Population; D056968:Lac Repressors; D007785:Lactose / Q000378:metabolism; D051719:MutS DNA Mismatch-Binding Protein; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics; D012641:Selection, Genetic
D001426:Bacterial Proteins; D003470:Culture Media; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli; D012097:Repressor Proteins; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli; D007785:Lactose