Nutritional conditions and oxygen concentration affect spontaneous occurrence of homologous recombination events but not spontaneous mutagenesis in Escherichia coli.

Nutritional conditions and oxygen concentration affect spontaneous occurrence of homologous recombination events but not spontaneous mutagenesis in Escherichia coli. Genes Genet Syst. 2020 May 11;: Authors: Le LAT, Chang PY, Ando S, Conrad TM, Nunose S, Sakai A, Uefune H, Furukohri A, Akiyama MT, Maki H Abstract Effects of environmental factors for growth of Escherichia coli on spontaneous mutagenesis and homologous recombination events are described. By analyzing rifampicin-resistant (Rifr) mutation frequencies in an E. coli strain lacking MutM and MutY repair enzymes, which suppress base substitution mutations caused by 8-oxoguanine (7,8 dihydro-8-oxoguanine; 8-oxoG) in DNA, we examined levels of oxidative DNA damage produced in normally growing cells. The level of 8-oxoG DNA damage was about 9- and 63-fold higher in cells grown in M9-glucose and M9-glycerol media, respectively, than in those grown in LB medium. We also found that about 14-fold more 8-oxoG DNA damage was produced in cells grown in about 0.1% oxygen than in those grown in the normal atmosphere. However, Rifr mutation frequency in wild-type cells was unchanged in such different growth conditions, suggesting that the capacity of repair mechanisms is sufficient to suppress mutations caused by 8-oxoG even at very high levels in cells growing in the particular conditions. On the other hand, the frequency of spontaneous homologous recombination events in wild-type E. coli...
Source: Genes and Genetic Systems - Category: Genetics & Stem Cells Authors: Tags: Genes Genet Syst Source Type: research