Comparative Genomics of the Escherichia coli Strains АВ1157, АВ2463, АВ2494, and АВ1885

Abstract

Whole genome sequencing of the Escherichia coli strain АВ1157 and its mutants AB1885 uvrB5, AB2463 recA13, and AB2494 lexA1, which have deficient DNA repair, recombination, and mutagenesis systems, was performed. It was found that the genomes of the AB2463 recA13 and AB2494 lexA1 strains differ from the genome of ancestral strain in several hundred mutations which arose most probably in the course of a single treatment of AB1157 with N-methyl-N-nitro-N-nitrosoguanidine. At the same time, the genome of the strain AB1885 obtained after treatment with nitrous acid contained ten times fewer differences from its parent strain. Mutations in the AB2463 recA13 and AB2494 lexA1 genomes were predominantly represented by GC to AT transitions distributed randomly along the genomes, and their locations did not coincide in these strains. The effect of spontaneous mutations on the differences between the strains studied that appeared during the period from their isolation to the sequence experiments seems to be insignificant. Earlier known genetic and phenotypic traits are annotated on the molecular level.