Reversion of Frameshift Mutations by Mutator Genes in Escherichia coli

Abstract

The Escherichia coli mutator genes mutU4, mutS3, and mut-25 (a possible allele of mutL), previously known to induce transitional base changes, increased significantly the frequencies of reversion of lacZ frameshift mutations. mutTI, previously shown to induce only the transversion of adenine-thymine to cytosine-guanine, had no effect on the reversion of lacZ frameshift mutations. With mutator genes other than mutTi, small increases were found in the frequencies of reversion of trpA frameshift mutations. 994 on July 31, 2020 by guest

SOS mutator effect in E. coli mutants deficient in mismatch correction.

“…We interpret the lack of induced X mutagenesis in the E. coli dam mutant (Figures 2C and 3) as a consequence of the killing of unmethylated mismatch-bearing X DNA by the mismatch repair enzymes rather than the absence of SOS mutator activity (as in recA mutants) for the following reasons: (i) the induced c and R + X mutants can be partially recovered in E. coli dam mutH and dam mutS double mutants ( Figures 2C and 3); (ii) the recovery of mutants is accompanied by an Vaccaro and Siegel (1977) ES866 as ES548 but recA recA Vaccaro and Siegel (1977) ES872 as ES866 but mutL mutL recA Vaccaro and Siegel (1977) ES895 as ES866 but mutS mutS recA Vaccaro and Siegel (1977) RH4447 as ES548 but mutH mutH ES548 x KMBL3773 as ES548 but mutU4 mutU4 Siegel and Kamel (1974) ES583 as ES548 but uvrE502 uvrE502 Siegel and Kamel (1974) C600 F-(hr leu lac tonB SuI ) used as indicator strains 594 Fgal-I gal-2 lac Str R Su-increase in viable phage (Figure 4), and (iii) the killing of X phages in irradiated dam mutants occurs in the dose range in which the SOS mutator effect is highest (Figure 4). Analogous to these results is the observation that E. coli cells are sensitized to u.v.…”

Heteroduplex deoxyribonucleic acid base mismatch repair in bacteria.

“…Types of mutations elicited. Transitions and frameshift mutations accounted for the increase in spontaneous mutagenesis observed for strains carrying mutH (118, 257, 2%), mutL (255-257, 261, 2%), mutS (254,(256)(257)(258)296), and mutU (255-257, 263, 264, 296) mutations. The same result was observed for insertion mutant strains mutH, mutL, mutS, and mutU of Salmonella typhimurium (247).…”

Effect of site-specific DNA methylation and mutagenesis on recognition by methylated DNA-binding protein from human placenta

“…Heteroduplex RF was prepared as described above except that the primer for synthesis was one of the mutant oligonucleotides (primers 3, 6, 7, 14, 16, 27, or 28). The purified, covalently closed heteroduplex RF (5-10 ng) was transfected into DNA mismatch repair-deficient Escherichia coli ES553 (mutL) provided by E. Siegel (5); this host was used in order to increase the frequency of mutant phage (manuscript in preparation). Transfection was performed as described by Kramer et al (6) except that fresh YT medium was added for overnight incubation.…”