Mismatch repair in Escherichia coli cells lacking single-strand exonucleases ExoI, ExoVII, and RecJ - PubMed (original) (raw)

Mismatch repair in Escherichia coli cells lacking single-strand exonucleases ExoI, ExoVII, and RecJ

R S Harris et al. J Bacteriol. 1998 Feb.

Abstract

In vitro, the methyl-directed mismatch repair system of Escherichia coli requires the single-strand exonuclease activity of either ExoI, ExoVII, or RecJ and possibly a fourth, unknown single-strand exonuclease. We have created the first precise null mutations in genes encoding ExoI and ExoVII and find that cells lacking these nucleases and RecJ perform mismatch repair in vivo normally such that triple-null mutants display normal mutation rates. ExoI, ExoVII, and RecJ are either redundant with another function(s) or are unnecessary for mismatch repair in vivo.

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Figures

FIG. 1

FIG. 1

Growth curves of strains carrying null mutations in xonA, xseA, and recJ. Each point represents the mean of the viable cell counts from three independent cultures. Error bars, one standard error of the mean. (A) JC11450 derivatives; (B) FC40 derivatives. Squares, Exo+ strains; triangles, Δ_xonA300_::cat ΔxseA18::amp recJ284::Tn_10_ strains; circles, mutL strains.

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