Mismatch Repair in Escherichia coli Cells Lacking Single-Strand Exonucleases ExoI, ExoVII, and RecJ |
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| Authors: | Reuben S. Harris Kimberly J. Ross Mary-Jane Lombardo Susan M. Rosenberg |
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| Affiliation: | Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9,1. and Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7,2. Canada, and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 770303. |
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| 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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