Characterization of a DNA mismatch-binding activity in yeast extracts

UMMS Affiliation

Department of Biochemistry and Molecular Biology

Publication Date


Document Type



*Base Composition; Base Sequence; Binding, Competitive; Cell Nucleus; DNA, Fungal; Escherichia coli; Genes, Bacterial; Genes, Fungal; Molecular Sequence Data; Nucleic Acid Heteroduplexes; Oligodeoxyribonucleotides; Saccharomyces cerevisiae


Life Sciences | Medicine and Health Sciences


An activity present in nuclear extracts of the yeast Saccharomyces cerevisiae binds specifically to oligonucleotides containing DNA mismatches, as judged by a band shift assay. The specificity of this activity for mismatched DNA was confirmed by competition experiments; binding to radiolabeled heteroduplexes was abolished in the presence of excess unlabeled heteroduplex but not when excess unlabeled homoduplex was added. Both T/G and T/- (single base deletion) mispairs were recognized in each of two sequence contexts. Binding was also observed with G/G, G/A, A/C, and T/C mismatches, but recognition of a C/C mispair was very weak. Competition studies with the various mismatches were consistent with the idea that a single activity recognizes all mispairs tested. Extracts from strains mutant in either or both of two putative mismatch recognition functions, MSH2 and MSH3, were also tested. Mismatch-binding activity was present in extracts of msh3- strains but completely absent in msh2- strains. The molecular weight of the major binding protein was estimated by UV cross-linking experiments to be approximately 110 kDa, in good agreement with the size predicted for Msh2 protein (Reenan, R. A. and Kolodner, R. D. (1992) Genetics 132, 963-973).


J Biol Chem. 1993 Feb 15;268(5):3507-13.

Journal/Book/Conference Title

The Journal of biological chemistry

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