Purification and characterization of a mammalian homolog of Escherichia coli MutY mismatch repair protein from calf liver mitochondria.
A protein homologous to the Escherichia coli MutY glycosylase, referred to as mtMYH, has been purified from calf liver mitochondria. SDS-polyacrylamide gel electrophoresis, western blot analysis as well as gel filtration chromatography predicted the molecular mass of the purified calf mtMYH to be 35-40 kDa. Gel mobility shift analysis showed that the purified mtMYH formed specific binding complexes with A/8-oxoG, G/8-oxoG and T/8-oxoG, weakly with C/8-oxoG, but not with A/G and A/C mismatches. The purified mtMYH exhibited DNA glycosylase activity removing adenine mispaired with G, C or 8-oxoG and weakly removing guanine mispaired with 8-oxoG. The mtMYH glycosylase activity was insensitive to high concentrations of NaCl and EDTA. The purified mtMYH cross-reacted with antibodies against both intact MutY and a peptide of human MutY homolog (hMYH). DNA glycosylase activity of mtMYH was inhibited by anti-MutY antibodies but not by anti-hMYH peptide antibodies. Together with the previously described mitochondrial MutT homolog (MTH1) and 8-oxoG glycosylase (OGG1, a functional MutM homolog), mtMYH can protect mitochondrial DNA from the mutagenic effects of 8-oxoG.
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Department of Biochemistry and Molecular Biology, University of Maryland at Baltimore, 108 N. Greene Street, Baltimore, MD 21201, USA.
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D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D020137:Base Pair Mismatch / Q000235:genetics; D002417:Cattle; D003429:Cross Reactions / Q000276:immunology; D004247:DNA / Q000235:genetics / Q000378:metabolism; D045647:DNA Glycosylases; D019286:Endopeptidase K / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D008930:Mitochondria, Liver / Q000201:enzymology* / Q000378:metabolism; D008970:Molecular Weight; D009699:N-Glycosyl Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D000906:Antibodies; C024829:8-hydroxyguanine; D006147:Guanine; D004247:DNA; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D019286:Endopeptidase K