Parker A, Gu Y, Lu A L
Department of Biochemistry and Molecular Biology, University of Maryland at Baltimore, 108 N. Greene Street, Baltimore, MD 21201, USA.
Nucleic Acids Res. 2000 Sep 1;28(17):3206-15. doi: 10.1093/nar/28.17.3206.
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.
一种与大肠杆菌MutY糖基化酶同源的蛋白质，被称为mtMYH，已从小牛肝脏线粒体中纯化出来。SDS-聚丙烯酰胺凝胶电泳、蛋白质免疫印迹分析以及凝胶过滤色谱法预测纯化后的小牛mtMYH分子量为35-40 kDa。凝胶迁移率变动分析表明，纯化后的mtMYH与A/8-氧代鸟嘌呤、G/8-氧代鸟嘌呤和T/8-氧代鸟嘌呤形成特异性结合复合物，与C/8-氧代鸟嘌呤的结合较弱，但与A/G和A/C错配不形成结合复合物。纯化后的mtMYH表现出DNA糖基化酶活性，可去除与G、C或8-氧代鸟嘌呤错配的腺嘌呤，并能较弱地去除与8-氧代鸟嘌呤错配的鸟嘌呤。mtMYH糖基化酶活性对高浓度的NaCl和EDTA不敏感。纯化后的mtMYH与针对完整MutY和人MutY同源物（hMYH）肽段的抗体发生交叉反应。mtMYH的DNA糖基化酶活性受到抗MutY抗体的抑制，但不受抗hMYH肽段抗体的抑制。与先前描述的线粒体MutT同源物（MTH1）和8-氧代鸟嘌呤糖基化酶（OGG1，一种功能性MutM同源物）一起，mtMYH可以保护线粒体DNA免受8-氧代鸟嘌呤的诱变作用。
