Kwak Geun-Hee, Kim Jae-Ryong, Kim Hwa-Young
Department of Biochemistry and Molecular Biology, Aging-associated Vascular Disease Research Center, Yeungnam University College of Medicine, Daegu 705-717, Korea.
BMB Rep. 2009 Feb 28;42(2):113-8. doi: 10.5483/bmbrep.2009.42.2.113.
Despite the growing body of evidence suggesting a role for MsrA in antioxidant defense, little is currently known regarding the function of MsrB in cellular protection against oxidative stress. In this study, we overexpressed the mammalian MsrB and MsrA genes in Saccharomyces cerevisiae and assessed their subcellular localization and antioxidant functions. We found that the mitochondrial MsrB3 protein (MsrB3B) was localized to the cytosol, but not to the mitochondria, of the yeast cells. The mitochondrial MsrB2 protein was detected in the mitochondria and, to a lesser extent, the cytosol of the yeast cells. In this study, we report the first evidence that MsrB3 overexpression in yeast cells protected them against H(2)O(2)-mediated cell death. Additionally, MsrB2 overexpression also provided yeast cells with resistance to oxidative stress, as did MsrA overexpression. Our results show that mammalian MsrB and MsrA proteins perform crucial functions in protection against oxidative stress in lower eukaryotic yeast cells.
尽管越来越多的证据表明甲硫氨酸亚砜还原酶A（MsrA）在抗氧化防御中发挥作用，但目前对于甲硫氨酸亚砜还原酶B（MsrB）在细胞抵御氧化应激中的功能却知之甚少。在本研究中，我们在酿酒酵母中过表达了哺乳动物的MsrB和MsrA基因，并评估了它们的亚细胞定位和抗氧化功能。我们发现，线粒体MsrB3蛋白（MsrB3B）定位于酵母细胞的胞质溶胶，而非线粒体。线粒体MsrB2蛋白在酵母细胞的线粒体中被检测到，在胞质溶胶中的含量较少。在本研究中，我们首次报道了在酵母细胞中过表达MsrB3可保护其免受过氧化氢介导的细胞死亡。此外，过表达MsrB2也使酵母细胞具有抗氧化应激能力，过表达MsrA同样如此。我们的结果表明，哺乳动物的MsrB和MsrA蛋白在低等真核酵母细胞抵御氧化应激中发挥着关键作用。
