From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan 7N 5E5, Canada.
the Department of Biological Sciences, Auburn University, Auburn, Alabama 36849.
J Biol Chem. 2018 Feb 9;293(6):1887-1896. doi: 10.1074/jbc.RA117.000265. Epub 2017 Dec 13.
Copper is required for the activity of cytochrome oxidase (COX), the terminal electron-accepting complex of the mitochondrial respiratory chain. The likely source of copper used for COX biogenesis is a labile pool found in the mitochondrial matrix. In mammals, the proteins that transport copper across the inner mitochondrial membrane remain unknown. We previously reported that the mitochondrial carrier family protein Pic2 in budding yeast is a copper importer. The closest Pic2 ortholog in mammalian cells is the mitochondrial phosphate carrier SLC25A3. Here, to investigate whether SLC25A3 also transports copper, we manipulated its expression in several murine and human cell lines. knockdown or deletion consistently resulted in an isolated COX deficiency in these cells, and copper addition to the culture medium suppressed these biochemical defects. Consistent with a conserved role for SLC25A3 in copper transport, its heterologous expression in yeast complemented copper-specific defects observed upon deletion of Additionally, assays in and in reconstituted liposomes directly demonstrated that SLC25A3 functions as a copper transporter. Taken together, these data indicate that SLC25A3 can transport copper both and .
铜是细胞色素氧化酶（COX）活性所必需的，后者是线粒体呼吸链的末端电子接受复合物。用于 COX 生物发生的铜的可能来源是在线粒体基质中发现的不稳定池。在哺乳动物中，将铜穿过线粒体内膜运输的蛋白质仍不清楚。我们之前曾报道过，芽殖酵母中的线粒体载体家族蛋白 Pic2 是铜的输入器。哺乳动物细胞中最接近的 Pic2 直系同源物是线粒体磷酸载体 SLC25A3。在这里，为了研究 SLC25A3 是否也能转运铜，我们在几种鼠和人细胞系中操纵其表达。敲低或缺失 SLC25A3 的表达一致导致这些细胞中 COX 缺陷，向培养基中添加铜可抑制这些生化缺陷。与 SLC25A3 在铜转运中的保守作用一致，其在酵母中的异源表达补充了缺失时观察到的铜特异性缺陷。此外，在 和重组脂质体中的测定直接证明 SLC25A3 作为铜转运蛋白发挥作用。综上所述，这些数据表明 SLC25A3 可以在 和 中转运铜。
