The mammalian phosphate carrier SLC25A3 is a mitochondrial copper transporter required for cytochrome c oxidase biogenesis

• Type of Material: Article
• Authors: Aren Boulet, University of Saskatchewan; Katherine E. Vest, Auburn University; Margaret K. Maynard, Auburn University; Micah G. Gammon, Auburn University; Antoinette Russell, Auburn University; Alexander T. Mathews, Auburn University; Shelbie E. Cole, Auburn University; Xinyu Zhu, Auburn University; Casey B. Phillips, Auburn University; Jennifer Kwong, Emory University; Sheel C. Dodani, University of Texas at Dallas; Scot C. Leary, University of Saskatchewan; Paul A. Cobine, Auburn University
• Language: English
• Date: 2018-01-01
• Publisher: Emory University Libraries
• Publication Version: Final Published Version
• Copyright Statement: © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.
• Final Published Version (URL): http://dx.doi.org/10.1074/jbc.RA117.000265
• Title of Journal or Parent Work: Journal of Biological Chemistry
• Volume: 293
• Issue: 6
• Start Page: 1887
• End Page: 1896
• Grant/Funding Information: This work was supported in part by National Science Foundation Grant MCB1158497 (to P. A. C.), National Institutes of Health Grants R01GM120211 (to P. A. C. and S. C. L.) and R01GM079465 (to Christopher J. Chang (University of California-Berkeley) for work performed by S. C. D.), and Canadian Institutes of Health Research (to S. C. L.).
• Keywords: cytochrome c oxidase (complex IV); mitochondria; copper transport; membrane transport; copper
• Research Categories: Biology, General; Chemistry, Biochemistry

Abstract

Copper is required for the activity of cytochrome c 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. SLC25A3 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 PIC2. Additionally, assays in Lactococcus lactis and in reconstituted liposomes directly demonstrated that SLC25A3 functions as a copper transporter. Taken together, these data indicate that SLC25A3 can transport copper both in vitro and in vivo.