Mfc1 is a novel copper transporter during meiosis

Meiosis is a specialized cell division process by which diploid germ line cells generate haploid gametes, which are required for sexual reproduction. During this process, several micronutrients are required, including copper ions. Despite important roles for copper-dependent proteins during meiosis, their mechanisms of action remain poorly understood. In a recently publication, we reported the discovery of Mfc1, the first example ever reported of a meiosis-specific copper transporter. Although Mfc1 did not exhibit any significant amino acid sequence similarities with members of the Ctr family of copper transporters, it harbored putative copper coordination motifs. Microarray data showed that mfc1(+) was the most highly induced of all meiotic genes detected under copper-limiting conditions. Analysis of Mfc1 localization during meiosis revealed that it localized at the forespore membrane during middle and late phases of the meiotic program. Interestingly, live-cell copper imaging using a copper-binding tracker revealed accumulation of copper ions into the forespore in wild-type cells. In contrast, mutant cells lacking Mfc1 displayed an intracellular distribution of copper ions that was dispersed throughout the ascospores without any marked preference for the forespore. We propose that Mfc1 is required to mobilize copper into the forespore, thereby providing copper to copper-requiring enzymes of the developing spores.