Beaudoin Jude, Ioannoni Raphaël, Labbé Simon
Département de Biochimie; Faculté de Médecine et des Sciences de la Santé; Université de Sherbrooke; Sherbrooke, QC Canada.
Commun Integr Biol. 2012 Mar 1;5(2):118-21. doi: 10.4161/cib.18716.
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.
减数分裂是一种特殊的细胞分裂过程，通过该过程二倍体生殖系细胞产生单倍体配子，而单倍体配子是有性生殖所必需的。在此过程中，需要多种微量营养素，包括铜离子。尽管铜依赖性蛋白在减数分裂过程中发挥着重要作用，但其作用机制仍知之甚少。在最近发表的一篇文章中，我们报道了Mfc1的发现，它是有史以来报道的第一个减数分裂特异性铜转运蛋白的例子。尽管Mfc1与铜转运蛋白Ctr家族的成员没有任何显著的氨基酸序列相似性，但它含有假定的铜配位基序。微阵列数据显示，在铜限制条件下检测到的所有减数分裂基因中，mfc1(+)的诱导程度最高。对减数分裂过程中Mfc1定位的分析表明，它在减数分裂程序的中期和后期定位于前孢子膜。有趣的是，使用铜结合追踪器进行的活细胞铜成像显示，野生型细胞中铜离子在前孢子中积累。相比之下，缺乏Mfc1的突变细胞显示铜离子在细胞内的分布分散在整个子囊孢子中，对前孢子没有任何明显的偏好。我们认为，Mfc1是将铜转运到前孢子所必需的，从而为发育中的孢子中需要铜的酶提供铜。
