Dissection of the relative contribution of the Schizosaccharomyces pombe Ctr4 and Ctr5 proteins to the copper transport and cell surface delivery functions
Dissection of the relative contribution of the Schizosaccharomyces pombe Ctr4 and Ctr5 proteins to the copper transport and cell surface delivery functions
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DOI：
10.1099/mic.0.046854-0
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发表时间：
2011-04-01
期刊：
影响因子：
2.8
通讯作者：
Puig, Sergi
中科院分区：
文献类型：
--
作者：
Beaudoin, Jude;Thiele, Dennis J.;Puig, Sergi
Ctr 1蛋白家族介导真核生物中高亲和力铜（Cu）的获得。在裂殖酵母裂殖酵母粟酒裂殖酵母中，Cu的吸收是通过由Ctr 4和Ctr 5蛋白形成的异聚复合物进行的。与人类和酿酒酵母Ctr 1蛋白不同，Ctr 4和Ctr 5不能独立地在Cu获得中发挥作用。相反，这两种蛋白质物理相互作用，形成Ctr 4 Ctr 5异聚复合物，并相互依赖的分泌到质膜和铜转运活性。在本研究中，我们使用了S。酿酒酵母突变体的缺陷，在高亲和力铜吸收剖析的相对贡献Ctr 4和Ctr 5的铜转运功能。功能互补和定位分析表明，Ctr 5蛋白跨膜结构域2中保守的Met-X（3）-Met基序对于Ctr 4 Ctr 5复合物的功能是必需的，而Ctr 4蛋白中的Met-X（3-）Met基序对于异源复合物的功能和质膜定位是必需的。此外，Ctr 4/Ctr 5嵌合蛋白揭示了在Ctr 4或Ctr 5中发现的独特性质，并且足以在粟酒裂殖酵母细胞的细胞表面上摄取Cu。功能性嵌合体含有Ctr 4中央和Ctr 5羧基末端结构域（CTD）。我们建议，Ctr 4中央域介导铜运输在这个异源复合物，而Ctr 5 CTD功能的调节贩运的铜运输复合物的细胞表面。
The Ctr1 family of proteins mediates high-affinity copper (Cu) acquisition in eukaryotic organisms. In the fission yeast Schizosaccharomyces pombe, Cu uptake is carried out by a heteromeric complex formed by the Ctr4 and Ctr5 proteins. Unlike human and Saccharomyces cerevisiae Ctr1 proteins, Ctr4 and Ctr5 are unable to function independently in Cu acquisition. Instead, both proteins physically interact with each other to form a Ctr4 Ctr5 heteromeric complex, and are interdependent for secretion to the plasma membrane and Cu transport activity. In this study, we used S. cerevisiae mutants that are defective in high-affinity Cu uptake to dissect the relative contribution of Ctr4 and Ctr5 to the Cu transport function. Functional complementation and localization assays show that the conserved Met-X(3)-Met motif in transmembrane domain 2 of the Ctr5 protein is dispensable for the functionality of the Ctr4 Ctr5 complex, whereas the Met-X(3-)Met motif in the Ctr4 protein is essential for function and for localization of the hetero-complex to the plasma membrane. Moreover, Ctr4/Ctr5 chimeric proteins reveal unique properties found either in Ctr4 or in Ctr5, and are sufficient for Cu uptake on the cell surface of Sch. pombe cells. Functional chimeras contain the Ctr4 central and Ctr5 carboxyl-terminal domains (CTDs). We propose that the Ctr4 central domain mediates Cu transport in this hetero-complex, whereas the Ctr5 CTD functions in the regulation of trafficking of the Cu transport complex to the cell surface.