Structural Elements in the Transmembrane and Cytoplasmic Domains of the Metal Transporter SLC30A10 Are Required for Its Manganese Efflux Activity*
Structural Elements in the Transmembrane and Cytoplasmic Domains of the Metal Transporter SLC30A10 Are Required for Its Manganese Efflux Activity*
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DOI：
10.1074/jbc.m116.726935
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发表时间：
2016-06
期刊：
影响因子：
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通讯作者：
Charles E. Zogzas;M. Aschner;Somshuvra Mukhopadhyay
中科院分区：
文献类型：
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作者：
Charles E. Zogzas;M. Aschner;Somshuvra Mukhopadhyay
SLC30A10的纯合突变导致家族性锰诱导帕金森病的发展。我们之前证明了SLC30A10是一种细胞表面定位的锰外排转运蛋白，帕金森病引起的突变阻断了其运输和外排活性。有趣的是，SLC30家族中的其他转运蛋白介导锌外排。确定SLC30A10转运锰的机制（目前尚不清楚）对于了解其在帕金森病中的作用至关重要。在此，我们基于细菌锌转运体YiiP的结构，生成了SLC30A10的预测结构，并进行了功能研究。在YiiP中，第二跨膜段的残基Asp-45和Asp-49侧链和第五跨膜段的His-153和Asp-157侧链协调锌，并需要转运。SLC30A10中第二跨膜段对应的残基为Asn-43和Asp-47，第五跨膜段对应的残基为His-244和Asp-248。令人惊讶的是，虽然Asp-248的丙氨酸取代消除了锰的外排，但Asn-43和Asp-47没有。相反，需要在第一个跨膜段（Glu-25）或第四个跨膜段（Asn-127）中与Asp-248相邻的带电或极性残基侧链。进一步分析表明，细胞质c端结构域的His-333和His-350残基是充分发挥活性所必需的。然而，c端结构域未能将锰转运能力转移到相关的锌转运体上。总之，我们的研究结果表明，SLC30A10的跨膜结构域和c端结构域的残基共同赋予了SLC30A10最佳的锰转运能力，并表明SLC30A10跨膜结构域的离子配位机制可能与YiiP/其他SLC30蛋白中的离子配位机制有很大不同。
Homozygous mutations in SLC30A10 lead to the development of familial manganese-induced parkinsonism. We previously demonstrated that SLC30A10 is a cell surface-localized manganese efflux transporter, and parkinsonism-causing mutations block its trafficking and efflux activity. Interestingly, other transporters in the SLC30 family mediate zinc efflux. Determining the mechanisms that allow SLC30A10 to transport manganese, which are unclear, is essential to understand its role in parkinsonism. Here, we generated a predicted structure of SLC30A10, based on the structure of the bacterial zinc transporter YiiP, and performed functional studies. In YiiP, side chains of residues Asp-45 and Asp-49 in the second and His-153 and Asp-157 in the fifth transmembrane segments coordinate zinc and are required for transport. In SLC30A10, the corresponding residues are Asn-43 and Asp-47 in the second and His-244 and Asp-248 in the fifth transmembrane segments. Surprisingly, although alanine substitution of Asp-248 abolished manganese efflux, that of Asn-43 and Asp-47 did not. Instead, side chains of charged or polar residues adjacent to Asp-248 in the first (Glu-25) or fourth (Asn-127) transmembrane segments were required. Further analyses revealed that residues His-333 and His-350 in the cytoplasmic C-terminal domain were required for full activity. However, the C-terminal domain failed to transfer manganese transport capability to a related zinc transporter. Overall, our results indicate that residues in the transmembrane and C-terminal domains together confer optimal manganese transport capability to SLC30A10 and suggest that the mechanism of ion coordination in the transmembrane domain of SLC30A10 may be substantially different from that in YiiP/other SLC30 proteins.