Structural Characterization of the N-Terminal Domain of the Dictyostelium discoideum Mitochondrial Calcium Uniporter.
Structural Characterization of the N-Terminal Domain of the Dictyostelium discoideum Mitochondrial Calcium Uniporter.
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盘基网柄菌线粒体钙单向转运蛋白 N 端结构域的结构表征。
DOI：
10.1021/acsomega.9b04045
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发表时间：
2020
期刊：
影响因子：
4.1
通讯作者：
OuYang,Bo
中科院分区：
文献类型：
--
作者：
Yuan,Yuan;Cao,Chan;Wen,Maorong;Li,Min;Dong,Ying;Wu,Lijie;Wu,Jian;Cui,Tanxing;Li,Dianfan;Chou,JamesJ;OuYang,Bo
线粒体钙单向转运体（MCU）在线粒体钙摄取到基质中起关键作用。在后生动物中，单向转运蛋白是一个严格调控的多组分系统，包括成孔亚基MCU和几个调节剂（MICU 1，MICU 2和Essential MCU Regulator，EMRE）。后生动物MCU的钙离子传导活性需要单跨膜蛋白EMRE，而盘基网骨藻（Dictyosteelium discoideum，Dd）则发展了一种简化的单向转运蛋白，其钙离子内流仅需成孔MCU（DdMCU）即可。在这里，我们报告的N-末端域（NTD）的DdMCU在1.7 μ m分辨率的晶体结构。DdMCU-NTD含有四个螺旋和两条折叠的链，这与其他MCU-NTD同系物的已知结构完全不同。DdMCU-NTD在溶液中的生物化学和生物物理分析表明，该结构域作为高阶低聚物存在。诱变结果表明，酸性残基Asp 60，Glu 72，和Glu 74，这似乎介导的接口II，如在晶体结构中观察到的，参与DdMCU-NTD的自组装。有趣的是，低聚复合物在钙的存在下被破坏。我们建议，钙触发的NTD的解离调节通道活动的DdMCU的一个未知的机制。
The mitochondrial calcium uniporter (MCU) plays a critical role in mitochondrial calcium uptake into the matrix. In metazoans, the uniporter is a tightly regulated multicomponent system, including the pore-forming subunit MCU and several regulators (MICU1, MICU2, and Essential MCU REgulator, EMRE). The calcium-conducting activity of metazoan MCU requires the single-transmembrane protein EMRE.Dictyostelium discoideum(Dd), however, developed a simplified uniporter for which the pore-forming MCU (DdMCU) alone is necessary and sufficient for calcium influx. Here, we report a crystal structure of the N-terminal domain (NTD) of DdMCU at 1.7 Å resolution. The DdMCU-NTD contains four helices and two strands arranged in a fold that is completely different from the known structures of other MCU-NTD homologues. Biochemical and biophysical analyses of DdMCU-NTD in solution indicated that the domain exists as high-order oligomers. Mutagenesis showed that the acidic residues Asp60, Glu72, and Glu74, which appeared to mediate the interface II, as observed in the crystal structure, participated in the self-assembly of DdMCU-NTD. Intriguingly, the oligomeric complex was disrupted in the presence of calcium. We propose that the calcium-triggered dissociation of NTD regulates the channel activity of DdMCU by a yet unknown mechanism.