S92 phosphorylation induces structural changes in the N-terminus domain of human mitochondrial calcium uniporter
S92 phosphorylation induces structural changes in the N-terminus domain of human mitochondrial calcium uniporter
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DOI：
10.1038/s41598-020-65994-y
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发表时间：
2020-06-04
影响因子：
4.6
通讯作者：
Eom, Soo Hyun
中科院分区：
文献类型：
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作者：
Lee, Youngjin;Park, Jongseo;Eom, Soo Hyun
线粒体钙单向转运体（MCU）在线粒体钙稳态中起重要作用，并调节细胞功能，如能量合成，细胞生长和发育。因此，MCU活性受到其调节剂以及翻译后修饰的严格控制，包括通过蛋白激酶如富含脯氨酸的酪氨酸激酶2（Pyk 2）和AMP活化的蛋白激酶（AMPK）的磷酸化。在我们的体外激酶测定中，MCU N-末端结构域（NTD）被定位于线粒体基质中的蛋白激酶C亚型（PKC β II、PKC δ和PKC β）磷酸化。此外，我们发现保守的S92被PKC亚型磷酸化。为了揭示MCU S92磷酸化（S92 p）的结构效应，我们确定了S92 E和D119 A突变体的MCU NTD的晶体结构，并分析了WT和S92 p的分子动力学模拟。我们观察到由于S92-D119氢键的断裂，MCU NTDS 92 E、NTDD 119 A和NTDS 92 p中保守的loop 2-loop 4（L2-L4环）的构象变化。结果表明，S92的磷酸化诱导构象变化，以及在L2-L4环的负电荷的增强，这可能会影响两个MCU-EMRE四聚体的二聚化。
The mitochondrial calcium uniporter (MCU) plays essential roles in mitochondrial calcium homeostasis and regulates cellular functions, such as energy synthesis, cell growth, and development. Thus, MCU activity is tightly controlled by its regulators as well as post-translational modification, including phosphorylation by protein kinases such as proline-rich tyrosine kinase 2 (Pyk2) and AMP-activated protein kinase (AMPK). In our in vitro kinase assay, the MCU N-terminal domain (NTD) was phosphorylated by protein kinase C isoforms (PKC beta II, PKC delta, and PKC epsilon) localized in the mitochondrial matrix. In addition, we found the conserved S92 was phosphorylated by the PKC isoforms. To reveal the structural effect of MCU S92 phosphorylation (S92p), we determined crystal structures of the MCU NTD of S92E and D119A mutants and analysed the molecular dynamics simulation of WT and S92p. We observed conformational changes of the conserved loop2-loop4 (L2-L4 loops) in MCU NTDS92E, NTDD119A, and NTDS92p due to the breakage of the S92-D119 hydrogen bond. The results suggest that the phosphorylation of S92 induces conformational changes as well as enhancements of the negative charges at the L2-L4 loops, which may affect the dimerization of two MCU-EMRE tetramers.