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Mechanisms of EMRE-Dependent MCU Opening in the Mitochondrial Calcium Uniporter Complex.


ABSTRACT: The mitochondrial calcium uniporter is a multi-subunit Ca2+-activated Ca2+ channel, made up of the pore-forming MCU protein, a metazoan-specific EMRE subunit, and MICU1/MICU2, which mediate Ca2+ activation. It has been established that metazoan MCU requires EMRE binding to conduct Ca2+, but how EMRE promotes MCU opening remains unclear. Here, we demonstrate that EMRE controls MCU activity via its transmembrane helix, while using an N-terminal PKP motif to strengthen binding with MCU. Opening of MCU requires hydrophobic interactions mediated by MCU residues near the pore's luminal end. Enhancing these interactions by single mutation allows human MCU to transport Ca2+ without EMRE. We further show that EMRE may facilitate MCU opening by stabilizing the open state in a conserved MCU gating mechanism, present also in non-metazoan MCU homologs. These results provide insights into the evolution of the uniporter machinery and elucidate the mechanism underlying the physiologically crucial EMRE-dependent MCU activation process.

SUBMITTER: Van Keuren AM 

PROVIDER: S-EPMC7764451 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Mechanisms of EMRE-Dependent MCU Opening in the Mitochondrial Calcium Uniporter Complex.

Van Keuren Anna M AM   Tsai Chen-Wei CW   Balderas Enrique E   Rodriguez Madison X MX   Chaudhuri Dipayan D   Tsai Ming-Feng MF  

Cell reports 20201201 10


The mitochondrial calcium uniporter is a multi-subunit Ca<sup>2+</sup>-activated Ca<sup>2+</sup> channel, made up of the pore-forming MCU protein, a metazoan-specific EMRE subunit, and MICU1/MICU2, which mediate Ca<sup>2+</sup> activation. It has been established that metazoan MCU requires EMRE binding to conduct Ca<sup>2+</sup>, but how EMRE promotes MCU opening remains unclear. Here, we demonstrate that EMRE controls MCU activity via its transmembrane helix, while using an N-terminal PKP motif  ...[more]

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