Calcium regulation of the human mitochondrial ATP-Mg/Pi carrier SLC25A24 uses a locking pin mechanism

Harborne, Steven P D, King, Martin S, Crichton, Paul G and Kunji, Edmund R S (2017) Calcium regulation of the human mitochondrial ATP-Mg/Pi carrier SLC25A24 uses a locking pin mechanism. Scientific Reports, 7. ISSN 2045-2322

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Abstract

Mitochondrial ATP-Mg/Pi carriers import adenine nucleotides into the mitochondrial matrix and export phosphate to the cytosol. They are calcium-regulated to control the size of the matrix adenine nucleotide pool in response to cellular energetic demands. They consist of three domains: an N-terminal regulatory domain containing four calcium-binding EF-hands, a linker loop domain with an amphipathic α-helix and a C-terminal mitochondrial carrier domain for the transport of substrates. Here, we use thermostability assays to demonstrate that the carrier is regulated by calcium via a locking pin mechanism involving the amphipathic α-helix. When calcium levels in the intermembrane space are high, the N-terminus of the amphipathic α-helix is bound to a cleft in the regulatory domain, leading to substrate transport by the carrier domain. When calcium levels drop, the cleft closes, and the amphipathic α-helix is released to bind to the carrier domain via its C-terminus, locking the carrier in an inhibited state.

Item Type: Article
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Pure Connector
Date Deposited: 04 Apr 2017 05:29
Last Modified: 12 Nov 2020 00:50
URI: https://ueaeprints.uea.ac.uk/id/eprint/63157
DOI: 10.1038/srep45383

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