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

TitleCalcium regulation of the human mitochondrial ATP-Mg/Pi carrier SLC25A24 uses a locking pin mechanism.
Publication TypeJournal Article
Year of Publication2017
AuthorsHarborne, SPD, King, MS, Crichton, PG, Kunji, ERS
JournalSci Rep
Volume7
Pagination45383
Date Published2017 Mar 28
ISSN2045-2322
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.

DOI10.1038/srep45383
Alternate JournalSci Rep
Citation Key10.1038/srep45383
PubMed ID28350015
PubMed Central IDPMC5369052