1. Functional diversity among cardiolipin binding sites on the mitochondrial ADP/ATP carrier.
- Author
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Senoo, Nanami, Chinthapalli, Dinesh K, Baile, Matthew G, Golla, Vinaya K, Saha, Bodhisattwa, Oluwole, Abraham O, Ogunbona, Oluwaseun B, Saba, James A, Munteanu, Teona, Valdez, Yllka, Whited, Kevin, Sheridan, Macie S, Chorev, Dror, Alder, Nathan N, May, Eric R, Robinson, Carol V, and Claypool, Steven M
- Subjects
CARDIOLIPIN ,BINDING sites ,PROTEIN-lipid interactions ,MOLECULAR dynamics ,TERTIARY structure ,TRANSLOCATOR proteins - Abstract
Lipid-protein interactions play a multitude of essential roles in membrane homeostasis. Mitochondrial membranes have a unique lipid-protein environment that ensures bioenergetic efficiency. Cardiolipin (CL), the signature mitochondrial lipid, plays multiple roles in promoting oxidative phosphorylation (OXPHOS). In the inner mitochondrial membrane, the ADP/ATP carrier (AAC in yeast; adenine nucleotide translocator, ANT in mammals) exchanges ADP and ATP, enabling OXPHOS. AAC/ANT contains three tightly bound CLs, and these interactions are evolutionarily conserved. Here, we investigated the role of these buried CLs in AAC/ANT using a combination of biochemical approaches, native mass spectrometry, and molecular dynamics simulations. We introduced negatively charged mutations into each CL-binding site of yeast Aac2 and established experimentally that the mutations disrupted the CL interactions. While all mutations destabilized Aac2 tertiary structure, transport activity was impaired in a binding site-specific manner. Additionally, we determined that a disease-associated missense mutation in one CL-binding site in human ANT1 compromised its structure and transport activity, resulting in OXPHOS defects. Our findings highlight the conserved significance of CL in AAC/ANT structure and function, directly tied to specific lipid-protein interactions. Synopsis: Three molecules of cardiolipin, the signature mitochondrial phospholipid, tightly interact with the ADP/ATP carrier (AAC/ANT). This study demonstrates that each cardiolipin-AAC/ANT interaction is structurally and functionally important. Negatively charged mutations into the cardiolipin binding sites of yeast Aac2 disrupted cardiolipin-Aac2 interaction. Aac2 tertiary structure was destabilized in the mutants with disrupted cardiolipin binding. Disruption of cardiolipin binding impaired Aac2 transport activity in a site-specific manner. A disease-associated mutation in human ANT1 compromises ANT1 structure and transport activity due to a disturbed cardiolipin-ANT1 interaction. The binding of three cardiolipin molecules to the mitochondrial ADP/ATP carrier supports the protein's tertiary structure and transport activity. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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