1
|
Giladi M, Fojtík L, Strauss T, Da'adoosh B, Hiller R, Man P, Khananshvili D. Structural dynamics of Na + and Ca 2+ interactions with full-size mammalian NCX. Commun Biol 2024; 7:463. [PMID: 38627576 PMCID: PMC11021524 DOI: 10.1038/s42003-024-06159-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 04/05/2024] [Indexed: 04/19/2024] Open
Abstract
Cytosolic Ca2+ and Na+ allosterically regulate Na+/Ca2+ exchanger (NCX) proteins to vary the NCX-mediated Ca2+ entry/exit rates in diverse cell types. To resolve the structure-based dynamic mechanisms underlying the ion-dependent allosteric regulation in mammalian NCXs, we analyze the apo, Ca2+, and Na+-bound species of the brain NCX1.4 variant using hydrogen-deuterium exchange mass spectrometry (HDX-MS) and molecular dynamics (MD) simulations. Ca2+ binding to the cytosolic regulatory domains (CBD1 and CBD2) rigidifies the intracellular regulatory loop (5L6) and promotes its interaction with the membrane domains. Either Na+ or Ca2+ stabilizes the intracellular portions of transmembrane helices TM3, TM4, TM9, TM10, and their connecting loops (3L4 and 9L10), thereby exposing previously unappreciated regulatory sites. Ca2+ or Na+ also rigidifies the palmitoylation domain (TMH2), and neighboring TM1/TM6 bundle, thereby uncovering a structural entity for modulating the ion transport rates. The present analysis provides new structure-dynamic clues underlying the regulatory diversity among tissue-specific NCX variants.
Collapse
Affiliation(s)
- Moshe Giladi
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv, 69978, Israel.
- Tel-Aviv Sourasky Medical Center, Tel Aviv, 6423906, Israel.
| | - Lukáš Fojtík
- Division BioCeV, Institute of Microbiology of the Czech Academy of Sciences, Prumyslova, 595, 252 50 Vestec, Prague, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University, 128 00, Prague, Czech Republic
| | - Tali Strauss
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Benny Da'adoosh
- Blavatnik Center for Drug Discovery, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Reuben Hiller
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Petr Man
- Division BioCeV, Institute of Microbiology of the Czech Academy of Sciences, Prumyslova, 595, 252 50 Vestec, Prague, Czech Republic.
- Department of Biochemistry, Faculty of Science, Charles University, 128 00, Prague, Czech Republic.
| | - Daniel Khananshvili
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel Aviv, 69978, Israel.
| |
Collapse
|