Ca2+ efflux facilitated by co-transport of inorganic phosphate anion in the H+/Ca2+ antiporter YfkE

• Published in: Communications biology Vol. 6; no. 1; p. 573
• Main Authors: Niu, Wei, Zhou, Wenchang, Lu, Shuo, Vu, Trung, Jayaraman, Vasanthi, Faraldo-Gómez, José D, Zheng, Lei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 29.05.2023; Nature Publishing Group UK; Nature Portfolio
• Subjects: Biology; Ca2+/H+-exchanging ATPase; Calcium (intracellular); Calcium efflux; Calcium homeostasis; Calcium phosphates; Calcium signalling; Calcium transport; Cell membranes; Homeostasis; Hydrogen; Phosphate; Phosphates
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-023-04944-6

Abstract Ca 2+ is an important signaling messenger. In microorganisms, fungi, and plants, H + /Ca 2+ antiporters (CAX) are known to play key roles in the homeostasis of intracellular Ca 2+ by catalyzing its efflux across the cell membrane. Here, we reveal that the bacterial CAX homolog YfkE transports Ca 2+ in two distinct modes: a low-flux H + /Ca 2+ exchange mode and a high-flux mode in which Ca 2+ and phosphate ions are co-transported (1:1) in exchange for H + . Coupling with phosphate greatly accelerates the Ca 2+ efflux activity of YfkE. Our studies reveal that Ca 2+ and phosphate bind to adjacent sites in a central translocation pathway and lead to mechanistic insights that explain how this CAX alters its conserved alpha-repeat motifs to adopt phosphate as a specific “transport chaperon” for Ca 2+ translocation. This finding uncovers a co-transport mechanism within the CAX family that indicates this class of proteins contributes to the cellular homeostasis of both Ca 2+ and phosphate.