Intracellular Ca²⁺ regulation of H⁺/Ca²⁺ antiporter YfkE mediated by a Ca²⁺ mini-sensor.

ABSTRACT: The H⁺/Ca²⁺ (calcium ion) antiporter (CAX) plays an important role in maintaining cellular Ca²⁺ homeostasis in bacteria, yeast, and plants by promoting Ca²⁺ efflux across the cell membranes. However, how CAX facilitates Ca²⁺ balance in response to dynamic cytosolic Ca²⁺ perturbations is unknown. Here, we identified a type of Ca²⁺ "mini-sensor" in YfkE, a bacterial CAX homolog from Bacillus subtilis. The mini-sensor is formed by six tandem carboxylate residues within the transmembrane (TM)5-6 loop on the intracellular membrane surface. Ca²⁺ binding to the mini-sensor triggers the transition of the transport mode of YfkE from a high-affinity to a low-affinity state. Molecular dynamics simulation an

SUBMITTER: Lu S 

PROVIDER: S-EPMC7229650 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature