Open AccessConformational changes during the reaction cycle of Plasma Membrane Ca2+-ATPase in the autoinhibited and activated states
Author(s) -
Nicolás A. Saffioti,
Marilina de Sautú,
Ana Sol Riesco,
Mariela Ferreira-Gomes,
Juan Pablo F.C. Rossi,
Irene C. Mangialavori
Publication year - 2021
Publication title -
biochemical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 265
eISSN - 1470-8728
pISSN - 0264-6021
DOI - 10.1042/bcj20210036
Subject(s) - calmodulin , plasma membrane ca2+ atpase , dephosphorylation , chemistry , biophysics , atpase , proteolysis , conformational change , extracellular , membrane , phosphorylation , intracellular , binding site , biochemistry , enzyme , phosphatase , biology
Plasma membrane Ca2+-ATPase (PMCA) transports Ca2+ by a reaction cycle including phosphorylated intermediates. Calmodulin binding to the C-terminal tail disrupts autoinhibitory interactions, activating the pump. To assess the conformational changes during the reaction cycle, we studied the structure of different PMCA states using a fluorescent probe, hydrophobic photolabeling, controlled proteolysis and Ca2+-ATPase activity.  Our results show that calmodulin binds to E2P-like states, and during dephosphorylation, the hydrophobicity in the nucleotide-binding pocket decreases and the Ca2+ binding site becomes inaccessible to the extracellular medium. Autoinhibitory interactions are disrupted in E1Ca and in the E2P ground state whereas they are stabilized in the E2∙Pi product state. Finally, we propose a model that describes the conformational changes during the Ca2+ transport of PMCA.