Role of Mg2+ and magnesium fluoride in the induction of the E2P-like state in the Na,K-ATPase

MERCEDES CENTENO; MARIELA FERREIRA GOMES; ROLANDO ROSSI; MONTES MÓNICA RAQUEL

Villa Carlos Paz, Córdoba

Congreso; Reunión Anual Sociedad Argentina de Biofísica; 2013

Sociedad Argentina de Biofísica

Role of Mg2+ and magnesium fluoride in the induction of the E2P-like state in the Na,K-ATPase Centeno, M.; Ferreira Gomes, M.S.; Rossi, R. C.; Montes, M. R. Instituto de Química y Fisicoquímica Biológicas y Departamento de Química Biológica Dr. Paladini. Universidad de Buenos Aires. mmontes@qb.ffyb.uba.ar The Na,K-ATPase is a membrane-bound ion pump that generates electrochemical gradients for Na+ and K+ across the plasma membranes of animal cells. The enzyme oscillates between two major conformations, E1, which has high affinity for Na+ and E2, with high affinity for K+. The crystal structure of the Na,K-ATPase in the E2P form stabilized by magnesium fluoride with occluded K+ ((E2.MgF4[K2]) was the first complex described (1). In order to establish the relationship between structure and function, this work studied by kinetic studies the changes in conformational transitions produced by the binding of magnesium fluoride, magnesium and K+ to the Na,K-ATPAse. Our results show that Mg2+ binds to either E1 and E2 states of the ATPase whereas magnesium fluoride binds to the E2-Mg state and then shifts the conformation of the enzyme to the E2P-like structure. With grants of ANPCYT, CONICET y UBACYT References (1) Morth et al. Nature. 2007. 1043