Dwarf open reading frame (DWORF) is a direct activator of the sarcoplasmic reticulum calcium pump SERCA

eLife

L Michel Espinoza-Fonseca¹  Rodrigo Aguayo-Ortiz¹  Nishadh Rathod²  Howard S Young²  M'Lynn E Fisher²  M Joanne Lemieux²  Aleksey V Zima³  Seth L Robia³  Elisa Bovo³  Marsha P Pribadi³  Ellen E Cho³  Michael P Dalton³ 

[1] Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, United States;Department of Biochemistry, University of Alberta, Edmonton, Canada;Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States;

关键词: calcium ATPase;    membrane reconstitution;    cellular calcium dynamics;    fluorescence resonance energy transfer;    molecular dynamics simulations;    None;   

DOI  :  10.7554/eLife.65545

来源: eLife Sciences Publications, Ltd

【 摘 要 】

The sarco-plasmic reticulum calcium pump (SERCA) plays a critical role in the contraction-relaxation cycle of muscle. In cardiac muscle, SERCA is regulated by the inhibitor phospholamban. A new regulator, dwarf open reading frame (DWORF), has been reported to displace phospholamban from SERCA. Here, we show that DWORF is a direct activator of SERCA, increasing its turnover rate in the absence of phospholamban. Measurement of in-cell calcium dynamics supports this observation and demonstrates that DWORF increases SERCA-dependent calcium reuptake. These functional observations reveal opposing effects of DWORF activation and phospholamban inhibition of SERCA. To gain mechanistic insight into SERCA activation, fluorescence resonance energy transfer experiments revealed that DWORF has a higher affinity for SERCA in the presence of calcium. Molecular modeling and molecular dynamics simulations provide a model for DWORF activation of SERCA, where DWORF modulates the membrane bilayer and stabilizes the conformations of SERCA that predominate during elevated cytosolic calcium.

【 授权许可】

CC BY