Faculty Collaboration Database

Effects of the Arg9Cys and Arg25Cys mutations on phospholamban's conformational equilibrium in membrane bilayers. Biochim Biophys Acta Biomembr 2018 Jun;1860(6):1335-1341

Date

03/05/2018

Pubmed ID

29501609

Pubmed Central ID

PMC6428084

DOI

10.1016/j.bbamem.2018.02.030

Scopus ID

2-s2.0-85045940567 (requires institutional sign-in at Scopus site)   13 Citations

Abstract

Approximately, 70% of the Ca²⁺ ion transport into the sarcoplasmic reticulum is catalyzed by the sarcoplasmic reticulum Ca²⁺-ATPase (SERCA), whose activity is endogenously regulated by phospholamban (PLN). PLN comprises a TM inhibitory region and a cytoplasmic regulatory region that harbors a consensus sequence for cAMP-dependent protein kinase (PKA). The inhibitory region binds the ATPase, reducing its apparent Ca²⁺ binding affinity. β-adrenergic stimulation activates PKA, which phosphorylates PLN at Ser 16, reversing its inhibitory function. Mutations and post-translational modifications of PLN may lead to dilated cardiomyopathy (DCM) and heart failure. PLN's cytoplasmic region interconverts between a membrane-associated T state and a membrane-detached R state. The importance of these structural transitions on SERCA regulation is emerging, but the effects of natural occurring mutations and their relevance to the progression of heart disease are unclear. Here we use solid-state NMR spectroscopy to investigate the structural dynamics of two lethal PLN mutations, R9C and R25C, which lead to DCM. We found that the R25C mutant enhances the dynamics of PLN and shifts the conformational equilibrium toward the R state confirmation, whereas the R9C mutant drives the amphipathic cytoplasmic domain toward the membrane-associate state, enriching the T state population. The changes in membrane interactions caused by these mutations may explain the aberrant regulation of SERCA.

Author List

Nelson SED, Ha KN, Gopinath T, Exline MH, Mascioni A, Thomas DD, Veglia G

Author

Gopinath Tata PhD Assistant Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acid Sequence
Amino Acid Substitution
Calcium-Binding Proteins
Cardiomyopathy, Dilated
Consensus Sequence
Humans
Lipid Bilayers
Membrane Proteins
Mutation, Missense
Nuclear Magnetic Resonance, Biomolecular
Point Mutation
Protein Conformation
Protein Domains
Protein Structure, Secondary
Recombinant Proteins
Sarcoplasmic Reticulum Calcium-Transporting ATPases