S100A1 binds to the calmodulin-binding site of ryanodine receptor and modulates skeletal muscle excitation-contraction coupling.

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TitleS100A1 binds to the calmodulin-binding site of ryanodine receptor and modulates skeletal muscle excitation-contraction coupling.
Publication TypeJournal Article
Year of Publication2008
AuthorsProsser, BL, Wright, NT, Hernández-Ochoa, EO, Varney, KM, Liu, Y, Olojo, RO, Zimmer, DB, Weber, DJ, Schneider, MF
JournalJ Biol Chem
Volume283
Issue8
Pagination5046-57
Date Published2008 Feb 22
ISSN0021-9258
KeywordsAnimals, Binding Sites, Calmodulin, Cardiomyopathies, Membrane Potentials, Mice, Mice, Knockout, Muscle Contraction, Muscle Fibers, Skeletal, Muscle, Skeletal, Muscular Diseases, Myocardium, Nuclear Magnetic Resonance, Biomolecular, Peptides, Ryanodine Receptor Calcium Release Channel, S100 Proteins, Sarcoplasmic Reticulum
Abstract

S100A1, a 21-kDa dimeric Ca2+-binding protein, is an enhancer of cardiac Ca2+ release and contractility and a potential therapeutic agent for the treatment of cardiomyopathy. The role of S100A1 in skeletal muscle has been less well defined. Additionally, the precise molecular mechanism underlying S100A1 modulation of sarcoplasmic reticulum Ca2+ release in striated muscle has not been fully elucidated. Here, utilizing a genetic approach to knock out S100A1, we demonstrate a direct physiological role of S100A1 in excitation-contraction coupling in skeletal muscle. We show that the absence of S100A1 leads to decreased global myoplasmic Ca2+ transients following electrical excitation. Using high speed confocal microscopy, we demonstrate with high temporal resolution depressed activation of sarcoplasmic reticulum Ca2+ release in S100A1-/- muscle fibers. Through competition assays with sarcoplasmic reticulum vesicles and through tryptophan fluorescence experiments, we also identify a novel S100A1-binding site on the cytoplasmic face of the intact ryanodine receptor that is conserved throughout striated muscle and corresponds to a previously identified calmodulin-binding site. Using a 12-mer peptide of this putative binding domain, we demonstrate low micromolar binding affinity to S100A1. NMR spectroscopy reveals this peptide binds within the Ca2+-dependent hydrophobic pocket of S100A1. Taken together, these data suggest that S100A1 plays a significant role in skeletal muscle excitation-contraction coupling, primarily through specific interactions with a conserved binding domain of the ryanodine receptor. This warrants further investigation into the use of S100A1 as a therapeutic target for the treatment of both cardiac and skeletal myopathies.

DOI10.1074/jbc.M709231200
Alternate JournalJ. Biol. Chem.
PubMed ID18089560
Grant ListCA107331 / CA / NCI NIH HHS / United States
GM58888 / GM / NIGMS NIH HHS / United States
R01 AR055099 / AR / NIAMS NIH HHS / United States
R01 AR055099 / AR / NIAMS NIH HHS / United States
R01 GM058888 / GM / NIGMS NIH HHS / United States
S10 R15741 / / PHS HHS / United States
S10 RR10441 / RR / NCRR NIH HHS / United States
S10 RR16812 / RR / NCRR NIH HHS / United States
T32 AR007592 / AR / NIAMS NIH HHS / United States