Actin-Myosin Interaction: Structure, Function and Drug Discovery

Abstract

Actin-myosin interactions play crucial roles in the generation of cellular force and movement. The molecular mechanism involves structural transitions at the interface between actin and myosin’s catalytic domain, and within myosin’s light chain domain, which contains binding sites for essential (ELC) and regulatory light chains (RLC). High-resolution crystal structures of isolated actin and myosin, along with cryo-electron micrographs of actin-myosin complexes, have been used to construct detailed structural models for actin-myosin interactions. However, these methods are limited by disorder, particularly within the light chain domain, and they do not capture the dynamics within this complex under physiological conditions in solution. Here we highlight the contributions of site-directed fluorescent probes and time-resolved fluorescence resonance energy transfer (TR-FRET) in understanding the structural dynamics of the actin-myosin complex in solution. A donor fluorescent probe on actin and an acceptor fluorescent probe on myosin, together with high performance TR-FRET, directly resolves structural states in the bound actin-myosin complex during its interaction with adenosine triphosphate (ATP). Results from these studies have profound implications for understanding the contractile function of actomyosin and establish the feasibility for the discovery of allosteric modulators of the actin-myosin interaction, with the ultimate goal of developing therapies for muscle disorders.

Actin-binding compounds, discovered by FRET-based high-throughput screening, differentially affect skeletal and cardiac muscle

“…The current study shows that actin-binding compounds, previously discovered by high-throughput FRET screening, have specific biochemical and functional effects that are distinct in cardiac and skeletal actin, and in cardiac and skeletal muscle. This sets the stage to apply the original high-throughput FRET screen to larger small-molecule libraries, leading to the discovery of novel actin-binding compounds with specific therapeutic potential for treating disorders of cardiac or skeletal muscle (11,40).…”

Resistance Training Alleviates Skeletal Muscle Atrophy in Rats Exposed to Hypoxia by inhibiting Autophagy Mediated by Acetyl-FoxO1

“…1F). Myosin is an important protein involved in the formation of thick muscle filaments, and changes in myosin content reflect concomitant changes in muscle mass and tension [31]. As E3 ubiquitin ligases, atrogin1 and MuRF1 ubiquitinate and label skeletal muscle-specific proteins to target hydrolysis by 26S proteases, which were once considered to be key proteins for activating the ubiquitin-proteasome pathway (UPP).…”

Horse gluteus is a null-sarcolipin muscle with enhanced sarcoplasmic reticulum calcium transport

“…1 Abbreviations and acronyms used are: ATP2A1, gene encoding SERCA1 protein isoforms; ATP2A2, gene encoding SERCA2 protein isoforms; ATP2A3, gene encoding SERCA3 protein isoforms; Ca 2+ , calcium; CASQ, calsequestrin; codRNA, protein-coding RNA; DWORF, dwarf open reading-frame peptide; g, gravitational force equivalent of 9.8 m/s 2 standardized to 1 g at average Earth surface; GP, glycogen phosphorylase; IU, international unit of enzyme activity, defined as the production of 1 µmol product per milligram protein per minute; K Ca , apparent Ca 2+ dissociation constant, defined as the Ca 2+ concentration required for half-maximal activation of SERCA activity; KLH, keyhole limpet hemocyanin; lncRNA, long non-coding RNA; mAb, monoclonal antibody; MD, molecular dynamics; MRLN, myoregulin; mRNA, message RNA; pAb, polyclonal antibody; pI, protein isoelectric point defined as the pH at which the net protein charge is zero; PLN, phospholamban; ProtK, proteinase K; qRT-PCR, mRNA quantitation using real-time reverse transcription polymerase chain reaction; RER, recurrent exertional rhabdomyolysis; RNA-seq, whole transcriptome shotgun sequencing; RYR, ryanodine receptor Ca 2+ release channel; SEM, standard error of the mean; SERCA, sarco/endoplasmic reticulum Ca 2+ -transporting ATPase; SLN, sarcolipin; sORF, small open reading frame; SOICR, store overload-induced Ca 2+ release; SR, sarcoplasmic reticulum; TG, thapsigargin; T i , the temperature at which 50% transition occurs between peak enzyme activity and thermal inactivation; TM, transmembrane helix; TPM, transcripts per million reads; V max , maximal enzyme velocity of SERCA measured at saturating concentration of ionized Ca 2+ (1-10 µM) and Mg-ATP (1-10 mM). 2 RNA-seq data from Arabian horse gluteal muscle were deposited in the Sequence Read Archive (SRA) database with accession number SRP082284. Gene expression values from rabbit muscle were mined from RNA-seq data deposited with SRA accession number SAMN00013649.…”