Effect of nucleotides and their analogues on essential light chains in myosin head.
The domain movement in myosin head plays a decisive role in the energy transduction process of the muscle contraction. During hydrolysis of ATP, the specific formation of strong binding of myosin head for actin causes conformational changes. As a consequence, the light chain-binding motif generates the powerstroke. In our work maleimide spin labels were covalently attached to Cys-177 residue of ELC in subfragment-1 (S1). Our goal was to study the orientation dependence and the motion of S1, which were incorporated into glycerinated skeletal muscle fibres. The electron paramagnetic resonance spectroscopy (EPR) spectra of the probes depended strongly on the orientation of the fibre axis relative to the magnetic field, indicating that the essential light chain (ELC) and the neck were ordered. The probes were undergoing rapid motion within a cone. The half-width of the cone was estimated to be 65+/-5 degrees (SD, n=8). Addition of ADP affected little the hyperfine splitting and the angular spread of the probe distribution. In the presence of ADP and orthovanadate the intensity of the spectra decreased, which showed the dissociation of S1 and this was accompanied with the disappearance of the orientation dependence.
Hartvig
Nóra
N
Central Research Laboratory, Faculty of Medicine, University of Pécs, 12 Szigeti Str., H-7643 Pécs, Hungary.
Gaszner
Balázs
B
Kiss
Márta
M
Lorinczy
Dénes
D
Belágyi
Joseph
J
D000244:Adenosine Diphosphate / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D003198:Computer Simulation; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D066298:In Vitro Techniques; D008301:Maleimides; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000378:metabolism; D015336:Molecular Probe Techniques; D009038:Motion; D018485:Muscle Fibers, Skeletal / Q000737:chemistry* / Q000378:metabolism; D018482:Muscle, Skeletal; D018994:Myosin Light Chains / Q000737:chemistry / Q000378:metabolism; D015879:Myosin Subfragments / Q000737:chemistry / Q000378:metabolism; D009218:Myosins / Q000737:chemistry* / Q000378:metabolism; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016658:Psoas Muscles; D011817:Rabbits; D013113:Spin Labels
D008301:Maleimides; D020409:Molecular Motor Proteins; D018994:Myosin Light Chains; D015879:Myosin Subfragments; D009711:Nucleotides; D013113:Spin Labels; C043592:maleimide; D000244:Adenosine Diphosphate; D009218:Myosins