Actin-induced changes in the dynamics of myosin subfragment-1 detected by nuclear magnetic resonance.
Analysis of high resolution 1H NMR spectra for myosin and myosin subfragment-1 (S-1) indicates that S-1 has an unusual structure, about 20% of which is mobile. The rest of the myosin molecule and F-actin are rigid by comparison. A wide variety of perturbations do not affect the S-1 internal mobility and suggest that the mobile structure is located in the interior of S-1. Actin binding uniquely quenches the internal motions entirely. The F and G forms have a similar effect. Nucleotide binding restores the internal motions under conditions known to cause dissociation of the acto-S-1 complex. A model of force generation by the actomyosin-nucleotide system, which incorporates this striking actin-induced change in S-1 structural dynamics, is proposed and discussed.
D000199:Actins / Q000378:metabolism*; D000818:Animals; D009682:Magnetic Resonance Spectroscopy; D009119:Muscle Contraction; D015879:Myosin Subfragments; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011487:Protein Conformation
D000199:Actins; D015879:Myosin Subfragments; D010446:Peptide Fragments; D009218:Myosins