Myosin-induced volume increase of the hyper-mobile water surrounding actin filaments.
Microwave dielectric spectroscopy can measure the rotational mobility of water molecules that hydrate proteins and the hydration-shell volume. Using this technique, we have recently shown that apart from typical hydrating water molecules with lowered mobility there are other water molecules around the actin filaments (F-actin) which have a much higher mobility than that of bulk water [Biophys. J. 85 (2003) 3154]. We report here that the volume of this water component (hyper-mobile water) markedly increases without significant change of the volume of the ordinary hydration shell when the myosin motor-domain (S1, myosin subfragment-1) binds to F-actin. No hyper-mobile component was found in the hydration shell of S1 itself. The present results strongly suggest that the solvent space around S1 bound to F-actin is diffusionally asymmetric, which supports our model of force generation by actomyosin proposed previously [op. cit.].
Department of Materials Science and Engineering, Tohoku University, Aoba-yama 02, Sendai 980-8579, Japan. msuzuki@material.tohoku.ac.jp
Makoto
M
Suzuki
Syed Rashel
SR
Kabir
Md Shahjahan Parvez
MS
Siddique
Umme Salma
US
Nazia
Takashi
T
Miyazaki
Takao
T
Kodama
D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000648:ultrastructure; D001665:Binding Sites; D003198:Computer Simulation; D017097:Electric Impedance; D008872:Microwaves; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000648:ultrastructure; D009038:Motion; D009218:Myosins / Q000737:chemistry* / Q000648:ultrastructure; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012997:Solvents / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D013314:Stress, Mechanical; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry*
D020409:Molecular Motor Proteins; D012997:Solvents; D014867:Water; D009218:Myosins