Open AccessMgATP‐induced conformational changes in a single myosin molecule observed by atomic force microscopy: Periodicity of substructures in myosin rods
Author(s) -
Taniguchi Mieko,
Suzuki Shigehito,
Yamane Takashi,
Matsumoto Osamu,
Okuda Ayumu,
Taga Tooru,
Nishino Yasunobu
Publication year - 2003
Publication title -
scanning
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.359
H-Index - 47
eISSN - 1932-8745
pISSN - 0161-0457
DOI - 10.1002/sca.4950250502
Subject(s) - myosin , crossbridge , chemistry , myosin head , molecule , rod , biophysics , substructure , crystallography , myosin light chain kinase , biochemistry , medicine , alternative medicine , organic chemistry , structural engineering , pathology , engineering , biology
This paper discusses the conformational changes in a single myosin molecule directly observed using atomic force microscopy (AFM). The myosin molecules were pretreated in rigor solutions without MgATP or in relaxed solutions with various concentrations of MgATP. The images of these molecules were obtained using a tapping mode AFM. The results indicate that the orientation of the myosin's heads and tail strongly depend on the MgATP concentration. Without using MgATP, almost all of the myosin molecules are in the extended form; however, when MgATP is used, the molecules bend according to the level of MgATP concentration. The mean‐square end‐to‐end distance of the myosin molecules is significantly shorter with p[MgATP] = 4 than with p[MgATP] = 6. The rod region did not show the same level of intensity along their length in the extended form. The rods exhibited clusters of discontinuity, which were identified as substructures. The size of these substructures change at intervals that are multiples of 14.3‐14.5 nm, which reflects the periodicity of the α;‐helical coiled coils. The substructure clusters also correspond to the myosin cross‐bridge spacing in muscles (14.3 or 43 nm). These results suggest that the myosin's head bends in conjunction with the bending or tilting in the helical substructures. Conformational changes of the myosin molecule induced by MgATP seem to mimic the molecular motions in a muscle's force generation process.