Single-molecule stepping and structural dynamics of myosin X.
Myosin X is an unconventional myosin with puzzling motility properties. We studied the motility of dimerized myosin X using the single-molecule fluorescence techniques polTIRF, FIONA and Parallax to measure the rotation angles and three-dimensional position of the molecule during its walk. It was found that Myosin X steps processively in a hand-over-hand manner following a left-handed helical path along both single actin filaments and bundles. Its step size and velocity are smaller on actin bundles than individual filaments, suggesting myosin X often steps onto neighboring filaments in a bundle. The data suggest that a previously postulated single alpha-helical domain mechanically extends the lever arm, which has three IQ motifs, and either the neck-tail hinge or the tail is flexible. These structural features, in conjunction with the membrane- and microtubule-binding domains, enable myosin X to perform multiple functions on varied actin structures in cells.
Sun
Yujie
Y
Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Sato
Osamu
O
Ruhnow
Felix
F
Arsenault
Mark E
ME
Ikebe
Mitsuo
M
Goldman
Yale E
YE
D000199:Actins / Q000737:chemistry; D009218:Myosins / Q000737:chemistry*; D011487:Protein Conformation; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence
D000199:Actins; D009218:Myosins