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Myosin VI Walks "Wiggly" on Actin
with Large and Variable Tilting.
Mol Cell. 28:954-964. 2007
Myosin VI is an unconventional motor
protein
with unusual motility properties such as its direction
of motion and path on actin and a large
stride relative to its short lever arms. To understand
these features, the rotational dynamics of
the lever arm were studied by single-molecule
polarized total internal reflection fluorescence>
(polTIRF) microscopy during processive motility
of myosin VI along actin. The axial angle is
distributed in two peaks, consistent with the
hand-over-hand model. The changes in lever
arm angles during discrete steps suggest that
it exhibits large and variable tilting in the plane
of actin and to the sides. These motions imply
that, in addition to the previously suggested
flexible tail domain, there is a compliant region
between the motor domain and lever arm that
allows myosin VI to accommodate the helical
position of binding sites while taking variable
step sizes along the actin filament.
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University of Pennsylvania
