Movement and force produced by a single myosin head

@article{Molloy1995MovementAF,
  title={Movement and force produced by a single myosin head},
  author={Justin E. Molloy and Julie E. Burns and John Kendrick‐Jones and Richard T. Tregear and David C. S. White},
  journal={Nature},
  year={1995},
  volume={378},
  pages={209-212}
}
MUSCLE contraction is driven by the cyclical interaction of myosin with actin, coupled to the breakdown of ATP. Studies of the interaction of filamentous myosin1 and of a double-headed proteolytic fragment, heavy meromyosin (HMM)2,3, with actin have demonstrated discrete mechanical events, arising from stochastic interaction of single myosin molecules with actin. Here we show, using an optical-tweezers transducer2,4, that a single myosin subfragment-1 (S1), which is a single myosin head, can… 
The motor protein myosin-I produces its working stroke in two steps
TLDR
The slower kinetics of myosin-I have allowed us to observe the separate mechanical states that contribute to its working stroke, and an optical-tweezers transducer is used to measure the mechanical transitions made by a single myOSin head while it is attached to actin.
Two independent mechanical events in the interaction cycle of skeletal muscle myosin with actin.
TLDR
The finding of a second mechanical event in the working stroke of skeletal muscle myosin provides the molecular basis for a simple model of actomyosin interaction that can account for the variation, in different fiber types, of the rate of the cross-bridge cycle and provides a common scheme for the chemo-mechanical transduction within the myOSin family.
The size and the speed of the working stroke of muscle myosin and its dependence on the force
TLDR
It is shown that with 150 μs force steps it is possible to separate the elastic response from the subsequent early rapid component of filament sliding due to the working stroke in the attached myosin heads, and determine how the size and the speed of the working strokes depend on the clamped force.
Mechanism of muscle contraction based on stochastic properties of single actomyosin motors observed in vitro
TLDR
Computer simulations show that multiple cooperating heads undergoing stochastic steps generate a long (>60 nm) sliding distance per ATP between actin and myosin filaments, i.e., the movement is loosely coupled to the ATPase cycle as observed in muscle.
Two heads of myosin are better than one for generating force and motion.
  • M. Tyska, D. Dupuis, S. Lowey
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1999
TLDR
Measurements of unitary displacement and force produced by double-headed and single-headed smooth- and skeletal-muscle myosin suggest that muscle myosins require both heads to generate maximal force and motion.
Load-dependent kinetics of force production by smooth muscle myosin measured with optical tweezers
TLDR
A new technique based on optical tweezers to rapidly apply force to a single smooth muscle myosin crossbridge that produced movement in two phases that contribute 4 nm + 2 nm of displacement.
A single myosin head moves along an actin filament with regular steps of 5.3 nanometres
TLDR
A new instrument is developed with which individual myosin subfragment-1 molecules are captured and directly manipulated using a scanning probe to resolve the individual mechanical events of force generation by actomyosin.
A model of stereocilia adaptation based on single molecule mechanical studies of myosin I.
TLDR
A new model is proposed to explain the slow phase of sensory adaptation of the hair cells of the inner ear, consistent with the classical 'T2' behaviour of single muscle fibres.
Molecular model of muscle contraction.
  • T. Duke
  • Biology, Chemistry
    Proceedings of the National Academy of Sciences of the United States of America
  • 1999
TLDR
The model indicates that when large numbers of myosin molecules act collectively, their chemical cycles can be synchronized, and that this leads to stepwise motion of the thin filament.
Single-myosin crossbridge interactions with actin filaments regulated by troponin-tropomyosin.
TLDR
Data support the hypothesis that thin filament inhibition in the absence of Ca(2+) is largely achieved by modulating the rate of attachment and/or transition from the weakly to strongly bound state, as well as the investigations of single- and multiple-myosin molecules with regulated thin filaments.
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