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A kinetic model of coordinated myosin V
Yudong Wu1, Yi Qin Gao, Martin Karplus
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Biochemistry
|May 10, 2007
Summary
This study introduces a kinetic model for myosin V walking on actin, explaining how ATP and ADP concentrations affect its speed and distance. The model aligns with experimental data, revealing myosin
Area of Science:
- Molecular biology
- Biophysics
- Cellular mechanics
Background:
- Myosin V is a motor protein crucial for intracellular transport along actin filaments.
- Understanding myosin V's kinetics is essential for elucidating cellular processes like cargo movement.
- Previous models have simplified the complex interactions governing myosin V's processivity.
Purpose of the Study:
- To develop a quantitative kinetic model for myosin V's processive movement on actin under zero external force.
- To investigate the influence of adenosine triphosphate (ATP) and adenosine diphosphate (ADP) concentrations on myosin V's walking velocity and run length.
- To explain experimentally observed trends in myosin V's behavior, including its response to varying ATP levels.
Main Methods:
- Development of a multi-pathway kinetic model incorporating processivity termination.
- Integration of experimentally determined kinetic parameters into the model.
- Computational analysis of walking velocities and run lengths across a range of ATP and ADP concentrations.
Main Results:
- The model accurately predicts trends observed in experimental data regarding myosin V's movement.
- It quantifies the proportion of pathways involving an intermediate state.
- The model explains why increased ATP concentration can lead to faster but shorter runs in the absence of ADP.
Conclusions:
- The developed kinetic model provides a robust framework for understanding myosin V's processive motion.
- Myosin V's speed and run length are sensitive to ATP and ADP concentrations, with implications for cellular transport efficiency.
- Under physiological conditions, increased ATP availability is predicted to enhance both myosin V's speed and processivity.
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