Information flow, gating, and energetics in dimeric molecular motors

Area of Science:

• Molecular biology
• Biophysics
• Biochemistry

Background:

• Molecular motors like kinesin and myosin are essential for intracellular transport.
• These dimeric proteins move processively along polar tracks using ATP hydrolysis.
• The mechanism of "gating," or how one motor head regulates the other, remains unclear.

Purpose of the Study:

• To investigate the energy utilization and inter-head communication in molecular motors.
• To develop a framework for quantifying gating based on information flow.
• To determine the relationship between force, information flow, and motor efficiency.

Main Methods:

• Developed a theoretical framework using information theory and stochastic thermodynamics.
• Applied the framework to analyze kinesin-1 and Myosin V motor proteins.
• Investigated the effect of external load on information flow and motor performance.

Main Results:

• Gating can be quantified as information flow between the two motor heads.
• Positive cooperativity and information flow occur at loads below a critical force (F).
• Information flow ceases, and backward steps increase when the load exceeds F, independent of ATP energy.

Conclusions:

• Gating involves coordinated chemical transitions and communication between motor heads.
• Optimal transport efficiency for molecular motors occurs at low loads (below F).
• These findings suggest molecular motors operate under low load conditions in vivo.