Torque generation by axonemal outer-arm dynein.

Area of Science:

• Molecular Motors
• Cell Biology
• Biophysics

Background:

• Cilia generate movement using outer-arm dynein.
• The mechanical properties of dynein subparticles are not fully understood.

Purpose of the Study:

• Investigate the torque generation mechanism of Tetrahymena ciliary outer-arm dynein.
• Determine the role of different dynein subparticles (αβγ, βγ, α) in microtubule rotation.

Main Methods:

• Utilized three-dimensional tracking microscopy.
• Performed microtubule corkscrewing assays with varying ATP concentrations.
• Analyzed mixtures of dynein subparticles at different ratios.

Main Results:

• All tested dynein subparticles (αβγ, βγ, α) exhibited clockwise microtubule rotation.
• Microtubule corkscrewing pitch was largely ATP-independent, except at low ATP where αβγ and α showed longer pitches.
• The α-subparticle significantly and non-linearly increased the corkscrewing pitch in mixtures with βγ.

Conclusions:

• Torque generation is an intrinsic property of axonemal dynein subparticles, not solely dependent on the three-headed form.
• Distinct mechanical properties exist among the α, βγ, and αβγ dynein subparticles.
• The α-subparticle plays a crucial role in modulating the torque generated by outer-arm dynein.