Axle-less F1-ATPase rotates in the correct direction

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• F1-adenosine triphosphatase (ATPase) functions as an ATP-driven rotary molecular motor.
• Its structure comprises a central gamma subunit rotating within a stator cylinder of alternating alpha and beta subunits.
• The gamma subunit's rotor shaft penetrates the stator's central cavity.

Purpose of the Study:

• To investigate the role of the F1-ATPase rotor shaft's length in its rotary function.
• To determine if a fixed pivot or rigid axle is necessary for the motor's rotation.

Main Methods:

• Stepwise truncation of the gamma subunit's rotor shaft.
• Observation and analysis of the rotary motion of truncated F1-ATPase mutants.
• Assessing torque generation and rotary speeds.

Main Results:

• All truncated F1-ATPase mutants demonstrated rotation in the correct direction, indicating torque generation.
• Shorter mutants exhibited reduced average rotary speeds and occasional irregular motion.
• The enzyme rotated effectively without a fixed pivot or rigid axle.

Conclusions:

• The length of the F1-ATPase rotor shaft can be significantly reduced without abolishing rotary motion.
• Torque generation and rotation are possible even when the rotor shaft is partially exposed.
• A fixed pivot or rigid axle is not a prerequisite for F1-ATPase function.