SPECTROSCOPY, IMAGING, OTHER TECHNIQUES |
A programmable optical angle clamp for rotary molecular motors
Teuta Pilizota 1, Thomas Bilyard 1, Fan Bai 1, Masamitsu Futai 2, Hiroyuki Hosokawa 2 and Richard M Berry 1*
1 Oxford University
2 Japan Science and Technology Agency
* To whom correspondence should be addressed. E-mail: r.berry1{at}physics.ox.ac.uk.
Submitted on June 10, 2006
Revised on July 27, 2006
Accepted on 8 March 2007
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Abstract |
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Optical tweezers are widely used for experimental investigation of linear molecular motors. The rates and force-dependence of steps in the mechanochemical cycle of linear motors have been probed giving detailed insight into motor mechanisms. With similar goals in mind for rotary molecular motors we present here an optical trapping system designed as an angle clamp to study the bacterial flagellar motor and F1-ATPase. The trap position was controlled by a digital signal processing board and a host computer via acousto-optic deflectors, the motor position via a 3-D piezo-electric stage and the motor angle using a pair of polystyrene beads as a handle for the optical trap. Bead-pair angles were detected using back focal plane interferometry with a resolution of up to 1°, and controlled using a feedback algorithm with a precision of up to 2° and a bandwidth of up to 1.6 kHz. Details of the optical trap, algorithm and alignment procedures are given. Preliminary data showing angular control of F1-ATPase and angular and speed control of the bacterial flagellar motor are presented.
Key Words:
bacterial flagellar motor, feedback, optical tweezers, rotary motors
