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Biophysics of Rotary Molecular Motors |
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Dr. Richard M Berry
University Lecturer
Clarendon Laboratory Room 273
Phone: +44 (0) 1865 272288
Fax: +44 (0) 1865 272400
Email:
r.berry1@physics.ox.ac.uk
Web:
http://webnix.physics.ox.ac.uk/biophysics/
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Single-molecule
studies of Biological Rotary Motors
The aim of the research is to understand at a fundamental level
how biological rotary motors work. This inter-disciplinary field is
rapidly expanding following technical advances that allow the
measurement of individual mechanical steps of single biological
molecular machines.
The motors we study are the bacterial flagellar motor and
the F1 and F0 motors of ATP-synthase.
These are tiny machines self-assembled in living cells from a
handful of protein molecules. The flagellar motor has a diameter of
50 nm and maximum speed up to 1700 revs per second, F1
and F0 are about 10 nm across and about 10 times slower.
The flagellar motor and F0 run on an electric current of
positive ions that flows across the cell membrane. F1
runs on ATP, a high-energy molecule that is the "energy currency" of
living things. (In ATP-synthase F0 drives F1
in reverse, causing it to generate ATP.)
We use a range of techniques to do experiments on these molecular
motors one at a time. "Optical tweezers" consist of a laser
beam that pushes motors with picoNewton forces and measures their
position with nanometre accuracy. Electrorotation allows us
to twist motors to change their rotation speed. A variety of genetic
and biochemical techniques are used to prepare and manipulate the
motors.
Single-molecule fluorescence
microscopy and other novel techniques are also under development as
part of the new Interdisciplinary Research Collaboration in
Bio-Nanotechnology, based in the physics department.
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Key Publications
Direct observation of steps in rotation of the
bacterial flagellar motor. Sowa Y,
Rowe AD, Leake MC, Yakushi T, Homma M, Ishijima A, Berry RM. (2005).
Nature. 437:916-919.
The first ever observation of the fundamental process in the
flagellar motor.
Stoichiometry and turnover in single,
functioning membrane protein complexes.
Leake MC, Chandler JH, Wadhams GH, Bai F, Berry RM, Armitage JP.
(2006).
Nature. 443:355-358
Counting individual molecules in the flagellar motor using
fluorescence microscopy.
Torque generating units of the flagellar motor of
Escherichia coli have a high duty ratio.
Ryu, W.S., Berry, R.M. and Berg, H.C. (2000)
Nature. 403:444-447
Torque vs speed measurements of flagellar motors with different
molecular compositions.
A programmable optical angle
clamp for rotary molecular motors.
Pilizota T, Bilyard T, Bai
F, Futai M, Hosokawa H, Berry RM. (2007).
Biophys. J. 93:264-275.
Pushing single molecules with laser beams.
Non-equivalence of membrane voltage and ion-gradient as
driving forces for the bacterial flagellar motor at low
load.
Lo C-J, Leake MC, Pilizota T, Berry RM. (2007).
Biophys. J.
93:294-302.
Ion concentration is better than voltage for spinning the
flagellar motor.
Rapid chiral assembly of rigid DNA building
blocks for molecular nanofabrication.
Goodman R. P., Schaap I. A. T., Tardin C. F.,
Erben C. M., Berry R. M., Schmidt C. F., Turberfield A. J.
(2005)
Science. 310:1661-1665
Collaboration with the DNA nanostructures group.
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