A giant liposome for single-molecule observation of conformational changes in membrane proteins
Journal article, 2009
We present an experimental system that allows visualization of conformational changes in membrane proteins at the single-molecule level. The target membrane protein is reconstituted in a giant liposome for independent control of the aqueous environments on the two sides of the membrane. For direct observation of conformational changes, an extra-liposomal site(s) of the target protein is bound to a glass surface, and a probe that is easily visible under a microscope, such as a micron-sized plastic bead, is attached to another site on the intra-liposomal side. A conformational change, or an angular motion in the tiny protein molecule, would manifest as a visible motion of the probe. The attachment of the protein on the glass surface also immobilizes the liposome, greatly facilitating its manipulation such as the probe injection. As a model system, we reconstituted ATP synthase (FOF1) in liposomes tens of mu m in size, attached the protein specifically to a glass surface, and demonstrated its ATP-driven rotation in the membrane through the motion of a submicron bead. (c) 2009 Elsevier B.V. All rights reserved.
kinetic mechanism
mitochondrial adenosine-triphosphatase
Single-molecule
resonance energy-transfer
stepwise rotation
flagellar motor
change
Giant liposome
escherichia-coli
ATP synthase
Conformational
channel
unilamellar vesicles
c-subunit ring
atp synthase
Membrane protein
Author
Y. Onoue
Sokendai Graduate University for Advanced Studies
Waseda University
T. Suzuki
Tokyo Institute of Technology
Japan Science and Technology Agency
M. Davidson
Chalmers University of Technology
Mattias Karlsson
Chalmers University of Technology
Owe Orwar
Chalmers, Chemical and Biological Engineering, Physical Chemistry
M. Yoshida
Japan Science and Technology Agency
Tokyo Institute of Technology
K. Kinosita
Waseda University
Biochimica et Biophysica Acta - Biomembranes
0005-2736 (ISSN)
Vol. 1788 6 1332-1340Subject Categories (SSIF 2011)
Physical Chemistry
Chemical Sciences
DOI
10.1016/j.bbamem.2009.01.015