Author/Authors :
Jeney, Sylvia Biozentrum University of Basel - M E Müller Institute for Structural Biology, Switzerland , Jeney, Sylvia Ecole Polytechnique Fédérale de Lausanne (EPFL) - Laboratory of Complex Matter Physics (LPMC), Switzerland , Mor, Flavio Ecole Polytechnique Fédérale de Lausanne (EPFL) - Laboratory of Complex Matter Physics (LPMC), Switzerland , Koszali, Roland University of Applied Sciences of Western Switzerland - School of Business and Engineering Vaud (HEIG-VD), Institute for Information and Communication Technologies (IICT), Switzerland , Forró, László Ecole Polytechnique Fédérale de Lausanne (EPFL) - Laboratory of Complex Matter Physics (LPMC), Switzerland , Moy, Vincent T. University of Miami Miller - School of Medicine - Department of Physiology and Biophysics, USA
Abstract :
We introduce a method for the acquisition of single molecule force measurements of ligand-receptor interactions using the photonic force microscope (PFM). Biotin-functionalized beads,manipulated with an optical trap,and a streptavidin-functionalized coverslip were used to measure the effect of different pulling forces on the lifetime of individual streptavidin-biotin complexes. By optimizing the design of the optical trap and selection of the appropriate bead size,pulling forces in excess of 50 pN were achieved. Based on the amplitude of three-dimensional (3D) thermal position fluctuations of the attached bead,we were able to select for a bead-coverslip interaction that was mediated by a single streptavidin-biotin complex. Moreover,the developed experimental system was greatly accelerated by automation of data acquisition and analysis. In force-dependent kinetic measurements carried out between streptavidin and biotin,we observed that the streptavidin-biotin complex exhibited properties of a catch bond,with the lifetime increasing tenfold when the pulling force increased from 10 to 20 pN. We also show that silica beads were more appropriate than polystyrene beads for the force measurements,as tethers,longer than 200 nm,could be extracted from polystyrene beads.
