Erik Schäffer

Single molecule nanomechanics with optical tweezers

Previous and current research

Our research is focussed on understanding the role of intermolecular forces in the interaction between biological molecules.  Intermolecular forces, which include electrostatic, van der Waals, and entropic interactions, are key in many active and passive biological processes.  For example, motor proteins actively exert forces on cytoskeletal filaments as they drive cell division or motility. On the other hand, mechanoreceptor molecules respond to forces exerted on cells by external stimuli.  In the Nanomechanics group, we use a high-resolution, three-dimensional optical tweezers apparatus to measure intermolecular frictional and elastic forces that are central to three biological processes: (a) the frictional forces associated with the electrostatically mediated diffusion of the kinesin-related protein MCAK along microtubules, (b) the elastic force necessary to deform the ankyrin-repeat domain thought to gate the transduction channel of Drosophila mechanoreceptors, and (c) the deformation of DNA during recombination mediated by the Redβ recombinase complex.  In each case, the measurements test key hypotheses about how these proteins work to fulfill their cellular functions.

Microspheres trapped with optical tweezers

Optical tweezers assay to probe the intermolecular forces between motor proteins and microtubules on a single molecule level

Future prospects and goals

The long term goal is by applying state-of-the-art single-molecule techniques to learn more about the mechanical aspects of protein-protein interactions.   How are these interactions mediated and realized on a single molecule level and what influences have intermolecular forces?  By providing the technological means, we want to approach and answer fundamental biological questions.  The focus on answering specific biological questions is expected to stimulate further instrument development, which, in turn, is hoped to broaden the applicability of this technology in biology.

About

1992-1997: Physics studies at the TU Stuttgart, Germany & M.Sc. from the University of Massachusetts, Amherst, USA 1998-2001: Dr. rer. nat. in Polymer Physics, University Konstanz & University Groningen, Netherlands 2002-2006: Post-doc with Joe Howard, MPI-CBG, Dresden, Germany since 2007: Junior group leader, Biotec Center, TU Dresden, Germany

Selected publications

Bormuth, V., Varga, V., Howard, J., and Schäffer, E. Protein Friction Limits Diffusive and Directed Movements of Kinesin Motors on Microtubules. Science 325, 870-873 (2009).

Bormuth, V., Jannasch, A., Ander, M., van Kats, C., van Blaaderen, A., Howard, J., and Schäffer, E. Optical trapping of coated microspheres.  Optics Express16, 13831-13844 (2008).

Grill, S.W., Howard, J., Schäffer, E., Stelzer, E.H.K., and Hyman, A.A. The distribution of active force generators controls mitotic spindle position. Science 301, 518–521 (2003).

Schäffer, E., Thurn-Albrecht, T., Russell, T.P., and Steiner, U. Electrically induced structure formation and pattern transfer. Nature 403, 874–877 (2000).

Walheim, S., Schäffer, E., Mlynek, J., and Steiner, U. Nanophase-separated polymer films as high-performance antireflection coatings. Science 283, 520–522 (1999).

Home page