BIOTEC: Schäffer

Erik Schäffer -Single Molecule Nanomechanics with Optical Tweezers

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, TU Dresden, Germany

Previous and current research

Our research is focused 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 forces that are central to several biological processes. For example, we currently focus on the frictional forces associated with the electrostatically mediated diffusion of the kinesin-related protein MCAK along microtubules, the elastic force necessary to deform the ankyrin-repeat domain thought to gate the transduction channel of Drosophila mechanoreceptors, and the deformation of DNA during recombination mediated by the Red recombinase complex. In each case, the measurements test key hypotheses about how these proteins work to fulfill their cellular functions.

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.

Microspheres trapped with optical tweezers.

Selected Publications

Mahamdeh, M. and Schäffer, E. Optical tweezers with millikelvin precision of temperature-controlled objectives and base-pair resolution. Optics Express17, 17190-17199 (2009).

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).

Bormuth, V., Howard, J., and Schäffer, E. LED illumination for video-enhanced DIC imaging of single microtubules. J. Microsc. 226, 1-5 (2007).

Schäffer, E., Nørrelykke, S., and Howard, J. Surface forces and drag coefficients of microspheres near a plane surface measured with optical tweezers. Langmuir 23, 3654-3665 (2007).

Toli?-Nørrelykke, S.*, Schäffer, E.*, Howard, J., Pavone, F., Jülicher, F., and Flyvbjerg, H. Calibration of optical tweezers with positional detection in the back-focal plane. Rev. Sci. Inst. 77, 103101 (2006). (* shared first author)

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).