Light-tugged molecules reveal molecular forces

To better understand how interactions between molecules within a cell regulate such activities as the properties of the cytoskeleton as well as critical division and growth processes, researchers at the Massachusetts Institute of Technology (Cambridge, MA), Stony Brook University (Stony Brook, NY), the University of Kaiserslautern (Kaiserslautern, Germany), and Harvard Medical School (Boston, NY) are tugging at molecules with a spring made of light using optical tweezers.

To better understand how interactions between molecules within a cell regulate such activities as the properties of the cytoskeleton as well as critical division and growth processes, researchers at the Massachusetts Institute of Technology (Cambridge, MA), Stony Brook University (Stony Brook, NY), the University of Kaiserslautern (Kaiserslautern, Germany), and Harvard Medical School (Boston, NY) are tugging at molecules with a spring made of light using optical tweezers.

Actin filaments, a collection of proteins that provide the structural integrity of a cell, are linked together and directed by actin-binding proteins (ABP). To understand the ABP molecular forces, one actin filament was immobilized on a cover-slip surface, and another was tethered to a polystyrene bead that serves as a means to supply a force load from an optical trap. As ABP is introduced to this flow-cell environment, forces between ABP and the two actin filaments (as the ABP unfolds and bonds rupture) can be measured by adjusting the tugging forces of the optical trap and monitoring how far the bead moves out of the optical spring before snapping back to an equilibrium position. Analysis of the measured forces revealed that both ABP unbinding and unfolding are important in regulating cytoskeleton properties with a higher probability of unbinding seen in single ABP-actin filament interactions. Contact Matthew J. Lang at mjlang@mit.edu.

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