Koen Visscher

Associate Professor, Physics

Koen Visscher, PhD, recognizes that molecular motors drive fundamental processes in biology that are crucial to life, such as DNA replication, RNA transcription, protein synthesis, ATP synthesis and mitosis. His team is beginning to understand how some motor molecules, like myosin and kinesin and RNA polymerase, convert chemical energy into mechanical work and produce force and displacement. Research in the laboratory is focused on the ribosome, one of nature's most ancient motors. Crystal structures of the ribosome have recently become available, but a dynamic picture is lacking. In vitro motility assays are being developed to study the displacements of a single ribosome when it moves along mRNA while piecing together amino acids. Although the ribosome can perform these tasks by itself, the rate of protein synthesis and thus its velocity increases dramatically by binding of GTPases known as Elongation Factors, which raises interesting questions about its (motor) mechanism. The miniscule displacements (nanometers) and forces (piconewtons) produced by single ribosomes will be recorded using single-molecule fluorescence microscopy and optical tweezers. Force and velocity measurements under a variety of conditions, which already have provided valuable clues about myosin, kinesin and RNA-polymerase, are equally insightful for the much more complex ribosome.