Simbios Talk by Jung-Chi Liao, Stanford University, October 31, 2007

Title:  Integrating computational analysis and protein engineering to study myosin mechanics

Myosin converts ATP chemical energy into mechanical work such as muscle contractions, cell division, and vesicle transports. It is important to understand its mechanochemical energy transduction. We have developed a computational program, AlloPathFinder, to identify allosteric communication pathways based on conservation analysis. Applying this program to the myosin structures, we identified the allosteric pathways from the ATP-binding site to myosin's lever arm. These pathways traverse switch II and the relay helix, consistent with the understood picture of myosin allosteric communication.

Among all myosins, myosin VI is special because it is the only myosin known to move toward the minus end of the polar actin filament. We have designed chimeric myosin VI with artificial lever arms to identify key structural elements of myosin VI dictating its reverse directionality. We implemented computational modeling and molecular dynamics simulation to guide the chimera design. We then used in vitro motility and total internal reflection fluorescence assays to test these chimeras. We found that as few as 18 amino acids are enough to change the myosin directionality.