Dr. Douglas Martin – Brandeis University
“Structure and function of kinesin: a fluorescent look at a molecular motor”
Molecular motors are proteins which use chemical energy available in the cell to do mechanically useful work. These macromolecules are involved in processes such as muscle contraction, intracellular transport and cell division. The overall focus of my research is to understand the mechanism by which a particular molecular motor, kinesin, uses the chemical energy of ATP to move an external load. While energy transduction is a key component of this question, the structure of kinesin relative to the track along which it runs plays a significant role in understanding how kinesin is able to effectively transport its cargo. In this talk I will describe microscopy experiments using fluorescence resonance energy transfer (a fluorescence technique sensitive to length scales of a few nanometers) to determine the orientation of kinesin bound to its track (a microtubule). In particular, the orientation of the neck, which connects the two motors to the cargo and which coordinates the activity of the motors, is measured for the first time. The observed orientation may help explain two key features of kinesin’s mechanism: processivity (kinesin takes hundreds of steps in a row) and asymmetry (two sequential steps are not identical).
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