Single Molecule Nano-Biology
Takayuki Nishizaka, Gakushuin University
Life process is the integration of extraordinarily diverse networks comprised of various biomolecules such as proteins, nucleic acids and related signaling chemicals. When we focus on a biological phenomenon and hypothesize a simplified model, a schematic cartoon might be drawn showing that a couple of or multiple biomolecules interact each other as if we directly look at them through our eyes. What if we truly watch interactions between target biomolecules when they work under a microscope? Single molecule nano–biology will enable that.
View muscle contraction for example. When you lift something with your arm, one filament called actin slides past the other filament called myosin in myofibrils in your muscle cells. Interestingly enough, filaments displace only five nanometers in one chemical cycle of ATP hydrolysis. You can directly feel the movement of your arm, but it is difficult to imagine and intuitively understand that billions of chemical reactions and tiny mechanical changes occur between these proteins in your cells. However, with advanced fluorescence microscopes and application of various optical methods, you can watch the behavior of single motor proteins on a TV monitor. Such techniques enable us to clearly prove or deny our hypothesized cartoons. Additionally, it will help us understand how biomolecules work when they are subject to thermal forces in the surrounding fluid.
In this session, two front runners in single molecule biophysics show their latest achievements. The marvelous mechanism of a motor protein “kinesin”, which transports organelle cargos in cells and actually walks by moving their foot–like structures, is described by Dr. Michio Tomishige. Dr. Eric Greene studies at the single molecular level the proteins that directly interact with DNA. I, as a chair, will briefly review significant advances in the characterization and manipulation of individual molecules over the last thirteen years, and present my ongoing work regarding rotation and chemomechanical coupling of FoF1–ATP synthase. All researches will provide information on structures and functions which are hardly obtained by conventional techniques, and thus highlight advances in this rapidly expanding field.