Group Ishikawa

My laboratory will study the mechanism of ATP-driven motor proteins, especially dynein and FoF1 ATP synthase using three-dimensional cryo-electron microscopy. To explore the range of motion of motor proteins in complex with their partners, structures of each individual (not averaged) particles (a molecule or a complex of molecules) must be visualized at sufficiently high resolution. We will develop the methodology that fulfills these demands, combining two methods of 3D cryo-electron microscopy: single particle analysis and electron tomography. Electron tomography, which takes micrographs by tilting specimens at various view angles in the microscope, reconstructs each individual particle separately without averaging, unlike other methods of structural biology, so that we can visualize structural variability between particles, which is essential to characterize motor proteins. By introducing the approach of single particle analysis (image classification and subaveraging) into electron tomography, I expect that we can obtain as high a resolution as single particle analysis (20-10 Å), setting solution conditions (nucleotides, ions, pH etc.) freely. Thus, this methodology can be considered as the way to visualize various snapshots of individual molecules in motion. Fitting structures of solved molecules to low resolution electron microscopy maps would allow visualization of the process at quasi-atomic resolution.