High-resolution structural analysis of the kinesin-microtubule complex by electron cryo-microscopy.

To understand the interaction of kinesin and microtubules, it is necessary to study the three-dimensional (3D) structures of the kinesin-microtubule complex at a high enough resolution to identify structural components such as alpha-helices and beta-sheets. Electron cryo-microscopy combined with computer image analysis is the most common method to study such complexes that cannot be crystallized. By selecting microtubules that have a helical symmetry, 3D structures of the complex can be calculated using the helical 3D reconstruction method. Details of the interaction are studied by docking the individual crystal structures of the kinesin motor domains and tubulin heterodimer into the 3D maps of the complex. To study the structural changes during ATP hydrolysis, structures of the complexes in the presence and absence of different nucleotides are compared.