STRUCTURAL-CHANGES ACCOMPANYING GTP HYDROLYSIS IN MICROTUBULES - INFORMATION FROM A SLOWLY HYDROLYZABLE ANALOG GUANYLYL-(ALPHA,BETA)-METHYLENE-DIPHOSPHONATE

We have used cryoelectron microscopy to try to understand the structural basis for the role of GTP hydrolysis in destabilizing the microtubule lattice. We have measured a structural difference introduced into microtubules by replacing GTP with guanylyl-(alpha,beta)-methylene-diphosphonate (GMPCPP). In a stable GMPCPP microtubule lattice, the moire patterns change and the tubulin subunits increase in size by 1.5 Angstrom. This information provides a clue to the role of hydrolysis in inducing the structural change at the end of a microtubule during the transition from a growing to a shrinking phase.