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 structur al basis for the role of GTP hydrolysis in destabilizing the microtubu le lattice. We have measured a structural difference introduced into m icrotubules by replacing GTP with guanylyl-(alpha,beta)-methylene-diph osphonate (GMPCPP). In a stable GMPCPP microtubule lattice, the moire patterns change and the tubulin subunits increase in size by 1.5 Angst rom. This information provides a clue to the role of hydrolysis in ind ucing the structural change at the end of a microtubule during the tra nsition from a growing to a shrinking phase.