9313199 Farrell The goal of the proposal is to obtain crystals of the tubulin dimer suitable for X-ray diffraction studies and to use them to obtain the three-dimensional structure of tubulin. For initial screens of crystallization conditions Dr. Farrell will isolate chemically homogeneous tubulin from a yeast strain we have constructed which contains a single a-tubulin gene and a single b-tubulin gene. If necessary, the tubulin genes would be further altered to optimize the chances of obtaining tubulin suitable for crystallization. Tubulin will be isolated from yeast using a new method that Dr. Farrell has recently developed. The method yields approximately 5-10 mg of pure tubulin from 88L of fermenter-grown cells. This method, together with the ease of gene manipulation in yeast, has made it possible for the first time to use gene alteration techniques to assist in obtaining chemically and conformationally homogeneous tubulin for crystallization. ***
