Magic-Angle-Spinning NMR Enables First-Ever Determination of Atomic-Resolution Structure of a Microtubule-Associated Protein Assembled on Polymerized Microtubules

A latticework of tiny tubes called microtubules gives your cells their shape and also acts like a railroad track that essential proteins travel on. But if there is a glitch in the connection between train and track, diseases can occur. In the November 24, 2015 issue of PNAS, Tatyana Polenova, Ph.D., Professor of Chemistry and Biochemistry, and her team at the University of Delaware (UD), together with John C. Williams, Ph.D., Associate Professor at the Beckman Research Institute of City of Hope in Duarte, California, reveal for the first time -- atom by atom -- the structure of a protein bound to a microtubule. The protein of focus, CAP-Gly, short for "cytoskeleton-associated protein-glycine-rich domains," is a component of dynactin, which binds with the motor protein dynein to move cargoes of essential proteins along the microtubule tracks. Mutations in CAP-Gly have been linked to such neurological diseases and disorders as Perry syndrome and distal spinal bulbar muscular dystrophy. The research team used magic-angle-spinning nuclear magnetic resonance spectrometry (NMR) in the Department of Chemistry and Biochemistry at UD to unveil the structure of the CAP-Gly protein assembled on polymerized microtubules. The CAP-Gly protein has 1,329 atoms, and each tubulin dimer, which is a building block for microtubules, has nearly 14,000 atoms. "This is the first time anyone has been able to get an atomic-resolution structure of any microtubule-associated protein assembled on polymerized microtubules," Dr. Polenova says.
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