RT Journal Article
SR Electronic
T1 Kinesin-5 promotes microtubule nucleation and assembly by stabilizing a lattice-competent conformation of tubulin
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 520072
DO 10.1101/520072
A1 Geng-Yuan Chen
A1 Ana B. Asenjo
A1 Yalei Chen
A1 Jake Mascaro
A1 David F. J. Arginteanu
A1 Hernando Sosa
A1 William O. Hancock
YR 2019
UL http://biorxiv.org/content/early/2019/01/14/520072.abstract
AB Besides sliding apart antiparallel microtubules during spindle elongation, the mitotic kinesin-5, Eg5 promotes microtubule polymerization, emphasizing its importance in mitotic spindle length control. Here, we characterize the Eg5 microtubule polymerase mechanism by assessing motor-induced changes in the longitudinal and lateral tubulin-tubulin bonds that form the microtubule lattice. Isolated Eg5 motor domains promote microtubule nucleation, growth and stability. Eg5 binds preferentially to microtubules over free tubulin, and colchicine-like inhibitors that stabilize the bent conformation of tubulin allosterically inhibit Eg5 binding, consistent with a model in which Eg5 induces a curved-to-straight transition in tubulin. Domain swap experiments establish that the family-specific Loop11, which resides near the nucleotide-sensing Switch-II domain, is necessary and sufficient for the polymerase activity of Eg5. Thus, we propose a microtubule polymerase mechanism in which Eg5 at the plus-end promotes a curved-to-straight transition in tubulin that enhances lateral bond formation and thereby promotes microtubule growth and stability.