title: Mechanistic Origin of Microtubule Dynamic Instability and Its Modulation by EB Proteins.
abstract: Microtubule (MT) dynamic instability is driven by GTP hydrolysis and regulated by microtubule-associated proteins, including the plus-end tracking end-binding protein (EB) family. We report six cryo-electron microscopy (cryo-EM) structures of MTs, at 3.5 Å or better resolution, bound to GMPCPP, GTPγS, or GDP, either decorated with kinesin motor domain after polymerization or copolymerized with EB3. Subtle changes around the E-site nucleotide during hydrolysis trigger conformational changes in α-tubulin around an "anchor point," leading to global lattice rearrangements and strain generation. Unlike the extended lattice of the GMPCPP-MT, the EB3-bound GTPγS-MT has a compacted lattice that differs in lattice twist from that of the also compacted GDP-MT. These results and the observation that EB3 promotes rapid hydrolysis of GMPCPP suggest that EB proteins modulate structural transitions at growing MT ends by recognizing and promoting an intermediate state generated during GTP hydrolysis. Our findings explain both EBs end-tracking behavior and their effect on microtubule dynamics.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Biophysics Graduate Program, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Alushin
authors.affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Brown
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA. Electronic address: enogales@lbl.gov.
authors.forename: Eva
authors.initials: E
authors.lastname: Nogales
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D034421:Sus scrofa / Q000378:metabolism*
chemical_list: D008869:Microtubule-Associated Proteins