6WVM

High curvature lateral interaction within a 13-protofilament, Taxol stabilized microtubule

Summary for 6WVM

• Entry DOI: 10.2210/pdb6wvm/pdb
• EMDB information: 21923
• Descriptor: Tubulin alpha-1B chain, Tubulin beta chain, GUANOSINE-5'-TRIPHOSPHATE, ... (6 entities in total)
• Functional Keywords: microtubule, structural protein
• Biological source: Bos taurus (Bovine); More
• Total number of polymer chains: 4
• Total formula weight: 204005.67

Authors

Debs, G.E.,Cha, M.,Huehn, A.R.,Sindelar, C.V. (deposition date: 2020-05-06, release date: 2020-05-20, Last modification date: 2024-03-06)

Primary citation

Debs, G.E.,Cha, M.,Liu, X.,Huehn, A.R.,Sindelar, C.V.
Dynamic and asymmetric fluctuations in the microtubule wall captured by high-resolution cryoelectron microscopy.
Proc.Natl.Acad.Sci.USA, 117:16976-16984, 2020

PubMed Abstract: Microtubules are tubular polymers with essential roles in numerous cellular activities. Structures of microtubules have been captured at increasing resolution by cryo-EM. However, dynamic properties of the microtubule are key to its function, and this behavior has proved difficult to characterize at a structural level due to limitations in existing structure determination methods. We developed a high-resolution cryo-EM refinement method that divides an imaged microtubule into its constituent protofilaments, enabling deviations from helicity and other sources of heterogeneity to be quantified and corrected for at the single-subunit level. We demonstrate that this method improves the resolution of microtubule 3D reconstructions and substantially reduces anisotropic blurring artifacts, compared with methods that utilize helical symmetry averaging. Moreover, we identified an unexpected, discrete behavior of the m-loop, which mediates lateral interactions between neighboring protofilaments and acts as a flexible hinge between them. The hinge angle adopts preferred values corresponding to distinct conformations of the m-loop that are incompatible with helical symmetry. These hinge angles fluctuate in a stochastic manner, and perfectly cylindrical microtubule conformations are thus energetically and entropically penalized. The hinge angle can diverge further from helical symmetry at the microtubule seam, generating a subpopulation of highly distorted microtubules. However, the seam-distorted subpopulation disappears in the presence of Taxol, a microtubule stabilizing agent. These observations provide clues into the structural origins of microtubule flexibility and dynamics and highlight the role of structural polymorphism in defining microtubule behavior.

PubMed: 32636254
DOI: 10.1073/pnas.2001546117

Experimental method

ELECTRON MICROSCOPY (3.3 Å)