Straight GDP-Tubulin Protofilaments Form in the Presence of Taxol

Élie-Caille, Céline; Severin, Fedor F.; Helenius, Jonne; Howard, Jonathon; Müller, Daniel J.; Hyman, Anthony A.

doi:10.1016/j.cub.2007.08.063

Cited by 182 publications

(176 citation statements)

References 22 publications

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“…Our demonstration that the conformation of unpolymerized ␣␤-tubulin:GTP:Mg 2ϩ is curved, along with EM or AFM results showing assembly/ disassembly intermediates with partial curvature (5,8,9,34), support the idea that straightening occurs incrementally in response to multiple lateral associations (Fig. S5).…”

Section: Lateral Interactions Between ␥-Tubulins Are Adaptable and Arsupporting

confidence: 82%

The lattice as allosteric effector: Structural studies of αβ- and γ-tubulin clarify the role of GTP in microtubule assembly

Rice

Montabana

Agard

2008

Proc. Natl. Acad. Sci. U.S.A.

226

248

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GTP-dependent microtubule polymerization dynamics are required for cell division and are accompanied by domain rearrangements in the polymerizing subunit, ␣␤-tubulin. Two opposing models describe the role of GTP and its relationship to conformational change in ␣␤-tubulin. The allosteric model posits that unpolymerized ␣␤-tubulin adopts a more polymerization-competent conformation upon GTP binding. The lattice model posits that conformational changes occur only upon recruitment into the growing lattice. Published data support a lattice model, but are largely indirect and so the allosteric model has prevailed. We present two independent solution probes of the conformation of ␣␤-tubulin, the 2.3 Å crystal structure of ␥-tubulin bound to GDP, and kinetic simulations to interpret the functional consequences of the structural data. These results (with our previous ␥-tubulin:GTP␥S structure) support the lattice model by demonstrating that major domain rearrangements do not occur in eukaryotic tubulins in response to GTP binding, and that the unpolymerized conformation of ␣␤-tubulin differs significantly from the polymerized one. Thus, geometric constraints of lateral self-assembly must drive ␣␤-tubulin conformational changes, whereas GTP plays a secondary role to tune the strength of longitudinal contacts within the microtubule lattice. ␣␤-Tubulin behaves like a bent spring, resisting straightening until forced to do so by GTP-mediated interactions with the growing microtubule. Kinetic simulations demonstrate that resistance to straightening opposes microtubule initiation by specifically destabilizing early assembly intermediates that are especially sensitive to the strength of lateral interactions. These data provide new insights into the molecular origins of dynamic microtubule behavior. dynamic instability ͉ microtubules M icrotubules are hollow cylindrical polymers of ␣␤-tubulin that are critical for intracellular trafficking and formation of the mitotic spindle required for chromosome segregation during cell division. Although vitally important, the molecular mechanisms underlying dynamic microtubule (MT) behavior are poorly understood. Microtubule assembly requires GTP-bound ␣␤-tubulin, and GTP hydrolysis by ␤-tubulin is required to generate dynamic MTs (reviewed in ref. 1). Structural studies have demonstrated two extreme conformations of ␣␤-tubulin: a ''straight'' conformation observed in the MT lattice (2), and a "curved" conformation observed in a structure of ␣␤-tubulin complexed with colchicine and a stathmin-like domain (3) (Fig. 1). There are two opposing models for the relationship between GTP and conformational change in ␣␤-tubulin. The allosteric model (recently reviewed in ref. 4) postulates that GTP binding to ␣␤-tubulin triggers long-range conformational changes yielding a substantially straighter conformation that is prestructured in solution for lateral interactions (5). The lattice model (6) postulates that in solution, ␣␤-tubulin adopts the MTincompatible, curved conformation independent of nuc...

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Section: Lateral Interactions Between ␥-Tubulins Are Adaptable and Arsupporting

confidence: 82%

The lattice as allosteric effector: Structural studies of αβ- and γ-tubulin clarify the role of GTP in microtubule assembly

Rice

Montabana

Agard

2008

Proc. Natl. Acad. Sci. U.S.A.

226

248

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“…This study focuses on elucidating the structure and interactions of paclitaxel-stabilized MTs (33)(34)(35) assembled at varying Tau/tubulin-dimer molar ratios [Φ Tau = 1/10, 1/13, 1/20, 1/40, and 1/100, spanning the physiological range observed in axons (36)] using synchrotron SAXS in the presence of an osmotic depletant. By varying osmotic pressure [induced by 20k polyethylene oxide (PEO)] (SI Appendix, SI Note S1 and Fig.…”

Section: Significancementioning

confidence: 99%

Direct force measurements reveal that protein Tau confers short-range attractions and isoform-dependent steric stabilization to microtubules

Chung

Choi

Miller

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Microtubules (MTs) are hollow cytoskeletal filaments assembled from αβ-tubulin heterodimers. Tau, an unstructured protein found in neuronal axons, binds to MTs and regulates their dynamics. Aberrant Tau behavior is associated with neurodegenerative dementias, including Alzheimer's. Here, we report on a direct force measurement between paclitaxel-stabilized MTs coated with distinct Tau isoforms by synchrotron small-angle X-ray scattering (SAXS) of MT-Tau mixtures under osmotic pressure (P). In going from bare MTs to MTs with Tau coverage near the physiological submonolayer regime (Tau/tubulin-dimer molar ratio; Φ Tau = 1/ 10), isoforms with longer N-terminal tails (NTTs) sterically stabilized MTs, preventing bundling up to P B ∼ 10,000-20,000 Pa, an order of magnitude larger than bare MTs. Tau with short NTTs showed little additional effect in suppressing the bundling pressure (P B ∼ 1,000-2,000 Pa) over the same range. Remarkably, the abrupt increase in P B observed for longer isoforms suggests a mushroom to brush transition occurring at 1/13 < Φ Tau < 1/10, which corresponds to MT-bound Tau with NTTs that are considerably more extended than SAXS data for Tau in solution indicate. Modeling of Tau-mediated MT-MT interactions supports the hypothesis that longer NTTs transition to a polyelectrolyte brush at higher coverages. Higher pressures resulted in isoform-independent irreversible bundling because the polyampholytic nature of Tau leads to short-range attractions. These findings suggest an isoform-dependent biological role for regulation by Tau, with longer isoforms conferring MT steric stabilization against aggregation either with other biomacromolecules or into tight bundles, preventing loss of function in the crowded axon environment.Tau | intrinsically disordered proteins | microtubule | SAXS | force measurement

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“…The hydrolysis of the nucleotide is not necessary for microtubule formation; however, the portion of microtubule carrying GTP, termed the ''GTP cap' , is stable and displays a steady state assembly [reviewed by Howard and Hyman, 2009]. In contrast, the GDP-bound tubulins are prone to dissociate from the microtubule by increasing the curvature of protofilaments in the microtubule and putting strain on the lattice [Elie-Caille et al, 2007].…”

Section: Dynamic Instabilitymentioning

confidence: 99%

Shaping microtubules into diverse patterns: Molecular connections for setting up both ends

Mimori-Kiyosue¹

2011

Cytoskeleton

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Microtubules serve as rails for intracellular trafficking and their appropriate organization is critical for the generation of cell polarity, which is a foundation of cell differentiation, tissue morphogenesis, ontogenesis and the maintenance of homeostasis. The microtubule array is not just a static railway network; it undergoes repeated collapse and reassembly in diverse patterns during cell morphogenesis. In the last decade much progress has been made toward understanding the molecular mechanisms governing complex microtubule patterning. This review first revisits the basic principle of microtubule dynamics, and then provides an overview of how microtubules are arranged in highly shaped and functional patterns in cells changing their morphology by factors controlling the fate of microtubule ends. V C 2011 Wiley Periodicals, Inc.

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Straight GDP-Tubulin Protofilaments Form in the Presence of Taxol

Cited by 182 publications

References 22 publications

The lattice as allosteric effector: Structural studies of αβ- and γ-tubulin clarify the role of GTP in microtubule assembly

The lattice as allosteric effector: Structural studies of αβ- and γ-tubulin clarify the role of GTP in microtubule assembly

Direct force measurements reveal that protein Tau confers short-range attractions and isoform-dependent steric stabilization to microtubules

Shaping microtubules into diverse patterns: Molecular connections for setting up both ends

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