scholarly journals The structure of tubulin-binding cofactor A fromLeishmania majorinfers a mode of association during the early stages of microtubule assembly

2015 ◽  
Vol 71 (5) ◽  
pp. 539-546 ◽  
Author(s):  
Keri L. Barrack ◽  
Paul K. Fyfe ◽  
William N. Hunter
Keyword(s):  
Crystal Structure ◽  
Electrostatic Interactions ◽  
Leishmania Major ◽  
Model System ◽  
Microtubule Assembly ◽  
Early Stages ◽  
Tubulin Binding ◽  
Microtubule Formation ◽  
Β Tubulin

Tubulin-binding cofactor A (TBCA) participates in microtubule formation, a key process in eukaryotic biology to create the cytoskeleton. There is little information on how TBCA might interact with β-tubulin en route to microtubule biogenesis. To address this, the protozoanLeishmania majorwas targeted as a model system. The crystal structure of TBCA and comparisons with three orthologous proteins are presented. The presence of conserved features infers that electrostatic interactions that are likely to involve the C-terminal tail of β-tubulin are key to association. This study provides a reagent and template to support further work in this area.

Crystal structure of tubulin folding cofactor A from Arabidopsis thaliana and its β-tubulin binding characterization

FEBS Letters ◽  
2010 ◽  
Vol 584 (16) ◽  
pp. 3533-3539 ◽  
Author(s):  
Lu Lu ◽  
Jie Nan ◽  
Wei Mi ◽  
Lan-Fen Li ◽  
Chun-Hong Wei ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Arabidopsis Thaliana ◽  
Tubulin Binding ◽  
Β Tubulin

scholarly journals Diffusion rather than intraflagellar transport likely provides most of the tubulin required for axonemal assembly in Chlamydomonas

2020 ◽  
Vol 133 (17) ◽  
pp. jcs249805 ◽  
Author(s):  
Julie Craft Van De Weghe ◽  
J. Aaron Harris ◽  
Tomohiro Kubo ◽  
George B. Witman ◽  
Karl F. Lechtreck
Keyword(s):  
Binding Site ◽  
Critical Concentration ◽  
Intraflagellar Transport ◽  
Microtubule Assembly ◽  
Strong Reduction ◽  
Tubulin Binding ◽  
Respective Contribution ◽  
Β Tubulin

ABSTRACTTubulin enters the cilium by diffusion and motor-based intraflagellar transport (IFT). However, the respective contribution of each route in providing tubulin for axonemal assembly remains unknown. Using Chlamydomonas, we attenuated IFT-based tubulin transport of GFP–β-tubulin by altering the IFT74N–IFT81N tubulin-binding module and the C-terminal E-hook of tubulin. E-hook-deficient GFP–β-tubulin was incorporated into the axonemal microtubules, but its transport frequency by IFT was reduced by ∼90% in control cells and essentially abolished when the tubulin-binding site of IFT81 was incapacitated. Despite the strong reduction in IFT, the proportion of E-hook-deficient GFP–β-tubulin in the axoneme was only moderately reduced. In vivo imaging showed more GFP–β-tubulin particles entering cilia by diffusion than by IFT. Extrapolated to endogenous tubulin, the data indicate that diffusion provides most of the tubulin required for axonemal assembly. We propose that IFT of tubulin is nevertheless needed for ciliogenesis, because it augments the tubulin pool supplied to the ciliary tip by diffusion, thus ensuring that free tubulin there is maintained at the critical concentration for plus-end microtubule assembly during rapid ciliary growth.

scholarly journals Crystal structure of the C-terminal domain of tubulin-binding cofactor C from Leishmania major

2015 ◽  
Vol 201 (1) ◽  
pp. 26-30 ◽  
Author(s):  
Keri L. Barrack ◽  
Paul K. Fyfe ◽  
Alex J. Finney ◽  
William N. Hunter
Keyword(s):  
Crystal Structure ◽  
Leishmania Major ◽  
Terminal Domain ◽  
Tubulin Binding

scholarly journals Protection from Free β-Tubulin by the β-Tubulin Binding Protein Rbl2p

2002 ◽  
Vol 22 (1) ◽  
pp. 138-147 ◽  
Author(s):  
Katharine C. Abruzzi ◽  
Adelle Smith ◽  
William Chen ◽  
Frank Solomon
Keyword(s):  
Binding Protein ◽  
In Vitro Assay ◽  
In Vitro Studies ◽  
Microtubule Assembly ◽  
Vitro Assay ◽  
Tubulin Binding ◽  
And Function ◽  
Β Tubulin ◽  
In Cells

ABSTRACT Free β-tubulin not in heterodimers with α-tubulin can be toxic, disrupting microtubule assembly and function. We are interested in the mechanisms by which cells protect themselves from free β-tubulin. This study focused specifically on the function of Rbl2p, which, like α-tubulin, can rescue cells from free β-tubulin. In vitro studies of the mammalian homolog of Rbl2p, cofactor A, have suggested that Rbl2p/cofactor A may be involved in tubulin folding. Here we show that Rbl2p becomes essential in cells containing a modest excess of β-tubulin relative to α-tubulin. However, this essential activity of Rbl2p/cofactorA does not depend upon the reactions described by the in vitro assay. Rescue of β-tubulin toxicity requires a minimal but substoichiometric ratio of Rbl2p to β-tubulin. The data suggest that Rbl2p binds transiently to free β-tubulin, which then passes into an aggregated form that is not toxic.

scholarly journals An α-Tubulin Mutant Destabilizes the Heterodimer: Phenotypic Consequences and Interactions with Tubulin-binding Proteins

1998 ◽  
Vol 9 (9) ◽  
pp. 2349-2360 ◽  
Author(s):  
Leticia R. Vega ◽  
James Fleming ◽  
Frank Solomon
Keyword(s):  
Binding Proteins ◽  
Microtubule Assembly ◽  
Wild Type ◽  
Cellular Regulation ◽  
Tubulin Binding ◽  
Cold Sensitive ◽  
Mutant Cells ◽  
Dependent Processes ◽  
Β Tubulin

Many effectors of microtubule assembly in vitro enhance the polymerization of subunits. However, several Saccharomyces cerevisiae genes that affect cellular microtubule-dependent processes appear to act at other steps in assembly and to affect polymerization only indirectly. Here we use a mutant α-tubulin to probe cellular regulation of microtubule assembly.tub1-724 mutant cells arrest at low temperature with no assembled microtubules. The results of several assays reported here demonstrate that the heterodimer formed between Tub1-724p and β-tubulin is less stable than wild-type heterodimer. The unstable heterodimer explains several conditional phenotypes conferred by the mutation. These include the lethality of tub1-724haploid cells when the β-tubulin–binding protein Rbl2p is either overexpressed or absent. It also explains why theTUB1/tub1-724 heterozygotes are cold sensitive for growth and why overexpression of Rbl2p rescues that conditional lethality. Both haploid and heterozygous tub1-724 cells are inviable when another microtubule effector, PAC2, is overexpressed. These effects are explained by the ability of Pac2p to bind α-tubulin, a complex we demonstrate directly. The results suggest that tubulin-binding proteins can participate in equilibria between the heterodimer and its components.

scholarly journals Structural convergence for tubulin binding of CPAP and vinca domain microtubule inhibitors

2021 ◽  
Author(s):  
Valérie Campanacci ◽  
Agathe Urvoas ◽  
Liza Ammar Khodja ◽  
Magali Aumont-Nicaise ◽  
Magali Noiray ◽  
...  
Keyword(s):  
Small Molecules ◽  
Binding Mode ◽  
Microtubule Assembly ◽  
Cellular Proteins ◽  
Microtubule Inhibitors ◽  
Tubulin Binding ◽  
Characteristic Features ◽  
Α Helix ◽  
Open Question ◽  
Β Tubulin

Microtubule dynamics is regulated by various cellular proteins and perturbed by small molecule compounds. To what extent the mechanism of the former resembles that of the latter is an open question. We report here structures of tubulin bound to the PN2-3 domain of CPAP, a protein controlling the length of the centrioles. We show that an α-helix of the PN2-3 N-terminal region binds and caps the longitudinal surface of the tubulin β subunit. Moreover, a PN2-3 N-terminal stretch lies in a β-tubulin site also targeted by fungal and bacterial peptide-like inhibitors of the vinca domain, sharing a very similar binding mode with these compounds. Therefore, our results identify several characteristic features of cellular partners that bind to this site and highlight a structural convergence of CPAP with small molecules inhibitors of microtubule assembly.

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Molecular tapes in the structure of isoguaninium chloride

2017 ◽  
Vol 74 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Urszula Anna Budniak ◽  
Paulina Maria Dominiak
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Charge Density ◽  
Interaction Energy ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Structure

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6-amino-2-oxo-1H,7H-purin-3-ium chloride), C5H6N5O+·Cl−, has been determined by single-crystal X-ray diffraction. Structure analysis was supported by electrostatic interaction energy (E es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50\overline{4}). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.

The search for formal electrostatic effects on molecular conformation and crystal packing: crystal structure of 2,2′′-disubstituted (HversusPPh2) 1,1′-(1,2-phenylene)bis(3-methyl-1H-imidazol-3-ium) bis(trifluoromethanesulfonate)

2016 ◽  
Vol 72 (3) ◽  
pp. 198-202
Author(s):  
Carine Duhayon ◽  
Yves Canac ◽  
Laurent Dubrulle ◽  
Carine Maaliki ◽  
Remi Chauvin
Keyword(s):  
Crystal Structure ◽  
Electrostatic Interactions ◽  
Molecular Conformation ◽  
Crystal Packing ◽  
Relative Orientation ◽  
Electron Delocalization ◽  
Electrostatic Effects ◽  
Conformational Freedom ◽  
The Stability ◽  
Bond Character

Electrostatic interactions between localized integral charges make the stability and structure of highly charged small and rigid organics intriguing. Can σ/π-electron delocalization compensate reduced conformational freedom by lowering the repulsion between identical charges? The crystal structure of the title salt, C14H16N42+·2CF3SO3−, (2), is described and compared with that of the 2,2′′-bis(diphenylphosphanyl) derivative, (4). The conformations of the dications and their interactions with neighbouring trifluoromethanesulfonate anions are first analyzed from the standpoint of formal electrostatic effects. Neither cation exhibits any geometrical strain induced by the intrinsic repulsion between the positive charges. In contrast, the relative orientation of the imidazolium rings [i.e. antifor (2) andsynfor (4)] is controlled by different configurations of the interactions with the closest trifluoromethanesulfonate anions. The long-range arrangement is also found to be specific: beyond the formal electrostatic packing, C—H...O and C—H...F contacts have no definite `hydrogen-bond' character but allow the delineation of layers, which are either pleated or flat in the packing of (2) or (4), respectively.

scholarly journals Atomic model of microtubule-bound tau

2018 ◽  
Author(s):  
Elizabeth H. Kellogg ◽  
Nisreen M.A. Hejab ◽  
Simon Poepsel ◽  
Kenneth H. Downing ◽  
Frank DiMaio ◽  
...  
Keyword(s):  
High Resolution ◽  
Physiological Role ◽  
Biochemical Data ◽  
Disease Pathogenesis ◽  
Developmentally Regulated ◽  
Computational Approaches ◽  
Selective Stabilization ◽  
Tubulin Binding ◽  
Future Treatments ◽  
Β Tubulin

AbstractTau is a developmentally regulated protein found in axons, whose physiological role is to stabilize and bundle microtubules (MTs). Hyper-phosphorylation of tau is thought to cause its detachment from MTs and subsequent aggregation into pathological fibrils that have been implicated in Alzheimer’s disease pathogenesis. Despite its known MT binding role, there is no consensus regarding which tau residues are crucial for tau-MT interactions, where on the MT tau binds, and how binding results in MT stabilization. We have used cryo-EM to visualize the interaction of different tau constructs with MTs at high resolution (3.2-4.8 Å) and used computational approaches to generate atomic models of tau-tubulin interactions. Our work shows that the highly conserved tubulin-binding repeats within tau adopt very similar structures in their interactions with the MT. Each tau repeat binds the MT exterior and adopts an extended structure along the crest of the protofilament (PF), interacting with both α- and β-tubulin, thus stabilizing the interface between tubulin dimers. Our structures agree with and explain previous biochemical data concerning the effect of phosphorylation on MT affinity and lead to a model in which tau repeats bind in tandem along a PF, tethering together tubulin dimers and stabilizing longitudinal polymerization interfaces. These structural findings could establish a basis of future treatments aiming at the selective stabilization of tau-MT interactions.

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