Role of cofactors B (TBCB) and E (TBCE) in tubulin heterodimer dissociation

Kortázar, Danel; Fanarraga, Mónica L.; Carranza, Gerardo; Bellido, Javier; Villegas, Juan; Ávila, Jesús; Zabala, Juan Carlos

doi:10.1016/j.yexcr.2006.09.002

Cited by 69 publications

(86 citation statements)

References 53 publications

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“…To better understand the turnover process, we cloned, overexpressed and purified human TBCB and TBCE (Kortazar et al, 2007;Carranza et al, 2013) and analyzed their ability to dissociate tubulin dimers ( Fig. 1; supplementary material Fig.…”

Section: Characterization Of A-tubulin-b-tubulin Dissociation By Tbcementioning

confidence: 99%

“…TBCE and TBCB cooperate in tubulin dissociation both in vivo and in vitro, by sequestering a-tubulin and forming a stable ternary a-tubulin-TBCE-TBCB complex (hereafter denoted aEB) (Kortazar et al, 2007). Here, we used electron microscopy (EM) and single-particle image processing to determine the structures of human TBCE and the aEB complex, both of which are involved in a-tubulin proteostasis.…”

Section: Introductionmentioning

confidence: 99%

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The structure of the TBCE/TBCB chaperones and α-tubulin complex shows a tubulin dimer dissociation mechanism

Serna

Carranza

Martín‐Benito

et al. 2015

Journal of Cell Science

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BSTRACTTubulin proteostasis is regulated by a group of molecular chaperones termed tubulin cofactors (TBC). Whereas tubulin heterodimer formation is well-characterized biochemically, its dissociation pathway is not clearly understood. Here, we carried out biochemical assays to dissect the role of the human TBCE and TBCB chaperones in a-tubulin-b-tubulin dissociation. We used electron microscopy and image processing to determine the threedimensional structure of the human TBCE, TBCB and a-tubulin (aEB) complex, which is formed upon a-tubulin-b-tubulin heterodimer dissociation by the two chaperones. Docking the atomic structures of domains of these proteins, including the TBCE UBL domain, as we determined by X-ray crystallography, allowed description of the molecular architecture of the aEB complex. We found that heterodimer dissociation is an energy-independent process that takes place through a disruption of the a-tubulin-b-tubulin interface that is caused by a steric interaction between b-tubulin and the TBCE cytoskeleton-associated protein glycine-rich (CAP-Gly) and leucinerich repeat (LRR) domains. The protruding arrangement of chaperone ubiquitin-like (UBL) domains in the aEB complex suggests that there is a direct interaction of this complex with the proteasome, thus mediating a-tubulin degradation.

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Section: Characterization Of A-tubulin-b-tubulin Dissociation By Tbcementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The structure of the TBCE/TBCB chaperones and α-tubulin complex shows a tubulin dimer dissociation mechanism

Serna

Carranza

Martín‐Benito

et al. 2015

Journal of Cell Science

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“…Axonal microtubules are regulated at many levels, and any of these could potentially involve KBP. For example, stathmin controls the availability of soluble tubulin molecules (Fletcher and Rorth, 2007); the tubulin specific chaperone e (tbce) ensures proper folding of ␣-tubulin and regulates tubulin heterodimer formation (Kortazar et al, 2007); SCG10 regulates the dynamics of microtubules in growing axons (Belmont and Mitchison, 1996;Riederer et al, 1997;Suh et al, 2004); and microtubule-associated proteins (MAPs), such as tau, have a number of important functions. In fact, tbce mutant mice have a somewhat similar phenotype to our kbp mutant, with disruption to axonal microtubules and subsequent axonal degeneration (Martin et al, 2002).…”

Section: Kbp Microtubule Organization and Axonal Developmentmentioning

confidence: 99%

KBP is essential for axonal structure, outgrowth and maintenance in zebrafish, providing insight into the cellular basis of Goldberg-Shprintzen syndrome

et al. 2008

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Mutations in Kif1-binding protein/KIAA1279 (KBP) cause the devastating neurological disorder Goldberg-Shprintzen syndrome (GSS) in humans. The cellular function of KBP and the basis of the symptoms of GSS, however, remain unclear. Here, we report the identification and characterization of a zebrafish kbp mutant. We show that kbp is required for axonal outgrowth and maintenance. In vivo time-lapse analysis of neuronal development shows that the speed of early axonal outgrowth is reduced in both the peripheral and central nervous systems in kbp mutants. Ultrastructural studies reveal that kbp mutants have disruption to axonal microtubules during outgrowth. These results together suggest that kbp is an important regulator of the microtubule dynamics that drive the forward propulsion of axons. At later stages, we observe that many affected axons degenerate. Ultrastructural analyses at these stages demonstrate mislocalization of axonal mitochondria and a reduction in axonal number in the peripheral, central and enteric nervous systems. We propose that kbp is an important regulator of axonal development and that axonal cytoskeletal defects underlie the nervous system defects in GSS.

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“…Experiments found that, in vivo, such a delicate balance is maintained because of a variety of factors that modulate the dynamic instability of MTs: GTP hydrolysis (3,9), molecular motors such as Kin-13 and other microtubuleassociated proteins (MAPs), and cofactors such as E and B, which increase the depolymerization rate (10,11); MAPs such as CLIP-170, which stabilize the MT lattice preventing catastrophes (12); and katanin and spastin, which sever MTs (13). However, in vitro MT dynamic instability occurs under modest conditions: either as a result of GTP hydrolysis (14) or under cold denaturation even in a nonhydrolyzable GMPCPP MT variant (9).…”

mentioning

confidence: 99%

Probing the origin of tubulin rigidity with molecular simulations

Dima

Joshi²

2008

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

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Tubulin heterodimers are the building blocks of microtubules, a major component of the cytoskeleton, whose mechanical properties are fundamental for the life of the cell. We uncover the microscopic origins of the mechanical response in microtubules by probing features of the energy landscape of the tubulin monomers and tubulin heterodimer. To elucidate the structures of the unfolding pathways and reveal the multiple unfolding routes, we performed simulations of a self-organized polymer (SOP) model of tubulin. The SOP representation, which is a coarse-grained description of chains, allows us to perform force-induced simulations at loading rates and time scales that closely match those used in single-molecule experiments. We show that the forced unfolding of each monomer involves a bifurcation in the pathways to the stretched state. After the unfolding of the C-term domain, the unraveling continues either from the N-term domain or from the middle domain, depending on the monomer and the pathway. In contrast to the unfolding complexity of the monomers, the dimer unfolds according to only one route corresponding to the unraveling of the C-term domain and part of the middle domain of ␤-tubulin. We find that this surprising behavior is due to the viscoelastic properties of the interface between the monomers. We map precise features of the complex energy landscape of tubulin by surveying the structures of the various metastable intermediates, which, in the dimer case, are characterized only by changes in the ␤-tubulin monomer.coarse-grained simulations ͉ dynamic instability ͉ forced unfolding ͉ single molecule ͉ unfolding pathways T he mechanical properties of microtubules (MTs) play crucial roles in processes such as cell division and matrix remodeling induced by mechanical loading of connective tissues. Because of their dynamic instability, i.e., stochastic alternation of slow growth and rapid shrinking phases between MTs and soluble tubulin subunits, MTs are able to transport chromosomes and other cellular organelles inside the cell (1). Blockage of dynamic instability by drugs such as taxol, which reduce the flexibility of the MT structure, promotes mitotic arrest and leads to cell death (2, 3). This behavior makes MTs a main target for cancer drugs (2), but efforts to design effective drugs are hampered, in part, by the lack of clear understanding of the microscopic origin of MT instability and of the MT behavior under tension (4).MTs are hollow cylinders, with large persistence lengths (5), composed of protofilaments aligned in parallel and joined laterally through mostly electrostatic contacts (6). Each protofilament consists of ␣-␤ tubulin dimers assembled in a head-totail fashion and joined noncovalently by hydrophobic and polar bonds along the longitudinal axis of the filament. The plus end of a MT is composed of ␤-tubulin (␤-tub), whereas the minus end consists of ␣-tubulin (␣-tub). During interphase, the minus end is attached to the centrosome, whereas the plus end has a GTP cap that contains at least one l...

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Role of cofactors B (TBCB) and E (TBCE) in tubulin heterodimer dissociation

Cited by 69 publications

References 53 publications

The structure of the TBCE/TBCB chaperones and α-tubulin complex shows a tubulin dimer dissociation mechanism

The structure of the TBCE/TBCB chaperones and α-tubulin complex shows a tubulin dimer dissociation mechanism

KBP is essential for axonal structure, outgrowth and maintenance in zebrafish, providing insight into the cellular basis of Goldberg-Shprintzen syndrome

Probing the origin of tubulin rigidity with molecular simulations

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