scholarly journals Effects of tubulin acetylation and tubulin acetyltransferase binding on microtubule structure

2014 ◽  
Vol 25 (2) ◽  
pp. 257-266 ◽  
Author(s):  
Stuart C. Howes ◽  
Gregory M. Alushin ◽  
Toshinobu Shida ◽  
Maxence V. Nachury ◽  
Eva Nogales
Keyword(s):  
Posttranslational Modifications ◽  
Luminal Surface ◽  
Microtubule Associated Proteins ◽  
Interaction Sites ◽  
Tubulin Acetylation ◽  
Cryo Electron Microscopy ◽  
Site Of Action ◽  
Associated Proteins ◽  
Tubulin Structure ◽  
Microtubule Structure

Tubulin undergoes posttranslational modifications proposed to specify microtubule subpopulations for particular functions. Most of these modifications occur on the C-termini of tubulin and may directly affect the binding of microtubule-associated proteins (MAPs) or motors. Acetylation of Lys-40 on α-tubulin is unique in that it is located on the luminal surface of microtubules, away from the interaction sites of most MAPs and motors. We investigate whether acetylation alters the architecture of microtubules or the conformation of tubulin, using cryo–electron microscopy (cryo-EM). No significant changes are observed based on protofilament distributions or microtubule helical lattice parameters. Furthermore, no clear differences in tubulin structure are detected between cryo-EM reconstructions of maximally deacetylated or acetylated microtubules. Our results indicate that the effect of acetylation must be highly localized and affect interaction with proteins that bind directly to the lumen of the microtubule. We also investigate the interaction of the tubulin acetyltransferase, αTAT1, with microtubules and find that αTAT1 is able to interact with the outside of the microtubule, at least partly through the tubulin C-termini. Binding to the outside surface of the microtubule could facilitate access of αTAT1 to its luminal site of action if microtubules undergo lateral opening between protofilaments.

scholarly journals Microtubule-Associated Proteins with Regulatory Functions by Day and Pathological Potency at Night

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 357
Author(s):  
Judit Oláh ◽  
Attila Lehotzky ◽  
Sándor Szunyogh ◽  
Tibor Szénási ◽  
Ferenc Orosz ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Posttranslational Modifications ◽  
Therapeutic Drug ◽  
Microtubule Network ◽  
Microtubule Associated Proteins ◽  
Tubulin Acetylation ◽  
Associated Proteins ◽  
Regulatory Functions ◽  
Tubulin Polymerization Promoting Protein

The sensing, integrating, and coordinating features of the eukaryotic cells are achieved by the complex ultrastructural arrays and multifarious functions of the cytoskeleton, including the microtubule network. Microtubules play crucial roles achieved by their decoration with proteins/enzymes as well as by posttranslational modifications. This review focuses on the Tubulin Polymerization Promoting Protein (TPPP/p25), a new microtubule associated protein, on its “regulatory functions by day and pathological functions at night”. Physiologically, the moonlighting TPPP/p25 modulates the dynamics and stability of the microtubule network by bundling microtubules and enhancing the tubulin acetylation due to the inhibition of tubulin deacetylases. The optimal endogenous TPPP/p25 level is crucial for its physiological functions, to the differentiation of oligodendrocytes, which are the major constituents of the myelin sheath. Pathologically, TPPP/p25 forms toxic oligomers/aggregates with α-synuclein in neurons and oligodendrocytes in Parkinson’s disease and Multiple System Atrophy, respectively; and their complex is a potential therapeutic drug target. TPPP/p25-derived microtubule hyperacetylation counteracts uncontrolled cell division. All these issues reveal the anti-mitotic and α-synuclein aggregation-promoting potency of TPPP/p25, consistent with the finding that Parkinson’s disease patients have reduced risk for certain cancers.

scholarly journals Intracellular Proadrenomedullin-Derived Peptides Decorate the Microtubules and Contribute to Cytoskeleton Function

Endocrinology ◽  
2008 ◽  
Vol 149 (6) ◽  
pp. 2888-2898 ◽  
Author(s):  
Dan L. Sackett ◽  
Laurent Ozbun ◽  
Enrique Zudaire ◽  
Lisa Wessner ◽  
John M. Chirgwin ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Morphological Changes ◽  
Microtubule Associated Proteins ◽  
Microtubule Stabilization ◽  
Gene Coding ◽  
Intracellular Compartments ◽  
Associated Proteins ◽  
G2 Phase ◽  
Interfering Rna

Adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) are secretory hormones, but it is not unusual to find them in intracellular compartments. Using yeast-2 hybrid technology, we found interactions between AM and several microtubule-associated proteins (MAPs), and between PAMP and tubulin. Expression of fluorescent-tagged AM and PAMP as well as immunofluorescence for the native peptides showed a complete decoration of the microtubules and colocalization with other MAPs. PAMP, but not AM, bound to tubulin in vitro and destabilized tubulin polymerization. Down-regulation of the gene coding for both AM and PAMP through small interfering RNA technology resulted in morphological changes, microtubule stabilization, increase in posttranslational modifications of tubulin such as acetylation and detyrosination, reduction in cell motility, and partial arrest at the G2 phase of the cell cycle, when compared with cells transfected with the same vector carrying a scrambled sequence. These results show that PAMP is a novel MAP, whereas AM may be exerting more subtle effects in regulating cytoskeleton function.

scholarly journals Template-free 13-protofilament microtubule–MAP assembly visualized at 8 Å resolution

2010 ◽  
Vol 191 (3) ◽  
pp. 463-470 ◽  
Author(s):  
Franck J. Fourniol ◽  
Charles V. Sindelar ◽  
Béatrice Amigues ◽  
Daniel K. Clare ◽  
Geraint Thomas ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Information ◽  
Binding Mode ◽  
Microtubule Associated Proteins ◽  
Cryo Electron Microscopy ◽  
Associated Proteins ◽  
Template Free ◽  
Map Function ◽  
Insight Into

Microtubule-associated proteins (MAPs) are essential for regulating and organizing cellular microtubules (MTs). However, our mechanistic understanding of MAP function is limited by a lack of detailed structural information. Using cryo-electron microscopy and single particle algorithms, we solved the 8 Å structure of doublecortin (DCX)-stabilized MTs. Because of DCX’s unusual ability to specifically nucleate and stabilize 13-protofilament MTs, our reconstruction provides unprecedented insight into the structure of MTs with an in vivo architecture, and in the absence of a stabilizing drug. DCX specifically recognizes the corner of four tubulin dimers, a binding mode ideally suited to stabilizing both lateral and longitudinal lattice contacts. A striking consequence of this is that DCX does not bind the MT seam. DCX binding on the MT surface indirectly stabilizes conserved tubulin–tubulin lateral contacts in the MT lumen, operating independently of the nucleotide bound to tubulin. DCX’s exquisite binding selectivity uncovers important insights into regulation of cellular MTs.

scholarly journals Mitotic Acetylation of Microtubules Promotes Centrosomal PLK1 Recruitment and Is Required to Maintain Bipolar Spindle Homeostasis

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1859
Author(s):  
Sylvia Fenosoa Rasamizafy ◽  
Claude Delsert ◽  
Gabriel Rabeharivelo ◽  
Julien Cau ◽  
Nathalie Morin ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Mitotic Spindle ◽  
Mitotic Progression ◽  
Post Translational Modifications ◽  
Microtubule Associated Proteins ◽  
Mitotic Kinase ◽  
Tubulin Acetylation ◽  
Associated Proteins ◽  
Spindle Microtubules ◽  
Bipolar Spindles

Tubulin post-translational modifications regulate microtubule properties and functions. Mitotic spindle microtubules are highly modified. While tubulin detyrosination promotes proper mitotic progression by recruiting specific microtubule-associated proteins motors, tubulin acetylation that occurs on specific microtubule subsets during mitosis is less well understood. Here, we show that siRNA-mediated depletion of the tubulin acetyltransferase ATAT1 in epithelial cells leads to a prolonged prometaphase arrest and the formation of monopolar spindles. This results from collapse of bipolar spindles, as previously described in cells deficient for the mitotic kinase PLK1. ATAT1-depleted mitotic cells have defective recruitment of PLK1 to centrosomes, defects in centrosome maturation and thus microtubule nucleation, as well as labile microtubule-kinetochore attachments. Spindle bipolarity could be restored, in the absence of ATAT1, by stabilizing microtubule plus-ends or by increasing PLK1 activity at centrosomes, demonstrating that the phenotype is not just a consequence of lack of K-fiber stability. We propose that microtubule acetylation of K-fibers is required for a recently evidenced cross talk between centrosomes and kinetochores.

scholarly journals Copolymerization of two distinct tubulin isotypes during microtubule assembly in vitro.

1990 ◽  
Vol 110 (1) ◽  
pp. 97-104 ◽  
Author(s):  
H N Baker ◽  
S W Rothwell ◽  
W A Grasser ◽  
K T Wallis ◽  
D B Murphy
Keyword(s):  
Posttranslational Modifications ◽  
Microtubule Assembly ◽  
Homogeneous Distribution ◽  
Chicken Brain ◽  
Microtubule Associated Proteins ◽  
Tubulin Isotypes ◽  
Associated Proteins ◽  
Specific Activities

Cells contain multiple tubulin isotypes that are the products of different genes and posttranslational modifications. It has been proposed that tubulin isotypes become segregated into different classes of microtubules each adapted to specific activities and functions. To determine if mixtures of tubulin isotypes segregate into different classes of polymers in vitro, we used immunoelectron microscopy to examine the composition of microtubule copolymers that assembled from mixtures of purified tubulin subunits from chicken brain and erythrocytes, each of which has been shown to exhibit distinct assembly properties in vitro. We observed that (a) the two isotypes coassemble rapidly and efficiently despite the fact that each isotype exhibits its own unique biochemical and assembly properties; (b) at low monomer concentrations the ratio of tubulin isotypes changes along the lengths of elongating copolymers resulting in gradients in immuno-gold labeling; (c) two distinct classes of copolymers each containing a distinct ratio of isotypes assemble simultaneously in the same subunit mixture; and (d) subunits and polymers of different isotypes associate nearly equally well with each other, there being only a slight bias favoring interactions among subunits and polymers of the same isotype. The observations agree with previous studies on the homogeneous distribution of multiple isotypes within cells and suggest that if segregation of isotypes does occur in vivo, it is most likely directed by cell-specific microtubule-associated proteins (MAPs) or specialized intracellular conditions.

scholarly journals Acetylation/deacetylation and microtubule associated proteins influence flagellar axonemal stability and sperm motility

2020 ◽  
Vol 40 (12) ◽  
Author(s):  
Veena Chawan ◽  
Smita Yevate ◽  
Rahul Gajbhiye ◽  
Vijay Kulkarni ◽  
Priyanka Parte
Keyword(s):  
Animal Models ◽  
Sperm Motility ◽  
Specific Inhibitor ◽  
Human Sperm ◽  
Histone Deacetylase 6 ◽  
Microtubule Associated Proteins ◽  
Acetylation Status ◽  
Tubulin Acetylation ◽  
Associated Proteins

Abstract PTMs and microtubule-associated proteins (MAPs) are known to regulate microtubule dynamicity in somatic cells. Reported literature on modulation of α-tubulin acetyl transferase (αTAT1) and histone deacetylase 6 (HDAC6) in animal models and cell lines illustrate disparity in correlating tubulin acetylation status with stability of MT. Our earlier studies showed reduced acetyl tubulin in sperm of asthenozoospermic individuals. Our studies on rat sperm showed that on inhibition of HDAC6 activity, although tubulin acetylation increased, sperm motility was reduced. Studies were therefore undertaken to investigate the influence of tubulin acetylation/deacetylation on MT dynamicity in sperm flagella using rat and human sperm. Our data on rat sperm revealed that HDAC6 specific inhibitor Tubastatin A (T) inhibited sperm motility and neutralized the depolymerizing and motility debilitating effect of Nocodazole. The effect on polymerization was further confirmed in vitro using pure MT and recHDAC6. Also polymerized axoneme was less in sperm of asthenozoosperm compared to normozoosperm. Deacetylase activity was reduced in sperm lysates and axonemes exposed to T and N+T but not in axonemes of sperm treated similarly suggesting that HDAC6 is associated with sperm axonemes or MT. Deacetylase activity was less in asthenozoosperm. Intriguingly, the expression of MDP3 physiologically known to bind to HDAC6 and inhibit its deacetylase activity remained unchanged. However, expression of acetyl α-tubulin, HDAC6 and microtubule stabilizing protein SAXO1 was less in asthenozoosperm. These observations suggest that MAPs and threshold levels of MT acetylation/deacetylation are important for MT dynamicity in sperm and may play a role in regulating sperm motility.

scholarly journals Microtubule-associated proteins-dependent colchicine stability of acetylated cold-labile brain microtubules from the Atlantic cod, Gadus morhua.

1991 ◽  
Vol 113 (2) ◽  
pp. 331-338 ◽  
Author(s):  
M Billger ◽  
E Strömberg ◽  
M Wallin
Keyword(s):  
Posttranslational Modifications ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Bovine Brain ◽  
General Effect ◽  
Acetylated Tubulin ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
The Stability ◽  
Brain Microtubules

Assembly of brain microtubule proteins isolated from the Atlantic cod, Gadus morhua, was found to be much less sensitive to colchicine than assembly of bovine brain microtubules, which was completely inhibited by low colchicine concentrations (10 microM). The degree of disassembly by colchicine was also less for cod microtubules. The lack of colchicine effect was not caused by a lower affinity of colchicine to cod tubulin, as colchicine bound to cod tubulin with a dissociation constant, Kd, and a binding ratio close to that of bovine tubulin. Cod brain tubulin was highly acetylated and mainly detyrosinated, as opposed to bovine tubulin. When cod tubulin, purified by means of phosphocellulose chromatography, was assembled by addition of DMSO in the absence of microtubule-associated proteins (MAPs), the microtubules became sensitive to low concentrations of colchicine. They were, however, slightly more stable to disassembly, indicating that posttranslational modifications induce a somewhat increased stability to colchicine. The stability was mainly MAPs dependent, as it increased markedly in the presence of MAPs. The stability was not caused by an extremely large amount of cod MAPs, since there were slightly less MAPs in cod than in bovine microtubules. When "hybrid" microtubules were assembled from cod tubulin and bovine MAPs, these microtubules became less sensitive to colchicine. This was not a general effect of MAPs, since bovine MAPs did not induce a colchicine stability of microtubules assembled from bovine tubulin. We can therefore conclude that MAPs can induce colchicine stability of colchicine labile acetylated tubulin.

Cardiomyocyte Microtubules: Control of Mechanics, Transport, and Remodeling

2021 ◽  
Vol 84 (1) ◽  
Author(s):  
Keita Uchida ◽  
Emily A. Scarborough ◽  
Benjamin L. Prosser
Keyword(s):  
Posttranslational Modifications ◽  
Protein Translation ◽  
Calcium Handling ◽  
Annual Review ◽  
Publication Date ◽  
Microtubule Associated Proteins ◽  
New Concepts ◽  
Cardiomyocyte Contractility ◽  
Associated Proteins ◽  
Cytoskeletal Elements

Microtubules are essential cytoskeletal elements found in all eukaryotic cells. The structure and composition of microtubules regulate their function, and the dynamic remodeling of the network by posttranslational modifications and microtubule-associated proteins generates diverse populations of microtubules adapted for various contexts. In the cardiomyocyte, the microtubules must accommodate the unique challenges faced by a highly contractile, rigidly structured, and long-lasting cell. Through their canonical trafficking role and positioning of mRNA, proteins, and organelles, microtubules regulate essential cardiomyocyte functions such as electrical activity, calcium handling, protein translation, and growth. In a more specialized role, posttranslationally modified microtubules form load-bearing structures that regulate myocyte mechanics and mechanotransduction. Modified microtubules proliferate in cardiovascular diseases, creating stabilized resistive elements that impede cardiomyocyte contractility and contribute to contractile dysfunction. In this review, we highlight the most exciting new concepts emerging from recent studies into canonical and noncanonical roles of cardiomyocyte microtubules. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Role of microtubule-associated proteins in the control of microtubule assembly

1995 ◽  
Vol 75 (4) ◽  
pp. 835-864 ◽  
Author(s):  
R. B. Maccioni ◽  
V. Cambiazo
Keyword(s):  
Posttranslational Modifications ◽  
Mammalian Cells ◽  
Intracellular Transport ◽  
Cell Types ◽  
Regulatory Elements ◽  
Microtubule Assembly ◽  
Specific Cell ◽  
Surface Receptors ◽  
Microtubule Associated Proteins ◽  
Associated Proteins

In eukaryotic cells, microtubules, actin, and intermediate filaments interact to form the cytoskeletal network involved in determination of cell architecture, intracellular transport, modulation of surface receptors, mitosis, cell motility, and differentiation. Cytoskeletal organization and dynamics depend on protein self-associations and interactions with regulatory elements such as microtubule-associated proteins (MAPs). The MAP family includes large proteins like MAP-1A, MAP-1B, MAP-1C, MAP-2, and MAP-4 and smaller components like tau and MAP-2C. This review focuses on relevant aspects of MAP function, with emphasis on their roles in modulating cytoskeletal interactions. In this context, MAP expression mechanisms and posttranslational modifications are also discussed. Microtubule-associated proteins have a rather widespread distribution among cells, but certain MAPs have been identified in specific cell types. Within single neurons, MAP-2 is dendritic while tau is preferentially an axonal protein. Their expression is developmentally regulated. Even though MAPs share a capacity to interact with the COOH-terminal tubulin domain, stabilize microtubules, and link them with other cytoskeletal polymers, they exhibit structural differences. However, MAP-2, MAP-4, and tau have common repetitive microtubule-binding motifs. Microtubule-associated proteins not only control cytoskeletal integrity, but they also appear to interact with highly structural elements of cells. Molecular biological approaches permitted localization of new MAPs in cultured mammalian cells and invertebrate organisms and other microtubule-interacting proteins that exhibit transient interactions with microtubules. The structural/functional aspects of several new MAP-like proteins in centrosomes and the mitotic spindle, functionally implicated in cell cycle events, are also analyzed.

scholarly journals CSAP localizes to polyglutamylated microtubules and promotes proper cilia function and zebrafish development

2012 ◽  
Vol 23 (11) ◽  
pp. 2122-2130 ◽  
Author(s):  
Chelsea B. Backer ◽  
Jennifer H. Gutzman ◽  
Chad G. Pearson ◽  
Iain M. Cheeseman
Keyword(s):  
Posttranslational Modifications ◽  
Normal Brain ◽  
Microtubule Associated Proteins ◽  
Functional Capabilities ◽  
Culture Cells ◽  
Associated Proteins ◽  
Spindle Microtubules ◽  
Left Right Asymmetry ◽  
Work Supports ◽  
Normal Brain Development

The diverse populations of microtubule polymers in cells are functionally distinguished by different posttranslational modifications, including polyglutamylation. Polyglutamylation is enriched on subsets of microtubules including those found in the centrioles, mitotic spindle, and cilia. However, whether this modification alters intrinsic microtubule dynamics or affects extrinsic associations with specific interacting partners remains to be determined. Here we identify the microtubule-binding protein centriole and spindle–associated protein (CSAP), which colocalizes with polyglutamylated tubulin to centrioles, spindle microtubules, and cilia in human tissue culture cells. Reducing tubulin polyglutamylation prevents CSAP localization to both spindle and cilia microtubules. In zebrafish, CSAP is required for normal brain development and proper left–right asymmetry, defects that are qualitatively similar to those reported previously for depletion of polyglutamylation-conjugating enzymes. We also find that CSAP is required for proper cilia beating. Our work supports a model in which polyglutamylation can target selected microtubule-associated proteins, such as CSAP, to microtubule subpopulations, providing specific functional capabilities to these populations.

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