Lessons from bacterial homolog of tubulin, FtsZ for microtubule dynamics

FtsZ, a homolog of tubulin, is found in almost all bacteria and archaea where it has a primary role in cytokinesis. Evidence for structural homology between FtsZ and tubulin came from their crystal structures and identification of the GTP box. Tubulin and FtsZ constitute a distinct family of GTPases and show striking similarities in many of their polymerization properties. The differences between them, more so, the complexities of microtubule dynamic behavior in comparison to that of FtsZ, indicate that the evolution to tubulin is attributable to the incorporation of the complex functionalities in higher organisms. FtsZ and microtubules function as polymers in cell division but their roles differ in the division process. The structural and partial functional homology has made the study of their dynamic properties more interesting. In this review, we focus on the application of the information derived from studies on FtsZ dynamics to study microtubule dynamics and vice versa. The structural and functional aspects that led to the establishment of the homology between the two proteins are explained to emphasize the network of FtsZ and microtubule studies and how they are connected.

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A mutation uncouples the tubulin conformational and GTPase cycles, revealing allosteric control of microtubule dynamics

eLife ◽

10.7554/elife.10113 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 59

Author(s):

Elisabeth A Geyer ◽

Alexander Burns ◽

Beth A Lalonde ◽

Xuecheng Ye ◽

Felipe-Andres Piedra ◽

...

Keyword(s):

Conformational Change ◽

Dynamic Instability ◽

Dynamic Properties ◽

Microtubule Dynamics ◽

Gtpase Activity ◽

Microtubule Dynamic ◽

Gtp Hydrolysis ◽

Allosteric Control

Microtubule dynamic instability depends on the GTPase activity of the polymerizing αβ-tubulin subunits, which cycle through at least three distinct conformations as they move into and out of microtubules. How this conformational cycle contributes to microtubule growing, shrinking, and switching remains unknown. Here, we report that a buried mutation in αβ-tubulin yields microtubules with dramatically reduced shrinking rate and catastrophe frequency. The mutation causes these effects by suppressing a conformational change that normally occurs in response to GTP hydrolysis in the lattice, without detectably changing the conformation of unpolymerized αβ-tubulin. Thus, the mutation weakens the coupling between the conformational and GTPase cycles of αβ-tubulin. By showing that the mutation predominantly affects post-GTPase conformational and dynamic properties of microtubules, our data reveal that the strength of the allosteric response to GDP in the lattice dictates the frequency of catastrophe and the severity of rapid shrinking.

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What Kind of Friction Model Is Needed to Predict Brake Squeal?

ASME 2012 Noise Control and Acoustics Division Conference ◽

10.1115/ncad2012-0576 ◽

2012 ◽

Cited By ~ 1

Author(s):

Tore Butlin ◽

Jim Woodhouse

Keyword(s):

Large Scale ◽

Dynamic Properties ◽

Theoretical Work ◽

Friction Model ◽

Coupled Systems ◽

Brake Squeal ◽

Model Framework ◽

Wide Range ◽

Pin On Disc ◽

Almost All

Predictive models of friction-induced vibration have proved elusive despite decades of research. There are many mechanisms that can cause brake squeal; friction coupled systems can be highly sensitive to small perturbations; and the dynamic properties of friction at the contact zone seem to be poorly understood. This paper describes experimental and theoretical work aimed at identifying the key ingredients of a predictive model. A large-scale experiment was carried out to identify squeal initiations using a pin-on-disc test rig: approximately 30,000 squeal initiations were recorded, covering a very wide range of frequencies. The theoretical model allows for completely general linear systems coupled at a single sliding point by friction: squeal is predicted using a linearised stability analysis. Results will be presented that show that almost all observed squeal events can be predicted within this model framework, but that some subsets require innovative friction modelling: predictions are highly dependent on the particular choice of friction model and its associated parameters.

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Identification of ’Effective’ Linear Joints Using Coupling and Joint Identification Techniques

Journal of Vibration and Acoustics ◽

10.1115/1.2893835 ◽

1998 ◽

Vol 120 (2) ◽

pp. 331-338 ◽

Cited By ~ 71

Author(s):

Y. Ren ◽

C. F. Beards

Keyword(s):

Dynamic Properties ◽

Real Life ◽

Model Parameters ◽

Coupling Technique ◽

Alternative Approach ◽

Identification Technique ◽

Joint Identification ◽

Stiff Joint ◽

Almost All ◽

Identification Techniques

Almost all real-life structures are assembled from components connected by various types of joints. Unlike many other parts, the dynamic properties of a joint are difficult to model analytically. An alternative approach for establishing a theoretical model of a joint is to extract the model parameters from experimental data using joint identification techniques. The accuracy of the identification is significantly affected by the properties of the joints themselves. If a joint is stiff, its properties are often difficult to identify accurately. This is because the responses at both ends of the joint are linearly-dependent. To make things worse, the existence of a stiff joint can also affect the accuracy of identification of other effective joints (the term “effective joints” in this paper refers to those joints which otherwise can be identified accurately). This problem is tackled by coupling these stiff joints using a generalized coupling technique, and then the properties of the remaining joints are identified using a joint identification technique. The accuracy of the joint identification can usually be improved by using this approach. Both numerically simulated and experimental results are presented.

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Viriditoxin Stabilizes Microtubule Polymers in SK-OV-3 Cells and Exhibits Antimitotic and Antimetastatic Potential

Marine Drugs ◽

10.3390/md18090445 ◽

2020 ◽

Vol 18 (9) ◽

pp. 445 ◽

Cited By ~ 1

Author(s):

Mingzhi Su ◽

Changhao Zhao ◽

Dandan Li ◽

Jiafu Cao ◽

Zhiran Ju ◽

...

Keyword(s):

Essential Role ◽

Human Cancer ◽

Cell Movement ◽

Marine Fungus ◽

Microtubule Dynamics ◽

Tubulin Polymerization ◽

Structural Homology ◽

Bacterial Cell Division ◽

Paecilomyces Variotii ◽

Human Cancer Cells

Microtubules play a crucial role in mitosis and are attractive targets for cancer therapy. Recently, we isolated viriditoxin, a cytotoxic and antibacterial compound, from a marine fungus Paecilomyces variotii. Viriditoxin has been reported to inhibit the polymerization of bacterial FtsZ, a tubulin-like GTPase that plays an essential role in bacterial cell division. Given the close structural homology between FtsZ and tubulin, we investigated the potential antimitotic effects of viriditoxin on human cancer cells. Viriditoxin, like paclitaxel, enhanced tubulin polymerization and stabilized microtubule polymers, thereby perturbing mitosis in the SK-OV-3 cell line. However, the morphology of the stabilized microtubules was different from that induced by paclitaxel, indicating subtle differences in the mode of action of these compounds. Microtubule dynamics are also essential in cell movement, and viriditoxin repressed migration and colony formation ability of SK-OV-3 cells. Based on these results, we propose that viriditoxin interrupts microtubule dynamics, thus leading to antimitotic and antimetastatic activities.

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Mathematical modeling of microtubule dynamic instability: new insight into the link between gtp-hydrolysis and microtubule aging

ESAIM Mathematical Modelling and Numerical Analysis ◽

10.1051/m2an/2017025 ◽

2018 ◽

Vol 52 (6) ◽

pp. 2433-2456 ◽

Cited By ~ 2

Author(s):

Ayuna Barlukova ◽

Diana White ◽

Gérard Henry ◽

Stéphane Honoré ◽

Florence Hubert

Keyword(s):

Dynamic Instability ◽

Dynamic Properties ◽

Model Parameters ◽

Microtubule Dynamic ◽

Gtp Hydrolysis ◽

Unique Type ◽

Microtubule Targeting Agents ◽

Age Dependent ◽

Type Of Behavior ◽

Insight Into

Microtubules (MTs) are protein polymers that exhibit a unique type of behavior referred to as dynamic instability. That is, they undergo periods of growth (through the addition of GTP-tubulin) and shortening (through the subtraction of GDP-tubulin). Shortening events are very fast, where this transition is referred to as a catastrophe. There are many processes that regulate MT dynamic instability, however, recent experiments show that MT dynamics may be highly regulated by a MTs age, where young MTs are less likely to undergo shortening events than older ones. In this paper, we develop a novel modeling approach to describe how the age of a MT affects its dynamic properties. In particular, we extend on a previously developed model that describes MT dynamics, by proposing a new concept for GTP-tubulin hydrolysis (the process by which newly incorporated GTP-tubulin is hydrolyzed to lower energy GDP-tubulin). In particular, we assume that hydrolysis is mainly vectorial, age-dependent and delayed according to the GTP-tubulin incorporation into the MT. Through numerical simulation, we are able to show how MT age affects certain properties that define MT dynamics. For example, simulations illustrate how the aging process leads to an increase in the rate of GTP-tubulin hydrolysis for older MTs, as well as increases in catastrophe frequency. Also, since it has been found that MT dynamic instability is affected by chemotherapy microtubule-targeting agents (MTAs), we highlight the fact that our model can be used to investigate the action of MTAs on MT dynamics by varying certain model parameters.

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In Xenopus laevis, the product of a developmentally regulated mRNA is structurally and functionally homologous to a Saccharomyces cerevisiae protein involved in translation fidelity.

Molecular and Cellular Biology ◽

10.1128/mcb.13.5.2815 ◽

1993 ◽

Vol 13 (5) ◽

pp. 2815-2821 ◽

Cited By ~ 21

Author(s):

J P Tassan ◽

K Le Guellec ◽

M Kress ◽

M Faure ◽

J Camonis ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Sequence Analysis ◽

Structural Homology ◽

Developmentally Regulated ◽

Functional Homology ◽

Translation Fidelity ◽

Functional Homolog ◽

Xenopus Egg ◽

Higher Eukaryotes ◽

Nonsense Codons

We have performed a differential screen of a Xenopus egg cDNA library and selected two clones (Cl1 and Cl2) corresponding to mRNA which are specifically adenylated and recruited into polysomes after fertilization. Sequence analysis of Cl1 reveals that the corresponding protein is 67.5% identical (83% similar) to the product of the Saccharomyces cerevisiae SUP45 (also called SUP1 or SAL4) gene. This gene, when mutated, is an omnipotent suppressor of nonsense codons. When expressed in a sup45 mutant, the Xenopus Cl1 cDNA was able to suppress sup45-related phenotypes, showing that the structural homology reflects a functional homology. Our discovery of a structural and functional homolog in Xenopus cells implies that the function of SUP45 is not restricted to lower eukaryotes and that the SUP45 protein may perform a crucial cellular function in higher eukaryotes.

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β-Tubulin C354 Mutations that Severely Decrease Microtubule Dynamics Do Not Prevent Nuclear Migration in Yeast

Molecular Biology of the Cell ◽

10.1091/mbc.e02-01-0003 ◽

2002 ◽

Vol 13 (8) ◽

pp. 2919-2932 ◽

Cited By ~ 51

Author(s):

Mohan L. Gupta ◽

Claudia J. Bode ◽

Douglas A. Thrower ◽

Chad G. Pearson ◽

Kathy A. Suprenant ◽

...

Keyword(s):

Essential Gene ◽

Dynamic Properties ◽

Microtubule Dynamics ◽

Cytoplasmic Microtubule ◽

Bud Emergence ◽

Spindle Elongation ◽

Mutant Cells ◽

Β Tubulin

Microtubule dynamics are influenced by interactions of microtubules with cellular factors and by changes in the primary sequence of the tubulin molecule. Mutations of yeast β-tubulin C354, which is located near the binding site of some antimitotic compounds, reduce microtubule dynamicity greater than 90% in vivo and in vitro. The resulting intrinsically stable microtubules allowed us to determine which, if any, cellular processes are dependent on dynamic microtubules. The average number of cytoplasmic microtubules decreased from 3 in wild-type to 1 in mutant cells. The single microtubule effectively located the bud site before bud emergence. Although spindles were positioned near the bud neck at the onset of anaphase, the mutant cells were deficient in preanaphase spindle alignment along the mother-bud axis. Spindle microtubule dynamics and spindle elongation rates were also severely depressed in the mutants. The pattern and extent of cytoplasmic microtubule dynamics modulation through the cell cycle may reveal the minimum dynamic properties required to support growth. The ability to alter intrinsic microtubule dynamics and determine the in vivo phenotype of cells expressing the mutant tubulin provides a critical advance in assessing the dynamic requirements of an essential gene function.

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Crio-fixation of Pachytene Cells

Microscopy and Microanalysis ◽

10.1017/s1431927620000458 ◽

2020 ◽

Vol 26 (S1) ◽

pp. 43-43

Author(s):

R. Ortiz-Hernandez ◽

G. H. Vázquez-Nin ◽

O. Echeverría-Martínez ◽

C. Höög ◽

A. Hernández-Hernández

Keyword(s):

Cell Division ◽

Sexual Reproduction ◽

Meiotic Recombination ◽

Germ Line ◽

Genetic Material ◽

Freeze Substitution ◽

Homologous Chromosome Pairing ◽

Division Process ◽

Classic Approach ◽

Almost All

AbstractGenetic variability in organisms with sexual reproduction is produced by a complex mechanism of cell division of the germ line cells known as meiosis. During meiosis, homologous chromosomes pair and exchange genetic material (meiotic recombination), process that is essential to complete the meiotic division and to produce variability. Homologous chromosome pairing is mediated by the synaptonemal complex (SC). The SC is a proteinaceous structure composed of two lateral elements (LEs) and a central region (CR). Any defect in SC structure impairs meiotic recombination leading to blockage of the cell division process and infertility1. The SC has been observed since the introduction of the electron microscope (EM) in the biological field and it has been reported to be present in almost all the organisms with sexual reproduction, conserving a very similar structure and organisation along the different species2,3. The classic approach to study the SC structure is to chemically fixate the sexual tissues (gonads), dehydrate and embedded them in plastic resins that provide a support for sample sectioning and observation under the EM. However, chemical fixation followed by dehydration is well known to produce artefacts in the structure of many biological samples. Recently, we have combined fluorescence activated cell sorting of cells with SCs with high-pressure freezing and freeze- substitution and have found that the structure of the CR looks different from that observed in chemically fixated samples. These data have prompted us to analyse the organization of the CR components under cryo-processing.

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Discrete regions of the kinesin-8 Kip3 tail differentially mediate astral microtubule stability and spindle disassembly

Molecular Biology of the Cell ◽

10.1091/mbc.e18-03-0199 ◽

2018 ◽

Vol 29 (15) ◽

pp. 1866-1877 ◽

Cited By ~ 8

Author(s):

Sandeep Dave ◽

Samuel J. Anderson ◽

Pallavi Sinha Roy ◽

Emmanuel T. Nsamba ◽

Angela R. Bunning ◽

...

Keyword(s):

Dynamic Properties ◽

Microtubule Dynamics ◽

Motor Domain ◽

Spindle Positioning ◽

Cellular Processes ◽

Microtubule Stability ◽

Astral Microtubule ◽

Cellular Context ◽

Spindle Disassembly ◽

The Stability

To function in diverse cellular processes, the dynamic properties of microtubules must be tightly regulated. Cellular microtubules are influenced by a multitude of regulatory proteins, but how their activities are spatiotemporally coordinated within the cell, or on specific microtubules, remains mostly obscure. The conserved kinesin-8 motor proteins are important microtubule regulators, and family members from diverse species combine directed motility with the ability to modify microtubule dynamics. Yet how kinesin-8 activities are appropriately deployed in the cellular context is largely unknown. Here we reveal the importance of the nonmotor tail in differentially controlling the physiological functions of the budding yeast kinesin-8, Kip3. We demonstrate that the tailless Kip3 motor domain adequately governs microtubule dynamics at the bud tip to allow spindle positioning in early mitosis. Notably, discrete regions of the tail mediate specific functions of Kip3 on astral and spindle microtubules. The region proximal to the motor domain operates to spatially regulate astral microtubule stability, while the distal tail serves a previously unrecognized role to control the timing of mitotic spindle disassembly. These findings provide insights into how nonmotor tail domains differentially control kinesin functions in cells and the mechanisms that spatiotemporally control the stability of cellular microtubules.

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Predicted effects of severing enzymes on the length distribution and total mass of microtubules

10.1101/752006 ◽

2019 ◽

Author(s):

Y.-W. Kuo ◽

O. Trottier ◽

J. Howard

Keyword(s):

Steady State ◽

Numerical Solutions ◽

Dynamic Instability ◽

Computational Simulation ◽

Length Distribution ◽

Microtubule Dynamics ◽

Microtubule Dynamic ◽

Cytoskeletal Network ◽

Hydrolyzing Enzymes ◽

In Cells

AbstractMicrotubules are dynamic cytoskeletal polymers whose growth and shrinkage are highly regulated as eukaryotic cells change shape, move and divide. One family of microtubule regulators includes the ATP-hydrolyzing enzymes spastin, katanin and fidgetin, which sever microtubule polymers into shorter fragments. Paradoxically, severases can increase microtubule number and mass in cells. Recent work with purified spastin and katanin accounts for this phenotype by showing that, in addition to severing, these enzymes modulate microtubule dynamics by accelerating the conversion of microtubules to the growing state and thereby promoting their regrowth. This leads to the observed exponential increase in microtubule mass. Spastin also influences the steady-state distribution of microtubule lengths, changing it from an exponential, as predicted by models of microtubule dynamic instability, to a peaked distribution. This effect of severing and regrowth by spastin on the microtubule length distribution has not been explained theoretically. To solve this problem, we formulated and solved a master equation for the time evolution of microtubule lengths in the presence of severing and microtubule dynamic instability. We then obtained numerical solutions to the steady-state length distribution and showed that the rate of severing and the speed of microtubule growth are the dominant parameters determining the steady-state length distribution. Furthermore, we found that the amplification rate is predicted to increase with severing, which is a new result. Our results establish a theoretical basis for how severing and dynamics together can serve to nucleate new microtubules, constituting a versatile mechanism to regulate microtubule length and mass.SignificanceThe numbers and lengths of microtubules are tightly regulated in cells. Severing enzymes fragment microtubules into shorter filaments and are important for cell division and tissue development. Previous work has shown that severing can lead to an increase in total microtubule number and mass, but the effect of severing on microtubule length is not understood quantitatively. Combining mathematical modeling and computational simulation, we solve the microtubule length distribution in the presence of severing enzymes and explore how severing activity and microtubule dynamics collectively control microtubule number and length. These results advance our understanding of the physical basis of severing as a regulatory mechanism shaping the cellular cytoskeletal network.

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