A new perspective on microtubule dynamics: destruction by molecular motors and self-repair

During anaphase B, molecular motors slide interpolar microtubules to elongate the mitotic spindle, contributing to the separation of chromosomes. However, sliding of antiparallel microtubules reduces their overlap, which may lead to spindle breakage, unless microtubules grow to compensate sliding. How sliding and growth are coordinated is still poorly understood. In this study, we have used the fission yeast S. pombe to measure microtubule dynamics during anaphase B. We report that the coordination of microtubule growth and sliding relies on promoting rescues at the midzone edges. This makes microtubules stable from pole to midzone, while their distal parts including the plus ends alternate between assembly and disassembly. Consequently, the midzone keeps a constant length throughout anaphase, enabling sustained sliding without the need for a precise regulation of microtubule growth speed. Additionally, we found that in S. pombe, which undergoes closed mitosis, microtubule growth speed decreases when the nuclear membrane wraps around the spindle midzone.

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Self-repair protects microtubules from their destruction by molecular motors:

10.1101/499020 ◽

2018 ◽

Cited By ~ 8

Author(s):

Sarah Triclin ◽

Daisuke Inoue ◽

Jeremie Gaillard ◽

Zaw Min Htet ◽

Morgan De Santis ◽

...

Keyword(s):

Chromosome Segregation ◽

Molecular Motors ◽

Intracellular Transport ◽

Atp Hydrolysis ◽

Low Energy ◽

Mechanical Work ◽

Repair Mechanism ◽

Tubulin Dimer ◽

Self Repair

Microtubules are dynamic polymers that are used for intracellular transport and chromosome segregation during cell division. Their instability stems from the low energy of tubulin dimer interactions, which sets the growing polymer close to its disassembly conditions. Microtubules function in coordination with kinesin and dynein molecular motors, which use ATP hydrolysis to produce mechanical work and move on microtubules. This raises the possibility that the forces produced by walking motors can break dimer interactions and trigger microtubule disassembly. We tested this hypothesis by studying the interplay between microtubules and moving molecular motors in vitro. Our results show that the mechanical work of molecular motors can remove tubulin dimers from the lattice and rapidly destroy microtubules. This effect was not observed when free tubulin dimers were present in the assay. Using fluorescently labelled tubulin dimers we found that dimer removal by motors was compensated for by the insertion of free tubulin dimers into the microtubule lattice. This self-repair mechanism allows microtubules to survive the damage induced by molecular motors as they move along their tracks. Our study reveals the existence of coupling between the motion of kinesin and dynein motors and the renewal of the microtubule lattice.

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MOLECULAR MOTORS CONTROL LENGTH OF ANTIPARALLEL MICROTUBULE OVERLAPS

Modern Physics Letters B ◽

10.1142/s0217984911500278 ◽

2012 ◽

Vol 26 (04) ◽

pp. 1150027 ◽

Cited By ~ 1

Author(s):

ZIQING WANG ◽

CAIHUA ZHANG ◽

GUODONG WANG

Keyword(s):

Experimental Data ◽

Monte Carlo Simulation ◽

Monte Carlo ◽

Molecular Motors ◽

Structural Changes ◽

Microtubule Dynamics ◽

Inhibition Mechanism ◽

Direct Inhibition ◽

Simulation Results

Using Monte Carlo simulation, we studied the controlling length of antiparallel microtubule overlaps by motors in the presence of PRC1. Two models for the inhibition mechanism of microtubule dynamics are developed. The comparison of the simulation results and the experimental data shows that the inhibition of microtubule dynamics is probably not due to a direct inhibition of polymerization and depolymerization of microtubule by the motor at plus end of microtubule but rather caused by global structural changes in the microtubule due to the presence of bound motor on the microtubule.

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SREM observation of the interaction between the in-situ deposited Pd small particles and MgO cleavage surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143523 ◽

1986 ◽

Vol 44 ◽

pp. 382-383

Author(s):

H.-J. Ou

Keyword(s):

Electron Microscopy ◽

Small Particle ◽

Small Particles ◽

Cleavage Surface ◽

Metallic Particles ◽

Microscopy Technique ◽

Ceramic Surfaces ◽

Reflection Electron Microscopy ◽

New Perspective

The understanding of the interactions between the small metallic particles and ceramic surfaces has been studied by many catalyst scientists. We had developed Scanning Reflection Electron Microscopy technique to study surface structure of MgO hulk cleaved surface and the interaction with the small particle of metals. Resolutions of 10Å has shown the periodic array of surface atomic steps on MgO. The SREM observation of the interaction between the metallic particles and the surface may provide a new perspective on such processes.

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Microtubule Dynamics and Organelle Transport in Reticulomyxa

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158510 ◽

1990 ◽

Vol 48 (3) ◽

pp. 194-195

Author(s):

Yih-Tai Chen ◽

Ursula Euteneuer ◽

Ken B. Johnson ◽

Michael P. Koonce ◽

Manfred Schliwa

Keyword(s):

Plasma Membrane ◽

Light Microscopy ◽

Cytoplasmic Dynein ◽

Living Cells ◽

Microtubule Dynamics ◽

Model Systems ◽

Organelle Transport ◽

Biochemical Characteristics ◽

Dependent Transport

The application of video techniques to light microscopy and the development of motility assays in reactivated or reconstituted model systems rapidly advanced our understanding of the mechanism of organelle transport and microtubule dynamics in living cells. Two microtubule-based motors have been identified that are good candidates for motors that drive organelle transport: kinesin, a plus end-directed motor, and cytoplasmic dynein, which is minus end-directed. However, the evidence that they do in fact function as organelle motors is still indirect.We are studying microtubule-dependent transport and dynamics in the giant amoeba, Reticulomyxa. This cell extends filamentous strands backed by an extensive array of microtubules along which organelles move bidirectionally at up to 20 μm/sec (Fig. 1). Following removal of the plasma membrane with a mild detergent, organelle transport can be reactivated by the addition of ATP (1). The physiological, pharmacological and biochemical characteristics show the motor to be a cytoplasmic form of dynein (2).

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Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146783 ◽

1993 ◽

Vol 51 ◽

pp. 188-189

Author(s):

Tim Oliver ◽

Michelle Leonard ◽

Juliet Lee ◽

Akira Ishihara ◽

Ken Jacobson

Keyword(s):

Silicone Rubber ◽

Molecular Motors ◽

Video Frame ◽

Traction Forces ◽

Cell Traction Forces ◽

Latex Beads ◽

Cell Traction ◽

Local Cell ◽

Microscopic Measurement ◽

Kinetics Of

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.

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