scholarly journals Force production of human cytoplasmic dynein is limited by its processivity

2020 ◽  
Vol 6 (15) ◽  
pp. eaaz4295 ◽  
Author(s):  
Sibylle Brenner ◽  
Florian Berger ◽  
Lu Rao ◽  
Matthew P. Nicholas ◽  
Arne Gennerich
Keyword(s):  
Optical Tweezers ◽  
Molecular Motor ◽  
Force Production ◽  
Cytoplasmic Dynein ◽  
Force Generation ◽  
New Paradigm ◽  
Average Force ◽  
Complex Motor ◽  
Hyperbolic Curve ◽  
Stall Force

Cytoplasmic dynein is a highly complex motor protein that generates forces toward the minus end of microtubules. Using optical tweezers, we demonstrate that the low processivity (ability to take multiple steps before dissociating) of human dynein limits its force generation due to premature microtubule dissociation. Using a high trap stiffness whereby the motor achieves greater force per step, we reveal that the motor’s true maximal force (“stall force”) is ~2 pN. Furthermore, an average force versus trap stiffness plot yields a hyperbolic curve that plateaus at the stall force. We derive an analytical equation that accurately describes this curve, predicting both stall force and zero-load processivity. This theoretical model describes the behavior of a kinesin motor under low-processivity conditions. Our work clarifies the true stall force and processivity of human dynein and provides a new paradigm for understanding and analyzing molecular motor force generation for weakly processive motors.

Molecular Motors: Force and Movement Generated by Single Myosin II Molecules

Physiology ◽  
2002 ◽  
Vol 17 (5) ◽  
pp. 213-218 ◽  
Author(s):  
Caspar Rüegg ◽  
Claudia Veigel ◽  
Justin E. Molloy ◽  
Stephan Schmitz ◽  
John C. Sparrow ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Molecular Motors ◽  
Molecular Motor ◽  
Myosin Ii ◽  
Force Production ◽  
Myosin Isoforms ◽  
Single Molecule Level ◽  
Recent Developments ◽  
Muscle Myosin

Muscle myosin II is an ATP-driven, actin-based molecular motor. Recent developments in optical tweezers technology have made it possible to study movement and force production on the single-molecule level and to find out how different myosin isoforms may have adapted to their specific physiological roles.

scholarly journals Detailed analyses of stall force generation inMycoplasma mobilegliding

2017 ◽  
Author(s):  
Masaki Mizutani ◽  
Isil Tulum ◽  
Yoshiaki Kinosita ◽  
Takayuki Nishizaka ◽  
Makoto Miyata
Keyword(s):  
Optical Tweezers ◽  
Type Strain ◽  
Wild Type Strain ◽  
Gear Ratio ◽  
Solid Surfaces ◽  
Force Generation ◽  
Wild Type ◽  
Step Size ◽  
Large Gear ◽  
Stall Force

ABSTRACTMycoplasma mobileis a bacterium that uses a unique mechanism to glide on solid surfaces at a velocity of up to 4.5 µm/s. Its gliding machinery comprises hundreds of units that generate the force for gliding based on the energy derived from ATP; the units catch and pull on sialylated oligosaccharides fixed to solid surfaces. In the present study, we measured the stall force of wild-type and mutant strains ofM. mobilecarrying a bead manipulated using optical tweezers. The strains that had been enhanced for binding exhibited weaker stall forces than the wild-type strain, indicating that stall force is related to force generation rather than to binding. The stall force of the wild-type strain decreased linearly from 113 to 19 pN following the addition of 0–0.5 mM free sialyllactose (a sialylated oligosaccharide), with a decrease in the number of working units. Following the addition of 0.5 mM sialyllactose, the cells carrying a bead loaded using optical tweezers exhibited stepwise movements with force increments. The force increments ranged from 1 to 2 pN. Considering the 70-nm step size, this small unit force may be explained by the large gear ratio involved in theM. mobilegliding machinery.SIGNIFICANCEMycoplasmais a genus of bacteria that parasitizes animals. Dozens ofMycoplasmaspecies glide over the tissues of their hosts during infection. The gliding machinery ofMycoplasma mobile, the fastest species, includes intracellular motors and hundreds of legs on the cell surface. In the present study, we precisely measured force generation using a highly focused laser beam arrangement (referred to as optical tweezers) under various conditions. The measurements obtained in this study suggest that the rapid gliding exhibited byM. mobilearises from the large gear ratio of its gliding machinery.

Neuromuscular drive and force production are not altered during bilateral contractions

1998 ◽  
Vol 84 (1) ◽  
pp. 200-206 ◽  
Author(s):  
J. M. Jakobi ◽  
E. Cafarelli
Keyword(s):  
Motor Unit ◽  
Force Production ◽  
Young Male ◽  
Neuromuscular Control ◽  
Force Generation ◽  
Isometric Contractions ◽  
Firing Rates ◽  
Significant Limitation ◽  
Motor Unit Firing ◽  
Male Subjects

Jakobi, J. M., and E. Cafarelli. Neuromuscular drive and force production are not altered during bilateral contractions. J. Appl. Physiol. 84(1): 200–206, 1998.—Several investigators have studied the deficit in maximal voluntary force that is said to occur when bilateral muscle groups contract simultaneously. A true bilateral deficit (BLD) would suggest a significant limitation of neuromuscular control; however, some of the data from studies in the literature are equivocal. Our purpose was to determine whether there is a BLD in the knee extensors of untrained young male subjects during isometric contractions and whether this deficit is associated with a decreased activation of the quadriceps, increased activation of the antagonist muscle, or an alteration in motor unit firing rates. Twenty subjects performed unilateral (UL) and bilateral (BL) isometric knee extensions at 25, 50, 75, and 100% maximal voluntary contraction. Total UL and BL force (Δ3%) and maximal rate of force generation (Δ2.5%) were not significantly different. Total UL and BL maximal vastus lateralis electromyographic activity (EMG; 2.7 ± 0.28 vs. 2.6 ± 0.24 mV) and coactivation (0.17 ± 0.02 vs. 0.20 ± 0.02 mV) were also not different. Similarly, the ratio of force to EMG during submaximal UL and BL contractions was not different. Analysis of force production by each leg in UL and BL conditions showed no differences in force, rate of force generation, EMG, motor unit firing rates, and coactivation. Finally, assessment of quadriceps activity with the twitch interpolation technique indicated no differences in the degree of voluntary muscle activation (UL: 93.6 ± 2.51 Hz, BL: 90.1 ± 2.43 Hz). These results provide no evidence of a significant limitation in neuromuscular control between BL and UL isometric contractions of the knee extensor muscles in young male subjects.

The effects of pH on force and stiffness development in mouse muscles

1987 ◽  
Vol 65 (8) ◽  
pp. 1798-1801 ◽  
Author(s):  
J. M. Renaud ◽  
R. B. Stein ◽  
T. Gordon
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Force Production ◽  
Muscle Length ◽  
Low Ph ◽  
Muscle Stiffness ◽  
Average Force ◽  
Cross Bridge ◽  
Effects Of Ph ◽  
Cross Bridges

Changes in force and stiffness during contractions of mouse extensor digitorum longus and soleus muscles were measured over a range of extracellular pH from 6.4 to 7.4. Muscle stiffness was measured using small amplitude (<0.1% of muscle length), high frequency (1.5 kHz) oscillations in length. Twitch force was not significantly affected by changes in pH, but the peak force during repetitive stimulation (2, 3, and 20 pulses) was decreased significantly as the pH was reduced. Changes in muscle stiffness with pH were in the same direction, but smaller in extent. If the number of attached cross-bridges in the muscle can be determined from the measurement of small amplitude, high frequency muscle stiffness, then these findings suggest that (a) the number of cross-bridges between thick and thin filaments declines in low pH and (b) the average force per cross-bridge also declines in low pH. The decline in force per cross-bridge could arise from a reduction in the ability of cross-bridges to generate force during their state of active force production and (or) in an increased percentage of bonds in a low force, "rigor" state.

scholarly journals Neck linker docking is critical for Kinesin-1 force generation in cells but at a cost to motor speed and processivity

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Breane G Budaitis ◽  
Shashank Jariwala ◽  
Dana N Reinemann ◽  
Kristin I Schimert ◽  
Guido Scarabelli ◽  
...  
Keyword(s):  
Optical Trap ◽  
Force Production ◽  
Force Generation ◽  
Motor Speed ◽  
Force Output ◽  
Mechanical Element ◽  
Membrane Bound ◽  
Dynamics Simulations ◽  
Run Lengths ◽  
In Cells

Kinesin force generation involves ATP-induced docking of the neck linker (NL) along the motor core. However, the roles of the proposed steps of NL docking, cover-neck bundle (CNB) and asparagine latch (N-latch) formation, during force generation are unclear. Furthermore, the necessity of NL docking for transport of membrane-bound cargo in cells has not been tested. We generated kinesin-1 motors impaired in CNB and/or N-latch formation based on molecular dynamics simulations. The mutant motors displayed reduced force output and inability to stall in optical trap assays but exhibited increased speeds, run lengths, and landing rates under unloaded conditions. NL docking thus enhances force production but at a cost to speed and processivity. In cells, teams of mutant motors were hindered in their ability to drive transport of Golgi elements (high-load cargo) but not peroxisomes (low-load cargo). These results demonstrate that the NL serves as a mechanical element for kinesin-1 transport under physiological conditions.

scholarly journals Cytoplasmic Dynein Mediates Adenovirus Binding to Microtubules

2004 ◽  
Vol 78 (18) ◽  
pp. 10122-10132 ◽  
Author(s):  
Samir A. Kelkar ◽  
K. Kevin Pfister ◽  
Ronald G. Crystal ◽  
Philip L. Leopold
Keyword(s):  
Molecular Motor ◽  
Retrograde Transport ◽  
Cytoplasmic Dynein ◽  
Bovine Brain ◽  
Microtubule Binding ◽  
Microtubule Associated Proteins ◽  
Primary Mode ◽  
Cell Lysate ◽  
Brain Maps ◽  
Associated Proteins

ABSTRACT During infection, adenovirus (Ad) capsids undergo microtubule-dependent retrograde transport as part of a program of vectorial transport of the viral genome to the nucleus. The microtubule-associated molecular motor, cytoplasmic dynein, has been implicated in the retrograde movement of Ad. We hypothesized that cytoplasmic dynein constituted the primary mode of association of Ad with microtubules. To evaluate this hypothesis, an Ad-microtubule binding assay was established in which microtubules were polymerized with taxol, combined with Ad in the presence or absence of microtubule-associated proteins (MAPs), and centrifuged through a glycerol cushion. The addition of purified bovine brain MAPs increased the fraction of Ad in the microtubule pellet from 17.3% ± 3.5% to 80.7% ± 3.8% (P < 0.01). In the absence of tubulin polymerization or in the presence of high salt, no Ad was found in the pellet. Ad binding to microtubules was not enhanced by bovine brain MAPs enriched for tau protein or by the addition of bovine serum albumin. Enhanced Ad-microtubule binding was also observed by using a fraction of MAPs purified from lung A549 epithelial cell lysate which contained cytoplasmic dynein. Ad-microtubule interaction was sensitive to the addition of ATP, a hallmark of cytoplasmic dynein-dependent microtubule interactions. Immunodepletion of cytoplasmic dynein from the A549 cell lysate abolished the MAP-enhanced Ad-microtubule binding. The interaction of Ad with both dynein and dynactin complexes was demonstrated by coimmunoprecipitation. Partially uncoated capsids isolated from cells 40 min after infection also exhibited microtubule binding. In summary, the primary mode of Ad attachment to microtubules occurs though cytoplasmic dynein-mediated binding.

A Dynamic Escape Problem of Molecular Motors

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Dean Culver ◽  
Bryan Glaz ◽  
Samuel Stanton
Keyword(s):  
Molecular Motors ◽  
Binding Sites ◽  
Molecular Motor ◽  
Myosin Ii ◽  
Three Dimensional ◽  
Production Capacity ◽  
Force Production ◽  
Actin Binding ◽  
Three Dimensional Model ◽  
Thermal Agitation

Abstract Animal skeletal muscle exhibits very interesting behavior at near-stall forces (when the muscle is loaded so strongly that it can barely contract). Near this physical limit, the myosin II proteins may be unable to reach advantageous actin binding sites through simple attractive forces. It has been shown that the advantageous utilization of thermal agitation is a likely source for an increased force-production capacity and reach in myosin-V (a processing motor protein), and here we explore the dynamics of a molecular motor without hand-over-hand motion including Brownian motion to show how local elastic energy well boundaries may be overcome. We revisit a spatially two-dimensional mechanical model to illustrate how thermal agitation can be harvested for useful mechanical work in molecular machinery inspired by this biomechanical phenomenon without rate functions or empirically inspired spatial potential functions. Additionally, the model accommodates variable lattice spacing, and it paves the way for a full three-dimensional model of cross-bridge interactions where myosin II may be azimuthally misaligned with actin binding sites. With potential energy sources based entirely on realizable components, this model lends itself to the design of artificial, molecular-scale motors.

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