scholarly journals Non-equilibrium effects of molecular motors on polymers

Soft Matter ◽  
2019 ◽  
Vol 15 (29) ◽  
pp. 5995-6005 ◽  
Author(s):  
M. Foglino ◽  
E. Locatelli ◽  
C. A. Brackley ◽  
D. Michieletto ◽  
C. N. Likos ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Molecular Motors ◽  
Coarse Grained ◽  
Polymer Substrates ◽  
Coarse Grained Model ◽  
Non Equilibrium

We present a generic coarse-grained model to describe molecular motors acting on polymer substrates, mimicking, for example, RNA polymerase on DNA or kinesin on microtubules.

scholarly journals Inferring non-equilibrium interactions from tracer response near confined active Janus particles

2021 ◽  
Vol 7 (18) ◽  
pp. eabd0719
Author(s):  
Jaideep Katuri ◽  
William E. Uspal ◽  
Mihail N. Popescu ◽  
Samuel Sánchez
Keyword(s):  
Symmetry Axis ◽  
Coarse Grained ◽  
Janus Particles ◽  
Janus Particle ◽  
Indirect Methods ◽  
Effective Interactions ◽  
Coarse Grained Model ◽  
Direct Mapping ◽  
Tracer Particles ◽  
Non Equilibrium

Chemically active Janus particles sustain non-equilibrium spatial variations in the chemical composition of the suspending solution; these induce hydrodynamic flow and (self-)motility of the particles. Direct mapping of these fields has so far proven to be too challenging. Therefore, indirect methods are needed, e.g., deconvolving the response of “tracer” particles to the activity-induced fields. Here, we study experimentally the response of silica particles, sedimented at a wall, to active Pt/silica Janus particles. The latter are either immobilized at the wall, with the symmetry axis perpendicular or parallel to the wall, or motile. The experiments reveal complex effective interactions that are dependent on the configuration and on the state of motion of the active particle. Within the framework of a coarse-grained model, the behavior of tracers near an immobilized Janus particle can be captured qualitatively once activity-induced osmotic flows on the wall are considered.

scholarly journals Multi-Scale Coarse Grained Model for the Stepping of Molecular Motors with application to Kinesin.

2021 ◽  
Author(s):  
Yonathan Y Goldtzvik ◽  
D Thirumalai
Keyword(s):  
Molecular Motors ◽  
Interaction Strength ◽  
Accurate Method ◽  
Significant Loss ◽  
Coarse Grained ◽  
Power Stroke ◽  
Coarse Grained Model ◽  
Multi Scale ◽  
Walking Mechanism ◽  
Conventional Kinesin

Conventional kinesin, a motor protein that transports cargo within cells, walks by taking multiple steps towards the plus end of the microtubule (MT). While significant progress has been made in understanding the details of the walking mechanism of kinesin there are many unresolved issues. From a computational perspective, a central challenge is the large size of the system, which limits the scope of time scales accessible in standard computer simulations. Here, we create a general multi-scale coarse-grained model for motors that enables us to simulate the stepping process of motors on polar tracks (actin and MT) with focus on kinesin. Our approach greatly shortens the computation times without a significant loss in detail, thus allowing us to better describe the molecular basis of the stepping kinetics. The small number of parameters, which are determined by fitting to experimental data, allows us to develop an accurate method that may be adopted to simulate stepping in other molecular motors. The model enables us to simulate a large number of steps, which was not possible previously. We show in agreement with experiments that due to the docking of the neck linker (NL) of kinesin, sometimes deemed as the power stroke, the space explored diffusively by the tethered head is severely restricted allowing the step to be in a tens of microseconds. We predict that increasing the interaction strength between the NL and the motor head, achievable by mutations in the NL, decreases the stepping time but reaches a saturation value. Furthermore, the full 3-dimensional dynamics of the cargo are fully resolved in our model, contributing to the predictive power and allowing us to study the important aspects of cargo-motor interactions.

scholarly journals Contraction of polymer gels created by the activity of molecular motors

Soft Matter ◽  
2019 ◽  
Vol 15 (22) ◽  
pp. 4467-4475 ◽  
Author(s):  
Mattia Bacca ◽  
Omar A. Saleh ◽  
Robert M. McMeeking
Keyword(s):  
Mechanical Behavior ◽  
Molecular Motors ◽  
Polymer Gels ◽  
Polymer Gel ◽  
Equilibrium Thermodynamics ◽  
Non Equilibrium

We propose a theory based on non-equilibrium thermodynamics to describe the mechanical behavior of an active polymer gel created by the inclusion of molecular motors in its solvent.

Insights Into Crowding Effects on Protein Stability From a Coarse-Grained Model

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Vincent K. Shen ◽  
Jason K. Cheung ◽  
Jeffrey R. Errington ◽  
Thomas M. Truskett
Keyword(s):  
Protein Stability ◽  
Coarse Grained ◽  
Protein Solutions ◽  
Native State ◽  
High Concentration ◽  
Coarse Grained Model ◽  
Excluded Volume Effects ◽  
Thermodynamic Phase ◽  
Broad Interest ◽  
Liquid Liquid Phase Separation

Proteins aggregate and precipitate from high concentration solutions in a wide variety of problems of natural and technological interest. Consequently, there is a broad interest in developing new ways to model the thermodynamic and kinetic aspects of protein stability in these crowded cellular or solution environments. We use a coarse-grained modeling approach to study the effects of different crowding agents on the conformational equilibria of proteins and the thermodynamic phase behavior of their solutions. At low to moderate protein concentrations, we find that crowding species can either stabilize or destabilize the native state, depending on the strength of their attractive interaction with the proteins. At high protein concentrations, crowders tend to stabilize the native state due to excluded volume effects, irrespective of the strength of the crowder-protein attraction. Crowding agents reduce the tendency of protein solutions to undergo a liquid-liquid phase separation driven by strong protein-protein attractions. The aforementioned equilibrium trends represent, to our knowledge, the first simulation predictions for how the properties of crowding species impact the global thermodynamic stability of proteins and their solutions.

Sign in / Sign up

Export Citation Format

Share Document