scholarly journals How Protein Motors Convert Chemical Energy into Mechanical Work

2004 ◽  
pp. 205-227 ◽  
Author(s):  
George Oster ◽  
Hongyun Wang
Keyword(s):  
Mechanical Work ◽  
Chemical Energy ◽  
Protein Motors

scholarly journals Positional isomers of a non-nucleoside substrate differentially affect myosin function

2019 ◽  
Author(s):  
M. Woodward ◽  
E. Ostrander ◽  
S.P. Jeong ◽  
X. Liu ◽  
B. Scott ◽  
...  
Keyword(s):  
Energy Source ◽  
Muscle Contraction ◽  
Motor Function ◽  
Molecular Motors ◽  
Molecular Motor ◽  
Vesicular Transport ◽  
Gain Control ◽  
Mechanical Work ◽  
Chemical Energy ◽  
Muscle Myosin

AbstractMolecular motors have evolved to transduce chemical energy from adenosine triphosphate into mechanical work to drive essential cellular processes, from muscle contraction to vesicular transport. Dysfunction of these motors is a root cause of many pathologies necessitating the need for intrinsic control over molecular motor function. Herein, we demonstrate that positional isomerism can be used as a simple and powerful tool to control the molecular motor of muscle, myosin. Using three isomers of a synthetic non-nucleoside triphosphate we demonstrate that myosin’s force and motion generating capacity can be dramatically altered at both the ensemble and single molecule levels. By correlating our experimental results with computation, we show that each isomer exerts intrinsic control by affecting distinct steps in myosin’s mechano-chemical cycle. Our studies demonstrate that subtle variations in the structure of an abiotic energy source can be used to control the force and motility of myosin without altering myosin’s structure.Statement of SignificanceMolecular motors transduce chemical energy from ATP into the mechanical work inside a cell, powering everything from muscle contraction to vesicular transport. While ATP is the preferred source of energy, there is growing interest in developing alternative sources of energy to gain control over molecular motors. We synthesized a series of synthetic compounds to serve as alternative energy sources for muscle myosin. Myosin was able to use this energy source to generate force and velocity. And by using different isomers of this compound we were able to modulate, and even inhibit, the activity of myosin. This suggests that changing the isomer of the substrate could provide a simple, yet powerful, approach to gain control over molecular motor function.

scholarly journals Single molecule study of cytoskeleton and membrane dynamics

2014 ◽  
Vol 70 (a1) ◽  
pp. C108-C108
Author(s):  
Yujie Sun
Keyword(s):  
Single Molecule ◽  
Molecular Motors ◽  
Membrane Dynamics ◽  
Mechanical Work ◽  
Chemical Energy ◽  
Cellular Structures ◽  
Cellular Trafficking ◽  
Single Molecule Fluorescence ◽  
Fluorescence Studies ◽  
Cellular Processes

Molecular motors are proteins that convert chemical energy directly into mechanical work in the cell, driving many cellular processes. Given their intrinsic unsynchronous nature, single molecule fluorescence and manipulation techniques are nearly the ultimate tools to understand the mechanisms of molecular motors. I will talk about single molecule fluorescence studies of cytoskeleton associated motors, and their roles in cellular trafficking and membrane shaping of intra-cellular structures.

scholarly journals A Parallel Ratchet-Stroke Mechanism Leads to an Optimum Force for Molecular Motor Function

2020 ◽  
Author(s):  
U.L. Mallimadugula ◽  
E.A. Galburt
Keyword(s):  
Experimental Data ◽  
Motor Function ◽  
Molecular Motors ◽  
Molecular Motor ◽  
Mechanical Work ◽  
Chemical Energy ◽  
Stochastic Simulations ◽  
Power Stroke ◽  
Theoretical Understanding ◽  
Parallel Path

ABSTRACTMolecular motors convert chemical potential energy into mechanical work and perform a great number of critical biological functions. Examples include the polymerization and manipulation of nucleic acids, the generation of cellular motility and contractility, the formation and maintenance of cell shape, and the transport of materials within cells. The mechanisms underlying these molecular machines are routinely divided into two categories: Brownian ratchet and power stroke. While a ratchet uses chemical energy to bias thermally activated motion, a stroke depends on a direct coupling between chemical events and motion. However, the multi-dimensional nature of protein energy landscapes allows for the possibility of multiple reaction paths connecting two states. Here, we investigate the properties of a hypothetical molecular motor able to utilize parallel ratchet and stroke translocation mechanisms. We explore motor velocity and force-dependence as a function of the energy landscape of each path and reveal the potential for such a mechanism to result in an optimum force for motor function. We explore how the presence of this optimum depends on the rates of the individual paths and show that the distribution of stepping times characterized by the randomness parameter may be used to test for parallel path mechanisms. Lastly, we caution that experimental data consisting solely of measurements of velocity as a function of ATP concentration and force cannot be used to eliminate the possibility of such a parallel path mechanism.SIGNIFICANCEMolecular motors perform various mechanical functions in cells allowing them to move, replicate and perform various housekeeping functions required for life. Biophysical studies often aim to determine the molecular mechanism by which these motors convert chemical energy to mechanical work by fitting experimental data with kinetic models that fall into one of two classes: Brownian ratchets or power strokes. However, nothing a priori requires that a motor function via a single mechanism. Here, we consider a theoretical construct where a motor has access to both class of mechanism in parallel. Combining stochastic simulations and analytical solutions we describe unique signatures of such a mechanism that could be observed experimentally. We also show that absence of these signatures does not formally eliminate the existence of such a parallel mechanism. These findings expand our theoretical understanding of the potential motor behaviors with which to interpret experimental results.

Three-dimensional reconstruction studies of mitotic spindle ultrastructure

1988 ◽  
Vol 46 ◽  
pp. 32-33
Author(s):  
C.L. Rieder ◽  
G. Rupp ◽  
S.P. Alexander ◽  
R.B. Nicklas
Keyword(s):  
Mitotic Spindle ◽  
Three Dimensional ◽  
Mechanical Work ◽  
Chemical Energy ◽  
Serial Sections ◽  
Three Dimensional Reconstruction ◽  
Daughter Cells ◽  
Spindle Poles ◽  
Dimensional Reconstruction ◽  
Clear Plastic

The mitotic spindle is composed chiefly of microtubules (MTs) and functions to equally distribute the replicated chromosomes to daughter cells. Spindles are generated from an interaction between the spindle poles and kinetochores. The former are responsible for generating spindle MTs while the latter act as sites for attaching the chromosomes to the MTs. As noted by McIntosh the emphasis of most mitotic investigations is structural “because the spindle is a kind of machine, and numerous structural questions are obvious as one tries to understand a device which converts chemical energy into mechanical work.”During the course of our mitosis studies it was frequently necessary to reconstruct the three-dimensional (3D) ultrastructure of spindles from serial sections. To do this we utilized the STERECON system developed at the Albany HVEM facility. Briefly, prints of serial sections are enlarged to an optimum final magnification. For each section, profiles are drawn on clear plastic sheets outlining the chromosomes, mitochondria, and spindle MTs.

X-ray analysis and the problem of muscle

1953 ◽  
Vol 141 (902) ◽  
pp. 59-62 ◽  
Keyword(s):  
Molecular Structure ◽  
Adenosine Triphosphate ◽  
Mechanical Work ◽  
Chemical Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Moving Parts

The present-day picture of muscle is briefly as follows: muscle is a machine for converting chemical energy into mechanical work; the ‘moving parts’ of this machine are built up of two proteins, actin and myosin; the known energy-producing reaction most closely linked to the contractile process is the dephosphorylation of adenosine triphosphate (ATP). In the present studies, low-angle X-ray diffraction technique has been used to study the molecular structure of these two proteins, actin and myosin, and their arrangement in living muscle under various conditions.

scholarly journals Efficient conversion of chemical energy into mechanical work by Hsp70 chaperones

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Salvatore Assenza ◽  
Alberto Stefano Sassi ◽  
Ruth Kellner ◽  
Benjamin Schuler ◽  
Paolo De Los Rios ◽  
...  
Keyword(s):  
Free Energy ◽  
Single Molecule ◽  
Atp Hydrolysis ◽  
Critical Role ◽  
Quantitative Agreement ◽  
Mechanical Work ◽  
Chemical Energy ◽  
Coarse Grained ◽  
Theoretical Approaches ◽  
Non Equilibrium

Hsp70 molecular chaperones are abundant ATP-dependent nanomachines that actively reshape non-native, misfolded proteins and assist a wide variety of essential cellular processes. Here, we combine complementary theoretical approaches to elucidate the structural and thermodynamic details of the chaperone-induced expansion of a substrate protein, with a particular emphasis on the critical role played by ATP hydrolysis. We first determine the conformational free-energy cost of the substrate expansion due to the binding of multiple chaperones using coarse-grained molecular simulations. We then exploit this result to implement a non-equilibrium rate model which estimates the degree of expansion as a function of the free energy provided by ATP hydrolysis. Our results are in quantitative agreement with recent single-molecule FRET experiments and highlight the stark non-equilibrium nature of the process, showing that Hsp70s are optimized to effectively convert chemical energy into mechanical work close to physiological conditions.

Recent Advances in Human Energetics

Physiology ◽  
1986 ◽  
Vol 1 (3) ◽  
pp. 112-114
Author(s):  
E Jequier ◽  
J-P Flatt
Keyword(s):  
Energy Balance ◽  
Oxidative Phosphorylation ◽  
Atp Synthesis ◽  
Substrate Oxidation ◽  
Mechanical Work ◽  
Chemical Energy ◽  
Muscular Work ◽  
Recent Advances ◽  
Overall Efficiency

Careful measurements of the energy balance of exercising humans permit the estimate of not only the overall efficiency of performing aerobic muscular work (27%) but also the efficiency of transforming chemical energy into mechanical work (41%), as well as the efficiency of oxidative phosphorylation (i.e., "ATP synthesis") during substrate oxidation (65%).

scholarly journals CONTRACTILE PROPERTIES OF COMPRESSED MONOLAYERS OF ACTOMYOSIN

1952 ◽  
Vol 36 (2) ◽  
pp. 139-152 ◽  
Author(s):  
Teru Hayashi
Keyword(s):  
Water Loss ◽  
Structural Organization ◽  
Dry Weight ◽  
Biological Properties ◽  
Enzymic Activity ◽  
Mechanical Work ◽  
Chemical Energy ◽  
Critical Weight ◽  
Cell Structures ◽  
Surface Spread

1. Surface-spread actomyosin, compressed into fibers, shows biological properties of contractility and enzymic activity. 2. In unloaded contractions, wet and dry weight determinations show no appreciable water loss in contraction. The fibers also evince a strong ATP-ase activity. 3. A structural continuity in the fibers by intermolecular linkages of the component actomyosin molecules is established during the formation of the fibers. Evidence includes their visible longitudinal structural organization, the lack of elongation effect of ATP when under tension, and their ability to lift appreciable loads, so that, like muscle, they can transform chemical energy into mechanical work. 4. Up to a limiting critical weight, the fibers perform more work with increasing imposed weight load. 5. Theoretical aspects are discussed, including the possibility that surface-spread protein is involved in the formation of cell structures. Possible explanations for the relative slowness of the fiber contractions are offered.

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