scholarly journals Chemophoresis Engine: Universal Principle of ATPase-driven Cargo Transport

2021 ◽  
Author(s):  
Takeshi Sugawara ◽  
Kunihiko Kaneko
Keyword(s):  
Intracellular Transport ◽  
General Mechanism ◽  
Spatiotemporal Pattern ◽  
Extended Model ◽  
Bacterial Cells ◽  
Universal Principle ◽  
Directed Motion ◽  
Directed Movement ◽  
Chemical Gradients ◽  
Pattern Dynamics

Cell polarity regulates the orientation of the cytoskeleton members that directs intracellular transport for cargo-like organelles, using chemical gradients sustained by ATP or GTP hydrolysis. However, how cargo transports are directly mediated by chemical gradients remains unknown. We previously proposed a physical mechanism that enables directed movement of cargos, referred to as chemophoresis. According to the mechanism, a cargo with reaction sites is subjected to a chemophoresis force in the direction of the increased concentration. Based on this, we introduce an extended model, the chemophoresis engine, as a general mechanism of cargo motion, which transforms chemical free energy into directed motion through the catalytic ATP hydrolysis. We applied the engine to plasmid motion in a parABS system to demonstrate the the self-organization system for directed plasmid movement and pattern dynamics of ParA-ATP concentration, thereby explaining plasmid equi-positioning and pole-to-pole oscillation observed in bacterial cells and in vitro experiments. We mathematically show the existence and stability of the plasmid-surfing pattern, which allows the cargo-directed motion through the symmetry-breaking transition of the ParA- ATP spatiotemporal pattern. Finally, based on its generality, we discuss the chemophoresis engine as a universal principle of hydrolysis-driven intracellular transport.

scholarly journals Neuronal receptors display cytoskeleton-independent directed motion on the plasma membrane

2018 ◽  
Author(s):  
R. D. Taylor ◽  
M. Heine ◽  
N. J. Emptage ◽  
L. C. Andreae
Keyword(s):  
Plasma Membrane ◽  
Neuronal Activity ◽  
Particle Tracking ◽  
Hippocampal Neurons ◽  
Intracellular Transport ◽  
Transmembrane Proteins ◽  
Single Particle Tracking ◽  
Directed Motion ◽  
Surface Movement ◽  
Transport Vesicles

AbstractDirected transport of transmembrane proteins is generally believed to occur via intracellular transport vesicles. However, using single particle tracking in rat hippocampal neurons with a pH-sensitive quantum dot probe which specifically reports surface movement of receptors, we have identified a subpopulation of neuronal EphB2 receptors that exhibit directed motion between synapses within the plasma membrane itself. This receptor movement occurs independently of the cytoskeleton but is dependent on cholesterol and is regulated by neuronal activity.

Pattern Dynamics in a Spatial Predator–Prey Model with Nonmonotonic Response Function

2018 ◽  
Vol 28 (06) ◽  
pp. 1850077 ◽  
Author(s):  
Xiaoling Li ◽  
Guangping Hu ◽  
Zhaosheng Feng
Keyword(s):  
Response Function ◽  
Turing Instability ◽  
Spatiotemporal Pattern ◽  
Weakly Nonlinear ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Pattern Dynamics ◽  
Spatial Systems ◽  
Different Types ◽  
Selection Of

In this paper, we study a diffusive predator–prey system with the nonmonotonic response function. The conditions on Hopf bifurcation and Turing instability of spatial systems are obtained. Near the Turing bifurcation point we apply the weakly nonlinear analysis to derive the amplitude equations of stationary pattern, to investigate the selection of spatiotemporal pattern. It shows that different types of patterns will occur in the model under various conditions. Numerical simulations agree well with our theoretical analysis when control parameters are in the Turing space. This study may provide some deep insights into the formation and selection of patterns for diffusive predator–prey systems.

Lithographically Fabricated 10-Micron Scale Autonomous Motors

2008 ◽  
Vol 1135 ◽  
Author(s):  
Yang Wang ◽  
Shih-to Fei ◽  
Vincent H. Crespi ◽  
Ayusman Sen ◽  
Thomas E. Mallouk
Keyword(s):  
Catalytic Reactions ◽  
Free Standing ◽  
Propulsion Systems ◽  
Directed Movement ◽  
Rotational Movement ◽  
Chemical Gradients ◽  
Micro Particles ◽  
Rotary Motors ◽  
Micro Machine ◽  
Complex Movement

ABSTRACTSelf-propulsion and directed movement of nano- and micro-particles can in principle provide novel components for applications in microrobotics and MEMS. Our research involves the design of catalytic propulsion systems and the control of colloidal movement based on this principle. We have designed autonomous nanomotors that mimic biological motors by using catalytic reactions to generate forces derived from chemical gradients. Through architectural control of bimetallic catalytic particles, we have recently developed systems that undergo more complex movement. For example, we have constructed 10-micron scale rotary motors by contact lithography. In these chiral motors, bimetallic Au-Pt patterns are free-standing and move in the pattern predicted by theory. These studies demonstrate that by designing the proper architecture, one can tailor the pattern of movement to specific applications, such as changing from translational to rotational movement. The potential for elaboration of these designs to more complex micro-machine assemblies is discussed.

scholarly journals How receptor diffusion influences gradient sensing

2015 ◽  
Vol 12 (102) ◽  
pp. 20141097 ◽  
Author(s):  
H. Nguyen ◽  
P. Dayan ◽  
G. J. Goodhill
Keyword(s):  
Fisher Information ◽  
Diffusion Constant ◽  
Theoretical Models ◽  
Eukaryotic Cells ◽  
Biological Processes ◽  
Directed Motion ◽  
Gradient Sensing ◽  
Chemical Gradients ◽  
Physical Limit ◽  
Spatial Differences

Chemotaxis, or directed motion in chemical gradients, is critical for various biological processes. Many eukaryotic cells perform spatial sensing, i.e. they detect gradients by comparing spatial differences in binding occupancy of chemosensory receptors across their membrane. In many theoretical models of spatial sensing, it is assumed, for the sake of simplicity, that the receptors concerned do not move. However, in reality, receptors undergo diverse modes of diffusion, and can traverse considerable distances in the time it takes such cells to turn in an external gradient. This sets a physical limit on the accuracy of spatial sensing, which we explore using a model in which receptors diffuse freely over the membrane. We find that the Fisher information carried in binding and unbinding events decreases monotonically with the diffusion constant of the receptors.

scholarly journals Progress and perspectives in signal transduction, actin dynamics, and movement at the cell and tissue level: lessons from Dictyostelium

2016 ◽  
Vol 6 (5) ◽  
pp. 20160047 ◽  
Author(s):  
Till Bretschneider ◽  
Hans G. Othmer ◽  
Cornelis J. Weijer
Keyword(s):  
Signal Transduction ◽  
Wound Repair ◽  
Membrane Receptors ◽  
Force Generation ◽  
Actin Dynamics ◽  
Bacterial Invasion ◽  
Directed Motion ◽  
Directed Movement ◽  
Produce Cell ◽  
Intracellular Signals

Movement of cells and tissues is a basic biological process that is used in development, wound repair, the immune response to bacterial invasion, tumour formation and metastasis, and the search for food and mates. While some cell movement is random, directed movement stimulated by extracellular signals is our focus here. This involves a sequence of steps in which cells first detect extracellular chemical and/or mechanical signals via membrane receptors that activate signal transduction cascades and produce intracellular signals. These intracellular signals control the motile machinery of the cell and thereby determine the spatial localization of the sites of force generation needed to produce directed motion. Understanding how force generation within cells and mechanical interactions with their surroundings, including other cells, are controlled in space and time to produce cell-level movement is a major challenge, and involves many issues that are amenable to mathematical modelling.

scholarly journals Exploratory search during directed navigation in C. elegans and Drosophila larva

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Mason Klein ◽  
Sergei V Krivov ◽  
Anggie J Ferrer ◽  
Linjiao Luo ◽  
Aravinthan DT Samuel ◽  
...  
Keyword(s):  
Protein Folding ◽  
Exploratory Search ◽  
Behavioral Strategies ◽  
Insect Larvae ◽  
Nematode Caenorhabditis Elegans ◽  
Directed Movement ◽  
C Elegans ◽  
Chemical Gradients ◽  
Drosophila Larva ◽  
Favorable Conditions

Many organisms—from bacteria to nematodes to insect larvae—navigate their environments by biasing random movements. In these organisms, navigation in isotropic environments can be characterized as an essentially diffusive and undirected process. In stimulus gradients, movement decisions are biased to drive directed navigation toward favorable environments. How does directed navigation in a gradient modulate random exploration either parallel or orthogonal to the gradient? Here, we introduce methods originally used for analyzing protein folding trajectories to study the trajectories of the nematode Caenorhabditis elegans and the Drosophila larva in isotropic environments, as well as in thermal and chemical gradients. We find that the statistics of random exploration in any direction are little affected by directed movement along a stimulus gradient. A key constraint on the behavioral strategies of these organisms appears to be the preservation of their capacity to continuously explore their environments in all directions even while moving toward favorable conditions.

Collective Dynamics of Kinesin-1 Motor Proteins Transporting a Common Load

2007 ◽  
Author(s):  
Adam G. Hendricks ◽  
Bogdan I. Epureanu ◽  
Edgar Meyho¨fer
Keyword(s):  
Single Molecule ◽  
Collective Behavior ◽  
Intracellular Transport ◽  
Atp Hydrolysis ◽  
Mechanistic Model ◽  
State Behavior ◽  
Directed Movement ◽  
The Difference ◽  
Transient And Steady State

Kinesin-1 is a motor protein essential to intracellular transport that converts the energy from ATP hydrolysis to directed movement along microtubules. Experimental and theoretical characterization of kinesin-1 has focused on single-molecule experiments. These experiments show that one motor is capable of transporting a cargo at speeds of about 1 μm/sec and maintaining contact with the microtubule for about 100 steps. In the cell, it is widely thought that several kinesin-1 motors cooperate to transport a cargo. Through a mechanistic model, we have extended the theoretical analysis of kinesin to describing transient and steady state behavior. A transient description is essential when studying collective behavior, as interaction between motors introduces time-varying loads. Herein, we interpret the kinesin motors as nonlinear, non-smooth oscillators and we employ metrics to characterize their cooperativity and to quantify their synchronization. These metrics are used to investigate the effect of the cargo linker stiffness, the load, and the difference in intrinsic velocity on the synchronization of two mechanically coupled motors.

scholarly journals Application of a pH-Sensitive Fluoroprobe (C-SNARF-4) for pH Microenvironment Analysis in Pseudomonas aeruginosa Biofilms

2005 ◽  
Vol 71 (5) ◽  
pp. 2501-2510 ◽  
Author(s):  
Ryan C. Hunter ◽  
Terry J. Beveridge
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Emission Spectra ◽  
Confocal Scanning Laser Microscopy ◽  
Bacterial Cells ◽  
Fluorescent Properties ◽  
Bulk Fluid ◽  
Chemical Gradients ◽  
Emission Changes ◽  
Confocal Scanning Laser ◽  
Ratiometric Probe

ABSTRACT An important feature of microbial biofilms is the development of four-dimensional physical and chemical gradients in space and time. There is need for novel approaches to probe these so-called microenvironments to determine their effect on biofilm-specific processes. In this study, we describe the use of seminaphthorhodafluor-4F 5-(and-6) carboxylic acid (C-SNARF-4) for pH microenvironment analysis in Pseudomonas aeruginosa biofilms. C-SNARF-4 is a fluorescent ratiometric probe that allows pH quantification independent of probe concentration and/or laser intensity. By confocal scanning laser microscopy, C-SNARF-4 revealed pH heterogeneity throughout the biofilm in both the x,y and x,z planes, with values ranging from pH 5.6 (within the biofilm) to pH 7.0 (bulk fluid). pH values were typically remarkably different than those just a few micrometers away. Although this probe has been successfully used in a number of eukaryotic systems, problems have been reported which describe spectral emission changes as a result of macromolecular interactions with the fluorophore. To assess how the biofilm environment may influence fluorescent properties of the dye, fluorescence of C-SNARF-4 was quantified via spectrofluorometry while the probe was suspended in various concentrations of representative biofilm matrix components (i.e., proteins, polysaccharides, and bacterial cells) and growth medium. Surprisingly, our data demonstrate that few changes in emission spectra occur as a result of matrix interactions below pH 7. These studies suggest that C-SNARF-4 can be used as a reliable indicator of pH microenvironments, which may help elucidate their influence on the medical and geobiological roles of natural biofilms.

scholarly journals Networked Chemoreceptors Benefit Bacterial Chemotaxis Performance

mBio ◽  
2016 ◽  
Vol 7 (6) ◽  
Author(s):  
Vered Frank ◽  
Germán E. Piñas ◽  
Harel Cohen ◽  
John S. Parkinson ◽  
Ady Vaknin
Keyword(s):  
Dynamic Range ◽  
Bacterial Chemotaxis ◽  
Detection Sensitivity ◽  
Functional Coupling ◽  
Bacterial Cells ◽  
Communication Interface ◽  
E Coli ◽  
Chemical Gradients ◽  
Receptor Complexes ◽  
Motile Bacteria

ABSTRACTMotile bacteria use large receptor arrays to detect and follow chemical gradients in their environment. Extended receptor arrays, composed of networked signaling complexes, promote cooperative stimulus control of their associated signaling kinases. Here, we used structural lesions at the communication interface between core complexes to create anEscherichia colistrain with functional but dispersed signaling complexes. This strain allowed us to directly study how networking of signaling complexes affects chemotactic signaling and gradient-tracking performance. We demonstrate that networking of receptor complexes provides bacterial cells with about 10-fold-heightened detection sensitivity to attractants while maintaining a wide dynamic range over which receptor adaptational modifications can tune response sensitivity. These advantages proved especially critical for chemotaxis toward an attractant source under conditions in which bacteria are unable to alter the attractant gradient.IMPORTANCEChemoreceptor arrays are found in many motile bacteria. However, although our understanding of bacterial chemotaxis is quite detailed, the signaling and behavioral advantages of networked receptor arrays had not been directly studied in cells. We have recently shown that lesions in a key interface of theE. colireceptor array diminish physical connections and functional coupling between core signaling complexes while maintaining their basic signaling capacity. In this study, we exploited an interface 2 mutant to show, for the first time, that coupling between core complexes substantially enhances stimulus detection and chemotaxis performance.

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