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 Structure and function of the archaeal response regulator CheY

2018 ◽  
Vol 115 (6) ◽  
pp. E1259-E1268 ◽  
Author(s):  
Tessa E. F. Quax ◽  
Florian Altegoer ◽  
Fernando Rossi ◽  
Zhengqun Li ◽  
Marta Rodriguez-Franco ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Response Regulator ◽  
Specific Interaction ◽  
Adaptor Protein ◽  
Structural Difference ◽  
Central Feature ◽  
Chemical Gradients ◽  
Rotary Motors ◽  
And Function ◽  
Chemotaxis System

Motility is a central feature of many microorganisms and provides an efficient strategy to respond to environmental changes. Bacteria and archaea have developed fundamentally different rotary motors enabling their motility, termed flagellum and archaellum, respectively. Bacterial motility along chemical gradients, called chemotaxis, critically relies on the response regulator CheY, which, when phosphorylated, inverses the rotational direction of the flagellum via a switch complex at the base of the motor. The structural difference between archaellum and flagellum and the presence of functional CheY in archaea raises the question of how the CheY protein changed to allow communication with the archaeal motility machinery. Here we show that archaeal CheY shares the overall structure and mechanism of magnesium-dependent phosphorylation with its bacterial counterpart. However, bacterial and archaeal CheY differ in the electrostatic potential of the helix α4. The helix α4 is important in bacteria for interaction with the flagellar switch complex, a structure that is absent in archaea. We demonstrated that phosphorylation-dependent activation, and conserved residues in the archaeal CheY helix α4, are important for interaction with the archaeal-specific adaptor protein CheF. This forms a bridge between the chemotaxis system and the archaeal motility machinery. Conclusively, archaeal CheY proteins conserved the central mechanistic features between bacteria and archaea, but differ in the helix α4 to allow binding to an archaellum-specific interaction partner.

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.

Active, Controlled Circular and Spin-Rotational Movement of Optically Trapped Airborne Micro-particles

2021 ◽  
Author(s):  
Jessica Arnold ◽  
aimable kalume ◽  
Gorden Videen ◽  
Yongle Pan ◽  
Chuji Wang
Keyword(s):  
Rotational Movement ◽  
Micro Particles ◽  
Optically Trapped

scholarly journals ArlCDE form the archaeal switch complex

2020 ◽  
Author(s):  
Zhengqun Li ◽  
Marta Rodriguez-Franco ◽  
Sonja-Verena Albers ◽  
Tessa E. F. Quax
Keyword(s):  
Response Regulator ◽  
Fluorescent Microscopy ◽  
Sensory System ◽  
Adaptor Protein ◽  
Protein Composition ◽  
Directed Movement ◽  
Chemical Gradients ◽  
Regulator Protein ◽  
Chemotaxis System ◽  
Response Regulator Protein

Cells require a sensory system and a motility structure to achieve directed movement. Bacteria and archaea both possess rotating filamentous motility structures that work in concert with the sensory chemotaxis system. This allows microorganisms to move along chemical gradients. The central response regulator protein CheY can bind to the motor of the motility structure, the flagellum in bacteria and the archaellum in archaea. Both motility structures have a fundamentally different protein composition and structural organization. Yet, both systems receive input from the chemotaxis system. We applied a fluorescent microscopy approach in the model euryarchaeon Haloferax volcanii, and shed light on the sequence order in which signals are transferred from the chemotaxis system to the archaellum. Our findings indicate that the euryarchaeal specific ArlCDE are part of the archaellum motor and that they directly receive input from the chemotaxis system via the adaptor protein CheF. Hence, ArlCDE are an important feature of the archaellum of euryarchaea, are essential for signal transduction during chemotaxis and represent the archaeal switch complex.

scholarly journals Formation, collective motion, and merging of macroscopic bacterial aggregates

2021 ◽  
Author(s):  
James Q Boedicker ◽  
George Courcoutbetis ◽  
Manasi Gangan ◽  
Sean Lim ◽  
Xiaokan Guo ◽  
...  
Keyword(s):  
Cell Density ◽  
Collective Motion ◽  
Aggregate Size ◽  
Enterobacter Cloacae ◽  
Soft Agar ◽  
Culture Dish ◽  
Directed Movement ◽  
Collective Behaviors ◽  
Chemical Gradients ◽  
Bacterial Aggregates

Chemotactic bacteria form emergent spatial patterns of variable cell density within cultures that are initially spatially uniform. These patterns are the result of chemical gradients that are created from the directed movement and metabolic activity of billions of cells. A recent study on pattern formation in wild bacterial isolates has revealed unique collective behaviors of the bacteria Enterobacter cloacae . As in other bacteria species, Enterobacter cloacae form macroscopic aggregates. Once formed, these bacterial clusters can migrate several millimeters, sometimes resulting in the merging of two or more clusters. To better understand these phenomena, we examine the formation and dynamics of thousands of bacterial clusters that form within a 22 cm square culture dish filled with soft agar over two days. At the macroscale, the aggregates display spatial order at short length scales, and the migration of cell clusters is superdiffusive, with a merging acceleration that is correlated with aggregate size. At the microscale, aggregates are composed of immotile cells surrounded by low density regions of motile cells. The collective movement of the aggregates is the result of an asymmetric flux of bacteria at the boundary. An agent based model is developed to examine how these phenomena are the result of both chemotactic movement and a change in motility at high cell density. These results identify and characterize a new mechanism for collective bacterial motility driven by a transient, density-dependent change in motility.

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.

Analyzing reactions of single mechanoenzyme molecules by light microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 426-427
Author(s):  
Jeff Gelles
Keyword(s):  
Image Processing ◽  
Reaction Mechanisms ◽  
Transient State ◽  
Nanometer Scale ◽  
Reaction Intermediates ◽  
Enzyme Molecule ◽  
Directed Movement ◽  
Enzyme Molecules ◽  
Individual Enzyme ◽  
Single Reaction

Mechanoenzymes are enzymes which use a chemical reaction to power directed movement along biological polymer. Such enzymes include the cytoskeletal motors (e.g., myosins, dyneins, and kinesins) as well as nucleic acid polymerases and helicases. A single catalytic turnover of a mechanoenzyme moves the enzyme molecule along the polymer a distance on the order of 10−9 m We have developed light microscope and digital image processing methods to detect and measure nanometer-scale motions driven by single mechanoenzyme molecules. These techniques enable one to monitor the occurrence of single reaction steps and to measure the lifetimes of reaction intermediates in individual enzyme molecules. This information can be used to elucidate reaction mechanisms and determine microscopic rate constants. Such an approach circumvents difficulties encountered in the use of traditional transient-state kinetics techniques to examine mechanoenzyme reaction mechanisms.

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