scholarly journals Simultaneous Force and Fluorescence Measurements of a Protein That Forms a Bond between a Living Bacterium and a Solid Surface

2005 ◽  
Vol 187 (6) ◽  
pp. 2127-2137 ◽  
Author(s):  
Brian H. Lower ◽  
Ruchirej Yongsunthon ◽  
F. Paul Vellano ◽  
Steven K. Lower
Keyword(s):  
Atomic Force Microscopy ◽  
Solid Surface ◽  
Chimeric Protein ◽  
Force Extension ◽  
Wormlike Chain ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Living Bacterium ◽  
Measured Force

ABSTRACT All microbial biofilms are initiated through direct physical contact between a bacterium and a solid surface, a step that is controlled by inter- and intramolecular forces. Atomic force microscopy and confocal laser scanning microscopy were used simultaneously to observe the formation of a bond between a fluorescent chimeric protein on the surface of a living Escherichia coli bacterium and a solid substrate in situ. The chimera was composed of a portion of outer membrane protein A (OmpA) fused to the cyan-fluorescent protein AmCyan. Sucrose gradient centrifugation and fluorescent confocal slices through bacteria demonstrated that the chimeric protein was targeted and anchored to the external cell surface. The wormlike chain theory predicted that this protein should exhibit a nonlinear force-extension “signature” consistent with the sequential unraveling of the AmCyan and OmpA domains. Experimentally measured force-extension curves revealed a unique pair of “sawtooth” features that were present when a bond formed between a silicon nitride surface (atomic force microscopy tip) and E. coli cells expressing the OmpA-AmCyan protein. The observed sawtooth pair closely matched the wormlike chain model prediction for the mechanical unfolding of the AmCyan and OmpA substructures in series. These sawteeth disappeared from the measured force-extension curves when cells were treated with proteinase K. Furthermore, these unique sawteeth were absent for a mutant stain of E. coli incapable of expressing the AmCyan protein on its outer surface. Together, these data show that specific proteins exhibit unique force signatures characteristic of the bond that is formed between a living bacterium and another surface.

scholarly journals Surface-Based Biochemical Activity Assays Complement Atomic Force Microscopy of the E. coli Translocase

2019 ◽  
Vol 116 (3) ◽  
pp. 300a
Author(s):  
Kanokporn Chattrakun ◽  
Chunfeng Mao ◽  
Priya Bariya ◽  
Gavin King
Keyword(s):  
Atomic Force Microscopy ◽  
Biochemical Activity ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force

Peculiarities of Phagocytosis of Opsonized and Nonopsonized Bacteria S. Aureus and E. Coli by Human Neutrophil Granulocytes Studied by Atomic Force Microscopy

2018 ◽  
Vol 12 (6) ◽  
pp. 496-505
Author(s):  
S. N. Pleskova ◽  
R. N. Kriukov ◽  
E. V. Razumkova ◽  
S. Yu. Zubkov ◽  
N. V. Abarbanel
Keyword(s):  
Atomic Force Microscopy ◽  
Human Neutrophil ◽  
Neutrophil Granulocytes ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force

Nanobubbles on solid surface imaged by atomic force microscopy

2000 ◽  
Vol 18 (5) ◽  
pp. 2573 ◽  
Author(s):  
Shi-Tao Lou ◽  
Zhen-Qian Ouyang ◽  
Yi Zhang ◽  
Xiao-Jun Li ◽  
Jun Hu ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Solid Surface ◽  
Force Microscopy ◽  
Atomic Force

Real-time observation of solubilization-induced morphological change in surfactant aggregates adsorbed on a solid surface

2017 ◽  
Vol 53 (98) ◽  
pp. 13172-13175 ◽  
Author(s):  
Keito Koizumi ◽  
Masaaki Akamatsu ◽  
Kenichi Sakai ◽  
Shinya Sasaki ◽  
Hideki Sakai
Keyword(s):  
Atomic Force Microscopy ◽  
Real Time ◽  
Morphological Change ◽  
Solid Surface ◽  
High Speed ◽  
Force Microscopy ◽  
Surfactant Aggregates ◽  
Atomic Force ◽  
Time Observation ◽  
Real Time Observation

A solubilization-induced morphological change in surfactant surface aggregates was imaged in real-time, using high-speed atomic force microscopy.

Nanobubble Formation at the Solid-Liquid Interface Studied by Atomic Force Microscopy

2005 ◽  
Vol 899 ◽  
Author(s):  
Abhinandan Agrawal ◽  
Gareth H. McKinley
Keyword(s):  
Atomic Force Microscopy ◽  
Solid Surface ◽  
Silicon Oxide ◽  
Slip Length ◽  
Hydrophobic Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Experimental Values ◽  
Solid Liquid ◽  
Wafer Surfaces

AbstractThe formation of nanobubbles at solid-liquid interfaces has been studied using the atomic force microscopy (AFM) imaging technique. Nanobubble formation strongly depends on both the hydrophobicity of the solid surface and the polarity of the liquid subphase. While nanobubbles do not form on flat hydrophilic (silicon oxide wafer) surfaces immersed in water, they appear spontaneously at the interface of water against smooth, hydrophobic (silanized wafer) surfaces. From the experimental observations we draw the conclusion that the features observed in the AFM images are deformable, air-filled bubbles. In addition to the hydrophobicity of the solid surface, differences in solubility of air between two miscible fluids can also lead to formation of nanobubbles. We observe that nanobubbles appear at the interface of water against hydrophilic silicon oxide surfaces after in-situ mixing of ethanol and water in the fluid-cell.The shapes of the nanobubbles are well approximated by spherical caps, with width much larger than the height of the caps. We quantify the morphological distribution of nanobubbles by evaluating several important bubble parameters including surface coverage and radii of curvature. In conjunction, with an analytical model available in the literature, we use this information to estimate that the present nanobubble morphology may give rise to slip lengths ∼1–2 µm in pressure driven flows for water flowing over the hydrophobic surface. The consistency of the calculated slip length with the experimental values reported in the literature, suggests that the apparent fluid slip observed experimentally at hydrophobic surfaces may arise from the presence of nanobubbles.

scholarly journals Atomic Force Microscopy Study of the Effect of Antimicrobial Peptides on the Cell Envelope of Escherichia coli

2005 ◽  
Vol 49 (10) ◽  
pp. 4085-4092 ◽  
Author(s):  
M. Meincken ◽  
D. L. Holroyd ◽  
M. Rautenbach
Keyword(s):  
Escherichia Coli ◽  
Atomic Force Microscopy ◽  
Morphological Changes ◽  
Cell Envelope ◽  
Microscopy Study ◽  
Target Cells ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Before And After

ABSTRACT The influences of the antibacterial magainin 2 and PGLa from the African clawed frog (Xenopus laevis) and the hemolytic bee venom melittin on Escherichia coli as the target cell were studied by atomic force microscopy (AFM). Nanometer-scale images of the effects of the peptides on this gram-negative bacterium's cell envelope were obtained in situ without the use of fixing agents. These high-resolution AFM images of the surviving and intact target cells before and after peptide treatment showed distinct changes in cell envelope morphology as a consequence of peptide action. Although all three peptides are lytic to E. coli, it is clear from this AFM study that each peptide causes distinct morphological changes in the outer membrane and in some cases the inner membrane, probably as a consequence of different mechanisms of action.

scholarly journals Thickness and Elasticity of Gram-Negative Murein Sacculi Measured by Atomic Force Microscopy

1999 ◽  
Vol 181 (22) ◽  
pp. 6865-6875 ◽  
Author(s):  
X. Yao ◽  
M. Jericho ◽  
D. Pink ◽  
T. Beveridge
Keyword(s):  
Atomic Force Microscopy ◽  
Atomic Force Microscope ◽  
Turgor Pressure ◽  
Original Position ◽  
Cell Axis ◽  
Gram Negative ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
K 12

ABSTRACT Atomic force microscopy was used to measure the thickness of air-dried, collapsed murein sacculi from Escherichia coliK-12 and Pseudomonas aeruginosa PAO1. Air-dried sacculi from E. coli had a thickness of 3.0 nm, whereas those fromP. aeruginosa were 1.5 nm thick. When rehydrated, the sacculi of both bacteria swelled to double their anhydrous thickness. Computer simulation of a section of a model single-layer peptidoglycan network in an aqueous solution with a Debye shielding length of 0.3 nm gave a mass distribution full width at half height of 2.4 nm, in essential agreement with these results. When E. colisacculi were suspended over a narrow groove that had been etched into a silicon surface and the tip of the atomic force microscope used to depress and stretch the peptidoglycan, an elastic modulus of 2.5 × 107 N/m2 was determined for hydrated sacculi; they were perfectly elastic, springing back to their original position when the tip was removed. Dried sacculi were more rigid with a modulus of 3 × 108 to 4 × 108N/m2 and at times could be broken by the atomic force microscope tip. Sacculi aligned over the groove with their long axis at right angles to the channel axis were more deformable than those with their long axis parallel to the groove axis, as would be expected if the peptidoglycan strands in the sacculus were oriented at right angles to the long cell axis of this gram-negative rod. Polar caps were not found to be more rigid structures but collapsed to the same thickness as the cylindrical portions of the sacculi. The elasticity of intactE. coli sacculi is such that, if the peptidoglycan strands are aligned in unison, the interstrand spacing should increase by 12% with every 1 atm increase in (turgor) pressure. Assuming an unstressed hydrated interstrand spacing of 1.3 nm (R. E. Burge, A. G. Fowler, and D. A. Reaveley, J. Mol. Biol. 117:927–953, 1977) and an internal turgor pressure of 3 to 5 atm (or 304 to 507 kPa) (A. L. Koch, Adv. Microbial Physiol. 24:301–366, 1983), the natural interstrand spacing in cells would be 1.6 to 2.0 nm. Clearly, if large macromolecules of a diameter greater than these spacings are secreted through this layer, the local ordering of the peptidoglycan must somehow be disrupted.

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

FEBS Letters ◽  
1996 ◽  
Vol 381 (1-2) ◽  
pp. 161-164 ◽  
Author(s):  
Jianxun Mou ◽  
D.M. Czajkowsky ◽  
Sitong Jun Sheng ◽  
Rouya Ho ◽  
Zhifeng Shao
Keyword(s):  
Atomic Force Microscopy ◽  
High Resolution ◽  
Surface Structure ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force

scholarly journals Multiscale Network Modeling of Fibrin Fibers and Fibrin Clots with Protofibril Binding Mechanics

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1223
Author(s):  
Sumith Yesudasan ◽  
Rodney D. Averett
Keyword(s):  
Atomic Force Microscopy ◽  
Mechanical Behavior ◽  
Network Model ◽  
Large Strains ◽  
Chain Model ◽  
Force Extension ◽  
Nonlinear Spring ◽  
Force Microscopy ◽  
Atomic Force ◽  
Fibrin Clots

The multiscale mechanical behavior of individual fibrin fibers and fibrin clots was modeled by coupling atomistic simulation data and microscopic experimental data. We propose a new protofibril element composed of a nonlinear spring network, and constructed this based on molecular simulations and atomic force microscopy results to simulate the force extension behavior of fibrin fibers. This new network model also accounts for the complex interaction of protofibrils with one another, the effects of the presence of a solvent, Coulombic attraction, and other binding forces. The network model was formulated to simulate the force–extension mechanical behavior of single fibrin fibers from atomic force microscopy experiments, and shows good agreement. The validated fibrin fiber network model was then combined with a modified version of the Arruda–Boyce eight-chain model to estimate the force extension behavior of the fibrin clot at the continuum level, which shows very good correlation. The results show that our network model is able to predict the behavior of fibrin fibers as well as fibrin clots at small strains, large strains, and close to the break strain. We used the network model to explain why the mechanical response of fibrin clots and fibrin fibers deviates from worm-like chain behavior, and instead behaves like a nonlinear spring.

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