scholarly journals Multifunctional and biodegradable self-propelled protein motors

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Abdon Pena-Francesch ◽  
Joshua Giltinan ◽  
Metin Sitti
Keyword(s):  
Protein Motors

Characterization of microtubules by dark-field STEM and replication

1991 ◽  
Vol 49 ◽  
pp. 152-153
Author(s):  
S.B. Andrews ◽  
R.D. Leapman ◽  
P.E. Gallant ◽  
T.S. Reese
Keyword(s):  
Protein Interactions ◽  
Low Dose ◽  
Unit Length ◽  
Dark Field ◽  
Carbon Films ◽  
Microtubule Associated Proteins ◽  
Molecular Weights ◽  
Freeze Dried ◽  
Protein Motors ◽  
Associated Proteins

As part of a study on protein interactions involved in microtubule (MT)-based transport, we used the VG HB501 field-emission STEM to obtain low-dose dark-field mass maps of isolated, taxol-stabilized MTs and correlated these micrographs with detailed stereo images from replicas of the same MTs. This approach promises to be useful for determining how protein motors interact with MTs. MTs prepared from bovine and squid brain tubulin were purified and free from microtubule-associated proteins (MAPs). These MTs (0.1-1 mg/ml tubulin) were adsorbed to 3-nm evaporated carbon films supported over Formvar nets on 600-m copper grids. Following adsorption, the grids were washed twice in buffer and then in either distilled water or in isotonic or hypotonic ammonium acetate, blotted, and plunge-frozen in ethane/propane cryogen (ca. -185 C). After cryotransfer into the STEM, specimens were freeze-dried and recooled to ca.-160 C for low-dose (<3000 e/nm2) dark-field mapping. The molecular weights per unit length of MT were determined relative to tobacco mosaic virus standards from elastic scattering intensities. Parallel grids were freeze-dried and rotary shadowed with Pt/C at 14°.

scholarly journals A simple surface modification to generate atomically-flat and hydrophobic substrates for gliding assays with protein motors

2021 ◽  
Author(s):  
Isadonna Tengganu ◽  
Neil Karerakattil ◽  
Swarup Dey ◽  
Devika Kishnan ◽  
Rizal Hariadi
Keyword(s):  
Single Molecule ◽  
Vapor Deposition ◽  
Glass Capillary ◽  
High Background ◽  
Protein Motors ◽  
Order Of Magnitude ◽  
Protein Motor ◽  
Glass Surfaces ◽  
Atomically Flat

In vitro gliding assay is a well-established assay for determining the activity of protein motors, such as actin-associated myosins and microtubule-associated kinesins and dyneins. In one of the conventional methods, protein motors are immobilized onto a nitrocellulose-coated coverslip and it propels actin filaments in the presence of ATP. Gliding assays also serve as the foundation for protein-motor-based nanotechnological devices such as biosensing and sorting. However, the preparation of nitrocellulose-coated coverslips is time-consuming and produces rough surfaces. Furthermore, the nitrocellulose film exhibits high background autofluorescence, which can be a problem in single-molecule measurements. Here, we investigated the use of hexamethyldisilazane (HMDS) to study actomyosin function and characterized its physical properties on glass coverslips and glass capillary tubes. We showed that the total preparation time to coat a coverslip with HMDS is <30 minutes, which is 1 order of magnitude faster than the >12-hour protocol for coating glass surfaces with nitrocellulose. In contrast to nitrocellulose film, HMDS vapor deposition is effortless and provides an atomically flat surface with low autofluorescence. In addition, HMDS does not interfere with myosin function, which is indicated by the similar actin gliding speed when compared with nitrocellulose. Our results show that HMDS vapor deposition is a more favorable surface treatment to nitrocellulose for in vitro gliding assay.

The Transient Characters of the Directed Motion of Protein Motors

2009 ◽  
Author(s):  
Weixia Wu ◽  
Yong Zhan ◽  
Yingrong Han ◽  
Yafei Chen ◽  
Hui Zhou ◽  
...  
Keyword(s):  
Directed Motion ◽  
Protein Motors

scholarly journals Tunable corrugated patterns in an active nematic sheet

2019 ◽  
Vol 116 (45) ◽  
pp. 22464-22470 ◽  
Author(s):  
Anis Senoussi ◽  
Shunnichi Kashida ◽  
Raphael Voituriez ◽  
Jean-Christophe Galas ◽  
Ananyo Maitra ◽  
...  
Keyword(s):  
Large Scale ◽  
Topological Defects ◽  
Hydrodynamic Theory ◽  
Active Matter ◽  
Free Standing ◽  
Chaotic Flows ◽  
Protein Motors ◽  
Out Of Plane ◽  
Restoring Forces ◽  
Far From Equilibrium

Active matter locally converts chemical energy into mechanical work and, for this reason, it provides new mechanisms of pattern formation. In particular, active nematic fluids made of protein motors and filaments are far-from-equilibrium systems that may exhibit spontaneous motion, leading to actively driven spatiotemporally chaotic states in 2 and 3 dimensions and coherent flows in 3 dimensions (3D). Although these dynamic flows reveal a characteristic length scale resulting from the interplay between active forcing and passive restoring forces, the observation of static and large-scale spatial patterns in active nematic fluids has remained elusive. In this work, we demonstrate that a 3D solution of kinesin motors and microtubule filaments spontaneously forms a 2D free-standing nematic active sheet that actively buckles out of plane into a centimeter-sized periodic corrugated sheet that is stable for several days at low activity. Importantly, the nematic orientational field does not display topological defects in the corrugated state and the wavelength and stability of the corrugations are controlled by the motor concentration, in agreement with a hydrodynamic theory. At higher activities these patterns are transient and chaotic flows are observed at longer times. Our results underline the importance of both passive and active forces in shaping active matter and demonstrate that a spontaneously flowing active fluid can be sculpted into a static material through an active mechanism.

Movement of Vesicles in Eucariotic Cells. Role of Intravesicle Protons as a Fuel and Modulation of Their Concentration by Drugs or Metabolic Changes.

1997 ◽  
Vol 489 ◽  
Author(s):  
G. P. Pescarmona ◽  
E. Morra ◽  
E. Aldieri ◽  
D. Ghigo ◽  
A. Bosia
Keyword(s):  
Actin Filaments ◽  
Atp Synthesis ◽  
Metabolic Changes ◽  
Proton Gradient ◽  
Actual Concentration ◽  
Similar Role ◽  
Protein Motors ◽  
Internal Ph ◽  
Acidic Vesicles

AbstractImport (endocytosis) and export (secretion) of molecules from the cells is mediated by vesicles (lysosomes, endosomes) sliding along microtubules or actin filaments. These vesicles share a common feature: an internal pH of about 5, with an inner protons concentration 1000 fold higher than in the surrounding cytoplasm. As the proton gradient in mitochondria is able to drive ATP synthesis we can expect a similar role (energy supplier) for protons in all acidic vesicles. To experimentally test the vesicles' transport we have loaded them with a fluorescent dye (chloroquine) and then measured its efflux over 5 hours. This efflux was reduced by all treatments lowering the actual concentration of protons in the vesicles, independently of the properties. Treatments included lowering intracellular NADH, inhibitors of ATP-dependent proton translocase and/or the Na+/H+antiport, drugs that accumulate into lysosomes, buffering its acidity (chloroquine, doxorubicin). These results support the idea of a role of a proton gradient as a fuel for protein motors.

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