Gating Kinetics of E. coli Poly-3-Hydroxybutyrate/Polyphosphate Channels in Planar Bilayer Membranes

1999 ◽  
Vol 170 (2) ◽  
pp. 135-145 ◽  
Author(s):  
S. Das
Keyword(s):  
Planar Bilayer ◽  
Bilayer Membranes ◽  
E Coli ◽  
Gating Kinetics ◽  
Kinetics Of

scholarly journals The fusion kinetics of influenza hemagglutinin expressing cells to planar bilayer membranes is affected by HA density and host cell surface.

1995 ◽  
Vol 106 (5) ◽  
pp. 783-802 ◽  
Author(s):  
G B Melikyan ◽  
W D Niles ◽  
F S Cohen
Keyword(s):  
Cell Surface ◽  
Fusion Protein ◽  
Pore Formation ◽  
Surface Proteins ◽  
Fusion Pore ◽  
Planar Bilayer ◽  
Bilayer Membranes ◽  
Pore Evolution ◽  
Fusion Pores ◽  
Kinetics Of

Time-resolved admittance measurements were used to follow formation of individual fusion pores connecting influenza virus hemagglutinin (HA)-expressing cells to planar bilayer membranes. By measuring in-phase, out-of-phase, and dc components of currents, pore conductances were resolved with millisecond time resolution. Fusion pores developed in stages, from small pores flickering open and closed, to small successful pores that remained open until enlarging their lumens to sizes greater than those of viral nucleocapsids. The kinetics of fusion and the properties of fusion pores were studied as functions of density of the fusion protein HA. The consequences of treating cell surfaces with proteases that do not affect HA were also investigated. Fusion kinetics were described by waiting time distributions from triggering fusion, by lowering pH, to the moment of pore formation. The kinetics of pore formation became faster as the density of active HA was made greater or when cell surface proteins were extensively cleaved with proteases. In accord with this faster kinetics, the intervals between transient pore openings within the flickering stage were shorter for higher HA density and more extensive cell surface treatment. Whereas the kinetics of fusion depended on HA density, the lifetimes of open fusion pores were independent of HA density. However, the lifetimes of open pores were affected by the proteolytic treatment of the cells. Faster fusion kinetics correlated with shorter pore openings. We conclude that the density of fusion protein strongly affects the kinetics of fusion pore formation, but that once formed, pore evolution is not under control of fusion proteins but rather under the influence of mechanical forces, such as membrane bending and tension.

Gating Kinetics of Stochastic Single K Channels

1981 ◽  
pp. 123-132 ◽  
Author(s):  
Jürgen F. Fohlmeister ◽  
William J. Adelman
Keyword(s):  
K Channels ◽  
Gating Kinetics ◽  
Kinetics Of

scholarly journals Effect of DNA-interacting drugs on phage T7 RNA polymerase.

1998 ◽  
Vol 45 (1) ◽  
pp. 127-132 ◽  
Author(s):  
M Piestrzeniewicz ◽  
K Studzian ◽  
D Wilmańska ◽  
G Płucienniczak ◽  
M Gniazdowski
Keyword(s):  
Rna Polymerase ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
T7 Rna Polymerase ◽  
Distamycin A ◽  
E Coli ◽  
Phage T7 ◽  
Drug Dependent ◽  
Dna Complex ◽  
Kinetics Of

9-Aminoacridine carboxamide derivatives studied here form with DNA intercalative complexes which differ in the kinetics of dissociation. Inhibition of total RNA synthesis catalyzed by phage T7 and Escherichia coli DNA-dependent RNA polymerases correlates with the formation of slowly dissociating acridine-DNA complex of time constant of 0.4-2.3 s. Their effect on RNA synthesis is compared with other ligands which form with DNA stable complexes of different steric properties. T7 RNA polymerase is more sensitive to distamycin A and netropsin than the E. coli enzyme while less sensitive to actinomycin D. Actinomycin induces terminations in the transcript synthesized by T7 RNA polymerase. Despite low dissociation rates of DNA complexes with acridines and pyrrole antibiotics no drug dependent terminations are observed with these ligands.

scholarly journals Kinetics of Targeted Phage Rescue in a Mouse Model of SystemicEscherichia coliK1

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
György Schneider ◽  
Nikolett Szentes ◽  
Marianna Horváth ◽  
Ágnes Dorn ◽  
Alysia Cox ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Protective Efficacy ◽  
Lytic Bacteriophage ◽  
E Coli ◽  
Causative Agents ◽  
High Level ◽  
Systemic Infections ◽  
Kinetics Of

Escherichia (E.) coliK1 strains remain common causative agents of neonatal sepsis and meningitis. We have isolated a lytic bacteriophage (ΦIK1) againstE. colistrain IHE3034 and tested its specificityin vitro, as well as distribution and protective efficacyin vivo. The phage was shown to be specific to the K1 capsular polysaccharide. In the lethal murine model, a high level of protection was afforded by the phage with strict kinetics. A single dose of 1 x 108phage particles administered 10 and 60 minutes following the bacterial challenge elicited 100 % and 95 % survival, respectively. No mice could be rescued if phage administration occurred 3 hours postinfection. Tissue distribution surveys in the surviving mice revealed that the spleen was the primary organ in which accumulation of active ΦIK1 phages could be detected two weeks after phage administration. These results suggest that bacteriophages have potential as therapeutic agents in the control of systemic infections.

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