Pulsatile release from pH triggered imidazoline switchable surfactant liposomes

TBEV-particles are assembled in an immature, noninfectious form in the endoplasmic reticulum by the envelopment of the viral core (containing the viral RNA) by a lipid membrane associated with two viral proteins, prM and E. Immature particles are transported through the cellular exocytic pathway and conformational changes induced by acidic pH in the trans-Golgi network allow the proteolytic cleavage of prM by furin, a cellular protease, resulting in the release of mature and infectious TBE-virions. The E protein controls cell entry by mediating attachment to as yet ill-defined receptors as well as by low-pH-triggered fusion of the viral and endosomal membrane after uptake by receptor-mediated endocytosis. Because of its key functions in cell entry, the E protein is the primary target of virus neutralizing antibodies, which inhibit these functions by different mechanisms. Although all flavivirus E proteins have a similar overall structure, divergence at the amino acid sequence level is up to 60 percent (e.g. between TBE and dengue viruses), and therefore cross-neutralization as well as (some degree of) cross-protection are limited to relatively closely related flaviviruses, such as those constituting the tick-borne encephalitis serocomplex.

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Electrophysiological Characterization of Transport Across Outer Membrane Channels from Gram-Negative Bacteria in Their Native Environment

10.26434/chemrxiv.8282204.v1 ◽

2019 ◽

Author(s):

Jiajun Wang ◽

Rémi Terrasse ◽

Jayesh Arun Bafna ◽

Lorraine Benier ◽

Mathias Winterhalter

Keyword(s):

Outer Membrane ◽

Lipid Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Multi Drug Resistance ◽

Gram Negative Bacteria ◽

Membrane Channels ◽

Gram Negative ◽

Electrophysiological Characterization

Multi-drug resistance in Gram-negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics, we extract, purify and reconstitute them into artificial planar membranes. To avoid this time-consuming procedure, here we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer which moreover allows also to some extend the characterization of membrane protein channels in their native environment. Two major membrane channels from Escherichia coli, OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution methods, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution. The addition of Enrofloxacin on the LPS side yields somewhat higher association (kon) and lower dissociation (koff) rates compared to LPS-free reconstitution. We conclude that using outer membrane vesicles is a fast and easy approach for functional and structural studies of membrane channels in the native membrane.

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Faculty Opinions recommendation of Structure of the BK potassium channel in a lipid membrane from electron cryomicroscopy.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1164668.626471 ◽

2009 ◽

Author(s):

Annette Dolphin

Keyword(s):

Potassium Channel ◽

Lipid Membrane ◽

Electron Cryomicroscopy

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Faculty Opinions recommendation of The vesicle trafficking protein Sar1 lowers lipid membrane rigidity.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.5723956.5700070 ◽

2010 ◽

Author(s):

David Stephens

Keyword(s):

Lipid Membrane ◽

Vesicle Trafficking ◽

Membrane Rigidity

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Capacitance extraction method for a free-standing bilayer lipid membrane formed over an aperture in a nanofabricated silicon chip

Japanese Journal of Applied Physics ◽

10.35848/1347-4065/ab79f0 ◽

2020 ◽

Vol 59 (SI) ◽

pp. SIIK02

Author(s):

Yasutaka Tomioka ◽

Shogo Takashima ◽

Masataka Moriya ◽

Hiroshi Shimada ◽

Fumihiko Hirose ◽

...

Keyword(s):

Extraction Method ◽

Lipid Membrane ◽

Bilayer Lipid Membrane ◽

Free Standing ◽

Capacitance Extraction ◽

Bilayer Lipid

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Phase Transitions in Phospholipid Monolayers Studied by Atomic Force Microscopy and Langmuir-Blodgett Technique

Revista de Chimie ◽

10.37358/rc.08.11.2008 ◽

2008 ◽

Vol 59 (11) ◽

Author(s):

Maria Tomoaia-Cotisel ◽

Aurora Mocanu

Keyword(s):

Atomic Force Microscopy ◽

Lipid Membrane ◽

Phase Behaviour ◽

Membrane Interface ◽

Force Microscopy ◽

Langmuir Blodgett ◽

Atomic Force ◽

Phospholipid Monolayers ◽

Air Water Interface ◽

Condensed Liquid

The phase behaviour and surface structure of dipalmitoyl phosphatidyl choline (DPPC) monolayers at the air/water interface, in the absence and the presence of procaine, have been investigated by Langmuir-Blodgett (LB) technique and atomic force microscopy. The LB films were transferred on mica, at a controlled surface pressure, characteristic for the expanded liquid to condensed liquid phase transition of pure DPPC monolayers. The results indicate that procaine penetrates into and specifically interacts with phospholipid monolayers stabilizing the lipid membrane interface.

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Effect of pH and NH4NO3 as a Spray Additive on Penetration of NAA Through Isolated Tomato Fruit Cuticle

HortScience ◽

10.21273/hortsci.33.3.550a ◽

1998 ◽

Vol 33 (3) ◽

pp. 550a-550 ◽

Cited By ~ 1

Author(s):

Royal G. Fader ◽

Martin J. Bukovac

Keyword(s):

Direct Measurement ◽

Sodium Citrate ◽

Tomato Fruit ◽

Initial Slope ◽

Control Effect ◽

Solution Ph ◽

Ph Change ◽

Effect Of Ph ◽

Spray Droplets ◽

Partition Behavior

We have reported that NH4NO3 (AN, 8 mM, pH 4.2), applied as simulated spray droplets, enhanced penetration of 14C-NAA through isolated leaf and fruit cuticles. One explanation for this response is that AN depresses NAA (pKa= 4.2) dissociation, increasing the nondissociated moiety, which penetrates more readily than the anion (NAA'). Direct measurement of AN (concn. 0-800 mM) effect on NAA (215 μM) dissociation as indexed by change in solution pH revealed no significant effect, with a pH change from 4.19 to 4.05. This change is not sufficient to account for the observed enhancement. When 14C-NAA, buffered (20 mM sodium citrate) at pH 3.2, 4.2, 5.2, 6.2, was partitioned against chloroform, there was a marked increase in NAA partitioning into chloroform as pH was decreased. AN (8 mM) did not alter this partition behavior, also indicating no effect on NAA dissociation. However, in cuticle penetration studies, using a finite dose system with 14C-NAA buffered at pH 3.2, 4.2, 5.2, 6.2, and in the presence and absence of 8 mM AN, there was no marked or consistent pH or AN (-70 to + 232 % of no AN control) effect on penetration as indexed by initial slope (4-12 h) or penetration after 120 h. The possible effects of AN and buffer on penetration of 14C-NAA from the droplet deposit will be discussed.

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Dimerization of the Antimicrobial Peptide Polyphemusin I into One Polypeptide Chain: Theoretical and Practical Consequences

Biotekhnologiya ◽

10.21519/0234-2758-2019-35-5-36-41 ◽

2019 ◽

Vol 35 (5) ◽

pp. 36-41

Author(s):

V.A. Zenin ◽

E.G. Sadykhov ◽

A.N. Fedorov

Keyword(s):

Antimicrobial Peptides ◽

Pore Formation ◽

Lipid Membrane ◽

Polypeptide Chain ◽

Unique Identifier ◽

Bacterial Cultures ◽

In Series ◽

The Russian Federation ◽

Peptide Dimerization ◽

Putative Mechanism

A strategy of sequential dimerization of monomers of antimicrobial peptides (AMPs) into one polypeptide chain has been implemented on the example of a beta-structural AMP polyphemusin I which is one of the most effective candidate for use as an antibiotic. The possible polyphemusin I monomer and dimer structures in lipid membrane were studied in this work via molecular modeling. To this end, these molecules were chemically synthesized so that the dimer represented two monomers connected in series into one polypeptide chain with a flexible linker. The antimicrobial effects of monomer and dimer were then tested on various bacterial cultures, and their similarity was shown. Therefore, we can conclude that the pore formation is not a putative mechanism of the polyphemusin I action. antimicrobial peptides, peptide dimerization, mechanism of antimicrobial action, polyphemusin The work was supported by the Ministry of Science and Higher Education of the Russian Federation (Project Unique Identifier RFMEFI57517X0151).

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