Channel current analysis estimates the pore-formation and the penetration of transmembrane peptides

The Analyst ◽  
2018 ◽  
Vol 143 (15) ◽  
pp. 3540-3543 ◽  
Author(s):  
Yusuke Sekiya ◽  
Shungo Sakashita ◽  
Keisuke Shimizu ◽  
Kenji Usui ◽  
Ryuji Kawano
Keyword(s):  
Pore Formation ◽  
Current Signal ◽  
Current Analysis ◽  
Transmembrane Peptides ◽  
Channel Current ◽  
Toroidal Pore ◽  
Model Peptides

We measured the current signal of the transmembrane model peptides using the barrel-stave, toroidal pore, and penetration models in order to establish a precise assignment of the channel signals.

scholarly journals Imaging the dynamics of individual electropores

2016 ◽  
Vol 113 (19) ◽  
pp. 5281-5286 ◽  
Author(s):  
Jason T. Sengel ◽  
Mark I. Wallace
Keyword(s):  
Real Time ◽  
Pore Formation ◽  
Single Channel ◽  
Time Dependent ◽  
Single Channel Recording ◽  
Applied Potential ◽  
Dynamic Behaviors ◽  
Disordered Phase ◽  
Dependent Behavior ◽  
Toroidal Pore

Electroporation is a widely used technique to permeabilize cell membranes. Despite its prevalence, our understanding of the mechanism of voltage-mediated pore formation is incomplete; methods capable of visualizing the time-dependent behavior of individual electropores would help improve our understanding of this process. Here, using optical single-channel recording, we track multiple isolated electropores in real time in planar droplet interface bilayers. We observe individual, mobile defects that fluctuate in size, exhibiting a range of dynamic behaviors. We observe fast (25 s−1) and slow (2 s−1) components in the gating of small electropores, with no apparent dependence on the applied potential. Furthermore, we find that electropores form preferentially in the liquid disordered phase. Our observations are in general supportive of the hydrophilic toroidal pore model of electroporation, but also reveal additional complexity in the interactions, dynamics, and energetics of electropores.

scholarly journals Effect of helical kink in antimicrobial peptides on membrane pore formation

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Alzbeta Tuerkova ◽  
Ivo Kabelka ◽  
Tereza Králová ◽  
Lukáš Sukeník ◽  
Šárka Pokorná ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Pore Formation ◽  
Molecular Level ◽  
Helical Peptides ◽  
Membrane Pore ◽  
Bacterial Membranes ◽  
Membrane Pores ◽  
Helical Peptide ◽  
Toroidal Pore ◽  
The Right

Every cell is protected by a semipermeable membrane. Peptides with the right properties, for example Antimicrobial peptides (AMPs), can disrupt this protective barrier by formation of leaky pores. Unfortunately, matching peptide properties with their ability to selectively form pores in bacterial membranes remains elusive. In particular, the proline/glycine kink in helical peptides was reported to both increase and decrease antimicrobial activity. We used computer simulations and fluorescence experiments to show that a kink in helices affects the formation of membrane pores by stabilizing toroidal pores but disrupting barrel-stave pores. The position of the proline/glycine kink in the sequence further controls the specific structure of toroidal pore. Moreover, we demonstrate that two helical peptides can form a kink-like connection with similar behavior as one long helical peptide with a kink. The provided molecular-level insight can be utilized for design and modification of pore-forming antibacterial peptides or toxins.

scholarly journals Lethal Hydroxyl Radical Accumulation by a Lactococcal Bacteriocin, Lacticin Q

2013 ◽  
Vol 57 (8) ◽  
pp. 3897-3902 ◽  
Author(s):  
Mengqi Li ◽  
Fuminori Yoneyama ◽  
Nayu Toshimitsu ◽  
Takeshi Zendo ◽  
Jiro Nakayama ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Pore Formation ◽  
Membrane Lipid ◽  
Gram Positive Bacteria ◽  
Antimicrobial Mechanism ◽  
Toroidal Pore ◽  
Hydroxyl Radical Scavengers ◽  
Selective Antimicrobial Activity

ABSTRACTThe antimicrobial mechanism of a lactococcal bacteriocin, lacticin Q, can be described by the toroidal pore model without any receptor. However, lacticin Q showed different degrees of activity (selective antimicrobial activity) against Gram-positive bacteria even among related species. The ability of lacticin Q to induce pore formation in liposomes composed of lipids from different indicator strains indicated that its selective antimicrobial activity could not be attributed only to membrane lipid composition. We investigated the accumulation of deleterious hydroxyl radicals after exposure to lacticin Q as a contributing factor to cell death in the indicator strains. When lacticin Q of the same concentration as the MIC or minimum bactericidal concentration was added to the indicator cultures, high levels of hydroxyl radical accumulation were detected. Treatment with hydroxyl radical scavengers, thiourea and 2,2′-bipyridyl, decreased the levels of hydroxyl radical accumulation and recovered cell viability. These results suggest that, with or without pore formation, the final antimicrobial mechanism of lacticin Q is the accumulation of hydroxyl radicals, which varies by strain, resulting in the selective antimicrobial activity of lacticin Q.

scholarly journals Membrane Permeabilization by Bordetella Adenylate Cyclase Toxin Involves Pores of Tunable Size

Biomolecules ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 183 ◽  
Author(s):  
David González-Bullón ◽  
Kepa B. Uribe ◽  
Eneko Largo ◽  
Garazi Guembelzu ◽  
Aritz B. García-Arribas ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Pore Formation ◽  
Whooping Cough ◽  
Regulatory Element ◽  
Cell Types ◽  
Gram Negative Bacteria ◽  
Heterogeneous Architecture ◽  
Sequential Mechanism ◽  
Toroidal Pore ◽  
Variable Stoichiometry

RTX (Repeats in ToXin) pore-forming toxins constitute an expanding family of exoproteins secreted by many Gram-negative bacteria and involved in infectious diseases caused by said pathogens. Despite the relevance in the host/pathogen interactions, the structure and characteristics of the lesions formed by these toxins remain enigmatic. Here, we capture the first direct nanoscale pictures of lytic pores formed by an RTX toxin, the Adenylate cyclase (ACT), secreted by the whooping cough bacterium Bordetella pertussis. We reveal that ACT associates into growing-size oligomers of variable stoichiometry and heterogeneous architecture (lines, arcs, and rings) that pierce the membrane, and that, depending on the incubation time and the toxin concentration, evolve into large enough “holes” so as to allow the flux of large molecular mass solutes, while vesicle integrity is preserved. We also resolve ACT assemblies of similar variable stoichiometry in the cell membrane of permeabilized target macrophages, proving that our model system recapitulates the process of ACT permeabilization in natural membranes. Based on our data we propose a non-concerted monomer insertion and sequential mechanism of toroidal pore formation by ACT. A size-tunable pore adds a new regulatory element to ACT-mediated cytotoxicity, with different pore sizes being putatively involved in different physiological scenarios or cell types.

scholarly journals Membrane remodeling by the lytic fragment of sticholysin II: implications for the toroidal pore model

2019 ◽  
Author(s):  
H. Mesa-Galloso ◽  
P.A. Valiente ◽  
R.F. Epand ◽  
M.E. Lanio ◽  
R.M. Epand ◽  
...  
Keyword(s):  
Pore Formation ◽  
Membrane Curvature ◽  
Membrane Remodeling ◽  
Structural Element ◽  
Flip Flop ◽  
Negatively Curved ◽  
N Terminus ◽  
Toroidal Pore ◽  
Insight Into

AbstractSticholysins are pore-forming toxins of biomedical interest and represent a prototype of proteins acting through the formation of protein-lipid or toroidal pores. Peptides spanning the N-terminus of sticholysins can mimic their permeabilizing activity and together with the full-length toxins have been used as a tool to understand the mechanism of pore formation in membranes. However, the lytic mechanism of these peptides and the lipid shape modulating their activity are not completely clear. In this paper, we combine molecular dynamics (MD) simulations and experimental biophysical tools to dissect different aspects of the pore-forming mechanism of StII1-30, a peptide derived from the N-terminus of sticholysin II. With this combined approach, membrane curvature induction and flip-flop movement of the lipids were identified as two important membrane remodeling steps mediated by StII1-30-pore forming activity. Pore-formation by this peptide was enhanced by the presence of the negatively-curved lipid phosphatidylethanolamine (PE) in membranes. This lipid emerged not only as a facilitator of membrane interactions but also as a structural element of the StII1-30-pore that is recruited to the pore ring upon its assembly. Collectively, these new findings support a toroidal model for the architecture of the pore formed by this peptide and provide new molecular insight into the role of PE as a membrane component that easily accommodates into the ring of toroidal pores aiding in its stabilization. This study contributes to a better understanding of the molecular mechanism underlying the permeabilizing activity of StII1-30 and peptides or proteins acting via a toroidal pore mechanism and offers an informative framework for the optimization of the biomedical application of this and similar molecules.State of significanceWe provide evidence about the ability of StII1-30 to form toroidal pores. Due to pore assembly, StII1-30-pore induces membrane curvature and facilitates flip-flop movement of the lipids. The negatively-curved lipid PE relocates from the membrane into the pore ring, being also a structural element of the pore StII1-30 forms. This peptide emerged as a new tool, together with the full-length toxin, to understand the mechanism of toroidal pore formation in membranes. This study provides new molecular insight into the role of curved lipids as co-factors of toroidal pores, which could aid in its stabilization by easily accommodating into the ring. This framework could underpin strategies for the rational use of peptides or proteins acting via toroidal pores.

scholarly journals Effect of Helical Kink in Antimicrobial Peptides on Membrane Pore Formation

2019 ◽  
Author(s):  
Alzbeta Tuerkova ◽  
Ivo Kabelka ◽  
Tereza Králová ◽  
Lukáš Sukeník ◽  
Šárka Pokorná ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Pore Formation ◽  
Molecular Level ◽  
Helical Peptides ◽  
Membrane Pore ◽  
Bacterial Membranes ◽  
Membrane Pores ◽  
Helical Peptide ◽  
Toroidal Pore ◽  
The Right

AbstractEvery cell is protected by a semipermeable membrane. Peptides with the right properties, e.g. Antimicrobial peptides (AMPs), can disrupt this protective barrier by formation of leaky pores. Unfortunately, matching peptide properties with their ability to selectively form pores in bacterial membranes remains elusive. In particular, the proline/glycine kink in helical peptides was reported to both increase and decrease antimicrobial activity. We used computer simulations and fluorescence experiments to show that a kink in helices affects the formation of membrane pores by stabilizing toroidal pores but disrupting barrel-stave pores. The position of the proline/glycine kink in the sequence further controls the specific structure of toroidal pore. Moreover, we demonstrate that two helical peptides can form a kink-like connection with similar behavior as one long helical peptide with a kink. The provided molecular-level insight can be utilized for design and modification of pore forming antibacterial peptides or toxins.

Effect of lipid shape on toroidal pore formation and peptide orientation in lipid bilayers

2017 ◽  
Vol 19 (32) ◽  
pp. 21340-21349 ◽  
Author(s):  
Sun Young Woo ◽  
Hwankyu Lee
Keyword(s):  
Lipid Bilayers ◽  
Pore Formation ◽  
Peptide Orientation ◽  
Toroidal Pore

Disordered and thinner bilayer w/lyso-lipids; tilted orientation of peptides in bilayer w/lyso-lipids; toroidal pores stabilized by peptides and lyso-lipids.

Channel current analysis of GaN HEMTs with source sense pin in DC/DC boost converters

2021 ◽  
Vol 21 (4) ◽  
pp. 713-723
Author(s):  
Buket Turan Azizoglu ◽  
Abdul Balikci ◽  
Eyup Akpinar ◽  
Enes Durbaba
Keyword(s):  
Current Analysis ◽  
Boost Converters ◽  
Channel Current ◽  
Gan Hemts
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