scholarly journals Functional Contributions of Positive Charges in the Pore-Lining Helix 3 of the Bordetella pertussis CyaA-Hemolysin to Hemolytic Activity and Ion-Channel Opening

Toxins ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 109 ◽  
Author(s):  
Chattip Kurehong ◽  
Chalermpol Kanchanawarin ◽  
Busaba Powthongchin ◽  
Panchika Prangkio ◽  
Gerd Katzenmeier ◽  
...  
Keyword(s):  
Ion Channel ◽  
Bordetella Pertussis ◽  
Hemolytic Activity ◽  
Channel Opening ◽  
Pore Lining

scholarly journals Identification of the Pore-lining Residues of the BM2 Ion Channel Protein of Influenza B Virus

2008 ◽  
Vol 283 (23) ◽  
pp. 15921-15931 ◽  
Author(s):  
Chunlong Ma ◽  
Cinque S. Soto ◽  
Yuki Ohigashi ◽  
Albert Taylor ◽  
Vasilios Bournas ◽  
...  
Keyword(s):  
Ion Channel ◽  
Influenza B Virus ◽  
Influenza B ◽  
Channel Protein ◽  
B Virus ◽  
Pore Lining

scholarly journals Acetylated tubulin is essential for touch sensation in mice

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Shane J Morley ◽  
Yanmei Qi ◽  
Loredana Iovino ◽  
Laura Andolfi ◽  
Da Guo ◽  
...  
Keyword(s):  
Ion Channel ◽  
Sensory Neurons ◽  
Mechanical Energy ◽  
Mechanical Stimuli ◽  
Acetylated Tubulin ◽  
Fundamental Level ◽  
Tubulin Acetylation ◽  
Channel Opening ◽  
Mechanosensitive Ion Channel ◽  
Touch Sensation

At its most fundamental level, touch sensation requires the translation of mechanical energy into mechanosensitive ion channel opening, thereby generating electro-chemical signals. Our understanding of this process, especially how the cytoskeleton influences it, remains unknown. Here we demonstrate that mice lacking the α-tubulin acetyltransferase Atat1 in sensory neurons display profound deficits in their ability to detect mechanical stimuli. We show that all cutaneous afferent subtypes, including nociceptors have strongly reduced mechanosensitivity upon Atat1 deletion, and that consequently, mice are largely insensitive to mechanical touch and pain. We establish that this broad loss of mechanosensitivity is dependent upon the acetyltransferase activity of Atat1, which when absent leads to a decrease in cellular elasticity. By mimicking α-tubulin acetylation genetically, we show both cellular rigidity and mechanosensitivity can be restored in Atat1 deficient sensory neurons. Hence, our results indicate that by influencing cellular stiffness, α-tubulin acetylation sets the force required for touch.

scholarly journals Atomistic basis of opening and conduction in mammalian inward rectifier potassium (Kir2.2) channels

2019 ◽  
Author(s):  
Eva-Maria Zangerl-Plessl ◽  
Sun-Joo Lee ◽  
Grigory Maksaev ◽  
Harald Bernsteiner ◽  
Feifei Ren ◽  
...  
Keyword(s):  
Md Simulations ◽  
Inward Rectifier ◽  
Ion Conduction ◽  
Kir Channel ◽  
Channel Opening ◽  
Spontaneous Wetting ◽  
Pore Lining ◽  
Crossing Point ◽  
Gate Region

Potassium ion conduction through open potassium channels is essential to control of membrane potentials in all cells. To elucidate the open conformation and hence the mechanism of K+ ion conduction in the classical inward rectifier Kir2.2, we introduced a negative charge (G178D) at the crossing point of the inner helix bundle (HBC), the location of ligand-dependent gating. This ‘forced open’ mutation generated channels that were active even in the complete absence of phosphoinositol-4,5-bisphosphate (PIP2), an otherwise essential ligand for Kir channel opening. Crystal structures were obtained at a resolution of 3.6 Å without PIP2 bound, or 2.8 Å in complex with PIP2. The latter revealed a slight widening at the HBC, through backbone movement. Molecular dynamics (MD) simulations showed that subsequent spontaneous wetting of the pore through the HBC gate region allowed K+ ion movement across the HBC and conduction through the channel. Further simulations reveal atomistic details of the opening process and highlight the role of pore lining acidic residues in K+ conduction through Kir2 channels.

scholarly journals Allosteric binding site in a Cys-loop receptor ligand-binding domain unveiled in the crystal structure of ELIC in complex with chlorpromazine

2016 ◽  
Vol 113 (43) ◽  
pp. E6696-E6703 ◽  
Author(s):  
Mieke Nys ◽  
Eveline Wijckmans ◽  
Ana Farinha ◽  
Özge Yoluk ◽  
Magnus Andersson ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Ion Channel ◽  
Binding Site ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Channel Pore ◽  
X Ray ◽  
Electrophysiological Recordings ◽  
Channel Opening ◽  
Dynamics Simulations

Pentameric ligand-gated ion channels or Cys-loop receptors are responsible for fast inhibitory or excitatory synaptic transmission. The antipsychotic compound chlorpromazine is a widely used tool to probe the ion channel pore of the nicotinic acetylcholine receptor, which is a prototypical Cys-loop receptor. In this study, we determine the molecular determinants of chlorpromazine binding in the Erwinia ligand-gated ion channel (ELIC). We report the X-ray crystal structures of ELIC in complex with chlorpromazine or its brominated derivative bromopromazine. Unexpectedly, we do not find a chlorpromazine molecule in the channel pore of ELIC, but behind the β8–β9 loop in the extracellular ligand-binding domain. The β8–β9 loop is localized downstream from the neurotransmitter binding site and plays an important role in coupling of ligand binding to channel opening. In combination with electrophysiological recordings from ELIC cysteine mutants and a thiol-reactive derivative of chlorpromazine, we demonstrate that chlorpromazine binding at the β8–β9 loop is responsible for receptor inhibition. We further use molecular-dynamics simulations to support the X-ray data and mutagenesis experiments. Together, these data unveil an allosteric binding site in the extracellular ligand-binding domain of ELIC. Our results extend on previous observations and further substantiate our understanding of a multisite model for allosteric modulation of Cys-loop receptors.

scholarly journals Functional Studies and Modeling of Pore-Lining Residue Mutants of the Influenza A Virus M2 Ion Channel

Biochemistry ◽  
2010 ◽  
Vol 49 (4) ◽  
pp. 696-708 ◽  
Author(s):  
Victoria Balannik ◽  
Vincenzo Carnevale ◽  
Giacomo Fiorin ◽  
Benjamin G. Levine ◽  
Robert A. Lamb ◽  
...  
Keyword(s):  
Ion Channel ◽  
Influenza A Virus ◽  
Influenza A ◽  
Functional Studies ◽  
Pore Lining

scholarly journals Stimulation of Bordetella pertussisAdenylate Cyclase Toxin Intoxication by Its Hemolysin Domain

2000 ◽  
Vol 68 (6) ◽  
pp. 3727-3730 ◽  
Author(s):  
Masaaki Iwaki ◽  
Kazunari Kamachi ◽  
Toshifumi Konda
Keyword(s):  
Adenylate Cyclase ◽  
Protein Interactions ◽  
Bordetella Pertussis ◽  
Hemolytic Activity ◽  
Cytoplasmic Membrane ◽  
Catalytic Domain ◽  
Protein Protein Interactions ◽  
Adenylate Cyclase Toxin ◽  
Stimulation Of

ABSTRACT The internalization of the N-terminal catalytic domain ofBordetella pertussis adenylate cyclase toxin (ACT) across the cytoplasmic membrane has been considered to occur independently from protein-protein interactions which can lead to oligomerization required for hemolytic activity by its C-terminal hemolysin domain. Here we report that when added in excess, this hemolysin domain stimulates the internalization, suggesting the involvement of protein-protein interactions in cell-invasive activity of ACT, as well as its hemolytic activity.

scholarly journals Differences in Purinergic Amplification of Osmotic Cell Lysis by the Pore-Forming RTX Toxins Bordetella pertussis CyaA and Actinobacillus pleuropneumoniae ApxIA: the Role of Pore Size

2013 ◽  
Vol 81 (12) ◽  
pp. 4571-4582 ◽  
Author(s):  
Jiri Masin ◽  
Radovan Fiser ◽  
Irena Linhartova ◽  
Radim Osicka ◽  
Ladislav Bumba ◽  
...  
Keyword(s):  
Pore Size ◽  
Bordetella Pertussis ◽  
Hemolytic Activity ◽  
Purinergic Signaling ◽  
Actinobacillus Pleuropneumoniae ◽  
Disulfonic Acid ◽  
Dependent Manner ◽  
Cell Permeabilization ◽  
Content Type ◽  
Rtx Toxins

ABSTRACTA large subgroup of therepeat intoxin (RTX) family of leukotoxins of Gram-negative pathogens consists of pore-forming hemolysins. These can permeabilize mammalian erythrocytes (RBCs) and provoke their colloid osmotic lysis (hemolytic activity). Recently, ATP leakage through pannexin channels and P2X receptor-mediated opening of cellular calcium and potassium channels were implicated in cell permeabilization by pore-forming toxins. In the study described here, we examined the role played by purinergic signaling in the cytolytic action of two RTX toxins that form pores of different sizes. The cytolytic potency of ApxIA hemolysin ofActinobacillus pleuropneumoniae, which forms pores about 2.4 nm wide, was clearly reduced in the presence of P2X7receptor antagonists or an ATP scavenger, such as pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS), Brilliant Blue G, ATP oxidized sodium salt, or hexokinase. In contrast, antagonists of purinergic signaling had no impact on the hemolytic potency of the adenylate cyclase toxin-hemolysin (CyaA) ofBordetella pertussis, which forms pores of 0.6 to 0.8 nm in diameter. Moreover, the conductance of pores formed by ApxIA increased with the toxin concentration, while the conductance of the CyaA single pore units was constant at various toxin concentrations. However, the P2X7receptor antagonist PPADS inhibited in a concentration-dependent manner the exacerbated hemolytic activity of a CyaA-ΔN489 construct (lacking 489 N-terminal residues of CyaA), which exhibited a strongly enhanced pore-forming propensity (>20-fold) and also formed severalfold larger conductance units in planar lipid bilayers than intact CyaA. These results point to a pore size threshold of purinergic amplification involvement in cell permeabilization by pore-forming RTX toxins.

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