scholarly journals Addition of K22 Converts Spider Venom Peptide Pme2a from an Activator to an Inhibitor of NaV1.7

Biomedicines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 37
Author(s):  
Kathleen Yin ◽  
Jennifer R. Deuis ◽  
Zoltan Dekan ◽  
Ai-Hua Jin ◽  
Paul F. Alewood ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Rational Design ◽  
Voltage Dependence ◽  
Spider Venom ◽  
Fast Inactivation ◽  
Peak Current ◽  
Native Peptide ◽  
Voltage Gated Sodium Channels ◽  
Nav Channels ◽  
And Shifts

Spider venom is a novel source of disulfide-rich peptides with potent and selective activity at voltage-gated sodium channels (NaV). Here, we describe the discovery of μ-theraphotoxin-Pme1a and μ/δ-theraphotoxin-Pme2a, two novel peptides from the venom of the Gooty Ornamental tarantula Poecilotheria metallica that modulate NaV channels. Pme1a is a 35 residue peptide that inhibits NaV1.7 peak current (IC50 334 ± 114 nM) and shifts the voltage dependence of activation to more depolarised membrane potentials (V1/2 activation: Δ = +11.6 mV). Pme2a is a 33 residue peptide that delays fast inactivation and inhibits NaV1.7 peak current (EC50 > 10 μM). Synthesis of a [+22K]Pme2a analogue increased potency at NaV1.7 (IC50 5.6 ± 1.1 μM) and removed the effect of the native peptide on fast inactivation, indicating that a lysine at position 22 (Pme2a numbering) is important for inhibitory activity. Results from this study may be used to guide the rational design of spider venom-derived peptides with improved potency and selectivity at NaV channels in the future.

scholarly journals The Tarantula Venom Peptide Eo1a Binds to the Domain II S3-S4 Extracellular Loop of Voltage-Gated Sodium Channel NaV1.8 to Enhance Activation

2022 ◽  
Vol 12 ◽  
Author(s):  
Jennifer R. Deuis ◽  
Lotten Ragnarsson ◽  
Samuel D. Robinson ◽  
Zoltan Dekan ◽  
Lerena Chan ◽  
...  
Keyword(s):  
Steady State ◽  
Binding Site ◽  
Rational Design ◽  
Voltage Dependence ◽  
Fast Inactivation ◽  
Extracellular Loop ◽  
Peak Current ◽  
Future Studies ◽  
Voltage Gated ◽  
Functional Characterisation

Venoms from cone snails and arachnids are a rich source of peptide modulators of voltage-gated sodium (NaV) channels, however relatively few venom-derived peptides with activity at the mammalian NaV1.8 subtype have been isolated. Here, we describe the discovery and functional characterisation of β-theraphotoxin-Eo1a, a peptide from the venom of the Tanzanian black and olive baboon tarantula Encyocratella olivacea that modulates NaV1.8. Eo1a is a 37-residue peptide that increases NaV1.8 peak current (EC50 894 ± 146 nM) and causes a large hyperpolarising shift in both the voltage-dependence of activation (ΔV50–20.5 ± 1.2 mV) and steady-state fast inactivation (ΔV50–15.5 ± 1.8 mV). At a concentration of 10 μM, Eo1a has varying effects on the peak current and channel gating of NaV1.1–NaV1.7, although its activity is most pronounced at NaV1.8. Investigations into the binding site of Eo1a using NaV1.7/NaV1.8 chimeras revealed a critical contribution of the DII S3-S4 extracellular loop of NaV1.8 to toxin activity. Results from this work may form the basis for future studies that lead to the rational design of spider venom-derived peptides with improved potency and selectivity at NaV1.8.

scholarly journals Spider Knottin Pharmacology at Voltage-Gated Sodium Channels and Their Potential to Modulate Pain Pathways

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 626 ◽  
Author(s):  
Yashad Dongol ◽  
Fernanda Caldas Cardoso ◽  
Richard J Lewis
Keyword(s):  
Chronic Pain ◽  
Sodium Channels ◽  
Structural Features ◽  
Voltage Gated ◽  
Subtype Selectivity ◽  
Voltage Gated Sodium Channels ◽  
Neuronal Signalling ◽  
Pain Pathways ◽  
Nav Channels ◽  
Chronic Pain Conditions

Voltage-gated sodium channels (NaVs) are a key determinant of neuronal signalling. Neurotoxins from diverse taxa that selectively activate or inhibit NaV channels have helped unravel the role of NaV channels in diseases, including chronic pain. Spider venoms contain the most diverse array of inhibitor cystine knot (ICK) toxins (knottins). This review provides an overview on how spider knottins modulate NaV channels and describes the structural features and molecular determinants that influence their affinity and subtype selectivity. Genetic and functional evidence support a major involvement of NaV subtypes in various chronic pain conditions. The exquisite inhibitory properties of spider knottins over key NaV subtypes make them the best lead molecules for the development of novel analgesics to treat chronic pain.

scholarly journals Tracking S4 movement by gating pore currents in the bacterial sodium channel NaChBac

2014 ◽  
Vol 144 (2) ◽  
pp. 147-157 ◽  
Author(s):  
Tamer M. Gamal El-Din ◽  
Todd Scheuer ◽  
William A. Catterall
Keyword(s):  
Membrane Potential ◽  
Sodium Channel ◽  
Sodium Channels ◽  
Voltage Dependence ◽  
Periodic Paralysis ◽  
Membrane Potentials ◽  
Structural Basis ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Gating Charges

Voltage-gated sodium channels mediate the initiation and propagation of action potentials in excitable cells. Transmembrane segment S4 of voltage-gated sodium channels resides in a gating pore where it senses the membrane potential and controls channel gating. Substitution of individual S4 arginine gating charges (R1–R3) with smaller amino acids allows ionic currents to flow through the mutant gating pore, and these gating pore currents are pathogenic in some skeletal muscle periodic paralysis syndromes. The voltage dependence of gating pore currents provides information about the transmembrane position of the gating charges as S4 moves in response to membrane potential. Here we studied gating pore current in mutants of the homotetrameric bacterial sodium channel NaChBac in which individual arginine gating charges were replaced by cysteine. Gating pore current was observed for each mutant channel, but with different voltage-dependent properties. Mutating the first (R1C) or second (R2C) arginine to cysteine resulted in gating pore current at hyperpolarized membrane potentials, where the channels are in resting states, but not at depolarized potentials, where the channels are activated. Conversely, the R3C gating pore is closed at hyperpolarized membrane potentials and opens with channel activation. Negative conditioning pulses revealed time-dependent deactivation of the R3C gating pore at the most hyperpolarized potentials. Our results show sequential voltage dependence of activation of gating pore current from R1 to R3 and support stepwise outward movement of the substituted cysteines through the narrow portion of the gating pore that is sealed by the arginine side chains in the wild-type channel. This pattern of voltage dependence of gating pore current is consistent with a sliding movement of the S4 helix through the gating pore. Through comparison with high-resolution models of the voltage sensor of bacterial sodium channels, these results shed light on the structural basis for pathogenic gating pore currents in periodic paralysis syndromes.

scholarly journals Domain IV voltage-sensor movement is both sufficient and rate limiting for fast inactivation in sodium channels

2013 ◽  
Vol 142 (2) ◽  
pp. 101-112 ◽  
Author(s):  
Deborah L. Capes ◽  
Marcel P. Goldschen-Ohm ◽  
Manoel Arcisio-Miranda ◽  
Francisco Bezanilla ◽  
Baron Chanda
Keyword(s):  
Sodium Channels ◽  
Voltage Sensor ◽  
Fast Inactivation ◽  
Voltage Range ◽  
Voltage Gated Sodium Channels ◽  
Channel Opening ◽  
The Individual ◽  
Electrical Impulses ◽  
Voltage Sensing Domain ◽  
Rate Limiting

Voltage-gated sodium channels are critical for the generation and propagation of electrical signals in most excitable cells. Activation of Na+ channels initiates an action potential, and fast inactivation facilitates repolarization of the membrane by the outward K+ current. Fast inactivation is also the main determinant of the refractory period between successive electrical impulses. Although the voltage sensor of domain IV (DIV) has been implicated in fast inactivation, it remains unclear whether the activation of DIV alone is sufficient for fast inactivation to occur. Here, we functionally neutralize each specific voltage sensor by mutating several critical arginines in the S4 segment to glutamines. We assess the individual role of each voltage-sensing domain in the voltage dependence and kinetics of fast inactivation upon its specific inhibition. We show that movement of the DIV voltage sensor is the rate-limiting step for both development and recovery from fast inactivation. Our data suggest that activation of the DIV voltage sensor alone is sufficient for fast inactivation to occur, and that activation of DIV before channel opening is the molecular mechanism for closed-state inactivation. We propose a kinetic model of sodium channel gating that can account for our major findings over a wide voltage range by postulating that DIV movement is both necessary and sufficient for fast inactivation.

Molecular determinant for the tarantula toxin Jingzhaotoxin-I slowing the fast inactivation of voltage-gated sodium channels

Toxicon ◽  
2016 ◽  
Vol 111 ◽  
pp. 13-21 ◽  
Author(s):  
Huai Tao ◽  
Xia Chen ◽  
Min Lu ◽  
Yuanyuan Wu ◽  
Meichun Deng ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Fast Inactivation ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Molecular Determinant

scholarly journals The role of NaV channels in synaptic transmission after axotomy in a microfluidic culture platform

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nickolai Vysokov ◽  
Stephen B. McMahon ◽  
Ramin Raouf
Keyword(s):  
Synaptic Transmission ◽  
Dorsal Horn ◽  
Sodium Channels ◽  
Culture System ◽  
Dorsal Horn Neurons ◽  
Voltage Gated Sodium Channels ◽  
Nav Channels ◽  
Dorsal Root Ganglia Neurons ◽  
First Pain

Abstract Voltage gated sodium channels are key players in aberrant pain signaling and sensitization of nociceptors after peripheral nerve injury. The extent to which sodium channel activity after injury contributes to synaptic transmission at the first pain synapse however remains unclear. To investigate the effect of axotomy on synaptic transmission between dorsal root ganglia neurons and dorsal horn neurons, we reconstructed the first pain synapse in a novel microfluidic based compartmentalized cell culture system, which recapitulates the connectivity of peripheral pain signaling. We show that following axotomy of the distal axons, inhibition of NaV1.7 and NaV1.8 sodium channels in incoming presynaptic DRG axons is no longer sufficient to block activation of these axons and the resulting synaptic transmission to dorsal horn neurons. We found that blockade of NaV1.6 activity is highly effective in reducing activation of incoming axons contributing to synaptic transmission after axotomy of DRG neurons. The microfluidic culture system described here offers an in vitro platform to recapitulate and study the first pain synapse.

scholarly journals Gating modifier toxins isolated from spider venom: Modulation of voltage-gated sodium channels and the role of lipid membranes

2018 ◽  
Vol 293 (23) ◽  
pp. 9041-9052 ◽  
Author(s):  
Akello J. Agwa ◽  
Steve Peigneur ◽  
Chun Yuen Chow ◽  
Nicole Lawrence ◽  
David J. Craik ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Lipid Membranes ◽  
Spider Venom ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Gating Modifier

scholarly journals Subtype Specificity of β-Toxin Tf1a from Tityus fasciolatus in Voltage Gated Sodium Channels

Toxins ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 339 ◽  
Author(s):  
Daniel Mata ◽  
Diogo Tibery ◽  
Leandro Campos ◽  
Thalita Camargos ◽  
Steve Peigneur ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Complex Mixture ◽  
Normal Function ◽  
Structural Function ◽  
Scorpion Toxins ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Subtype Specificity ◽  
Nav Channels ◽  
Predictive Strength

Scorpion venoms are a complex mixture of components. Among them the most important are peptides, which presents the capacity to interact and modulate several ion channel subtypes, including voltage-gated sodium channels (NaV). Screening the activity of scorpion toxins on different subtypes of NaV reveals the scope of modulatory activity and, in most cases, low channel selectivity. Until now there are approximately 60 scorpion toxins experimentally assayed on NaV channels. However, the molecular bases of interaction between scorpion toxins and NaV channels are not fully elucidated. The activity description of new scorpion toxins is crucial to enhance the predictive strength of the structural–function correlations of these NaV modulatory molecules. In the present work a new scorpion toxin (Tf1a) was purified from Tityus fasciolatus venom by RP-HPLC, and characterized using electrophysiological experiments on different types of voltage-gated sodium channels. Tf1a was able to modify the normal function of NaV tested, showing to be a typical β-NaScTx. Tf1a also demonstrated an unusual capability to alter the kinetics of NaV1.5.

scholarly journals Distribution of TTX-sensitive voltage-gated sodium channels in primary sensory endings of mammalian muscle spindles

2017 ◽  
Vol 117 (4) ◽  
pp. 1690-1701 ◽  
Author(s):  
Dario I. Carrasco ◽  
Jacob A. Vincent ◽  
Timothy C. Cope
Keyword(s):  
Sodium Channels ◽  
Molecular Mechanisms ◽  
Mammalian Species ◽  
Muscle Spindles ◽  
Tonic Firing ◽  
Muscle Stretch ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Nav Channels ◽  
Sensory Endings

Knowledge of the molecular mechanisms underlying signaling of mechanical stimuli by muscle spindles remains incomplete. In particular, the ionic conductances that sustain tonic firing during static muscle stretch are unknown. We hypothesized that tonic firing by spindle afferents depends on sodium persistent inward current (INaP) and tested for the necessary presence of the appropriate voltage-gated sodium (NaV) channels in primary sensory endings. The NaV1.6 isoform was selected for both its capacity to produce INaP and for its presence in other mechanosensors that fire tonically. The present study shows that NaV1.6 immunoreactivity (IR) is concentrated in heminodes, presumably where tonic firing is generated, and we were surprised to find NaV1.6 IR strongly expressed also in the sensory terminals, where mechanotransduction occurs. This spatial pattern of NaV1.6 IR distribution was consistent for three mammalian species (rat, cat, and mouse), as was tonic firing by primary spindle afferents. These findings meet some of the conditions needed to establish participation of INaP in tonic firing by primary sensory endings. The study was extended to two additional NaV isoforms, selected for their sensitivity to TTX, excluding TTX-resistant NaV channels, which alone are insufficient to support firing by primary spindle endings. Positive immunoreactivity was found for NaV1.1, predominantly in sensory terminals together with NaV1.6 and for NaV1.7, mainly in preterminal axons. Differential distribution in primary sensory endings suggests specialized roles for these three NaV isoforms in the process of mechanosensory signaling by muscle spindles. NEW & NOTEWORTHY The molecular mechanisms underlying mechanosensory signaling responsible for proprioceptive functions are not completely elucidated. This study provides the first evidence that voltage-gated sodium channels (NaVs) are expressed in the spindle primary sensory ending, where NaVs are found at every site involved in transduction or encoding of muscle stretch. We propose that NaVs contribute to multiple steps in sensory signaling by muscle spindles as it does in other types of slowly adapting sensory neurons.

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