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

Abstract

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.

Identification and Characterization of Novel Proteins from Arizona Bark Scorpion Venom That Inhibit Nav1.8, a Voltage-Gated Sodium Channel Regulator of Pain Signaling

“…ver, proteins that modulate VGSC activity can serve as templates for structure-guided engineering of drugs that block pain [37][38][39][40]. However, examining Nav1.8 inactivation mechanisms has been challenging.…”

“…Proteins that modulate VGSC activity can serve as templates for structure-guided engineering of drugs that block pain [ 37 , 38 , 39 , 40 ]. Venom proteins bind the extracellular linkers adjacent to the voltage sensors that control channel activation and inactivation.…”

Identification and characterization of novel proteins from Arizona bark scorpion venom that inhibit Nav1.8, a voltage-gated sodium channel regulator of pain signaling

“…Characterizing the structure-activity relationships between inhibitory proteins and OtNav1.8 will increase our understanding of the structural basis for Nav1.8 activation and inactivation gating. Moreover, amino acids at the core of structure-activity relationships are key to using a modified protein mutagenesis and screening approach similar to what has been accomplished engineering spider toxins that inhibit human Nav1.7 [39,65]. A better understanding of the molecular and biophysical mechanisms that regulate pain signal transmission, particularly mechanisms that inactivate signals, would advance efforts to develop drugs that block pain without addiction [61].…”

“…Venom proteins that target Nav1.7 have also provided templates for structure-guided mutagenesis to engineer new pain drugs. For example, mutagenesis of a spider venom protein changed the native protein from a Nav1.7 channel activator to a channel inhibitor [39]. While Nav1.8 activity is linked to mechanical, neuropathic and inflammatory pain, highlighting the potential for Nav1.8 to serve as an alternative drug target to Nav1.7 [7,8,10–18], the biophysical mechanisms that regulate Nav1.8 gating are not completely understood, particularly inactivation.…”

Animal Venoms—Curse or Cure?

“…Spider venom peptides, on the other hand, might be promising candidates for novel analgesics by targeting particular subtypes of voltage-gated sodium (Na V ) channels. Yin et al [ 67 ] not only provide the first characterisation of a toxin from the theraphosid genus Poecilotheria . They also demonstrate that, by simply introducing one additional residue, the toxin is converted from a Na V 1.7 activator into an inhibitor, which can be crucial for designing effective analgesic leads.…”