Engineering Potent and Selective
Analogues of GpTx-1,
a Tarantula Venom Peptide Antagonist of the Na<sub>V</sub>1.7 Sodium
Channel
- Publication date
- Publisher
Abstract
Na<sub>V</sub>1.7 is a voltage-gated
sodium ion channel implicated
by human genetic evidence as a therapeutic target for the treatment
of pain. Screening fractionated venom from the tarantula Grammostola porteri led to the identification of
a 34-residue peptide, termed GpTx-1, with potent activity on Na<sub>V</sub>1.7 (IC<sub>50</sub> = 10 nM) and promising selectivity against
key Na<sub>V</sub> subtypes (20× and 1000× over Na<sub>V</sub>1.4 and Na<sub>V</sub>1.5, respectively). NMR structural analysis
of the chemically synthesized three disulfide peptide was consistent
with an inhibitory cystine knot motif. Alanine scanning of GpTx-1
revealed that residues Trp<sup>29</sup>, Lys<sup>31</sup>, and Phe<sup>34</sup> near the C-terminus are critical for potent Na<sub>V</sub>1.7 antagonist activity. Substitution of Ala for Phe at position
5 conferred 300-fold selectivity against Na<sub>V</sub>1.4. A structure-guided
campaign afforded additive improvements in potency and Na<sub>V</sub> subtype selectivity, culminating in the design of [Ala5,Phe6,Leu26,Arg28]GpTx-1
with a Na<sub>V</sub>1.7 IC<sub>50</sub> value of 1.6 nM and >1000×
selectivity against Na<sub>V</sub>1.4 and Na<sub>V</sub>1.5
