Comprehensive engineering of the tarantula venom peptide huwentoxin-IV to inhibit the human voltage-gated sodium channel hNa_v1.7.

ABSTRACT: Pain is a significant public health burden in the United States, and current treatment approaches rely heavily on opioids, which often have limited efficacy and can lead to addiction. In humans, functional loss of the voltage-gated sodium channel Na_v1.7 leads to pain insensitivity without deficits in the central nervous system. Accordingly, discovery of a selective Na_v1.7 antagonist should provide an analgesic without abuse liability and an improved side-effect profile. Huwentoxin-IV, a component of tarantula venom, potently blocks sodium channels and is an attractive scaffold for engineering a Na_v1.7-selective molecule. To define the functional impact of alterations in huwentoxin-IV sequence, we produced a library of 373 point mutants and tested them for Na_v1.7 and Na_v1.2 activity. We then combined favorable individual changes to produce combinatorial mutants that showed further improvements in Na_v1.7 potency (E1N, E4D, Y33W, Q34S-Na_v1.7 pIC₅₀ = 8.1 ± 0.08) and increased selectivity over other Na_v isoforms (E1N, R26K, Q34S, G36I, Na_v1.7 pIC₅₀ = 7.2 ± 0.1, Na_v1.2 pIC₅₀ = 6.1 ± 0.18, Na_v1.3 pIC₅₀ = 6.4 ± 1.0), Na_v1.4 is inactive at 3 ?m, and Na_v1.5 is inactive at 10 ?m We also substituted noncoded amino acids at select positions in huwentoxin-IV. Based on these results, we identify key determinants of huwentoxin's Na_v1.7 inhibition and propose a model for huwentoxin-IV's interaction with Na_v1.7. These findings uncover fundamental features of huwentoxin involved in Na_v1.7 blockade, provide a foundation for additional optimization of this molecule, and offer a basis for the development of a safe and effective analgesic.

SUBMITTER: Neff RA 

PROVIDER: S-EPMC6996889 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature