A reexamination of poneratoxin from the venom of the bullet ant Paraponera clavata.
In 1991, Piek et al. [45] described a voltage-gated sodium channel (VGSC) modifier from "bullet ant" (Paraponera clavata) venom they called poneratoxin (PoTx). Using UV chromatography and Edman degradation they showed two "identical peptides" of 25 residues. We reinvestigated PoTx using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-TMS). De novo sequencing showed the two peptides were actually structurally different peptides: the originally described PoTx and a glycyl pro-peptide (glycyl-PoTx) that lacks C-terminus amidation. We examined P. clavata venom from different geographical locations and discovered two additional PoTx analogs: an A23E substitution analog and a D22N; A23V substitutions analog. We tested PoTx and these three natural analogs on the mammalian sensory voltage-gated sodium channel, Nav1.7, using whole cell voltage-clamp. PoTx and each analog induced slowly activating currents in response to small depolarizing steps and sustained currents due to blockade of channel inactivation, similar to that described previously in skeletal muscle [19]. Glycyl-PoTx had the same potency and efficacy as PoTx. A23E PoTx, with a decrease in both C-terminal net positive charge and hydrophobicity, had an eight-fold reduction in potency compared to PoTx. In contrast, the D22N; A23V PoTx, with an increase in both C-terminal net positive charge and hydrophobicity, had a nearly five-fold increase in potency compared to PoTx. We found that changes in PoTx C-terminus caused a significant change in PoTx potency.
Department of Biology, University of Illinois Springfield, Springfield, IL, United States; Department of Chemistry, University of Illinois Springfield, Springfield, IL, United States; Carbon Dynamics Institute, LLC, Sherman, IL, United States. Electronic address: srj@uis.edu.
Stephen R
SR
Johnson
Department of Biology, University of Illinois Springfield, Springfield, IL, United States; Department of Chemistry, University of Illinois Springfield, Springfield, IL, United States.
Hillary G
HG
Rikli
Southwestern Biological Institute, Tucson, AZ, United States.
Justin O
JO
Schmidt
Department of Neurology, University of Louisville, Louisville, KY, United States.
M Steven
MS
Evans
D000595:Amino Acid Sequence; D000818:Animals; D000862:Ant Venoms / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D001000:Ants / Q000502:physiology*; D002460:Cell Line; D002853:Chromatography, Liquid / Q000379:methods; D057927:Hydrophobic and Hydrophilic Interactions; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D062556:NAV1.7 Voltage-Gated Sodium Channel / Q000378:metabolism; D009498:Neurotoxins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D053719:Tandem Mass Spectrometry / Q000379:methods
D000862:Ant Venoms; D019476:Insect Proteins; D062556:NAV1.7 Voltage-Gated Sodium Channel; D009498:Neurotoxins; C072588:poneratoxin
Mass spectrometry; Neuroactive; Neurotoxin; Poneratoxin; Voltage-gated sodium channel