Localization of the voltage-sensor toxin receptor on KvAP.
A variety of venomous animals produce small protein toxins that impair the function of voltage-dependent cation channels by affecting the motions of the voltage-sensor domains and altering the energetics of the opening of the channel. In this study, we investigate the location of the receptor for tarantula venom voltage-sensor toxins on the voltage-dependent K+ channel from Aeropyrum pernix (KvAP), an archeabacterial channel that is functionally inhibited by members of this toxin family. We show that it is possible to purify the same set of toxins from venom of the tarantula Grammostola spatulata using either the purified KvAP voltage-sensor domain or the full-length KvAP channel. The equivalence of toxin retention profiles for the two channel proteins implies that the tarantula voltage-sensor toxin receptor resides exclusively on the voltage-sensor domain and that the pore is not required for the toxin-channel interaction. We have identified and characterized the functional properties of a subset of the tarantula toxins that bind to the KvAP voltage-sensor domain. Some of these toxins, VSTX1 and GSMTX4, have been previously isolated, while others, VSTX2 and VSTX3, are new members of the tarantula voltage-sensor toxin family. Some but not all toxins that bind to the voltage-sensor domain affect voltage-dependent gating of KvAP channels in lipid membranes.
Howard Hughes Medical Institute, Rockefeller University, 1230 York Avenue, New York, New York 10021, USA.
Vanessa
V
Ruta
Roderick
R
MacKinnon
D041522:Aeropyrum / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D019843:Archaeal Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017124:Conserved Sequence; D036341:Intercellular Signaling Peptides and Proteins; D008051:Lipid Bilayers / Q000378:metabolism; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013111:Spider Venoms / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
D019843:Archaeal Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008051:Lipid Bilayers; C411249:MTx4 protein, Grammostola spatulata; D010455:Peptides; D024642:Potassium Channels, Voltage-Gated; D013111:Spider Venoms; C487989:VSTX1 protein, Grammostola spatulata