A bivalent tarantula toxin activates the capsaicin receptor, TRPV1, by targeting the outer pore domain.
Toxins have evolved to target regions of membrane ion channels that underlie ligand binding, gating, or ion permeation, and have thus served as invaluable tools for probing channel structure and function. Here, we describe a peptide toxin from the Earth Tiger tarantula that selectively and irreversibly activates the capsaicin- and heat-sensitive channel, TRPV1. This high-avidity interaction derives from a unique tandem repeat structure of the toxin that endows it with an antibody-like bivalency. The "double-knot" toxin traps TRPV1 in the open state by interacting with residues in the presumptive pore-forming region of the channel, highlighting the importance of conformational changes in the outer pore region of TRP channels during activation.
Department of Physiology, University of California, San Francisco, San Francisco, CA 94143-2140, USA.
Christopher J
CJ
Bohlen
Avi
A
Priel
Sharleen
S
Zhou
David
D
King
Jan
J
Siemens
David
D
Julius
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D055724:Electrophysiological Phenomena; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D051381:Rats; D013111:Spider Venoms / Q000737:chemistry / Q000378:metabolism*; D050916:TRPV Cation Channels / Q000737:chemistry / Q000378:metabolism*; D012668:Trigeminal Ganglion / Q000166:cytology / Q000378:metabolism; D029867:Xenopus Proteins / Q000737:chemistry / Q000378:metabolism*
D013111:Spider Venoms; D050916:TRPV Cation Channels; C550099:TRPV1 protein, Xenopus; C493922:Trpv1 protein, rat; D029867:Xenopus Proteins