Energetic and structural interactions between delta-dendrotoxin and a voltage-gated potassium channel.
Dendrotoxin proteins isolated from Mamba snake venom block potassium channels with a high degree of specificity and selectivity. Using site-directed mutagenesis we have identified residues that constitute the functional interaction surfaces of delta-dendrotoxin and its voltage-gated potassium channel receptor. delta-Dendrotoxin uses a triangular patch formed by seven side-chains (Lys3, Tyr4, Lys6, Leu7, Pro8, Arg10, Lys26) to block K(+) currents carried by a Shaker potassium channel variant. The inhibitory surface of the toxin interacts with channel residues at Shaker positions 423, 425, 427, 431, and 449 near the pore. Amino acid mutations that interact across the toxin-channel interface were identified by mutant cycle analysis. These results constrain the possible orientation of dendrotoxin with respect to the K(+) channel structure. We propose that dendrotoxin binds near the pore entryway but does not act as a physical plug.
Imredy
J P
JP
Howard Hughes Medical Institute, Laboratory of Molecular Neurobiology and Biophysics, New York, NY 10021, USA.
MacKinnon
R
R
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001665:Binding Sites; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000737:chemistry / Q000378:metabolism; D004546:Elapid Venoms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D004594:Electrophysiology; D014644:Genetic Variation / Q000235:genetics; D015640:Ion Channel Gating; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D009865:Oocytes; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D051637:Shaker Superfamily of Potassium Channels; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D014982:Xenopus laevis
D029721:Drosophila Proteins; D004546:Elapid Venoms; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C496929:Sh protein, Drosophila; D051637:Shaker Superfamily of Potassium Channels; C020273:dendrotoxin