Interaction of agitoxin2, charybdotoxin, and iberiotoxin with potassium channels: Selectivity between voltage-gated and Maxi-K channels
To gain insight into the molecular determinants that define the specificity of interaction of pore‐blocking peptides, such as agitoxin 2 (AgTX2), charybdotoxin (ChTX), and iberiotoxin (IbTX) with the Shaker‐type voltage‐gated potassium channel Kv1.3, or the large‐conductance Ca2+‐activated K+ (Maxi‐...
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Published in | Proteins, structure, function, and bioinformatics Vol. 52; no. 2; pp. 146 - 154 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Hoboken
Wiley Subscription Services, Inc., A Wiley Company
01.08.2003
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Subjects | |
Online Access | Get full text |
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Summary: | To gain insight into the molecular determinants that define the specificity of interaction of pore‐blocking peptides, such as agitoxin 2 (AgTX2), charybdotoxin (ChTX), and iberiotoxin (IbTX) with the Shaker‐type voltage‐gated potassium channel Kv1.3, or the large‐conductance Ca2+‐activated K+ (Maxi‐K) channel, homology models of these channels were generated based on the crystal structure of the bacterial, KcsA, potassium channel. Peptide–channel complexes were analyzed to evaluate the predicted interaction interfaces between the peptides and the channels' outer vestibules. The docking model, for either AgTX2 or ChTX with the Kv1.3 channel, predicts a novel hydrogen bonding interaction between the Asn30 side‐chain of the peptide and the Asp381 side‐chain of the channel. This interaction is consistent with the >500‐fold decreased potency of both AgTX2 and ChTX mutants at position 30 for the Shaker channel [(Ranganathan et al., Neuron 1996;16:131–139); (Goldstein et al., Neuron 1994;12:1377–1388)]. This hydrogen bonding interaction also suggests that Gly30 in IbTX may be the critical determinant for its lack of activity against Shaker Kv channels. The model of the Maxi‐K channel reveals a narrower and more structurally restrained outer vestibule in which the aromatic residues Phe266 and Tyr294 may stabilize binding of IbTX and ChTX by π–π stacking with the aromatic residues Trp14 and Tyr36 of the peptides. This study also suggests that the extra net negative charge of IbTX is not related to the selectivity of this peptide for the Maxi‐K channel. Proteins 2003;52:146–154. © 2003 Wiley‐Liss, Inc. |
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Bibliography: | ArticleID:PROT10341 ark:/67375/WNG-Z1QG2BCX-6 istex:B3515A0E79DBC5A6FC67064115F46856983ADB16 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0887-3585 1097-0134 |
DOI: | 10.1002/prot.10341 |