title: N-Terminally extended analogues of the K⁺ channel toxin from Stichodactyla helianthus as potent and selective blockers of the voltage-gated potassium channel Kv1.3.
abstract: The voltage-gated potassium channel Kv1.3 is an important target for the treatment of autoimmune diseases and asthma. Blockade of Kv1.3 by the sea anemone peptide K⁺-channel toxin from Stichodactyla helianthus (ShK) inhibits the proliferation of effector memory T lymphocytes and ameliorates autoimmune diseases in animal models. However, the lack of selectivity of ShK for Kv1.3 over the Kv1.1 subtype has driven a search for Kv1.3-selective analogues. In the present study, we describe N-terminally extended analogues of ShK that contain a negatively-charged Glu, designed to mimic the phosphonate adduct in earlier Kv1.3-selective analogues, and consist entirely of common protein amino acids. Molecular dynamics simulations indicated that a Trp residue at position [-3] of the tetrapeptide extension could form stable interactions with Pro377 of Kv1.3 and best discriminates between Kv1.3 and Kv1.1. This led to the development of ShK with an N-terminal Glu-Trp-Ser-Ser extension ([EWSS]ShK), which inhibits Kv1.3 with an IC₅₀ of 34 pm and is 158-fold selective for Kv1.3 over Kv1.1. In addition, [EWSS]ShK is more than 2900-fold more selective for Kv1.3 over Kv1.2 and KCa3.1 channels. As a highly Kv1.3-selective analogue of ShK based entirely on protein amino acids, which can be produced by recombinant expression, this peptide is a valuable addition to the complement of therapeutic candidates for the treatment of autoimmune diseases.
authors: Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia.
authors: Shih C
authors: SC
authors: Chang
authors: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA.
authors: Redwan
authors: R
authors: Huq
authors: Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia.
authors: Sandeep
authors: S
authors: Chhabra
authors: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA.
authors: Christine
authors: C
authors: Beeton
authors: Peptides International, Louisville, KY, USA.
authors: Michael W
authors: MW
authors: Pennington
authors: Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Vic., Australia.
authors: Brian J
authors: BJ
authors: Smith
authors: Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia.
authors: Raymond S
authors: RS
authors: Norton
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D002460:Cell Line; D003064:Cnidarian Venoms; D015195:Drug Design; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D051664:Kv1.3 Potassium Channel / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D009498:Neurotoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D009842:Oligopeptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012615:Sea Anemones; D013329:Structure-Activity Relationship
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D003064:Cnidarian Venoms; D007527:Isoenzymes; C496974:Kcna3 protein, mouse; D051664:Kv1.3 Potassium Channel; D050505:Mutant Proteins; D009498:Neurotoxins; D009842:Oligopeptides; D026902:Potassium Channel Blockers; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins
keywords: N-terminal extension; ShK; electrophysiology; molecular dynamics; potassium channels