A potent and selective peptide blocker of the Kv1.3 channel: prediction from free-energy simulations and experimental confirmation.
The voltage-gated potassium channel Kv1.3 is a well-established target for treatment of autoimmune diseases. ShK peptide from a sea anemone is one of the most potent blockers of Kv1.3 but its application as a therapeutic agent for autoimmune diseases is limited by its lack of selectivity against other Kv channels, in particular Kv1.1. Accurate models of Kv1.x-ShK complexes suggest that specific charge mutations on ShK could considerably enhance its specificity for Kv1.3. Here we evaluate the K18A mutation on ShK, and calculate the change in binding free energy associated with this mutation using the path-independent free energy perturbation and thermodynamic integration methods, with a novel implementation that avoids convergence problems. To check the accuracy of the results, the binding free energy differences were also determined from path-dependent potential of mean force calculations. The two methods yield consistent results for the K18A mutation in ShK and predict a 2 kcal/mol gain in Kv1.3/Kv1.1 selectivity free energy relative to wild-type peptide. Functional assays confirm the predicted selectivity gain for ShK[K18A] and suggest that it will be a valuable lead in the development of therapeutics for autoimmune diseases.
School of Physics, University of Sydney, Sydney, New South Wales, Australia.
M Harunur
MH
Rashid
Germano
G
Heinzelmann
Redwan
R
Huq
Rajeev B
RB
Tajhya
Shih Chieh
SC
Chang
Sandeep
S
Chhabra
Michael W
MW
Pennington
Christine
C
Beeton
Raymond S
RS
Norton
Serdar
S
Kuyucak
D019943:Amino Acid Substitution; D000818:Animals; D001327:Autoimmune Diseases / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003198:Computer Simulation; D005260:Female; D051664:Kv1.3 Potassium Channel / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D020125:Mutation, Missense; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D011917:Rats, Inbred Lew; D013816:Thermodynamics
C496974:Kcna3 protein, mouse; C496975:Kcna3 protein, rat; D051664:Kv1.3 Potassium Channel; D010455:Peptides; D026902:Potassium Channel Blockers