Engineering a stable and selective peptide blocker of the Kv1.3 channel in T lymphocytesPennington, M.W., Beeton, C., Galea, C.A., Smith, B.J., Chi, V., Monaghan, K.P., Garcia, A., Rangaraju, S., Giuffrida, A., Plank, D., Crossley, G., Nugent, D., Khaytin, I., Lefievre, Y., Peshenko, I., Dixon, C., Chauhan, S., Orzel, A., Inoue, T., Hu, X., Moore, R.V., Norton, R.S., Chandy, K.G.
(2009) Mol.Pharmacol. 75: 762-773
- PubMed: 19122005
- DOI: 10.1124/mol.108.052704
- PubMed Abstract:
Kv1.3 potassium channels maintain the membrane potential of effector memory (T(EM)) T cells that are important mediators of multiple sclerosis, type 1 diabetes mellitus, and rheumatoid arthritis. The polypeptide ShK-170 (ShK-L5), containing an N-term ...
Kv1.3 potassium channels maintain the membrane potential of effector memory (T(EM)) T cells that are important mediators of multiple sclerosis, type 1 diabetes mellitus, and rheumatoid arthritis. The polypeptide ShK-170 (ShK-L5), containing an N-terminal phosphotyrosine extension of the Stichodactyla helianthus ShK toxin, is a potent and selective blocker of these channels. However, a stability study of ShK-170 showed minor pH-related hydrolysis and oxidation byproducts that were exacerbated by increasing temperatures. We therefore engineered a series of analogs to minimize the formation of these byproducts. The analog with the greatest stability, ShK-192, contains a nonhydrolyzable phosphotyrosine surrogate, a methionine isostere, and a C-terminal amide. ShK-192 shows the same overall fold as ShK, and there is no evidence of any interaction between the N-terminal adduct and the rest of the peptide. The docking configuration of ShK-192 in Kv1.3 shows the N-terminal para-phosphonophenylalanine group lying at the junction of two channel monomers to form a salt bridge with Lys(411) of the channel. ShK-192 blocks Kv1.3 with an IC(50) of 140 pM and exhibits greater than 100-fold selectivity over closely related channels. After a single subcutaneous injection of 100 microg/kg, approximately 100 to 200 pM concentrations of active peptide is detectable in the blood of Lewis rats 24, 48, and 72 h after the injection. ShK-192 effectively inhibits the proliferation of T(EM) cells and suppresses delayed type hypersensitivity when administered at 10 or 100 microg/kg by subcutaneous injection once daily. ShK-192 has potential as a therapeutic for autoimmune diseases mediated by T(EM) cells.
Bachem Bioscience Inc., King of Prussia, Pennsylvania, USA.