Transfer of rolf S3-S4 linker to HERG eliminates activation gating but spares inactivation.
Studies in Shaker, a voltage-dependent potassium channel, suggest a coupling between activation and inactivation. This coupling is controversial in hERG, a fast-inactivating voltage-dependent potassium channel. To address this question, we transferred to hERG the S3-S4 linker of the voltage-independent channel, rolf, to selectively disrupt the activation process. This chimera shows an intact voltage-dependent inactivation process consistent with a weak coupling, if any, between both processes. Kinetic models suggest that the chimera presents only an open and an inactivated states, with identical transition rates as in hERG. The lower sensitivity of the chimera to BeKm-1, a hERG preferential closed-state inhibitor, also suggests that the chimera presents mainly open and inactivated conformations. This chimera allows determining the mechanism of action of hERG blockers, as exemplified by the test on ketoconazole.
Choveau
Frank S
FS
INSERM, UMR915, Nantes, F-44035, France.
El Harchi
Aziza
A
Rodriguez
Nicolas
N
Louérat-Oriou
Bénédicte
B
Baró
Isabelle
I
Demolombe
Sophie
S
Charpentier
Flavien
F
Loussouarn
Gildas
G
D000704:Analysis of Variance; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D007654:Ketoconazole / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials; D008954:Models, Biological; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012604:Scorpion Venoms / Q000494:pharmacology
C425305:BeKm-1 toxin; D054815:Cyclic Nucleotide-Gated Cation Channels; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; D026902:Potassium Channel Blockers; D011993:Recombinant Fusion Proteins; D012604:Scorpion Venoms; D007654:Ketoconazole