Disruption of a Conservative Motif in the C-Terminal Loop of the KCNQ1 Channel Causes LQT Syndrome

Maria Karlova (1) , Denis Abramochkin (1) , Ksenia Pustovit (1) , Tatiana Nesterova (2, 3) , Valery Novoseletsky (1, 4) , Gildas Loussouarn (5) , Elena Zaklyazminskaya (6) , Olga Sokolova (1, 4)

1 MSU - Lomonosov Moscow State University
2 UB RAS - Ural Branch of Russian Academy of Sciences
3 UrFU - Ural Federal University [Ekaterinburg]
4 Shenzhen University [Shenzhen]
5 ITX - unité de recherche de l'institut du thorax UMR1087 UMR6291
6 Petrovsky National Research Centre of Surgery

We identified a single nucleotide variation (SNV) (c.1264A > G) in the KCNQ1 gene in a 5-year-old boy who presented with a prolonged QT interval. His elder brother and mother, but not sister and father, also had this mutation. This missense mutation leads to a p.Lys422Glu (K422E) substitution in the Kv7.1 protein that has never been mentioned before. We inserted this substitution in an expression plasmid containing Kv7.1 cDNA and studied the electrophysiological characteristics of the mutated channel expressed in CHO-K1, using the whole-cell configuration of the patch-clamp technique. Expression of the mutant Kv7.1 channel in both homo- and heterozygous conditions in the presence of auxiliary subunit KCNE1 results in a significant decrease in tail current densities compared to the expression of wild-type (WT) Kv7.1 and KCNE1. This study also indicates that K422E point mutation causes a dominant negative effect. The mutation was not associated with a trafficking defect; the mutant channel protein was confirmed to localize at the cell membrane. This mutation disrupts the poly-Lys strip in the proximal part of the highly conserved cytoplasmic A–B linker of Kv7.1 that was not shown before to be crucial for channel functioning.

Keywords: IKs; KCNQ1; Kv7.1; LQTS; inherited channelopathy; patch-clamp

Domains: Life Sciences [q-bio]; Cardiology and cardiovascular system

Maria Karlova, Denis Abramochkin, Ksenia Pustovit, Tatiana Nesterova, Valery Novoseletsky, et al.. Disruption of a Conservative Motif in the C-Terminal Loop of the KCNQ1 Channel Causes LQT Syndrome. International Journal of Molecular Sciences, 2022, 23 (14), pp.7953. ⟨10.3390/ijms23147953⟩. ⟨hal-03797267⟩