Characterization of the novel heterozygous SCN5A genetic variant Y739D associated with Brugada syndrome

Anastasia K Zaytseva; Artem M Kiselev; Alexander S Boitsov; Yulia V Fomicheva; Georgii S Pavlov; Boris S Zhorov; Anna A Kostareva

doi:10.1016/j.bbrep.2022.101249

Characterization of the novel heterozygous SCN5A genetic variant Y739D associated with Brugada syndrome

Biochem Biophys Rep. 2022 Mar 11:30:101249. doi: 10.1016/j.bbrep.2022.101249. eCollection 2022 Jul.

Authors

Anastasia K Zaytseva^{1

2}, Artem M Kiselev^{1

3}, Alexander S Boitsov¹, Yulia V Fomicheva¹, Georgii S Pavlov¹, Boris S Zhorov^{1

2

4}, Anna A Kostareva^{1

5}

Affiliations

¹ Almazov National Medical Research Centre, St. Petersburg, 197341, Russia.
² Sechenov Institute of Evolutionary Physiology & Biochemistry, Russian Academy of Sciences, St. Petersburg, 194223, Russia.
³ Institute of Cytology, Russian Academy of Sciences, Saint Petersburg, Russia.
⁴ Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, L8S 4K1, Canada.
⁵ Department of Woman and Child Health, Karolinska Institute, Stockholm, 17176, Sweden.

Abstract

Genetic variants in SCN5A gene were identified in patients with various arrhythmogenic conditions including Brugada syndrome. Despite significant progress of last decades in studying the molecular mechanism of arrhythmia-associated SCN5A mutations, the understanding of relationship between genetics, electrophysiological consequences and clinical phenotype is lacking. We have found a novel genetic variant Y739D in the SCN5A-encoded sodium channel Na_v1.5 of a male patient with Brugada syndrome (BrS). The objective of the study was to characterize the biophysical properties of Na_v1.5-Y739D and provide possible explanation of the phenotype observed in the patient. The WT and Y739D channels were heterologously expressed in the HEK-293T cells and the whole-cell sodium currents were recorded. Substitution Y739D reduced the sodium current density by 47 ± 2% at -20 mV, positively shifted voltage-dependent activation, accelerated both fast and slow inactivation, and decelerated recovery from the slow inactivation. The Y739D loss-of-function phenotype likely causes the BrS manifestation. In the hNa_v1.5 homology models, which are based on the cryo-EM structure of rat Na_v1.5 channel, Y739 in the extracellular loop IIS1-S2 forms H-bonds with K1381 and E1435 and pi-cation contacts with K1397 (all in loop IIIS5-P1). In contrast, Y739D accepts H-bonds from K1397 and Y1434. Substantially different contacts of Y739 and Y739D with loop IIIS5-P1 would differently transmit allosteric signals from VSD-II to the fast-inactivation gate at the N-end of helix IIIS5 and slow-inactivation gate at the C-end of helix IIIP1. This may underlie the atomic mechanism of the Y739D channel dysfunction.

Keywords: BrS, Brugada syndrome; Brugada syndrome; Homology modeling; INa, Sodium current; MC, Monte Carlo; MCM, MC-minimization; Nav, Voltage gated sodium channels; P-loops, Membrane-diving extracellular loops between helices S5 and S6; P1 and P2, P-loop helices N- and C-terminal, respectively, to the selectivity filter residues; S1-S6, transmembrane helices in Nav1.5; SCN5A; Sodium channel; Sodium channelopathies; VSD, Voltage-Sensing Domain; hNav1.5, human Nav1.5; rNav1.5, rat Nav1.5.