PhD Scientific Days 2023

Molecular Sciences - Posters L

The Effect of SARS-CoV-2 E Protein on the SERCA Regulatory System

Text of the abstract

Introduction: The SARS-CoV-2 coronavirus (COVID-19)-caused acute respiratory syndrome has emerged as a major global threat. The smallest structural protein of the SARS-CoV-2 virus, the envelope protein (E protein), regulates viral replication, but its exact role is not well understood. During the replication cycle of CoV, it was observed that E protein is expressed in high numbers in infected cells but in low numbers in the viral membrane, suggesting that this protein may play an important role in manipulating host cell systems. E protein has one transmembrane (TM) helix that forms a pentamer and as a viroporin, conduct cations across lipid membranes. This may disrupt the Ca2+ gradient in the endoplasmic reticulum,generated by the sarco/endoplasmic reticulum Ca2+ATPase (SERCA). Its regulator proteins, the so-called regulins (phospholamban: PLN, another-regulin: ALN, endoregulin: ELN) are also 1-TM proteins. Like the E protein, they are also capable of forming pentamers but they modify the SERCA activity in a monomeric form. The pentameric pool regulates the size of the monomeric pool, adding another layer of regulation to the SERCA system.
Aims: Our objective was to investigate the localisation of SARS-CoV-2 E protein, regulins and SERCA in cells and whether these proteins interact with each other, in particular SERCA and E protein, which we investigated by FRET. We also performed functional measurements to assess whether the interaction of SERCA and E protein alters Ca2+ homeostasis.
Methods and Result: Our FRET results confirm that the E protein is able to interact with members of the SERCA regulatory system, both SERCA itself and regulins (PLN and ELN). Examination of ER calcium dynamics shows that in the presence of the E protein, the ER Ca2+ signal is less stable and easily disturbed by paracrine stimulation.
Conclusion: Our results demonstrate that the altered Ca2+ signalling is not the result of the Ca2+ viroporin function of E protein, but the inhibition of Ca2+ ER reload by SERCA. Understanding how viral proteins modulate cellular signalling will contribute to understanding the complex phenotype of infections.
Funding: NKFIH 127961 és 137610

e-mail: blanka9707@gmail.com, Doctoral School of Theoretical and Translational Medicine, Supervisor: Dr. Padányi Rita