Recombinant SARS-CoV-2 envelope protein traffics to the trans-Golgi network following amphipol-mediated delivery into human cells

James M Hutchison,Ricardo Capone,Dustin D Luu,Karan H Shah,Arina Hadziselimovic,Wade D Van Horn,Charles R Sanders

doi:10.1016/j.jbc.2021.100940

Abstract

The severe acute respiratory syndrome coronavirus 2 envelope protein (S2-E) is a conserved membrane protein that is important for coronavirus (CoV) assembly and budding. Here, we describe the recombinant expression and purification of S2-E in amphipol-class amphipathic polymer solutions, which solubilize and stabilize membrane proteins, but do not disrupt membranes. We found that amphipol delivery of S2-E to preformed planar bilayers results in spontaneous membrane integration and formation of viroporin cation channels. Amphipol delivery of the S2-E protein to human cells results in plasma membrane integration, followed by retrograde trafficking to the trans-Golgi network and accumulation in swollen perinuclear lysosomal-associated membrane protein 1–positive vesicles, likely lysosomes. CoV envelope proteins have previously been proposed to manipulate the luminal pH of the trans-Golgi network, which serves as an accumulation station for progeny CoV particles prior to cellular egress via lysosomes. Delivery of S2-E to cells will enable chemical biological approaches for future studies of severe acute respiratory syndrome coronavirus 2 pathogenesis and possibly even development of “Trojan horse” antiviral therapies. Finally, this work also establishes a paradigm for amphipol-mediated delivery of membrane proteins to cells.

Highlights

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a focal point of science and society in 2020
These results demonstrate that recombinant SARS-CoV-2 envelope protein (S2-E) can be delivered into preformed lipid bilayers using amphipols, where the protein inserts into the bilayers and retains ion channel function, without compromising the bilayer integrity
We have shown that the S2-E protein can be stripped of lipid and detergent and purified into aqueous solutions in which its solubility is maintained solely by complexation with amphipols

Summary

ACCELERATED COMMUNICATION

Hutchison1,2,‡ , Ricardo Capone2,3,‡ , Dustin D. Sanders2,3,6,* From the 1Chemical and Physical Biology Graduate Program, 2Center for Structural Biology, 3Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; 4School of Molecular Sciences, 5The Biodesign Institute Centers for Personalized Diagnostics and Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA; 6Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA

Edited by Karen Fleming

Results and discussion

Conclusions