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Effect of mutations in the SARS‐CoV‐2 spike protein on protein stability, cleavage, and cell‐cell fusion function
Author(s) -
Neal Hadley,
Barrett Chelsea,
Edmonds Kearstin,
Moncman Carole,
Thompson Rachel,
Branttie Jean,
Boggs Kerri Beth,
Wu ChengYu,
Leung Daisy,
Dutch Rebecca
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.05044
Subject(s) - cell fusion , microbiology and biotechnology , cell , lipid bilayer fusion , fusion protein , cytoplasm , cleavage (geology) , biology , cell culture , viral entry , cell membrane , biochemistry , virology , recombinant dna , virus , viral replication , genetics , gene , paleontology , fracture (geology)
The SARS‐CoV‐2 spike protein (S) is the sole viral protein responsible for both viral binding to a host cell and the membrane fusion event needed for cell entry. In addition to facilitating fusion needed for viral entry, S can also drive cell‐cell fusion, a pathogenic effect observed in the lungs of SARS‐CoV‐2 infected patients. While several studies have investigated S requirements involved in viral particle entry, examination of S stability and factors involved in S cell‐cell fusion remain limited. We demonstrate that S must be processed at the S1/S2 border in order to mediate cell‐cell fusion, and that mutations at potential cleavage sites within the S2 subunit alter S processing at the S1/S2 border, thus preventing cell‐cell fusion. We also identify residues within the internal fusion peptide and the cytoplasmic tail that modulate S cell‐cell fusion. Additionally, we examine S stability and protein cleavage kinetics in a variety of mammalian cell lines, including a bat cell line related to the likely reservoir species for SARS‐CoV‐2, and provide evidence that proteolytic processing alters the stability of the S trimer. This work therefore offers insight into S stability, proteolytic processing, and factors that mediate S cell‐cell fusion, all of which help give a more comprehensive understanding of this highly sought‐after therapeutic target.