Liquid–liquid phase separation by SARS-CoV-2 nucleocapsid protein and RNA

Abstract

Dear Editor, The COVID-19 pandemic worldwide is caused by a novel coronavirus SARS-CoV-2 (the severe acute respiratory syndrome coronavirus 2). 1 After viral invasion into the host cells, the~30 kb viral genome RNA injected is translated into structural and nonstructural proteins to replicate viral genome and assemble more viral particles. Many copies of nucleocapsid (N) protein can bind to viral genome RNA and pack it into~100 nm particles, assisting membrane (M) and envelope (E) proteins to efficiently assemble the viral envelope. 2 The exact molecular mechanism by which N protein packs up the viral genome still remains elusive. An N protein of SARS-CoV-2 consists of an N-terminal RNAbinding domain (NTD) and a C-terminal dimerization domain (CTD) and shares~90% sequence identity with N protein of SARS-CoV (Supplementary information, Fig. S1a). The regions located between the N-terminus and NTD, between NTD and CTD, and between CTD and the C-terminus of the N protein of SARS-CoV-2 (thereafter referred to as N protein) are predicted to be intrinsically disordered (Supplementary information, Fig. S1b, c). At neutral pH, the N protein is positively charged (+24 e), consistent with its strong binding affinity with negatively charged

SARS-CoV-2 Nucleocapsid Protein Interacts with RIG-I and Represses RIG-Mediated IFN-β Production

“…However, studies have shown that SARS-CoV N protein disturbed the IFN-β levels [ 22 , 23 , 24 ], and recent studies have suggested that SARS-CoV-2 caused a delayed interferon response [ 6 ]. Indeed, SARS-CoV-2 N protein plays a key role in viral genome packaging and the replication cycle [ 38 , 39 ]. Here, we explored the relationship between SARS-CoV-2 N protein and IFN-β response.…”

“…Recent studies have shown that SARS-CoV-2 N protein plays a key role in viral genome packaging [ 38 , 39 ]. Indeed, RIG-I is a key sensor of RNA virus infection, which mediates the activation of type I interferons and other genes that collectively establish an antiviral host response.…”

The mechanism of SARS-CoV-2 nucleocapsid protein recognition by the human 14-3-3 proteins

“…2A) [20][21][22]. Such organization allows for a vast conformational change, which in combination with positively charged surfaces [23], facilitates nucleic acid binding [24]. Indeed, the crystal structure of the N-terminal domain (NTD) reveals an RNA binding groove [25][26][27], while crystal structures of the Cterminal domain (CTD) show a highly interlaced dimer with additional nucleic acid binding capacity [28,29].…”

SARS-CoV-2 nucleocapsid protein undergoes liquid–liquid phase separation into stress granules through its N-terminal intrinsically disordered region

“…Finally, we would like to point out that while we were in the process of preparing this manuscript, a paper was published showing that N protein phase separated with RNA and that this process could be enhanced by Zn 2+ 14 . Similar to these findings, we also demonstrated that N protein phase separation was triggered by HeLa cell total RNAs in a dose-dependent manner.…”