Post-translational modifications of coronavirus proteins: roles and function

Fung, To Sing; Liu, Ding Xiang

Phosphorylation of the SARS-CoV N protein may also affect its nucleocytoplasmic shuttling, which is mediated by its interaction with the host adapter protein 14-13-3 [129] . Additionally, SARS-CoV N protein was shown to translocate to cytoplasmic stress granules in response to cellular stress, while phosphorylation in the serinearginine rich region inhibited this translocation [133] . Since stress granules play important roles in translation control and antiviral immune response, phosphorylation of N protein may be a strategy used by SARS-CoV to antagonize host antiviral mechanisms [134] . At last, compared with SARS-CoV N protein expressed in Escherichia coli, recombinant SARS-CoV N protein produced by the baculovirus system in insect cells showed significantly higher immunoreactivity and antigenic specificity [135] . As dephosphorylation by PP1 also reduced the immunoreactivity of SARS-CoV N protein, it was proposed that phosphorylation might also contribute to the antigenicity SARS-CoV N protein [135] .