Post-translational modifications of coronavirus proteins: roles and function

Fung, To Sing; Liu, Ding Xiang

A novel form of PTM known as ADP-ribosylation was recently recognized, in which single or multiple ADPribose moieties are covalently attached to a protein. This process is catalyzed by enzymes called poly-ADP-ribose polymerases and utilizes nicotinamide adenine dinucleotide as the ADP-ribose donor. Interestingly, N proteins of MHV, PEDV, SARS-CoV and MERS-CoV were all shown to be ADP-ribosylated in the infected cells, while ADPribosylated MHV N protein was also detected in the purified virions [121] . Notably, MHV N protein expressed from transfected plasmids was only ADP-ribosylated in the context of virus infection, suggesting that enzymes catalyzing this modification are activated by coronavirus infection and additional viral components may be involved.