Effects of glutathionylation on guanylyltransferase activity of NS5 N-terminal capping domain from dengue, Japanese encephalitis and zika viruses

Abstract Three arboviruses, dengue virus, Zika virus and Japanese encephalitis virus, have wide distribution putting millions of people at risk of infection. These three flaviviruses show evolutionarily conserved features for the viral proteins, which consist of seven non-structural and three structural proteins. Non-structural protein 5 (NS5) is important for viral replication as it possesses multiple functions including both enzyme and non-enzyme roles. Oxidative stress induced by virus infection triggers glutathionylation of cell proteins. This study was to identify the effects of modification by glutathionylation on the guanylyltransferase activity of NS5 and identify the cysteine residues modified for the three flavivirus NS5 proteins. We found the three flavivirus proteins behaved in a similar fashion with increasing glutathionylation yielding decreasing guanylyltransferase activity. The three proteins also possessed conserved cysteines and these appeared to be modified for all three proteins. The glutathionylation appears to induce conformational changes that affect enzyme activity but possibly also create binding sites for host cell protein interactions that occur at later stages of viral propagation.