Modulation of host PP1 activity by virus

Protein phosphatase-1 PP1 is a member of the Serine/Threonine phosphatases. The enzyme regulates many important physiological processes, including gene transcription, translation, metabolism, cell growth and division. Different viruses modulate PP1 phosphatase activity in order to remove phospate from specific cellular substrates. Among them, eIF2alpha phosphorylation seems to be a common target for viral proteins. Indeed, papillomavirus E6, Asfivirus DP71L, herpes virus ICP34.5, EBV EBNA2 are able to dephosphorylate eIF2alpha via interaction with PP1. This mechanism is very important for viruses, since upon infection the host PKR usually trigger the phosphorylation of eIF-2alpha leading to complete shuttoff of translation in the infected cell. By dephosphroylating eIF-2alpha through PP1, viruses manage to circumvent this antiviral response and prevent translational shutoff.