Post-translational Modification of a Key Transcription Factor for HSV-1 Infection
Dr. Steven Triezenberg Laboratory of Transcriptional Regulation, Van Andel Institute
Herpes simplex virus type 1 (HSV-1) is a highly prevalent human virus that causes cold sores. The HSV-1 virion contains VP16, a potent transcriptional activator that recruits host cell proteins, including Oct-1, to initiate viral immediate early (IE) gene expression and therefore the lytic cycle. VP16 is also an important structural protein within the viral tegument. As VP16 is so multifunctional, we hypothesize that phosphorylation of serine 375 of VP16 is important for the regulation of VP16’s function throughout different times during the lytic cycle. Immunoblots revealed serine 375 phosphorylation at 20 hpi (hours post infection). Immunofluorescence assays of infected cells revealed detectable VP16 phosphorylation by 8 hpi, with dramatic increases through 24 hpi. Phosphorylated VP16 colocalized with AP1AR, a cellular adaptor protein implicated in tegument packaging. Phosphorylated VP16 was also detected in the virions by western blot. These data indicate that phosphorylation of serine 375 may be necessary for VP16’s role as a tegument protein. Alternatively, VP16 may need to be pre-phosphorylated to induce IE gene expression and initiate the following lytic cycle. Future work will characterize the role Ser375 phosphorylation plays in VP16’s interactions with host cell proteins throughout the lytic cycle.
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