Bovine herpesvirus-1 VP8 interacts with DNA damage binding protein-1 (DDB1) and is monoubiquitinated during infection

VP8 is the most abundant tegument protein of bovine herpesvirus-1 (BHV-1). In the present study DNA damage binding protein 1 (DDB1) was identified as interacting partner of VP8. MALDI-TOF mass spectroscopy analysis of proteins co-immunoprecipitated with VP8 identified DDB1 as a protein interacting with VP8. The interaction between VP8 and DDB1 was confirmed based on co-immunoprecipitation and co-localization in both VP8-transfected and BHV-1 infected cells. DDB1 was distributed both in the nucleus and the cytoplasm with some nuclear speckles prior to BHV-1 infection, became perinuclear by 4 h and was predominantly nuclear at 5 h post infection, where it co-localized with VP8. In contrast, in cells infected with a UL47 deletion mutant DDB1 remained cytoplasmic throughout the course of infection. This suggests that VP8 mediates nuclear re-localization of DDB1. Finally, VP8 was shown to be monoubiquitinated both in VP8-transfected and BHV-1-infected cells. These data suggest that BHV-1 VP8 interacts with DDB1-CUL4 E3 ubiquitin ligase, which correlates to monoubiquitination of this viral protein.

► DNA damage binding protein 1 (DDB1) is an interacting partner of BHV-1 VP8. ► DDB1–VP8 interaction was confirmed in VP8-transfected and BHV-1 infected cells. ► As DDB1 co-localized with VP8 to the nucleus, VP8 may mediate its nuclear transport. ► VP8 is monoubiquitinated suggesting interaction with DDB1-CUL4 E3 ubiquitin ligase.