The HPV genome is a double-stranded, covalently closed DNA molecule of 8kbp that is packaged in a chromatinized form. The viral E1 and E2 proteins are the key replication activators and form a complex that recognizes the viral origin. E1 acts as DNA helicase and recruits host cell proteins to initiate the replication of the genome. E2 is not only a loader for the E1 helicase but also modulates viral transcription and acts as segregation factor for the viral genomes upon cell division.
Our studies have uncovered that HPV encode E8^E2, an alternative E2 protein, which limits viral replication in undifferentiated cells by repressing viral transcription and E1/E2-dependent DNA replication. Using a panel of different technologies (immunoprecipitation-mass spectrometry, fluorescence microscopy, RNA interference, transcription and replication reporter assays), we have identified the cellular NCoR/SMRT repressor complex as a mediator of E8^E2´s repression activities.
- we investigate the molecular mechanism of repression by the E8^E2-NCoR/SMRT complex
- we investigate the long-term phenotypes of E8^E2 knock out PV genomes in tissue culture and animal models
we identify and characterize post-translational modifications (phosphorylation, acetylation, etc.) of the viral replication proteins E1, E2 and E8^E2C