Gene expression of DNA viruses requires nuclear import of the viral genome. Human Adenoviruses (Ads), like most DNA viruses, encode factors within early transcription units promoting their own gene expression and counteracting cellular antiviral defense mechanisms. The cellular transcriptional repressor Daxx prevents viral gene expression through the assembly of repressive chromatin remodeling complexes targeting incoming viral genomes. However, it has remained unclear how initial transcriptional activation of the adenoviral genome is achieved. Here we show that Daxx mediated repression of the immediate early Ad E1A promoter is efficiently counteracted by the capsid protein VI. This requires a conserved PPxY motif in protein VI. Capsid proteins from other DNA viruses were also shown to activate the Ad E1A promoter independent of Ad gene expression and support virus replication. Our results show how Ad entry is connected to transcriptional activation of their genome in the nucleus. Our data further suggest a common principle for genome activation of DNA viruses by counteracting Daxx related repressive mechanisms through virion proteins.
Transcriptional activation of the adenoviral genome is mediated by capsid protein VI
Schreiner, S.; Martinez, R.; Groitl, P.; Rayne, F.; Vaillant, R.; Wimmer, P.; Bossis, G.; Sternsdorf, T.; Marcinowski, L.; Ruzsics, Z.; Dobner, T.; Wodrich, H.
2012-02 / vol 8 / pages e1002549
10.1371/journal.ppat.1002549 PPATHOGENS-D-11-01833 [pii]
1553-7374 (Electronic) 1553-7366 (Linking)
Humans; Cells, Cultured; Transfection; Adenoviridae/*genetics; *Genome, Viral/genetics; Adaptor Proteins, Signal Transducing/genetics/physiology; Amino Acid Motifs/genetics/physiology; Capsid Proteins/chemistry/genetics/metabolism/*physiology; Gene Expression Regulation, Viral; Genes, Viral/physiology; Genetic Fitness/physiology; Mutant Proteins/chemistry/genetics/metabolism/physiology; Nuclear Proteins/genetics/physiology; Transcription Factors/genetics/metabolism/physiology; Transcriptional Activation/*genetics; Viral Proteins/chemistry/metabolism/physiology; Virus Replication/genetics