Default assembly of early adenovirus chromatin

Abstract

In adenovirus particles, the viral nucleoprotein is organized into a highly compacted core structure. Upon delivery to the nucleus, the viral nucleoprotein is very likely to be remodeled to a form accessible to the transcription and replication machinery. Viral protein VII binds to intra-nuclear viral DNA, as do at least two cellular proteins, SET/TAF-Ibeta and pp32, components of a chromatin assembly complex that is implicated in template remodeling. We showed previously that viral DNA-protein complexes released from infecting particles were sensitive to shearing after cross-linking with formaldehyde, presumably after transport of the genome into the nucleus. We report here the application of equilibrium-density gradient centrifugation to the analysis of the fate of these complexes. Most of the incoming protein VII was recovered in a form that was not cross-linked to viral DNA. This release of protein VII, as well as the binding of SET/TAF-Ibeta and cellular transcription factors to the viral chromatin, did not require de novo viral gene expression. The distinct density profiles of viral DNA complexes containing protein VII, compared to those containing SET/TAF-Ibeta or transcription factors, were consistent with the notion that the assembly of early viral chromatin requires both the association of SET/TAF-1beta and the release of protein VII.

Adeno-Associated Virus Vector Genomes Persist as Episomal Chromatin in Primate Muscle

“…The concept of a viral minichromosome was formulated to describe the organization of the circular SV40 genome with cellular histones in the nuclei of infected permissive cells (2,13,25). The linear adenovirus genome has been shown to be complexed with the virus-derived histone-like protein VII, which condenses the 36,000-bp adenoviral genome in the virion, but this protein is released from the viral DNA for chromatin assembly a few hours after infection (59). The parvoviruses AAV and MVM were also described as organized in chromatin structure within hours after infection in cell culture (3,36), and in the case of wild-type AAV did not require the presence of a helper virus or DNA replication.…”

Adenoviruses: update on structure and function

“…The core proteins V and VII interact with the virus DNA in such a way that the virus template is available at least for limited in vitro replication (Goding & Russell, 1983a), and since protein V seems to be dispensable (Ugai et al, 2007), and it is not present in the family Atadenoviridae (Gorman et al, 2005), it is plausible to postulate that virus DNA plus protein VII may be the functional template for replication and transcription in vivo, at least for the initial stages (Chatterjee et al, 1986;Haruki et al, 2006;Spector, 2007). Following endocytosis, and disruption of the endosome, entry of the virus core into the nucleus is governed by multiple signals in VII which target the genome to the nucleus and to the nucleolus (Lee et al, 2003;Wodrich et al, 2006).…”

Chromatin organization and virus gene expression

“…Adenovirus genomes are packaged as linear double stranded DNA with viral core proteins that form a chromatin‐like structure. The viral DNA is covalently linked with the viral encoded terminal binding protein (TP) and core proteins VII, V, and X (Xue et al, 2005; Haruki et al, 2006; Spector, 2007). Core protein VII has sequence similarity to histone H3 and basic sperm‐specific protein.…”

“…Several cellular proteins contribute to TAF activity, including the SET/TAF1B and pp32 proteins. These proteins can interact with adenovirus core protein VII, and function in remodeling of the incoming viral DNA (Xue et al, 2005; Haruki et al, 2006; Spector, 2007). The SET/TAF1B and pp32 proteins are also components of the INHAT complex that inhibits histone acetyltransferase (HAT) activity of cellular proteins p300 and CBP (Seo et al, 2001, 2002).…”