Human adenoviral DNA association with nucleosomes containing histone variant H3.3 during the early phase of infection is not dependent on viral transcription or replication

Abstract

Adenovirus (Ad) DNA undergoes dynamic changes in protein association as the virus progresses through its replicative cycle. Within the virion, the Ad DNA associates primarily with the virus-encoded, protamine-like protein VII. During the early phase of infection (∼6 h), the viral DNA showed declining association with VII, suggesting that VII was removed from at least some regions of the viral DNA. Within 6 h, the viral DNA was wrapped into a repeating nucleosome-like array containing the histone variant H3.3. Transcription elongation was not required to strip VII from the viral DNA or for deposition of H3.3. H3.1 did not associate with the viral DNA at any point during infection. During the late phase of infection (i.e., active DNA replication ∼12-24 h), association with H3 was dramatically reduced and the repeating nucleosome-like pattern was no longer evident. Thus, we have uncovered some of the changes in nucleoprotein structure that occur during lytic Ad infection.

Histone Deacetylase Inhibitor Suberoylanilide Hydroxamic Acid Suppresses Human Adenovirus Gene Expression and Replication

“…A preliminary study assessing hexon, penton, and fiber protein levels from the capsids of cell surface-attached and internalized virions indicated that the drug does not adversely affect virus attachment (data not shown), which is consistent with studies reporting that HDAC inhibitors do not downregulate cell surface expression of the coxsackie adenovirus receptor (39). HAdV DNA associates with nucleosomes soon after reaching the host cell nucleus (29,30), so we next examined the impact of SAHA on Ad-late/RFP genome "chromatinization" by using a chromatin immunoprecipitation (ChIP) assay at 6 h following infection and drug treatment. Consistent with previous studies (29,30), we found that the early E1A region associated with H3 ( Fig.…”

“…During infection, the pVII-wrapped viral DNA enters the host cell nuclei through the nuclear pores (28). In the early phase of infection, the HAdV DNA dissociates from pVII, associates with cellular proteins, including histones, and adopts a nucleoprotein structure similar to the host DNA (29,30). The nucleosome density on the viral DNA is significantly reduced during late infection, and at least some of the newly synthesized viral DNA must associate with pre-pVII for packaging into newly formed capsids (30)(31)(32).…”

“…In the early phase of infection, the HAdV DNA dissociates from pVII, associates with cellular proteins, including histones, and adopts a nucleoprotein structure similar to the host DNA (29,30). The nucleosome density on the viral DNA is significantly reduced during late infection, and at least some of the newly synthesized viral DNA must associate with pre-pVII for packaging into newly formed capsids (30)(31)(32). The cellular proteins involved in mediating these processes and the role of chromatin-modifying enzymes in the epigenetic regulation of the HAdV genome has not yet been fully elucidated (33).…”

“…HAdV DNA associates with nucleosomes soon after reaching the host cell nucleus (29,30), so we next examined the impact of SAHA on Ad-late/RFP genome "chromatinization" by using a chromatin immunoprecipitation (ChIP) assay at 6 h following infection and drug treatment. Consistent with previous studies (29,30), we found that the early E1A region associated with H3 ( Fig. 5A).…”

Viral and cellular interactions during adenovirus DNA replication

“…While it is likely that the modification of viral chromatin influences viral DNA replication, how the presence of cellular histones on viral DNA may influence this process is unknown. Although cellular histones may be present on both incoming and de novo viral genomes , it is unclear whether these histones are removed by the process of replication, or indeed whether they must be removed or temporarily displaced for replication to take place. What is clear is that encapsidated viral genomes are devoid of cellular histones .…”