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Parental adenovirus DNA accumulates in nucleosome-like structures in infected cells
Abstract:
Micrococcal-nuclease digestion of adenovirus 2(ad 2) infected HeLa cell nuclei early after infection has been used to investigate the nucleoprotein nature of parental viral DNA. Viral DNA is more susceptible to nuclease digestion than cellular DNA. The pattern of digestion products changes as digestion proceeds from an indistinct pattern 1 hour post infection(pi) to a nucleosome-like pattern at 6 hours pi. The major differences between viral and cellular nucleoprotein products were i) a subnucleosome fraction from viral DNA and ii) the repeat size of DNA in viral nucleosomes was 165 base pairs and in cellular nucleosomes, 195 base pairs. Up to 50% viral DNA in nuclei 6 hours pi seems to be in nucleosome-like structures. Such patterns are not seen on digestion of partially-uncoated virus or isolated cores.
Insights
Parental adenovirus DNA in infected HeLa cells shows increased susceptibility to micrococcal nuclease digestion. Viral DNA forms nucleosome-like structures with distinct repeat sizes compared to cellular DNA.
Area of Science:
- Molecular Biology
- Virology
- Epigenetics
Background:
- Adenovirus 2 (Ad 2) infection in HeLa cells provides a model to study viral DNA packaging.
- Understanding the nucleoprotein structure of parental viral DNA is crucial for viral replication and host-cell interaction.
Purpose of the Study:
- To investigate the nucleoprotein nature of parental viral DNA in Ad 2 infected HeLa cells.
- To compare the nuclease digestion patterns of viral and cellular DNA.
Main Methods:
- Micrococcal nuclease digestion of infected HeLa cell nuclei at various time points post-infection (pi).
- Analysis of DNA digestion products to determine susceptibility and structural organization.
Main Results:
- Viral DNA is more susceptible to micrococcal nuclease digestion than cellular DNA.
- Digestion patterns evolved from indistinct at 1 hour pi to nucleosome-like at 6 hours pi.
- Viral nucleosomes exhibited a DNA repeat size of 165 base pairs, differing from cellular nucleosomes (195 base pairs).
- Up to 50% of viral DNA appeared in nucleosome-like structures 6 hours pi.
Conclusions:
- Parental adenovirus DNA undergoes significant structural changes post-entry into HeLa cells.
- Viral DNA is packaged into nucleosome-like structures with distinct characteristics compared to host cell chromatin.