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Histone H3 modification in BHK cells infected with foot-and-mouth disease virus
Abstract:
Infection of BHK cells with foot-and-mouth disease virus (FMDV) causes a thorough change in the electrophoretic profile of whole nuclear histones. It consists in the disappearance of histone H3 and the appearance of a new polypeptide (Pi) which migrates between histones H2A and H4 on SDS-polyacrylamide gels. Protein Pi is detected at 2 hr postinfection (pi), the time in which viral RNA synthesis begins to increase, and reaches equimolecular amounts with the remaining core histones 1 hr later, when the disappearance of histone H3 is almost complete. Labeling of cells prior to infection demonstrates that Pi is not a novo product but the result of a viral-induced processing of a host precursor synthetized beforehand. Protein Pi comigrates with histone H2A/B in acetic acid/urea polyacrylamide gels and it shares common major peptides with histone H3 under controlled proteolysis with protease V8 or trypsin. The mononucleosomal and nucleosomal DNA pattern analysis after micrococcal nuclease treatment of nuclei from infected and mock-infected cells did not show any significant differences even though after 3 hr (p.i.), protein Pi replaces histone H3 in the nucleosomal structure. It was concluded that FMDV infection is responsible for a specific modification in the nucleus of infected cells which leads, after 3 hr (p.i.), to a complete histone H3 protein Pi transition in the nucleosomes.
Insights
Foot-and-mouth disease virus (FMDV) infection alters nuclear histones in BHK cells, replacing histone H3 with a new protein (Pi). This viral-induced modification occurs within hours, impacting nucleosome structure.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Foot-and-mouth disease virus (FMDV) is a significant pathogen affecting livestock.
- Viral infections can induce profound changes in host cell nuclear processes.
- Histones are crucial for DNA packaging and gene regulation within the nucleus.
Purpose of the Study:
- To investigate the impact of FMDV infection on the host cell's nuclear histone composition.
- To characterize the nature and timing of histone modifications during FMDV infection.
- To determine if these histone changes affect nucleosome structure.
Main Methods:
- Infection of BHK cells with FMDV.
- Analysis of nuclear histone electrophoretic profiles (SDS-PAGE).
- Pulse-chase labeling experiments to assess protein synthesis and processing.
- Proteolytic digestion and peptide mapping (V8 protease, trypsin).
- Micrococcal nuclease digestion to analyze nucleosomal DNA structure.
Main Results:
- FMDV infection led to the disappearance of histone H3 and the appearance of a novel polypeptide (Pi).
- Protein Pi emerged at 2 hours post-infection, coinciding with viral RNA synthesis, and reached equimolar amounts with other histones by 3 hours.
- Pi is a host-derived protein processed due to viral infection, not a de novo synthesis.
- Pi shares peptide similarities with histone H3, suggesting a relationship.
- Despite Pi replacing H3 in nucleosomes by 3 hours post-infection, nucleosomal DNA structure remained largely unchanged.
Conclusions:
- FMDV infection induces a specific nuclear modification in host cells.
- This modification involves the replacement of histone H3 with a viral-induced protein Pi within nucleosomes.
- The transition is completed by 3 hours post-infection, without significant alterations to the DNA packaging pattern.