Global profiling of histone modifications in the polyomavirus BK virion minichromosome.

During polyomavirus infection, the viral DNA adopts histones from host cells and forms minichromosomes as an important part of the viral life cycle. However, the detailed mechanisms of this histone incorporation remain unclear. Here, we profiled the histone posttranslational modifications (PTMs) in BKPyV minichromosomes and in the chromatin of BKPyV host cells. Through Triton-acetic acid-urea (TAU)-PAGE separation followed by nanoflow liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis, we identified different kinds of PTMs on histones from BKPyV minichromosomes and from host cells. We observed not only the common PTMs on histones such as acetylation, methylation, phosphorylation, ubiquitination, and formylation but also several novel PTM sites. Our results also confirmed that the BKPyV minichromosome is hyperacetylated. Our detailed histone PTM profiles for the BKPyV minichromosome provide insights for future exploration of the underlying mechanisms and biological relevance of these histone PTMs.