The bovine papillomavirus E2 transactivator protein is a multifunctional pr
otein that activates viral transcription, cooperates in initiation of viral
DNA replication, and is required for long-term episomal maintenance of vir
al genomes. We have shown previously that the E2 transactivator protein and
bovine papillomavirus type 1 genomes are associated with mitotic chromosom
es and have proposed that E2 links the genomes to cellular chromosomes to e
nsure segregation to daughter nuclei. In this study, we show that E2 is ass
ociated with cellular chromosomes at all stages of mitosis. We also further
map the regions of E2 that are required for this association. The transact
ivation domain of E2 is necessary and sufficient to mediate the interaction
with mitotic chromosomes; the DNA binding domain, and the flexible hinge r
egion that separates the two domains, is not required. Furthermore, mutatio
n of previously identified phosphorylation sites (serine residues 235, 298,
and 301) has no effect on the ability of the E2 protein to bind mitotic ch
romosomes. (C) 2000 Academic Press.