Roles of the hinge region and the DNA binding domain of the bovine papillomavirus type 1 E2 protein in initiation of DNA replication

The bovine papillomavirus (BPV-1) E2 protein is the regulator of extrachrom osomal replication of papillomaviruses. The mutants with C-terminal truncat ions and in-frame internal deletions were constructed to study the role of structural domains of E2 in the initiation of DNA replication. We show that the replication initiation function of E2 is absolutely dependent on the a bility of the protein to bind to DNA. Our study also confirms the borders o f the functional domains of the E2 protein; residues 1-192 form the activat ion domain and residues 310-410 the DNA binding-dimerization domain. Some c ritical length and flexibility, but not the particular amino acid sequence between these two functional domains is required for the activity of the pr otein to support replication. The hinge region, including the major phospho rylation sites of E2, is also dispensable for the mediation of attachment o f the BPV1 genome to the mitotic chromosomes. (C) 2001 Elsevier Science B.V . All rights reserved.