Papillomavirus E1 proteins: form, function, and features.

The E1 proteins are the essential origin recognition proteins for papillomavirus (PV) replication. E1 proteins bind to specific DNA elements in the viral origin of replication and assemble into hexameric helicases with the aid of a second viral protein, E2. The resultant helicase complex initiates origin DNA unwinding to provide the template for subsequent syntheses of progeny DNA.

Effects of mutations within two hydrophilic regions of the bovine papillomavirus type 1 E1 DNA-binding domain on E1-E2 interaction.

The interaction between papillomavirus E1 and E2 proteins is essential for viral genome replication. Using both in vivo and in vitro assays to evaluate the regions of the two proteins necessary for the E1-E2 interaction, three independent interactions were identified for bovine papillomavirus E1: the N terminus of E1 (E1N, residues 1-311) interacts with the E2 transactivation domain (E2TAD) and the E2 DNA-binding domain (E2DBD) and the C terminus of E1 (E1C, residues 315-605) interacts with E2. Nine mutations within E1N were evaluated for their effects on E2 interaction.