Characterization of the helicase and ATPase activity of human papillomavirus type 6b E1 protein

Human papillomavirus type 6b (HPV-6b) is one of the most common causes of human genital warts, an important sexually transmitted disease. Discovery of antiviral therapies for this condition has been hampered by the inability to propagate the virus using standard tissue culture techniques and through difficulties in expressing sufficient recombinant viral proteins in vitro. Replication of papillomavirus DNA requires two viral proteins, E1 and E2. In an effort to establish assays to discover compounds active against this virus, we have co-expressed HPV-6b E1 and E2 proteins in insect cells. We demonstrate that the two proteins form a heteromeric complex which can be purified by sequence-specific DNA affinity chromatography. We also demonstrate that the complex has both E1-associated ATPase and ATP-dependent DNA helicase activity and report further characterization of these functions.