Bovine papilloma virus (BPV)-encoded E1 protein contains multiple activities required for BPV DNA replication.
Replication of bovine papilloma virus (BPV) DNA requires two virus-encoded proteins, E1 and E2, while all other proteins are supplied by the host cell. Here, we describe the isolation of the E1 protein and show that it is a multifunctional protein. Purified E1 protein was required for the in vitro replication of BPV origin-containing DNA by extracts of mouse cells, as reported [Yang, L., Li, R., Mohr, I. J., Clark, R. & Botchan, M. R. (1991) Nature (London) 353, 628-632]. In addition, the E1 protein cosedimented with a number of other activities including (i) DNA helicase activity, (ii) BPV origin-containing DNA-specific binding activity, (iii) DNA-dependent ATPase activity, and (iv) BPV origin-specific unwinding of superhelical DNA. The E1 protein, acting as a helicase, moved in the 3'-->5' direction, like simian virus 40 (SV40) large tumor antigen, which plays a pivotal role in SV40 DNA replication. However, unlike the SV40 large tumor antigen, the helicase activity of E1 was stimulated 5-fold by the presence of a fork structure at the junction between single-stranded and double-stranded DNA and was supported efficiently by all eight nucleoside triphosphates. The E1-catalyzed ATPase activity required the presence of single-stranded or double-stranded DNAs.
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Graduate Program in Molecular Biology, Sloan-Kettering Cancer Center, New York, NY 10021.
Müller
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Lusky
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Hurwitz
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D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D052688:Bovine papillomavirus 1 / Q000254:growth & development*; D002460:Cell Line; D002474:Cell-Free System; D004265:DNA Helicases / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects*; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D015870:Gene Expression; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014764:Viral Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*
D004279:DNA, Viral; D004268:DNA-Binding Proteins; C069814:E1 protein, Bovine papillomavirus; D014764:Viral Proteins; D000251:Adenosine Triphosphatases; D004265:DNA Helicases