Bovine Papillomavirus (BPV1) Replication Protein E1: Associated ATPase and Binding to the Viral E2 Transactivator
Recent genetic evidence has unambiguously established that the replication of the bovine papillomavirus type 1 (BPV1) plasmid DNA in virally-transformed cells requires the expression of the entire viral open reading frames E1 and E2 (Ustav & Stenlund, 91). We and others have recently identified in BPV1-transformed cells a 70 kDa nuclear phosphoprotein, encoded by the entire viral ORF El (Santucci & al., 90, Sun & al., 90). We present here evidence showing that an ATPase activity is associated with this protein in partially purified fractions and immunoprecipitates. Covalent affinity labeling made by the use of an ATP analogue of the E1 protein reinforces the idea of an intrinsic ATPase activity. Moreover, as recently shown by others (Mohr & al., 90), we found in vitro indications of the existence of a molecular complex between the E1 protein and the viral E2 trans-activating transcription factor. ATPase activity was detected in association with this E1–E2 complex.
KeywordsImmobilization Lysine Polypeptide Methionine Charcoal
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