Interaction of distinct nuclear proteins with sequences controlling the expression of polyomavirus early genes.
The interaction between cellular factors and polyoma virus (Py) DNA was investigated by using a gel retention assay. Nuclear extracts from various cell lines (NIH 3T3, NIH 3T6, LTK-, F9) contained proteins that formed specific and distinct complexes with Py B enhancer fragments of either wild-type or F9-1 mutant origin. The presence of an excess amount of other well-characterized DNA sequences, including the Py A enhancer, the murine sarcoma virus enhancer, and the simian virus 40 enhancer-promoter region, did not interfere with this protein-DNA interaction. However, a fragment previously defined as containing the lymphotropic papovavirus enhancer shares the binding of some common factor. This observation, in combination with the results of retention gel assays at different Mg2+ concentrations, indicates the interaction of several nuclear factors and Py DNA. The assay systems that were used allowed a distinction between some factors on the basis of their different biochemical and sequence requirements. The contact sites of these complexes were mapped to the B enhancer region of Py with Bal 31-derived mutant restriction fragments and ExoIII nuclease and are compatible with the functional domains determined in vivo.
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005796:Genes; D005814:Genes, Viral; D006801:Humans; D051379:Mice; D009698:Nucleoproteins / Q000378:metabolism*; D011120:Polyomavirus / Q000235:genetics*; D011401:Promoter Regions, Genetic
D004279:DNA, Viral; D009698:Nucleoproteins; D004262:DNA Restriction Enzymes