Mutational analysis of transcriptional activation by the bovine papillomavirus type 1 E6.
While the bovine papillomavirus type 1 (BPV-1) E6 induces tumorigenic transformation of murine C127 cells, it does not bind or promote the degradation of p53. We recently showed the cellular protein ERC-55/E6BP binds BPV-1 E6 as well as the cancer-related human papillomavirus (HPV) E6 proteins. BPV-1 E6 also binds E6-AP, a ubiquitin ligase necessary for HPV E6-induced p53 degradation. We previously reported that the transforming activity of a set of BPV-1 E6 mutants correlated with their E6BP-binding ability. Another function of BPV-1 E6 is stimulation of transcription when targeted to a promoter, although cellular promoters responsive to BPV-1 E6 have not been identified. To examine whether its transcriptional function is required for oncogenic activity, or is related to its interactions with E6-AP or E6BP, a series of BPV-1 E6 mutants were analyzed as fusions to a sequence-specific DNA binding domain for activity in yeast and in mammalian cells. We show that some transformation defective mutants retained substantial levels of transcriptional activation activity. These mutants also distinguish transcriptional activation from E6-AP and E6BP binding. These results suggest the transcriptional activation function of BPV-1 E6 is not sufficient for cell transformation.
Chen
J J
JJ
Department of Dermatology, New England Medical Center and Tufts University School of Medicine, Boston, Massachusetts 02111, USA. jchen1@opal.tufts.edu
Hong
Y
Y
Androphy
E J
EJ
D016475:3T3 Cells; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism; D052688:Bovine papillomavirus 1 / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004279:DNA, Viral / Q000378:metabolism; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis; D008322:Mammals; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D027383:Papillomaviridae / Q000235:genetics / Q000378:metabolism; D010957:Plasmids; D017354:Point Mutation; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D004279:DNA, Viral; D008156:Luciferases; D009856:Oncogene Proteins, Viral; D011993:Recombinant Fusion Proteins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein; C059269:protein E6, Bovine papillomavirus