Competitive binding to a charged leucine motif represses transformation by a papillomavirus E6 oncoprotein.
E6 oncoproteins from HPV-16 and bovine papillomavirus type 1 (BPV-1) bind to similar leucine-rich peptides termed charged leucine motifs found on the cellular focal adhesion protein paxillin and the E3 ubiquitin ligase E6AP. BPV-1 E6 (BE6) mutants that do not bind to paxillin are defective at inducing cellular transformation. It is possible, however, that BE6 mutants that do not bind paxillin are defective for transformation for an unrelated reason than the ability to bind to charged leucine motifs. To address the role of BE6 interaction with charged leucine motifs, we fused a BE6-binding charged leucine motif to the amino terminus of BE6, thereby creating an autoinhibitory binding domain. We found that the fusion protein failed to bind to paxillin or transform murine C127 cells. Mutation of the amino terminal binding motif in the fusion protein restored both interaction with paxillin and transformation. This demonstrates that BE6 transformation requires binding to charged leucine motifs on particular cellular proteins and that transformation by papillomavirus oncoproteins can be repressed by competitive interactions with charged leucine motifs.
Bohl
J
J
Institute of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
Das
K
K
Dasgupta
B
B
Vande Pol
S B
SB
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002460:Cell Line; D002472:Cell Transformation, Viral; D002645:Chickens; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D016350:Leucine Zippers; D008025:Ligases / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D051419:Paxillin; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D012097:Repressor Proteins; D044767:Ubiquitin-Protein Ligases; D015032:Zinc / Q000378:metabolism
D003598:Cytoskeletal Proteins; C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; D012097:Repressor Proteins; C059269:protein E6, Bovine papillomavirus; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D015032:Zinc