title: Solution structure of the hDlg/SAP97 PDZ2 domain and its mechanism of interaction with HPV-18 papillomavirus E6 protein.
abstract: The E6 protein from high-risk types of human papillomavirus (HPV) binds PDZ-domain containing proteins and targets them for degradation. We used isothermal titration calorimetry to measure the interaction of a peptide from the C-terminus of HPV-18 E6 to the second PDZ domain (PDZ2) from the human homologue of the Drosophila discs large tumor suppressor protein (hDlg). Isothermal titration calorimetry experiments with a series of peptides showed that HPV-18 E6 bound hDlg PDZ2 about 5-fold stronger than HPV-16 E6, that the contribution of Arg154 to binding was about 1 kcal/mol, and that the binding was disabled by phosphorylation at Thr156. We then used NMR to determine the solution structure of the complex of PDZ2 bound to the HPV-18 E6 peptide. The resultant structures were of high quality and had backbone root-mean-square deviations of less than 0.5 A. The structure shows a novel mode of interaction in which six residues of the HPV-18 E6 peptide are contacted by the PDZ2 domain, in contrast to the typical four residues used by class I PDZ domains. Molecular dynamics simulations supported a model in which the C- and N-terminal ends of the peptide had different mobilities within the complex. Comparison of the NMR complex structure to previously determined X-ray structures of PDZ2 by itself and bound to different peptides allows a description of conformational changes required for PDZ2 to bind to HPV-18 E6.
authors: Department of Biochemistry, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts 02111, USA.
authors: Yuqi
authors: Y
authors: Liu
authors: Gillian D
authors: GD
authors: Henry
authors: Rashmi S
authors: RS
authors: Hegde
authors: James D
authors: JD
authors: Baleja
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D020816:Amino Acid Motifs; D001665:Binding Sites; D002152:Calorimetry, Differential Scanning; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000074288:Discs Large Homolog 1 Protein; D052161:Human papillomavirus 18 / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009856:Oncogene Proteins, Viral / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000138:chemical synthesis; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012996:Solutions
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C513314:DLG1 protein, human; D004268:DNA-Binding Proteins; D000074288:Discs Large Homolog 1 Protein; C068651:E6 protein, Human papillomavirus type 16; C052603:E6 protein, Human papillomavirus type 18; D008565:Membrane Proteins; D009856:Oncogene Proteins, Viral; D010455:Peptides; D012097:Repressor Proteins; D012996:Solutions