title: Intracellular Analysis of the Interaction between the Human Papillomavirus Type 16 E6 Oncoprotein and Inhibitory Peptides.
abstract: Oncogenic types of human papillomaviruses (HPVs) cause cervical cancer and other malignancies in humans. The HPV E6 oncoprotein is considered to be an attractive therapeutic target since its inhibition can lead to the apoptotic cell death of HPV-positive cancer cells. The HPV type 16 (HPV16) E6-binding peptide pep11, and variants thereof, induce cell death specifically in HPV16-positive cancer cells. Although they do not encompass the LxxLL binding motif found in cellular HPV16 E6 interaction partners, such as E6AP, the pep11 variants strongly bind to HPV16 E6 by contacting the recently identified E6AP binding pocket. Thus, these peptides can serve as prototype E6-inhibitory molecules which target the E6AP pocket. We here analyzed their intracellular interaction with HPV16 E6. By comprehensive intracellular binding studies and GST pull-down assays, we show that E6-binding competent pep11 variants induce the formation of a trimeric complex, consisting of pep11, HPV16 E6 and p53. These findings indicate that peptides, which do not contain the LxxLL motif, can reshape E6 to enable its interaction with p53. The formation of the trimeric HPV16 E6 / peptide / p53 complex was associated with an increase of endogenous HPV16 E6 protein amounts. Yet, total cellular p53 amounts were also increased, indicating that the E6 / E6AP-mediated degradation of p53 is blocked. These findings suggest that inhibition of oncogenic activities by targeting the E6AP pocket on HPV16 E6 could be a strategy for therapeutic intervention.
authors.affiliation: Molecular Therapy of Virus-Associated Cancers (F065), Program Infection and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Stutz
authors.affiliation: Molecular Therapy of Virus-Associated Cancers (F065), Program Infection and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors.forename: Eileen
authors.initials: E
authors.lastname: Reinz
authors.affiliation: Molecular Therapy of Virus-Associated Cancers (F065), Program Infection and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Honegger
authors.affiliation: Molecular Therapy of Virus-Associated Cancers (F065), Program Infection and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Bulkescher
authors.affiliation: Arbor Vita Corporation, Fremont, CA 94085, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schweizer
authors.affiliation: Institut de Recherche de l'École de Biotechnologie de Strasbourg (IREBS), 67412 Illkirch, France.
authors.forename: Katia
authors.initials: K
authors.lastname: Zanier
authors.affiliation: Institut de Recherche de l'École de Biotechnologie de Strasbourg (IREBS), 67412 Illkirch, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Travé
authors.affiliation: Molecular Therapy of Virus-Associated Cancers (F065), Program Infection and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lohrey
authors.affiliation: Molecular Therapy of Virus-Associated Cancers (F065), Program Infection and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Hoppe-Seyler
authors.affiliation: Molecular Therapy of Virus-Associated Cancers (F065), Program Infection and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Hoppe-Seyler
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D010455:Peptides; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53; D049452:Green Fluorescent Proteins; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases