title: Interaction of hepatitis B virus X protein with damaged DNA-binding protein p127: structural analysis and identification of antagonists.
abstract: The hepatitis B virus X protein is a multifunctional protein that is essential for natural infection and has also been implicated in liver cancer development. Previous studies have identified the DDB1 subunit of the damaged-DNA binding complex as a critical partner of X protein in the infection process, X-mediated cytotoxicity and stability of the viral protein. Here, we investigated the structural and functional constraints of X-DDB1 interaction using various mutational analyses. Our data show that the interaction interface of X with DDB1 is confined to a 15-residue epitope. All substitutions responsible for loss of binding mapped to this core-binding domain. In contrast, a marked increase in affinity for DDB1 resulted from substitutions at clustered positions lying close to the DDB1-binding epitope and correlated with loss of apoptotic potential. Selection of mutations in DDB1 that partially rescue the binding defect of an X mutant gave further insight into the contacts established between the two proteins. Importantly, both the core-binding domain of X and the gain-of-affinity X mutants inhibited DDB1- mediated stabilization of wild-type X protein. These X protein derivatives thus provide the basis for the development of therapeutic agents that antagonize X function through competitive inhibition of X-DDB1 interaction.
authors.affiliation: Unité de Recombinaison et Expression Génétique (INSERM U163), Institut Pasteur, Paris, France.
authors.forename: François
authors.initials: F
authors.lastname: Bergametti
authors.forename: Julie
authors.initials: J
authors.lastname: Bianchi
authors.forename: Catherine
authors.initials: C
authors.lastname: Transy
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017209:Apoptosis; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010449:Peptide Mapping; D011485:Protein Binding / Q000235:genetics; D016415:Sequence Alignment; D015534:Trans-Activators / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: C091435:DDB1 protein, human; D004268:DNA-Binding Proteins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein