title: Identification and molecular characterization of the RNA polymerase-binding motif of infectious bursal disease virus inner capsid protein VP3.
abstract: Infectious bursal disease virus (IBDV), a member of the Birnaviridae family, is the causative agent of one of the most important infectious poultry diseases. Major aspects of the molecular biology of IBDV, such as assembly and replication, are as yet poorly understood. We have previously shown that encapsidation of the putative virus-encoded RNA-dependent RNA polymerase VP1 is mediated by its interaction with the inner capsid protein VP3. Here, we report the characterization of the VP1-VP3 interaction. RNase A treatment of VP1- and VP3-containing extracts does not affect the formation of VP1-VP3 complexes, indicating that formation of the complex requires the establishment of protein-protein interactions. The use of a set of VP3 deletion mutants allowed the mapping of the VP1 binding motif of VP3 within a highly charged 16-amino-acid stretch on the C terminus of VP3. This region of VP3 is sufficient to confer VP1 binding activity when fused to an unrelated protein. Furthermore, a peptide corresponding to the VP1 binding region of VP3 specifically inhibits the formation of VP1-VP3 complexes. The presence of Trojan peptides containing the VP1 binding motif in IBDV-infected cells specifically reduces infective virus production, thus showing that formation of VP1-VP3 complexes plays a critical role in IBDV replication.
authors.affiliation: Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Maraver
authors.forename: Roberto
authors.initials: R
authors.lastname: Clemente
authors.forename: Jose Francisco
authors.initials: JF
authors.lastname: Rodríguez
authors.forename: Eleuterio
authors.initials: E
authors.lastname: Lombardo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D017353:Gene Deletion; D007243:Infectious bursal disease virus / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D011485:Protein Binding; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D012324:RNA-Dependent RNA Polymerase