title: A mutation in the DE loop of the VP1 protein that prevents polyomavirus transcription and replication.
abstract: Natural mutants of the DE loop of the Polyomavirus (Py) major coat protein VP1 have been previously shown to display an altered host specificity (L. Ricci, R. Maione, C. Passananti, A. Felsani, and P. Amati, 1992, J. Virol. 66, 7153-7158). To better understand the role of this outfacing loop of the VP1 protein in Py infectivity, we constructed and characterized a Py mutant (Py M17) harboring a deletion of 7 AA within the tip of the DE loop. The mutant virions obtained after DNA transfection were unable to replicate and initiate early transcription in fibroblast cells. Complementation experiments performed to rescue the deficient M17 replication by means of wt functions revealed the cis-dominance of the mutation. In situ cell fractionation experiments demonstrated that the Py mutant, like the Py wt, enters the cells, reaches the nucleus and that both the viral DNA and VP1 protein are found tightly bound to the nuclear matrix. These data suggest that the VP1 protein, associated to the viral DNA, conditions early viral gene expression and that the DE loop of the protein must be involved in this process.
authors.affiliation: Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biotecnologie Cellulari, Sezione di Genetica Molecolare, Università di Roma La Sapienza, Viale Regina Elena 324, Rome, 00161, Italy.
authors.forename: M I
authors.initials: MI
authors.lastname: Garcia
authors.forename: M
authors.initials: M
authors.lastname: Perez
authors.forename: M
authors.initials: M
authors.lastname: Caruso
authors.forename: O
authors.initials: O
authors.lastname: Sthandier
authors.forename: R
authors.initials: R
authors.lastname: Ferreira
authors.forename: M
authors.initials: M
authors.lastname: Cermola
authors.forename: C
authors.initials: C
authors.lastname: Macchia
authors.forename: P
authors.initials: P
authors.lastname: Amati
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002213:Capsid / Q000737:chemistry* / Q000235:genetics*; D036022:Capsid Proteins; D002460:Cell Line; D004279:DNA, Viral / Q000032:analysis; D051379:Mice; D009154:Mutation / Q000235:genetics*; D010456:Peptides, Cyclic / Q000235:genetics*; D011120:Polyomavirus / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D017384:Sequence Deletion; D014158:Transcription, Genetic / Q000235:genetics*; D014407:Tumor Cells, Cultured; D014771:Virion / Q000235:genetics / Q000648:ultrastructure; D014779:Virus Replication / Q000235:genetics*
chemical_list: D036022:Capsid Proteins; D004279:DNA, Viral; D010456:Peptides, Cyclic; C062481:VP1 protein, polyomavirus; C078763:D-loop peptide, synthetic