title: JC virus agnoprotein enhances large T antigen binding to the origin of viral DNA replication: evidence for its involvement in viral DNA replication.
abstract: Agnoprotein is required for the successful completion of the JC virus (JCV) life cycle and was previously shown to interact with JCV large T-antigen (LT-Ag). Here, we further characterized agnoprotein's involvement in viral DNA replication. Agnoprotein enhances the DNA binding activity of LT-Ag to the viral origin (Ori) without directly interacting with DNA. The predicted amphipathic α-helix of agnoprotein plays a major role in this enhancement. All three phenylalanine (Phe) residues of agnoprotein localize to this α-helix and Phe residues in general are known to play critical roles in protein-protein interaction, protein folding and stability. The functional relevance of all Phe residues was investigated by mutagenesis. When all were mutated to alanine (Ala), the mutant virus (F31AF35AF39A) replicated significantly less efficiently than each individual Phe mutant virus alone, indicating the importance of Phe residues for agnoprotein function. Collectively, these studies indicate a close involvement of agnoprotein in viral DNA replication.
authors: Department of Neuroscience, Laboratory of Molecular Neurovirology, Temple University School of Medicine, Philadelphia, PA 19140, United States.
authors: A Sami
authors: AS
authors: Saribas
authors: Martyn K
authors: MK
authors: White
authors: Mahmut
authors: M
authors: Safak
mesh_terms: D000595:Amino Acid Sequence; D000957:Antigens, Viral, Tumor / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D007577:JC Virus / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics; D054334:Viral Regulatory and Accessory Proteins / Q000737:chemistry / Q000235:genetics*; D014779:Virus Replication; D000086082:Viroporin Proteins
chemical_list: D000957:Antigens, Viral, Tumor; D004279:DNA, Viral; D011993:Recombinant Fusion Proteins; D054334:Viral Regulatory and Accessory Proteins; C042559:agnoprotein, polyomavirus; D000086082:Viroporin Proteins