title: Cooperative action of cellular proteins YB-1 and Pur alpha with the tumor antigen of the human JC polyomavirus determines their interaction with the viral lytic control element.
abstract: Human JC polyomavirus (JCV) is the etiologic agent of the neurodegenerative disease progressive mulifocal leukoencephalopathy. By using JCV as a model, we investigated the role of the viral early protein tumor antigen (TAg) in the binding of two cellular proteins, Pura alpha and YB-1, to JCV regulatory sequences. Results from band-shift assays with purified YB-1, Pur alpha, and TAg indicated that efficient binding of Pur alpha, a strong activator of early gene transcription, to a single-stranded target sequence corresponding to the viral lytic control element, is diminished in the presence of the late gene activator YB-1, which recognizes the opposite strand of the Pur alpha binding site. Of particular interest was the ability of Pur alpha and TAg to enhance binding of YB-1 to DNA molecules without being associated with this complex. Binding studies using a mutant peptide encompassing the N terminus of YB-1 indicated that the C terminus of YB-1 is important for its DNA binding activity. The ability of Pur alpha and TAg to increase binding of YB-1 to DNA is independent of the YB-1 C terminus. Similarly, results from band-shift assays using Pur alpha variants indicated that two distinct regions of this protein contribute either to its ability to bind DNA or to its ability to enhance YB-1 DNA binding activity. Based on the interaction of Pur alpha, YB-1, and TAg, and their binding to DNA, a model is proposed for the role of these proteins in transcription of viral early and late genes during the lytic cycle.
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107.
authors.forename: N N
authors.initials: NN
authors.lastname: Chen
authors.forename: C F
authors.initials: CF
authors.lastname: Chang
authors.forename: G L
authors.initials: GL
authors.lastname: Gallia
authors.forename: D A
authors.initials: DA
authors.lastname: Kerr
authors.forename: E M
authors.initials: EM
authors.lastname: Johnson
authors.forename: C P
authors.initials: CP
authors.lastname: Krachmarov
authors.forename: S M
authors.initials: SM
authors.lastname: Barr
authors.forename: R J
authors.initials: RJ
authors.lastname: Frisque
authors.forename: B
authors.initials: B
authors.lastname: Bollag
authors.forename: K
authors.initials: K
authors.lastname: Khalili
mesh_terms: D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005814:Genes, Viral; D007577:JC Virus / Q000235:genetics / Q000378:metabolism*; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D017924:Nucleopolyhedroviruses / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D018411:Spodoptera; D014157:Transcription Factors; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000378:metabolism; D051840:Y-Box-Binding Protein 1
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human