title: Two synthetic Sp1-binding sites functionally substitute for the 21-base-pair repeat region to activate simian virus 40 growth in CV-1 cells.
abstract: The 21-bp repeat region of simian virus 40 (SV40) activates viral transcription and DNA replication and contains binding sites for many cellular proteins, including Sp1, LSF, ETF, Ap2, Ap4, GT-1B, H16, and p53, and for the SV40 large tumor antigen. We have attempted to reduce the complexity of this region while maintaining its growth-promoting capacity. Deletion of the 21-bp repeat region from the SV40 genome delays the expression of viral early proteins and DNA replication and reduces virus production in CV-1 cells. Replacement of the 21-bp repeat region with two copies of DNA sequence motifs bound with high affinities by Sp1 promotes SV40 growth in CV-1 cells to nearly wild-type levels, but substitution by motifs bound less avidly by Sp1 or bound by other activator proteins does not restore growth. This indicates that Sp1 or a protein with similar sequence specificity is primarily responsible for the function of the 21-bp repeat region. We speculate about how Sp1 activates both SV40 transcription and DNA replication.
authors.affiliation: Department of Biochemistry, University of Missouri, Columbia 65212.
authors.forename: J
authors.initials: J
authors.lastname: Lednicky
authors.forename: W R
authors.initials: WR
authors.lastname: Folk
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D004261:DNA Replication; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D013539:Simian virus 40 / Q000235:genetics / Q000254:growth & development*; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000096:biosynthesis; D014779:Virus Replication
chemical_list: D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D014764:Viral Proteins