title: The simian virus 40 packaging signal ses is composed of redundant DNA elements which are partly interchangeable.
abstract: Using the experimental system of simian virus 40 (SV40) pseudovirions we have previously shown that SV40 requires a specific DNA element for packaging, ses, which was mapped to the SV40 regulatory region. ses was previously found to play a role in facilitating the nucleosomal rearrangement required for chromatin condensation and viral packaging. Here, the fine structure of ses was investigated by genetic studies. Analyses of ses+ revertants indicated that in order to function, ses must be present in close proximity to the origin of replication (ori), supporting a role in the regulation of the viral life cycle. Fine dissection of ses was performed using a series of plasmids carrying mutations and deletions in this region. The results suggest that multiple DNA elements participate in the SV40 packaging process, including the GC-boxes and elements derived from the enhancer. The elements are redundant, and they can function in various combinations. Packaging efficiency correlated with the number of GC-boxes, known to bind Sp1. In addition, AP-2 binding elements appeared to more important than others. These findings were supported by experiments which showed that packaging was significantly enhanced by adding AP-2 binding sites to plasmids with large deletions and lacking those sites. The results imply that binding of Sp1 and/or AP-2 may participate in the packaging process.
authors.affiliation: Department of Hematology, Hebrew University Hadassah Medical School, Jerusalem, Israel.
authors.forename: N
authors.initials: N
authors.lastname: Dalyot-Herman
authors.forename: O
authors.initials: O
authors.lastname: Ben-nun-Shaul
authors.forename: A
authors.initials: A
authors.lastname: Gordon-Shaag
authors.forename: A
authors.initials: A
authors.lastname: Oppenheim
mesh_terms: D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured / Q000821:virology; D002874:Chromosome Mapping / Q000379:methods; D004251:DNA Transposable Elements; D004279:DNA, Viral / Q000737:chemistry* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000502:physiology; D000882:Haplorhini; D007668:Kidney / Q000166:cytology / Q000821:virology; D008954:Models, Biological; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid; D017384:Sequence Deletion; D013539:Simian virus 40 / Q000235:genetics* / Q000502:physiology; D054334:Viral Regulatory and Accessory Proteins / Q000737:chemistry / Q000235:genetics; D019065:Virus Assembly / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D054334:Viral Regulatory and Accessory Proteins; C083115:activator protein-2 binding element