title: Distal sequences, but not ori-beta/OBR-1, are essential for initiation of DNA replication in the Chinese hamster DHFR origin.
abstract: In the Chinese hamster dihydrofolate reductase replication initiation zone, the ori-beta locus is preferred over other start sites. To test the hypothesis that ori-beta contains a genetic replicator, we restored a deletion in the 3' end of the DHFR gene with a cosmid that provides the missing sequence and simultaneously knocks out the downstream ori-beta locus. Replication initiates normally in ori-beta knockout cell lines, and the DHFR domain is still synthesized in early S phase. However, initiation is completely suppressed in the starting deletion variant lacking the 3' end of the gene. We conclude that ori-beta does not contain an essential replicator, but that distant sequence elements have profound effects on origin activity in this locus.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville 22908, USA.
authors.forename: R F
authors.initials: RF
authors.lastname: Kalejta
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: L D
authors.initials: LD
authors.lastname: Mesner
authors.forename: P A
authors.initials: PA
authors.lastname: Dijkwel
authors.forename: H B
authors.initials: HB
authors.lastname: Lin
authors.forename: J L
authors.initials: JL
authors.lastname: Hamlin
mesh_terms: D000818:Animals; D016466:CHO Cells; D002453:Cell Cycle / Q000235:genetics; D006224:Cricetinae; D004261:DNA Replication / Q000235:genetics*; D015180:Electrophoresis, Gel, Two-Dimensional; D005796:Genes / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D016297:Mutagenesis, Site-Directed; D011995:Recombination, Genetic; D018741:Replication Origin / Q000235:genetics*; D015183:Restriction Mapping; D017384:Sequence Deletion; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*; D013997:Time Factors
chemical_list: D013762:Tetrahydrofolate Dehydrogenase