title: A stem-loop structure, sequence non-specific, at the origin of DNA replication of porcine circovirus is essential for termination but not for initiation of rolling-circle DNA replication.
abstract: A stem-loop structure, formed by a pair of inverted repeats during DNA replication, is a conserved feature at the origin of DNA replication among plant and animal viruses, bacteriophages and plasmids that replicate their genomes via the rolling-circle replication (RCR) mechanism. In this work, a head-to-tail tandem construct of porcine circovirus capable of generating unit-length genomic DNA in Escherichia coli was employed to examine the role of the stem-loop structure with respect to the RCR initiation and termination process. The advantage of using a head-to-tail tandem construct is that the initiation and termination sites for generation of the unit-length viral genomes are physically separated, which allows independent examination of the initiation/termination processes. Nucleotide substitution mutational analysis showed that a pair of inverted repeats capable of forming a stem-loop structure was essential for termination, but not for initiation. The results also demonstrated that it is the stem-loop configuration, not nucleotide sequence specificity, that is critical for terminating RCR DNA replication.
authors.affiliation: Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, PO Box 70, Ames, IA 50010, USA. anheung@nadc.ars.usda.gov
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Cheung
mesh_terms: D000818:Animals; D001483:Base Sequence; D017925:Circovirus / Q000235:genetics*; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D018741:Replication Origin / Q000235:genetics*; D013552:Swine / Q000235:genetics*
chemical_list: D004279:DNA, Viral