title: Are single-stranded circles intermediates in plasmid DNA replication?
abstract: Plasmid pC194 exists as circular double-stranded and single-stranded DNA in Bacillus subtilis and Staphylococcus aureus. We report here that the plasmid pHV33, composed of pBR322 and pC194, exists as double- and single-stranded DNA in Escherichia coli, provided that the replication functions of pC194 are intact. Single-stranded pHV33 DNA is converted to double-stranded DNA by complementary strand synthesis probably initiated at rriB, a primosome assembly site present on pBR322. The efficiency of complementary strand synthesis affects the double-stranded copy number, which suggests that single-stranded DNA is a plasmid replication intermediate.
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics; D003090:Coliphages / Q000235:genetics*; D004261:DNA Replication; D004262:DNA Restriction Enzymes; D004270:DNA, Circular / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D008854:Microscopy, Electron; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D014176:Protein Biosynthesis; D013211:Staphylococcus aureus / Q000235:genetics
chemical_list: D004270:DNA, Circular; D004277:DNA, Single-Stranded; D004262:DNA Restriction Enzymes