title: Localization of the start sites of lagging-strand replication of rolling-circle plasmids from gram-positive bacteria.
abstract: A number of small, multicopy plasmids from Gram-positive bacteria replicate by an asymmetric rolling-circle mechanism. Previous studies with several of these plasmids have identified a palindromic sequence, SSOA, that acts as the single-strand origin (SSO) for the replication of the lagging-strand DNA. Although not all the SSOA sequences share DNA sequence homology, they are structurally very similar. We have used an in vitro system to study the lagging-strand replication of several plasmids from Gram-positive bacteria using the SSOA sequences of pT181, pE194 and pSN2 as representative of three different groups of Staphylococcus aureus plasmids. In addition, we have investigated the lagging-strand replication of the pUB110 plasmid that contains an alternative single-strand origin, SSOU. Our results confirm that RNA polymerase is involved in lagging-strand synthesis from both SSOA and SSOU-type lagging-strand origins. Interestingly, while initiation of lagging-strand DNA synthesis of pUB110 occurred predominantly at a single position within SSOU, replication of pT181, pSN2 and pE194 plasmids initiated at multiple positions from SSOA.
authors.affiliation: Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pennsylvania 15261, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Dempsey
authors.forename: A C
authors.initials: AC
authors.lastname: Zhao
authors.forename: S A
authors.initials: SA
authors.lastname: Khan
mesh_terms: D001483:Base Sequence; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010926:Placental Hormones / Q000494:pharmacology; D010957:Plasmids / Q000096:biosynthesis*; D018741:Replication Origin / Q000502:physiology*; D015183:Restriction Mapping; D016914:Ribonuclease H / Q000494:pharmacology; D012259:Ribonuclease, Pancreatic / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology; D012972:Sodium Hydroxide / Q000494:pharmacology; D013997:Time Factors
chemical_list: D004277:DNA, Single-Stranded; D010926:Placental Hormones; C022052:placental ribonuclease inhibitor; D012972:Sodium Hydroxide; D016914:Ribonuclease H; D012259:Ribonuclease, Pancreatic; D012293:Rifampin