title: Functional analysis of a palindromic sequence required for normal replication of several staphylococcal plasmids.
abstract: Most small multicopy antibiotic-resistance plasmids of Staphylococcus aureus contain a major axis of hyphenated dyad symmetry (palA) that is required for normal replication and stability, although located outside of the minimal replicon. Rearrangements affecting palA cause plasmid instability, a marked reduction in copy number, and the accumulation of large quantities of strand-specific circular single-stranded plasmid DNA. In view of the recent observation that pT181 initiates replication by a nick and 3'-extension mechanism (S. Khan, personal communication), it is suggested that these plasmids replicate by an asymmetric rolling-circle mechanism in which the displaced plus strand remains single stranded until palA is exposed, forming a hairpin that serves as the lagging strand origin.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001412:Bacillus subtilis / Q000235:genetics; D001483:Base Sequence; D002872:Chromosome Deletion; D004261:DNA Replication; D004352:Drug Resistance, Microbial; D011815:R Factors; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents