@article{mbs:/content/journal/micro/10.1099/mic.0.2008/017418-0, author = "Kwong, Stephen M. and Lim, Ricky and LeBard, Rebecca J. and Skurray, Ronald A. and Firth, Neville", title = "Analysis of the pSK1 replicon, a prototype from the staphylococcal multiresistance plasmid family", journal= "Microbiology", year = "2008", volume = "154", number = "10", pages = "3084-3094", doi = "https://doi.org/10.1099/mic.0.2008/017418-0", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.2008/017418-0", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "CAT, chloramphenicol acetyltransferase", keywords = "TSP, transcriptional start point", keywords = "EMSA, electrophoretic mobility shift assay", abstract = "Multidrug-resistant staphylococci often harbour plasmids that carry genes conferring resistance to several antimicrobial compounds. Many of these multiresistance plasmids appear to utilize a related theta-type replication system for which multiresistance plasmid pSK1 serves as a prototype. Essential pSK1 replication elements were identified by cloning segments of the replication region and testing the resulting plasmids for replication proficiency. An iterated region within rep and a DNA segment of up to 68 bp upstream of the rep promoter were both found to be essential for origin activity. The Rep protein was overexpressed as a 6×His-tagged C-terminal fusion protein and was shown to bind in vitro to four Rep boxes located within the rep coding region. Inactivation of a divergently oriented promoter upstream of rep, designated P rnaI , resulted in an elevated plasmid copy number. Comparative analyses suggest that the replication systems of many staphylococcal multiresistance plasmids share a similar genetic organization and utilize an antisense-RNA-mediated regulatory mechanism for copy number control.", }