title: Sequence of the R1 plasmid and comparison to F and R100.
abstract: The R1 antibiotic resistance plasmid, originally discovered in a clinical Salmonella isolate in London, 1963, has served for decades as a key model for understanding conjugative plasmids. Despite its scientific importance, a complete sequence of this plasmid has never been reported. We present the complete genome sequence of R1 along with a brief review of the current knowledge concerning its various genetic systems and a comparison to the F and R100 plasmids. R1 is 97,566 nucleotides long and contains 120 genes. The plasmid consists of a backbone largely similar to that of F and R100, a Tn21-like transposon that is nearly identical to that of R100, and a unique 9-kb sequence that bears some resemblance to sequences found in certain Klebsiella oxytoca strains. These three regions of R1 are separated by copies of the insertion sequence IS1. Overall, the structure of R1 and comparison to F and R100 suggest a fairly stable shared conjugative plasmid backbone into which a variety of mobile elements have inserted to form an "accessory" genome, containing multiple antibiotic resistance genes, transposons, remnants of phage genes, and genes whose functions remain unknown.
authors.affiliation: Department of Biology, Johns Hopkins University, 3400 N. Charles St. Baltimore, MD 21218, USA. Electronic address: katherinecox@jhu.edu.
authors.forename: Katherine E L
authors.initials: KEL
authors.lastname: Cox
authors.affiliation: Department of Biology, Johns Hopkins University, 3400 N. Charles St. Baltimore, MD 21218, USA. Electronic address: joel@jhu.edu.
authors.forename: Joel F
authors.initials: JF
authors.lastname: Schildbach
mesh_terms: D001435:Bacteriophages / Q000235:genetics / Q000378:metabolism; D002874:Chromosome Mapping; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D005144:F Factor / Q000737:chemistry / Q000378:metabolism; D041121:Klebsiella oxytoca / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D058977:Molecular Sequence Annotation; D011815:R Factors / Q000737:chemistry* / Q000378:metabolism; D012475:Salmonella / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004279:DNA, Viral
keywords: Conjugative plasmid; Plasmid DNA sequence; R1 plasmid; Tn21; tra operon