R1 plasmid

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The R1 Plasmid is a plasmid that was first isolated from Salmonella paratyphi bacteria in 1963.[1]

The R1 plasmid imparts multi-drug antibiotic resistance to its host bacteria.[2]

It's known as a "low copy" plasmid, meaning that it exists in relatively few copies in any given bacteria. Because of its low copy nature, R1 must rely on "type II" segregation system to ensure that at least one copy is contained in each daughter cell after mitosis.

Some genes on the R1 plasmid are:

  • ParM is a prokaryotic actin homologue which provides the force to drive copies of the R1 plasmid to opposite ends of rod shaped bacteria before mitosis.
  • The Hok/sok system a postsegregational killing system of the plasmid.
  • CopA-like RNA, an antisense RNA involved in replication control of the plasmid.


  1. ^ N. Datta & P. Kontomichalou, Nature 208 (1965) 239-241.
  2. ^ C. S. Campbell and R. D. Mullins, Journal of Cell Biology 179 (2007) 1059.