cos Plasmid in Bacillus Subtilis

  • R. Marrero
  • F. A. Chiafari
  • P. S. Lovett


The genome of temperate phage X is a linear duplex DNA molecule with single stranded termini. The single ends contain complementary base sequences allowing X DNA to circularize in vitro. Treatment of such hydrogen bonded circles with DNA ligase produces a covalently-closed circle. In vivo λ DNA replicates via the rolling circle model (1) and the viral DNA is packaged into phage heads as linear molecules. The cohesive ends of λ DNA appears to serve as initiation sites for packaging the λ genome (2). Insertion of the cohesive ends (cos) of λ DNA into a plasmid, by recombinant DNA technology, confers on the resulting cos plasmid susceptibility to packaging by λ in vivo or in vitro, if the size of the plasmid approximates that of the viral genome (3). Insertion of cos into a small plasmid, such as pBR322, generates a cos plasmid that can only be packaged into mature phage particles if additional DNA is cloned into the small cos plasmid to increase its molecular size. Thus, λ cos plasmids or cosmids serve as excellent vectors for cloning rather large DNA segments (3).


Buoyant Density Temperate Phage Cold Spring Harbor Symposium Phage Head Research Career Development Award 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer Science+Business Media New York 1981

Authors and Affiliations

  • R. Marrero
    • 1
  • F. A. Chiafari
    • 1
  • P. S. Lovett
    • 1
  1. 1.Department of Biological SciencesUniversity of Maryland Baltimore CountyCatonsvilleUSA

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