Elsevier

Gene

Volume 17, Issue 1, January 1982, Pages 27-44
Gene

Phasmids: hybrids between Co1E1 plasmids and E. coli bacteriophage lambda

https://doi.org/10.1016/0378-1119(82)90098-1Get rights and content

Abstract

Plasmids carrying cloned λ att sites may be integrated into the bacteriophage genome by the site-specific recombination mechanism of λ. The cross, referred to as “lifting” the plasmid, requires mixed infection of an Escherichia coli strain carrying the plasmid with two appropriately constructed “lifting” λ phages. One phage donates a short left arm and the other donates a short right arm. These two short arms are of insufficient length to produce a viable phage genome and yield no recombinants when crossed on standard bacteria. However, viable recombinants are obtained when the genome length is extended by integration of one or more plasmids. We call these recombinants phasmids. They contain multiple att sites introduced at the ends of the integrated plasmids, and in the presence of integrase, recombination between these att sites can be exploited to effect release of the plasmid components.

These novel genetic elements can be used in a variety of ways as vectors in genetic manipulation experiments. Sequences cloned in phasmids may be studied as a component of either a plasmid and or of a phage, and easily interconverted between the two states.

References (44)

  • J.S. Parkinson

    Deletion mutants of bacteriophage lambda, II. Genetic properties of att-defective mutants

    J. Mol. Biol.

    (1971)
  • F.W. Stahl et al.

    Rec-mediated recombinational hot spot activity in bacteriophage lambda, III. Chi mutations are site-mutations stimulating rec-mediated recombination

    J. Mol. Biol.

    (1975)
  • E.H. Szybalski et al.

    A comprehensive molecular map of bacteriophage lambda

    Gene

    (1979)
  • M. Taylor et al.

    Transformation of bacterial markers and transfer of phage markers with DNA isolated from a λ-φ80 hybrid phage carrying the tryptophan genes of E. coll Biochem

    Biophys. Res. Commun.

    (1964)
  • J. Weil et al.

    Characteristics of Xp4, a λ derivative containing 9% excess DNA

    Virology

    (1972)
  • K. Borck et al.

    The construction in vitro of transducing derivatives of phage λ

    Mol. Gen. Genet.

    (1976)
  • L. Castagnoli et al.

    The phasmid as a tool for plasmid genetics I. Fine structure of the β-lactamase gene

    Genet. Res.

    (1982)
  • G. Cesarini et al.

    The phasmid as a tool for plasmid genetics, II. Isolation of point mutations that affect replication of a Co1E1 related plasmid

    Genet. Res.

    (1982)
  • M. Fiandt et al.

    Electron micrographie mapping of deletions, insertions, inversions and homologies in the DNAs of coliphages λ and pH 180

  • M.E. Furth et al.

    Genetic structure of the replication origin of bacteriophage lambda

    Science

    (1977)
  • C.P. Georgopoulos

    Bacterial mutants in which the gene N function of bacteriophage lambda is blocked have an altered RNA polymerase

  • C.P. Georgopoulos et al.

    Escherichia coli mutants blocked in lambda DNA synthesis

  • Cited by (0)

    Present address: European Molecular Biology Laboratory, 69 Heidelberg, Postfach 10.2209 (F.R.G.).

    View full text