A plasmid vector with positive selection and directional cloning based on a conditionally lethal gene

Sergey A. Yazynin, Sergey M. Deyev, Milan Jucovič, Robert W. Hartley

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    22 Citations (Scopus)


    A plasmid vector with a multiple cloning site (MCS) for positive selection of cloned inserts in Escherichia coli (Ec) has been devised, based on the expression plasmid (pMT416) for the bacterial ribonuclease barnase (Barn). The host is protected from the lethal effect of moderate expression of barn by expression of the gene bars, encoding its inhibitor, barstar (Bars), placed on the same plasmid. Full expression, however, is lethal. Induction is also lethal with the derived plasmid, pMT440, which has the pUC19 MCS inserted into barn. Under inducing conditions, transformation by the vector is lethal unless the product of the modified barn is inactivated by insertion of cloned DNA fragments into the MCS. Plasmid pMT440 is, therefore, a generally useful selective cloning vector not requiring any special strain of Ec.

    Original languageEnglish
    Pages (from-to)131-132
    Number of pages2
    Issue number1
    Publication statusPublished - 22 Feb 1996



    • Barnase
    • Barstar
    • Polylinker
    • Ribonuclease

    ASJC Scopus subject areas

    • Medicine(all)
    • Genetics

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