title: Hypersensitivity to Hg2+ and hyperbinding activity associated with cloned fragments of the mercurial resistance operon of plasmid NR1.
abstract: The region of plasmid NR1 concerned with resistance to Hg2+ and organomercurials consists of sequences found on restriction endonuclease fragments EcoRI-H and EcoRI-I. When both fragments were cloned together into a derivative of plasmid ColE1, the hybrid plasmid conferred properties indistinguishable from those of the parental plasmid, NR1: resistance to Hg2+ and to the organomercurials merbromin and fluoresceinmercuric acetate and the inducible synthesis of the enzyme mercuric reductase. When fragment EcoRI-I was cloned into plasmid ColE1, cells containing the plasmid was as sensitive to Hg2+ and organomercurials as plasmidless strains. When fragment EcoRI-H was cloned into ColE1, cells with the hybrid plasmid were hypersensitive to Hg2+ and organomercurials. This hypersensitivity was inducible by prior exposure to low, subtoxic Hg2+ or merbromin levels. It was associated with an inducible hyperbinding activity attributed to a gene governing Hg2+ uptake and found on fragment EcoRI-H (which contains the proximal portion of a mercuric resistance [mer] operon).
mesh_terms: D003001:Cloning, Molecular; D004274:DNA, Recombinant; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D008628:Mercury / Q000378:metabolism / Q000494:pharmacology*; D009876:Operon; D009941:Organomercury Compounds / Q000378:metabolism / Q000494:pharmacology*; D011815:R Factors
chemical_list: D004274:DNA, Recombinant; D009941:Organomercury Compounds; D008628:Mercury