Cloning and comparison of mercury- and organomercurial-resistance determinants from a Pseudomonas stutzeri plasmid.
Plasmid pPB confers broad-spectrum mercury resistance (HgR) to a Pseudomonas stutzeri strain. Two pPB regions, separated by 25-30 kb and sharing homology with Tn501 mer (Hg detoxification) genes, were cloned separately and each was shown to carry a cluster of functional and independently regulated mer genes. One of the two gene clusters conferred resistance only to inorganic mercury, and had a structure identical to the classical model of narrow-spectrum mer operons. In the other cluster a novel merB gene, not homologous to the other known merB, but with the same function, was mapped upstream from merA, interposed between an organomercurial-responsive regulatory element and transport genes. Evidence suggests that merB and the other structural mer genes might be transcribed from two distinct promoters. The presence of two inverted repeat-like elements, identical to those of Tn5053, upstream from merR suggests that the pPB broad-spectrum-gene cluster could be part of a transposon-like element.
Dipartimento di Genetica e di Biologia dei Microrganismi, Milano, Italy.
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Reniero
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Galli
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Barbieri
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004352:Drug Resistance, Microbial; D005798:Genes, Bacterial; D008190:Lyases; D008628:Mercury; D008969:Molecular Sequence Data; D009876:Operon; D009941:Organomercury Compounds; D010088:Oxidoreductases / Q000235:genetics; D010957:Plasmids; D011549:Pseudomonas / Q000235:genetics*; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D009941:Organomercury Compounds; D010088:Oxidoreductases; C021551:mercuric reductase; D008190:Lyases; C097247:MerB protein, Bacteria; D008628:Mercury