Identification of three merB genes and characterization of a broad-spectrum mercury resistance module encoded by a class II transposon of Bacillus megaterium strain MB1.
The complete structure of a broad-spectrum mercury resistance module was shown by sequencing the Gram-positive bacterial transposon TnMERI1 of Bacillus megaterium MB1. The regions encoding organomercury resistance were identified. Upstream of a previously identified organomercurial lyase merB (merB1) region of TnMERI1, a second merR (merR2) and a second merB gene (merB2) were found. These genes constitute a second operon (mer operon 2) following a promoter/operator (P(merR2)) region. A third organomercurial lyase gene (merB3) was found immediately upstream of the mer operon (mer operon 1) followed by a promoter/operator (P(merB3)) region homologous to that of the mer operon 1 (P(merR1)-merR1-merE-like-merT-merP-merA). The complete genetic structure of the mercury resistance module is organized as P(merB3)-merB3-P(merR1)-merR1-merE-like-merT+ ++ -merP-merA-P(merR2)-merR2 -merB2-merB1. The subcloning analysis of these three merB genes showed distinct substrate specificity as different organomercury lyase genes.
Huang
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Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi-shi, Japan.
Narita
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Yamagata
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Endo
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D000595:Amino Acid Sequence; D001410:Bacillus megaterium / Q000737:chemistry / Q000187:drug effects / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004352:Drug Resistance, Microbial; D005798:Genes, Bacterial / Q000235:genetics; D008190:Lyases; D008627:Mercuric Chloride / Q000494:pharmacology; D008628:Mercury / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic; D009876:Operon; D009941:Organomercury Compounds / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D009941:Organomercury Compounds; D008627:Mercuric Chloride; D008190:Lyases; C097247:MerB protein, Bacteria; D008628:Mercury