Characterization of two regulatory genes of the mercury resistance determinants from TnMERI1 by luciferase-based examination.
The broad-spectrum mercury resistance transposon, TnMERI1, of Bacillus megaterium strain MB1, contains three proposed operator/promoter (O/P) transcriptional start sites and two regulatory genes (merR1 and merR2). A series of luciferase (lux)-based transcriptional fusion plasmids were studied in Escherichia coli to show that both merR1 and merR2 gene products repressed transcription from O/PmerB3, O/PmerR1, and O/PmerR2 under uninduced conditions. Derepression occurred when the merR1 gene was present and Hg(2+) functioned as an inducer. In the presence of organomercurial compounds, basal transcription of merB3 was needed to produce inorganic Hg(2+) as the inducer of expression regulated by MerR1 at O/PmerB3. The presence of merR2 repressed transcription from all three O/Pmer sites under both non-induced conditions and when inorganic Hg(2+) or organomercurials were added. These results show that MerR1 functions as a repressor in the absence of Hg(2+) and as an activator in the presence of Hg(2+), while MerR2 functions as a repressor.
Huang
Chieh Chen
CC
Laboratory of Environmental Biotechnology, Faculty of Engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo-shi, 985-8537, Miyagi, Japan.
Narita
Masaru
M
Yamagata
Takeshi
T
Phung
Le T
le T
Endo
Ginro
G
Silver
Simon
S
D001410:Bacillus megaterium / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004251:DNA Transposable Elements / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D005786:Gene Expression Regulation; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008190:Lyases / Q000378:metabolism; D008628:Mercury / Q000378:metabolism / Q000494:pharmacology; D010662:Phenylmercuric Acetate / Q000378:metabolism / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics; D020033:Protein Isoforms / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; C051124:MerR protein, Bacteria; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D008156:Luciferases; D008190:Lyases; C050953:alkylmercury lyase; D008628:Mercury; D010662:Phenylmercuric Acetate