| purification and functional characterization of merd. a coregulator of the mercury resistance operon in gram-negative bacteria. | mercury resistance operons (mer) from transposons tn21, tn501, and plasmid pdu1358 are highly homologous and inducible with hg2+. the regulatory gene merr is transcribed from one promoter, which is divergently oriented from the promoter for the other mer genes. merr, the product of the regulatory gene, negatively regulates its own expression as well as the expression of the other genes. merr activates transcription of the operon in the presence of inducing concentrations of hg2+. the most promot ... | 1991 | 1917975 |
| constitutive synthesis of a transport function encoded by the thiobacillus ferrooxidans merc gene cloned in escherichia coli. | mercuric reductase activity determined by the thiobacillus ferrooxidans mera gene (cloned and expressed constitutively in escherichia coli) was measured by volatilization of 203hg2+. (the absence of a merr regulatory gene in the cloned thiobacillus mer determinant provides a basis for the constitutive synthesis of this system.) in the absence of the thiobacillus merc transport gene, the mercury volatilization activity was cryptic and was not seen with whole cells but only with sonication-disrupt ... | 1990 | 2185229 |
| mercury operon regulation by the merr gene of the organomercurial resistance system of plasmid pdu1358. | the structural basis for induction of the mercury resistance operon with inorganic mercury and with the organomercurial compound phenylmercuric acetate was addressed by dna sequencing analysis and by lac fusion transcription experiments regulated by merr in trans from broad-spectrum-resistance plasmid pdu1358 (hg2+ and phenylmercury responding). the lac fusion results were compared with those from a narrow-spectrum-resistance (hg2+ responding but not phenylmercuric responding) operon and the pdu ... | 1989 | 2666393 |
| cloning and dna sequence of the mercuric- and organomercurial-resistance determinants of plasmid pdu1358. | the broad-spectrum mercurial-resistance plasmid pdu1358 was analyzed by cloning the resistance determinants and preparing a physical and genetic map of a 45-kilobase (kb) region of the plasmid that contains two separate mercurial-resistance operons that mapped about 20 kb apart. one encoded narrow-spectrum mercurial resistance to hg2+ and a few organomercurials; the other specified broad-spectrum resistance to phenylmercury and additional organomercurials. each determinant governed mercurial tra ... | 1987 | 3033633 |
| purification and characterization of a novel organometallic receptor protein regulating the expression of the broad spectrum mercury-resistant operon of plasmid pdu1358. | the narrow spectrum mercury-resistant (mer) operons of transposons tn21 and tn501 are inducible by inorganic mercury salts. the major regulatory gene merr is transcribed divergently from the other mer genes, which are cotranscribed. the merr protein represses its own expression, as well as the expression of the other mer genes in the absence of the inducers. the synthesis of the polycistronic mer message is stimulated by merr in the presence of the inducers. the merrbs protein encoded by the bro ... | 1994 | 8195221 |
| phylogeny of mercury resistance (mer) operons of gram-negative bacteria isolated from the fecal flora of primates. | nine polymorphic mer loci carried by 185 gram-negative fecal bacterial strains from humans and nonhuman primates are described. the loci were characterized with specific intragenic and intergenic pcr primers to amplify distinct regions covering approximately 80% of the typical gram-negative mer locus. these loci were grouped phylogenetically with respect to each other and with respect to seven previously sequenced mer operons from gram-negative bacteria (the latter designated loci 1, 2, 3, 6, 7, ... | 1997 | 9055422 |
| complex multiple antibiotic and mercury resistance region derived from the r-det of nr1 (r100). | the sequence of the 45.2-kb multidrug and mercury resistance region of prmh760, a large plasmid from a clinical isolate of klebsiella pneumoniae collected in 1997 in australia, was completed. most of the modules found in the resistance determinant (r-det), or tn2670, region of nr1 (also known as r100), isolated from a shigella flexneri strain in japan in the late 1950s, were present in prmh760 but in a different configuration. the location was also different, with the tn2670-derived region flank ... | 2004 | 15504849 |