Disease relevance of mercury

• Phylogeny of mercury resistance (mer) operons of gram-negative bacteria isolated from the fecal flora of primates [1].
• The mercury resistance (mer) operon of plasmid R100 was cloned onto various plasmid vectors to study the effect of mer gene amplification on the rate of Hg2+ reduction by Escherichia coli cells [2].
• By using fusions of the well-understood Tn21 mercury resistance operon (mer) with promoterless luxCDABE from Vibrio fischeri, we have constructed and tested three biosensors for Hg(II) [3].
• In contrast to the Thiobacillus ferrooxidans mer determinant, no merC gene was detected [4].
• At least three distinct transposons (related to a class II vancomycin-resistance transposon, Tn1546, from a clinical Enterococcus strain) and conjugative plasmids are implicated as mediators of the spread of these mer operons [5].

High impact information on mercury

• The paradigm example, Tn21, also carries genes for its own transposition and a mercury resistance (mer) operon [6].
• A possible seventh gene in the mer operon (merE), perhaps with a role in Hg(II) transport, lies in the junction between the integron and the mer operon [6].
• The MerR metalloregulatory protein is a heavy-metal receptor that functions as the repressor and Hg(II)-responsive transcription activator of the prokaryotic mercury-resistance (mer) genes [7].
• In vivo DNA-protein interactions at the divergent mercury resistance (mer) promoters. II. Repressor/activator (MerR)-RNA polymerase interaction with merOP mutants [8].
• Expression of the Tn21 mercury resistance (mer) operon is controlled by a metal-sensing repressor-activator, MerR [9].

Biological context of mercury

• Our assessment adds molecular detail to previous models of the evolution of Tn21 and is consistent with the insertion of the integron In2 into an ancestral Tn501-like mer transposon [6].
• With another approach in which probes derived from one of the isolated plasmids and a mercury resistance (mer) probe from Tn501 were used, similarities between plasmids from several different groups were found [10].
• Between 35 and 100% of the isolates from the four sites contained DNA sequences homologous to a DNA probe from the mercury resistance (mer) operon of the Tn501 Hgr determinant [11].
• Bioluminescence specified by pRB28, carrying merRo/pT, by pOS14, mediating active transport of Hg(II), and by pOS15, containing an intact mer operon, was measured in rich and minimal media [3].
• Specific DNA sequences from native bacterial populations present in soil, sediment, and sand samples were amplified by using the polymerase chain reaction with primers for either "universal" eubacterial 16S rRNA genes or mercury resistance (mer) genes [12].

Associations of mercury with other chemical compounds

• Analysis of the region interrupted by insertion of the integron suggests that the putative transposition regulator, tnpM, is the C-terminal vestige of a tyrosine kinase sensor present in the ancestral mer transposon [6].

References