Disease relevance of merR

• Plasmids from incompatibility groups C, B, S, L, and P, as well as the Pseudomonas transposons Tn501 and Tn3401, regulated the expression of the R100 mer genes in a similar fashion to the R100-1 merR product itself, suggesting that these elements are closely related [1].

High impact information on merR

• 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) [2].
• The lac fusion results were compared with those from a narrow-spectrum-resistance (Hg2+ responding but not phenylmercuric responding) operon and the pDU1358 merR deleted at the 3' end [2].
• A mutant form of pDU1358 merR missing the C-terminal 17 amino acids responded to inorganic Hg2+ but not to phenylmercury [2].
• Comparison of this sequence with DNA sequences of narrow-spectrum mer operons from transposon Tn501 and plasmid R100 showed that a major difference occurred in the 3' 29 base pairs of the merR gene, resulting in unrelated C-terminal 10 amino acids [2].
• The products of the merR and merD genes were not identified [3].

Biological context of merR

• Transcription of the mer genes of plasmid R100 is regulated by the product of the merR gene [1].
• The merR gene negatively regulates its own expression and also controls the transcription of the merTCA operon both negatively (in the absence of inducer) and positively (in the presence of inducer) [1].
• The 260-bp fragment also allows low-level constitutive expression of tet resistance when transactivated with merR mutants that have a "micro-constitutive" phenotype [4].

Other interactions of merR

• Mutations affecting the previously described mer genes merR (regulation), merT (transport), and merA (reductase) were characterized [5].

Analytical, diagnostic and therapeutic context of merR

• We used transcriptional mer-lac fusions of R100-1 in complementation tests to measure the ability of the merR products of different mercury-resistant transposons and plasmids to functionally interact with R100-1 [1].

References