Disease relevance of Mercury II

• The mercuric ion-resistance operons of plasmid R100 (originally from Shigella) and transposon Tn501 (originally from a plasmid isolated in Pseudomonas) have been compared by DNA sequence analysis [1].
• The ALDH-ADP-ribose bond was sensitive to base and mercuric ion and stable to acid and neutral hydroxylamine, properties shared with the ADP-ribosylcysteine linkage synthesized enzymatically by pertussis toxin [2].
• The Hg(2+) cation induces an autoimmune disease in the Brown Norway rat characterized by synthesis and glomerular deposits of anti-glomerular basement membrane antibodies, proteinuria, and interstitial nephritis [3].
• Thus, inhibition of biological functions of selenium could be seen as a different mechanism of Hg(2+) toxicity [4].
• Between 13 and 89% of the E. coli were resistant to mercury(II) or to at least one of eight antibiotics tested [5].

High impact information on Mercury II

• We demonstrate here one such mechanism that employs a single heavy metal receptor protein, MerR, to directly activate transcription of the bacterial mercuric ion resistance operon [6].
• Upon mercuric ion binding, Hg-MerR converts this polymerase complex into the transcriptionally active or 'open' form [7].
• Mercuric ion-resistance operons of plasmid R100 and transposon Tn501: the beginning of the operon including the regulatory region and the first two structural genes [1].
• Copper-induced conformational changes in the essential C-terminal peptide of hCCS are consistent with a "pivot, insert, and release" mechanism that is similar to one proposed for the well characterized metal handling enzyme, mercuric ion reductase [8].
• In this study, MerC from the Tn21-encoded mer operon was overexpressed and studied in vesicles and in purified form to clarify the role played by this protein in mercuric ion resistance [9].

Chemical compound and disease context of Mercury II

• Protein molecules extracted directly from unseeded freshwater and samples seeded with Pseudomonas aeruginosa PU21 (Rip64) were quantitatively assayed for mercuric reductase activity in microtiter plates by stoichiometric coupling of mercuric ion reduction to a colorimetric redox chain through NADPH oxidation [10].
• Of 100 strains of iron-oxidizing bacteria isolated, Thiobacillus ferrooxidans SUG 2-2 was the most resistant to mercury toxicity and could grow in an Fe(2+) medium (pH 2.5) supplemented with 6 microM Hg(2+) [11].
• Anomalous difference Fouriers were again used, revealing that Hg(2+) had substituted for the same Zn(2+) cofactor ion as had Pb(2+), a finding of fundamental importance for the understanding of mercury poisoning [12].
• Male Wistar rats were separated into 8 groups and each was treated with one of following compounds, mercury II chloride (HgCl(2)), 2-bromoethanamine hydrobromide (BEA), carbon tetrachloride (CCl(4)), alpha-naphthylisothiocyanate (ANIT), and three doses of Ce(NO(3))(3) (i.p. 2, 10 and 50mg/kg body weight) [13].
• In the BrdU test, a significantly (P<0.05) decreased toxicity was observed for Hg(2+) at 48 h, compared to the 24 h Hg(2+)-exposure [14].

Biological context of Mercury II

• Dimerization of the trinuclear mercury(II) complex [(o-C(6)F(4)Hg)(3)*mu(3)-acetone] via mercurophilic interactions [15].
• Crystal soaking experiments revealed a binding site for Zn(2+) and Hg(2+), two known PSA inhibitors [16].
• When the analysis was performed during the first 4 hours after treatment administration, we observed a decrease of Mayer waves of systolic blood pressure with nifedipine (2.21 +/- 1.45 mm Hg(2) versus 3.53 +/- 1.85 mm Hg(2) with placebo) [17].
• Correlations of DNA strand breaks and their repair with cell survival following acute exposure to mercury(II) and X-rays [18].
• In vivo effects of mercury (II) on deoxyuridine triphosphate nucleotidohydrolase, DNA polymerase (alpha, beta), and uracil-DNA glycosylase activities in cultured human cells: relationship to DNA damage, DNA repair, and cytotoxicity [19].

Anatomical context of Mercury II

• Hydroxylamine, but not mercuric ion releases [32P]ADP-ribose, whereas phosphodiesterase releases [32P]AMP from the particulate subcellular fraction, suggesting that labeling is a result of enzymatic mono-ADP-ribosylation of arginines [20].
• The 116-amino-acid MerT protein is sufficient for mercuric ion transport across the cytoplasmic membrane [21].
• It was found that the divalent cations Mn(2+) and Hg(2+) were able to induce in vitro the activation of beta1 integrins on rat lymphocytes [3].
• Mutated proteins were expressed in COS cells and probed with Hg(2+), [2-(trimethylammonium)ethyl]methanethiosulfonate (MTSET), and biotin-maleimide, applied to the extracellular media while placing the cells in two different media (K-medium and Na-medium) [22].
• Y401C+E758C rat skeletal muscle Na(+) channels (mu1) that form a disulfide bond spontaneously between two cysteines at the 401 and 758 positions showed a significantly lower sensitivity to Hg(2+) (K(d) = 18 microM) [23].

Associations of Mercury II with other chemical compounds

• Mercury (II) forms a covalent, 1:1 complex with NADPH which is indicated by the disappearance of the chromophore at 340 nm [24].
• Effects of surfactants on cobalamin dependent methyl transfer. Influence of aqueous and reversed micelles on the interaction of mercuric ion with methylcobalamin [25].
• Design of an Emission Ratiometric Biosensor from MerR Family Proteins: A Sensitive and Selective Sensor for Hg(2+) [26].
• Mutagenesis of the N- and C-terminal cysteine pairs of Tn501 mercuric ion reductase: consequences for bacterial detoxification of mercurials [27].
• In addition, 1 can do ion-exchange with heavy-metal ions like Hg(2+), Pb(2+), and Ag(+) [28].

Gene context of Mercury II

• Furthermore, apical, but not basolateral, application of Hg(2+) significantly reduces the transepithelial osmotic permeability, suggesting that apical AQP1 and AQP5 may contribute significantly to fluid secretion [29].
• The passive water permeability ( L(p)) of AQP6 is activated by Hg(2+) [30].
• CONCLUSIONS: These observations are consistent with the hypothesis that JNK is one of the signaling proteins mediating the effect of Hg(2+) on IL-4 expression in mast cells and is engaged in environmentally mediated immunomodulation [31].
• A small region of merR corresponding to residues 81-92 also was mutagenized in a search for other RD mutants and for mutants displaying sufficient transcriptional activation in the absence of mercuric ion to be classified as constitutive activation (CA) mutants [32].
• CONCLUSION: These data represent ostensibly the most direct line of evidence implicating a specific membrane protein (i.e., hOAT1) in the transport of a biologically relevant molecular species of Hg(2+) in a mammalian cell [33].

Analytical, diagnostic and therapeutic context of Mercury II

• Mechanism of mercury(II) reductase and influence of ligation on the reduction of mercury(II) by a water soluble 1,5-dihydroflavin [34].
• The flavoenzyme mercuric ion reductase from Bacillus sp. strain RC607 was purified by dye-ligand affinity chromatography [35].
• Purification, crystallization, and preliminary x-ray diffraction studies of the flavoenzyme mercuric ion reductase from Bacillus sp. strain RC607 [35].
• Thermal difference circular dichroism of Pf1 filamentous virus and effects of mercury(II), silver(I), and copper(II) [36].
• Their cobalt(2+) binding properties in the presence and absence of mercury(2+) were characterized by UV-vis and circular dichroism spectroscopies and it was shown that hCCS has the ability to bind two spectroscopically distinct cobalt ions whereas tCCS binds only one [37].

References