Fair trials and the use of improperly obtained evidence

Jackson, John D.; Summers, Sarah

doi:10.1017/cbo9781139093606.010

Cited by 3 publications

(3 citation statements)

References 18 publications

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“…Membrane fractions from E. coli CSH26Δ rec A cells expressing the merTP , merT , merC , or merF genes in pUC18/19 contained radiolabelled protein of the molecular masses expected from their primary structures (Fig. 1), except MerT which runs at a higher apparent M r , as found previously [8,23–25]. The MerC and MerF proteins (tracks 4 and 5, Fig.…”

Section: Resultssupporting

confidence: 73%

MerF is a mercury transport protein: different structures but a common mechanism for mercuric ion transporters?

Wilson¹,

Leang²,

Morby³

et al. 2000

FEBS Letters

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Mercury resistance determinants are widespread in Gram-negative bacteria, but vary in the number and identity of genes present. We have shown that the merF gene from plasmid pMER327/419 encodes a 8.7 kDa mercury transport protein, by determining in vivo mercury volatilisation when MerF is expressed in the presence of mercuric reductase. We have confirmed that MerC of Tn21 is also a mercuric ion transporter. We have been able to detect interaction of the periplasmic protein MerP only with the MerT transporter, and not with MerF or MerC. Hydropathy analysis led to the prediction of models for MerT, MerC and MerF having three, four and two transmembrane regions respectively. In all three cases one pair of cysteine residues is predicted to be within the inner membrane with a second pair of cysteine residues on the cytoplasmic face, and the second helix contains a proline and at least one charged residue. The mechanisms of mercuric ion transport may be similar in these transporters even though their structures in the membrane differ.z 2000 Federation of European Biochemical Societies.

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Section: Resultssupporting

confidence: 73%

MerF is a mercury transport protein: different structures but a common mechanism for mercuric ion transporters?

Wilson¹,

Leang²,

Morby³

et al. 2000

FEBS Letters

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“…1 Their resistance to mercury-containing compounds is attributed to the presence of a set of genes located on a transferable genetic component known as the mer operon. 2–4 Although the exact composition of proteins produced from the mer operon varies among the different strains of resistant bacteria, the most common form of the operon encodes for proteins that function to detoxify both organomercurial compounds and ionic Hg II by converting them to the less toxic elemental mercury (Hg 0 ). 5,6 The metabolic conversion of organomercurial compounds to Hg 0 requires two key enzymes encoded by the mer operon.…”

Section: Introductionmentioning

confidence: 99%

Structural and Biochemical Characterization of Organotin and Organolead Compounds Binding to the Organomercurial Lyase MerB Provide New Insights into Its Mechanism of Carbon–Metal Bond Cleavage

et al. 2017

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The organomercurial lyase MerB has the unique ability to cleave carbon–Hg bonds, and structural studies indicate that three residues in the active site (C96, D99, and C159 in E. coli MerB) play important roles in the carbon–Hg bond cleavage. However, the role of each residue in carbon–metal bond cleavage has not been well-defined. To do so, we have structurally and biophysically characterized the interaction of MerB with a series of organotin and organolead compounds. Studies with two known inhibitors of MerB, dimethyltin (DMT) and triethyltin (TET), reveal that they inhibit by different mechanisms. In both cases the initial binding is to D99, but DMT subsequently binds to C96, which induces a conformation change in the active site. In contrast, diethyltin (DET) is a substrate for MerB and the SnIV product remains bound in the active site in a coordination similar to that of HgII following cleavage of organomercurial compounds. The results with analogous organolead compounds are similar in that trimethyllead (TML) is not cleaved and binds only to D99, whereas diethyllead (DEL) is a substrate and the PbIV product remains bound in the active site. Binding and cleavage is an exothermic reaction, while binding to D99 has negligible net heat flow. These results show that initial binding of organometallic compounds to MerB occurs at D99 followed, in some cases, by cleavage and loss of the organic moieties and binding of the metal ion product to C96, D99, and C159. The N-terminus of MerA is able to extract the bound PbVI but not the bound SnIV. These results suggest that MerB could be utilized for bioremediation applications, but certain organolead and organotin compounds may present an obstacle by inhibiting the enzyme.

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“…[6][7][8][9] The mercury resistance is due to a dedicated set of genes that are regulated together by the mer operon. 10,11 The mer operon occurs in most cases on transferable genetic elements such as transposons or plasmids, and it is not part of the native genome. The activation of the mer operon occurs only in response to the presence of compounds containing mercury, which bind to the DNAbound MerR and activate expression of the mer operon.…”

mentioning

confidence: 99%

The Organomercurial LyaseMerB

Lello

Lafrance‐Vanasse

Omichinski

2011

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Enzyme; lyase; EC 4.99.1.2; an alkylmercury lyase or organomercurial lyase commonly known as MerB.MerB catalyzes the protonolysis of the carbon-mercury bond in organomercurials, yielding ionic mercury and the corresponding hydrocarbon (see Scheme 1). MerB is active on a large variety of substrates ranging from simple alkyl compounds like methylmercury, which is the most naturally abundant organomercurial, to polyaromatic heterocyclic compounds like merbromin. 3,4 MerB also catalyzes the cleavage of the carbon-tin bond in select organostannanes like tetravinyltin, but in a less efficient manner. 5 O C C U R R E N C EThe organomercurial lyase MerB is a cytosolic protein found in gram-positive and gram-negative bacterial strains that display resistance to both ionic mercury and organomecurial compounds. [6][7][8][9] The mercury resistance is due to a dedicated set of genes that are regulated together by the mer operon. 10,11 The mer operon occurs in most cases on transferable genetic elements such as transposons or plasmids, and it is not part of the native genome. The activation of the mer operon occurs only in response to the presence of compounds containing mercury, which bind to the DNAbound MerR and activate expression of the mer operon. 12 The composition of the mer operon can vary dramatically between different bacterial strains, but resistance to organomercurial requires the presence of two enzymes, the lyase MerB and the mercuric reductase MerA. 9 B I O L O G I C A L F U N C T I O NMerB belongs to a group of proteins that confers organomercurials with resistance to specific bacteria containing the mer operon. 9,13 The mercury detoxification 3D Structure Ribbon representation of the mercury-bound form of the organomercurial lyase MerB. PDB code: 3F0O. The core domain of the protein is colored in dark blue, the amino-terminal region of the protein is colored in teal, and the mercury ion is represented as a gray sphere. This representation and all other structural representations were prepared using PyMOL 1 unless noted otherwise.

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Fair trials and the use of improperly obtained evidence

Cited by 3 publications

References 18 publications

MerF is a mercury transport protein: different structures but a common mechanism for mercuric ion transporters?

MerF is a mercury transport protein: different structures but a common mechanism for mercuric ion transporters?

Structural and Biochemical Characterization of Organotin and Organolead Compounds Binding to the Organomercurial Lyase MerB Provide New Insights into Its Mechanism of Carbon–Metal Bond Cleavage

The Organomercurial LyaseMerB

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