EC Number   |
General Information |
Reference |
|---|
    1.16.1.1 | evolution |
MerA is part of the disulfide oxidoreductase (DSOR) family, are ancient enzymes that have arisen in high temperature environments after the great oxidation event about 2.4 billion years ago |
-, 744965 |
| 1.16.1.1 | evolution |
organomercurials are converted to less toxic Hg(0) in the cytosol by the sequential action of organomercurial lyase MerB and mercuric ion reductase MerA, requiring transfer of Hg(II) from MerB to MerA, with transfer to the metallochaperone-like NmerA domain as the kinetically favored pathway in this coevolved system, overview. Hg(II) removal from MerB by the N-terminal domain, NmerA, and catalytic core C-terminal cysteine pairs of its coevolved MerA and by GSH, the major competing cellular thiol in gamma-proteobacteria. The reaction with a 10fold excess of NmerA over HgMerB removes about 92% of Hg(II), while similar extents of reaction require more than 1000fold excess of GSH |
714219 |
| 1.16.1.1 | more |
comparison of structural changes upon metal binding in normally appended metal binding proteins: NmerA with and without Hg2+ , PDB entry 2KT3 and 2KT2, respectively |
714224 |
| 1.16.1.1 | more |
full-length MerA homodimer structure and transfer of Hg(II) from the solvent into the catalytic sites of the MerA core, overview. Enzyme structure-function analysis by molecular dynamics, coarse-grained simulations, small-angle neutron scattering, neutron spin-echo spectroscopy, and dynamic light scattering |
744515 |
| 1.16.1.1 | more |
many MerA proteins possess metallochaperone-like N-terminal domains (NmerA) that can transfer Hg2+ to the catalytic core domain (Core) for reduction to Hg0. These domains are tethered to the homodimeric core by an about 30-residue linkers that are susceptible to proteolysis, interactions of NmerA and the Core in the full-length protein, structure homology modelling amd structure-function analysis, detailed overview. Binding of Hg2+ to MerA does not alter its hydrodynamic volume |
728149 |
| 1.16.1.1 | more |
MerA is an inducible NADPH-dependent and flavin containing disulfide oxidoreductase enzyme. MerA-encoding plasmid R100-containing Escherichia coli strains are involved in environmental inorganic mercury detoxification |
713700 |
| 1.16.1.1 | more |
molecular mechanism of the Hg transfer is analyzed by quantum mechanical/molecular mechanical (QM/MM) calculations. The transfer is nearly thermoneutral and passes through a stable tricoordinated intermediate that is marginally less stable than the two end states. For the overall process, Hg2+ is always paired with at least two thiolates and thus is present at both the C-terminal and catalytic binding sites as a neutral complex. Prior to Hg2+ transfer, C141 is negatively charged. As Hg2+ is transferred into the catalytic site, a proton is transferred from C136 to C559' while C558' becomes negatively charged, resulting in the net transfer of a negative charge over a distance of about 7.5 A. Thus, the transport of this soft divalent cation is made energetically feasible by pairing a competition between multiple Cys thiols and/or thiolates for Hg2+ with a competition between the Hg2+ and protons for the thiolates. Reaction mechansim, formation of a tri-coordinated intermediate state, INT-III, detailed overview |
744330 |
| 1.16.1.1 | more |
strain R1-1 is resistant to concentration of over 0.01 mM Hg2+, transforms Hg(II) to Hg(0) during cellular growth, and possesses Hg-dependent NAD(P)H oxidation activities in crude cell extracts that are optimal at temperatures corresponding with the strains' optimal growth temperature of 70°C |
726730 |
| 1.16.1.1 | more |
the active site is formed by the interaction of the central domain of a subunit with another C-terminal domain. The central domain, described as a pyridine nucleotide oxidoreductase disulfide group, is where catalysis and the transfer of two electrons from NADPH to Hg(II) via FAD, occurs |
-, 745894 |
| 1.16.1.1 | more |
the resonance Raman (RR) spectra of various functional forms of MerA are indicative of a modulation of both ring II distortion and H-bonding states of the N5 site and ring III. The Cd(II) binding to the EH2-NADP(H) complexes, biomimetic intermediates in the reaction of Hg(II) reduction, provokes important spectral changes. They are interpreted in terms of flattening of the isoalloxazine ring and large decreases in H-bonding at the N5 site and ring III. The large flexibility of the FAD structure and environment in MerA is in agreement with proposed mechanisms involving C4a(flavin) adducts |
744823 |
