Crystallization (Comment) | Organism |
---|---|
purified recombinanat His-tagged enzyme Tn501 MerA, as NADP+/Hg2+ complex of mutant C136A/C141A, hanging drop vapor diffusion technique, mixing of 0.002 ml of 25 mg/ml protein solution with 0.0.02 ml of reservoir solution containing 0.1 M Tris, pH 9.4, 20 mM NADP+, 2.0 M (NH4)2SO4, equilibration against 0.5 ml of reservoir solution, X-ray diffraction structure determination and analysis at 1.6 A resolution, modeling | Pseudomonas aeruginosa |
Protein Variants | Comment | Organism |
---|---|---|
C136A/C141A | site-directed mutagenesis, the C136A/C141A catalytic core mutant. Mutation of either C136 or C141 or both results in a total loss of Hg2+ reductase activity. CRystal structure determination with bound substrates | Pseudomonas aeruginosa |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
Hg2+ + NADPH | Pseudomonas aeruginosa | - |
Hg + NADP+ + H+ | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Pseudomonas aeruginosa | - |
- |
- |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
Hg + NADP+ + H+ = Hg2+ + NADPH | molecular mechanism of the Hg transfer is analyzed by quantum mechanical/molecular mechanical (QM/MM) calculations, and simulation. 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, detailed overview | Pseudomonas aeruginosa |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
Hg2+ + NADPH | - |
Pseudomonas aeruginosa | Hg + NADP+ + H+ | - |
? |
Subunits | Comment | Organism |
---|---|---|
homodimer | interfacial active site of the MerA homodimer, structure overview | Pseudomonas aeruginosa |
More | structure comparisons of the mutant C136A/C141A (AACC) Hg2+/NADP+ complex (PDB 4K7Z) and the oxidized wild-type (CCCC) enzyme (PDB 1ZK7) | Pseudomonas aeruginosa |
Synonyms | Comment | Organism |
---|---|---|
MerA | - |
Pseudomonas aeruginosa |
mercuric reductase | - |
Pseudomonas aeruginosa |
Tn501 MerA | - |
Pseudomonas aeruginosa |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
FAD | binding structure, overview | Pseudomonas aeruginosa | |
NADPH | - |
Pseudomonas aeruginosa |
General Information | Comment | Organism |
---|---|---|
additional information | 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 | Pseudomonas aeruginosa |