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Enzyme Nomenclature
Information on EC 1.16.1.1 - mercury(II) reductase
for references in articles please use BRENDA:EC1.16.1.1
Word Map on EC 1.16.1.1
- 1.16.1.1
-
volatilization
-
organomercurial
-
mercury-resistant
- hgcl2
- methylmercury
- lipoamide
-
phytoremediation
-
mercury-contaminated
- ferrooxidans
-
geothermal
-
phenylmercury
-
metal-resistant
- environmental protection
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The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
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EC NUMBER 
COMMENTARY 
1.16.1.1
-
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RECOMMENDED NAME
GeneOntology No.
mercury(II) reductase
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Hg + NADP+ + H+ = Hg2+ + NADPH
-
-
-
-
Hg + NADP+ + H+ = Hg2+ + NADPH
FAD mediates the transfer of electrons between NADPH and Hg2+ bound to an adjacent pair of cysteine thiols (C136 and C141) in the buried active site, while a second pair of cysteines (C558 and C559) on the C-terminal tail mediates transfer of Hg2+ from other protein and small molecule thiols in solution to the active site cysteines through a ligand exchange mechanism, structure-function study, overview
-
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
redox reaction
-
-
-
-
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
phenylmercury acetate degradation
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SYSTEMATIC NAME
IUBMB Comments
Hg:NADP+ oxidoreductase
A dithiol enzyme.
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CAS REGISTRY NUMBER
COMMENTARY
67880-93-7
-
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
isolated from surface and sub-surface floodplain soil, Oak Ridge, USA, gene merA
-
-
i.e. Bacillus sphaericus, isolated from an industrial mercuric salt-contaminated soil, gene merA
UniProt
mercury-resistant Escherichia coli strain containing plasmid R100 encoding gene merA in the mer operon
-
-
marine-isolated mercury-resistant strain, isolated from seawater collected from Yantai coastal zone in Shandong Province, China, gene merA encoded in the mer operon
-
-
analysis of enzyme in several thermophylic crenarchaeal and gram-positive taxa isolates from a hot spring. An essential role for mercuric reductase is evident during growth in the mercury-contaminated environment. Despite environmental selection for mercury resistance and the proximity of community members, the enzyme retains the two distinct prokaryotic forms and avoids genetic homogenization
-
-
isolated from surface and sub-surface floodplain soil, Oak Ridge, USA, gene merA
-
-
isolated from surface and sub-surface floodplain soil, Oak Ridge, USA, gene merA
-
-
from the unique deep brine environment of Atlantis II in the Red Sea, lower convective layer, gene merA
UniProt
enzyme encoded by Tn5044 merA gene, thermosensitive resistance to mercury, expression and functional activity of enzyme are severely inhibited at 37-41.5°C
-
-
plasmid R100; Escherichia coli containing plasmid R100 encoding gene merA
UniProt
i.e. Bacillus sphaericus, isolated from an industrial mercuric salt-contaminated soil, gene merA
UniProt
possessing the Tn501 plasmid, a transposon determining resistance to mercuric ions
-
-
marine-isolated mercury-resistant strain, isolated from seawater collected from Yantai coastal zone in Shandong Province, China, gene merA encoded in the mer operon
-
-
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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
physiological function
additional information
physiological function
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. NmerA reacts more completely than GSH with HgMerB
physiological function
MerA catalyzes the bioconversion of toxic Hg2+ to the least toxic elemental Hg0
physiological function
the mercuric reductase is functional in high salt, stable at high temperatures, resistant to high concentrations of Hg2, and efficiently detoxifies Hg2 in vivo. Mercuric ion reductase catalyzes the reduction of Hg2+ to Hg0, which is volatile and can be disposed of nonenzymatically
additional information
-
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
additional information
-
comparison of structural changes upon metal binding in normally appended metal binding proteins: NmerA with and without Hg2+ , PDB entry 2KT3 and 2KT2, respectively
additional information
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
additional information
the two acidic residues immediately adjacent to the NmerA metal-binding motif in the ATII-LCL protein have a direct effect on both the halophilicity and catalytic efficiency of the enzyme. Presumably, by increasing the efficiency of delivery of Hg2 ions to the catalytic core for reduction, they also help the host to cope with the high concentrations of mercury present in its hypersaline environment
additional information
-
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
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2,4,6-trinitrobenzenesulfonate + NADPH
? + NADP+
-
-
-
?
2,4,6-trinitrobenzenesulfonate + NADPH
? + NADP+
-
-
-
?
Hg + NADP+ + H+
Hg2+ + NADPH
MerA catalyzes the bioconversion of toxic Hg2+ to the least toxic elemental Hg0, and is capable of reducing the Hg2+, via NADPH as an electron donor
-
-
?
Hg + NADP+ + H+
Hg2+ + NADPH
-
Cys11 and Cys14 are involved in metal binding, role for Tyr62 in modulating the pKa values of the cysteine thiols
-
-
?
Hg + NADP+ + H+
Hg2+ + NADPH
-
the enzmye reduces reactive Hg2+ to volatile and relatively inert monoatomic Hg0 vapor. Pseudomonas putida SP1 is able to volatilize almost 100% of the total mercury it is exposed to
-
-
r
Hg + NADP+ + H+
Hg2+ + NADPH
-
the enzmye reduces reactive Hg2+ to volatile and relatively inert monoatomic Hg0 vapor. Pseudomonas putida SP1 is able to volatilize almost 100% of the total mercury it is exposed to
-
-
r
Hg + NADP+ + H+
Hg2+ + NADPH
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
-
-
?
Hg2+ + NADH
Hg + NAD+ + H+
-
nearly identical activity with NADPH or NADH
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
-
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
-
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
-
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
last step in bacterial mercury detoxification pathway
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
Flavobacterium rigense
-
mercury resistance is due to the sequential action of two mercury-detoxificating enzymes, organomercurial lyase and mercuric reductase. Enzyme is induced by Hg2+ and organomercurials
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
Flavobacterium rigense PR2
-
mercury resistance is due to the sequential action of two mercury-detoxificating enzymes, organomercurial lyase and mercuric reductase. Enzyme is induced by Hg2+ and organomercurials
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
nearly identical activity with NADPH or NADH
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
the enzyme is a key component of an organomercurial detoxification system
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
the enzyme is a key component of an organomercurial detoxification system
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
-
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
the merA mutant exhibits mercury sensitivity relative to wild type and is defective in elemental mercury volatilization
-
-
?
Hg2+ + NADPH
Hg(0) + NADP+
-
key enzyme in detoxification of mercury in bacteria
-
-
r
Hg2+ + NADPH
Hg(0) + NADP+
-
mercuric ion resistance in bacteria requires transport of Hg2+ ions into the cytoplasmic compartment where they are reduced to the less toxic metallic mercury Hg0 by mercuric reductase
-
-
r
Hg2+ + NADPH
Hg(0) + NADP+
-
interactions between the inner membrane mercuric ion transporter, MerT, and the N-terminal domain of cytoplasmic mercuric reductase, transport is the rate-limiting step in mercury detoxification, overview
-
-
r
Hg2+ + NADPH
Hg(0) + NADP+
-
key enzyme in detoxification of mercury in bacteria
-
-
r
Hg2+ + NADPH
Hg(0) + NADP+
-
key enzyme in detoxification of mercury in bacteria
-
-
r
additional information
?
-
-
Tyr264 and Tyr605 are involved in substrate binding, Tyr264 is important for catalysis, possibly by destabilizing the binding of Hg(II) to the two ligating thiolates at the active site
-
-
-
additional information
?
-
-
Tyr264 and Tyr605 are involved in substrate binding, Tyr264 is important for catalysis, possibly by destabilizing the binding of Hg(II) to the two ligating thiolates at the active site
-
-
-
additional information
?
-
-
Cys558 plays a more important role in forming the reducible complex with Hg(II), while both Cys558 and Cys559 seem to be involved in efficient scavenging of Hg(II)
-
-
-
additional information
?
-
-
structure-function study of the N-terminal HMA domain NmerA of Tn501 mercuric ion reductase , i.e. MerA, using NMR and spectral techniques, overview. Determination of NMR solution structures of reduced and Hg2+-bound forms of NmerA
-
-
-
additional information
?
-
proposed model for reaction of NmerA with HgMerB and of GSH with HgMerB, overview
-
-
-
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
additional information
?
-
E0XF09
proposed model for reaction of NmerA with HgMerB and of GSH with HgMerB, overview
-
-
-
Hg + NADP+ + H+
Hg2+ + NADPH
Q93UN8
MerA catalyzes the bioconversion of toxic Hg2+ to the least toxic elemental Hg0, and is capable of reducing the Hg2+, via NADPH as an electron donor
-
-
?
Hg + NADP+ + H+
Hg2+ + NADPH
-
the enzmye reduces reactive Hg2+ to volatile and relatively inert monoatomic Hg0 vapor. Pseudomonas putida SP1 is able to volatilize almost 100% of the total mercury it is exposed to
-
-
r
Hg + NADP+ + H+
Hg2+ + NADPH
-
the enzmye reduces reactive Hg2+ to volatile and relatively inert monoatomic Hg0 vapor. Pseudomonas putida SP1 is able to volatilize almost 100% of the total mercury it is exposed to
-
-
r
Hg + NADP+ + H+
Hg2+ + NADPH
E0XF09
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
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
last step in bacterial mercury detoxification pathway
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
Flavobacterium rigense
-
mercury resistance is due to the sequential action of two mercury-detoxificating enzymes, organomercurial lyase and mercuric reductase. Enzyme is induced by Hg2+ and organomercurials
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
Flavobacterium rigense PR2
-
mercury resistance is due to the sequential action of two mercury-detoxificating enzymes, organomercurial lyase and mercuric reductase. Enzyme is induced by Hg2+ and organomercurials
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
the enzyme is a key component of an organomercurial detoxification system
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
-
the enzyme is a key component of an organomercurial detoxification system
-
-
?
Hg2+ + NADPH
Hg + NADP+ + H+
Q97VD9
the merA mutant exhibits mercury sensitivity relative to wild type and is defective in elemental mercury volatilization
-
-
?
Hg2+ + NADPH
Hg(0) + NADP+
-
key enzyme in detoxification of mercury in bacteria
-
-
r
Hg2+ + NADPH
Hg(0) + NADP+
-
mercuric ion resistance in bacteria requires transport of Hg2+ ions into the cytoplasmic compartment where they are reduced to the less toxic metallic mercury Hg0 by mercuric reductase
-
-
r
Hg2+ + NADPH
Hg(0) + NADP+
-
key enzyme in detoxification of mercury in bacteria
-
-
r
Hg2+ + NADPH
Hg(0) + NADP+
-
key enzyme in detoxification of mercury in bacteria
-
-
r
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
additional information
the enzymes contains FAD, utilizes NADPH as an electron donor, and requires an excess of exogenous thiols for activity
-
NADPH
-
; the first two steps of the reaction involve 1 mol NADPH per mol FAD, the third requires a second equivalent of NADPH
NADPH
-
; in presence of 1 mM cysteine only one equivalent of NADPH per FAD is required for full activation
NADPH
-
in the presence of an excess of NADPH, the final product of the reaction is probably an NADPH complex of two-electron-reduced enzyme, but below pH 6 the final spectrum becomes less intense suggesting a partial formation of four-electron-reduced enzyme
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
additional information
-
the organism is resistant to CdCl2, CoCl2, CrCl3, CuCl2, PbCl2, ZnSO4, and to 0.28 mM HgCl2
additional information
the mercuric reductase is functional in high salt and resistant to high concentrations of Hg2+
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
NADPH
-
substrate inhibition of the reaction with 2,4,6-trinitrobenzenesulfonate and NADPH
additional information
-
no inhibition by 2,4,6-trinitrobenzenesulfonate; not inhibitory: 0.1 mM NADP+; not inhibitory: 100 microM 2,4,6-trinitrobenzenesulfonate
-
additional information
-
the organism is highly resistant to the antibiotics ampicillin, kanamycin, chloramphenicol, and tetracycline
-
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
NADPH
-
100 microM, 30 min preincubation, relative initial rate 151%, 10 min preincubation with NADPH results in an increase of reactive thiol groups
thiol
-
exogenous thiols are required for catalytic reduction of Hg(II) to Hg2+, due to prevention or reversal of formation of an abortive complex of Hg(II) with the thiol/thiolate pair of two-electron reduced enzyme
additional information
-
0.1 mM NADP+ stimulates the 2,4,6-trinitrobenzenesulfonate-dependent NADPH oxidation more than 10fold
-
2-mercaptoethanol
-
thiol compound required, optimal concentration is 0.5 mM
cysteine
-
1 mM, 30 min preincubation, relative initial rate 121%; 30 mM, 30 min preincubation, relative initial rate 200%
EDTA
-
1 mM, 30 min preincubation, relative initial rate 104%; no effect
NADP+
-
strong stimulation of the reaction with 2,4,6-trinitrobenzenesulfonate and NADPH
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.0032
Hg2+
-
1 mM cysteine, 25°C, pH 7.3; in presence of 1 mM cysteine
0.035
Hg2+
-
recombinant catalytic core, presence of N-terminal sequence NmerA, 25°C, pH 7.3
additional information
additional information
Yersinia enterolytica
-
the Km-value for HgCl2 is dependent on the concentration of exogenous thiol compounds
-
additional information
additional information
steady-state kinetic analysis, overview, apparent second-order rate constant for Hg(II) transfer from MerB to NmerA
-
additional information
additional information
kinetics of wild-type and mutant enzymes, overview
-
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
12
Hg2+
-
recombinant catalytic core, presence of N-terminal sequence NmerA, 25°C, pH 7.3
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Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
0.13
cell extract, mercury-dependent oxidation of NADPH, pH 7.4, 25°C
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
7.3
7.4
7.5
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pH RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
6.5 - 9
-
pH 6.5: about 60% of maximal activity, pH 9.0: about 50% of maximal activity
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
25
37
45
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TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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pI VALUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
additional information
additional information
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
additional information
strain AAS1 is resistant to concentration 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 55°C
additional information
growth of strain G1 at sublethal concentrations of metal salts, Cd2+, Zn2+, Co2+, and K2Cr2O7-, in presence of absence of Hg2+, overview
additional information
-
growth of strain G1 at sublethal concentrations of metal salts, Cd2+, Zn2+, Co2+, and K2Cr2O7-, in presence of absence of Hg2+, overview
additional information
-
growth of strain G1 at sublethal concentrations of metal salts, Cd2+, Zn2+, Co2+, and K2Cr2O7-, in presence of absence of Hg2+, overview
-
additional information
-
the low virulence strain is part of the biofilm. Optimal pH for the growth and enzyme activity of strain SP1 in presence of HgCl2 is pH 8.0-9.0, whereas optimal pH for expression of merA is pH 5.0
additional information
-
the low virulence strain is part of the biofilm. Optimal pH for the growth and enzyme activity of strain SP1 in presence of HgCl2 is pH 8.0-9.0, whereas optimal pH for expression of merA is pH 5.0
-
additional information
the organism is grown in the lower convective layer of the brine pool at Atlantis II Deep in the Red Sea, with a maximum depth of over 2000 m, the pool is characterized by acidic pH 5.3, high temperature 68°C, , salinity of 26%, low light levels, anoxia, and high concentrations of heavy metals
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
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PDB
SCOP
CATH
ORGANISM
UNIPROT
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
54000
56000
58000
62000
69000
190000
additional information
additional information
-
the enzyme shows extensive sequence homology and functional similarities in the active site of mercuric reductase and nicotinamide disulfide oxidoreductase
additional information
-
nucleotide sequence of the gene encoding mercuric reductase
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SUBUNITS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
dimer
homodimer
monomer
trimer
additional information
homodimer
each monomer contributes one active site, made up of a pair of redox-active cysteines, to a catalytic core located at the dimer interface, three-dimensional structure homology modeling, overview
trimer
Yersinia enterolytica 138A14
-
3 * 70000, SDS-PAGE
-
additional information
-
N-terminal domain NmerA participates in acquisition and delivery of Hg2+ to the catalytic core during thr reduction catalyzed by full-length enzyme
additional information
-
N-terminal domain NmerA participates in acquisition and delivery of Hg2+ to the catalytic core during thr reduction catalyzed by full-length enzyme
-
additional information
Yersinia enterolytica
-
along with ageing, as well as limited proteolytic digestion, the enzyme evolves to give a dimeric molecule of 105000 Da composed of two identical subunits of 52000 Da
additional information
Yersinia enterolytica 138A14
-
along with ageing, as well as limited proteolytic digestion, the enzyme evolves to give a dimeric molecule of 105000 Da composed of two identical subunits of 52000 Da
-
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Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
80
additional information
the mercuric reductase is stable at high temperatures
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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
immobilization of the enzyme appears to significantly enhance storage stability
-
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OXIDATION STABILITY
ORGANISM
UNIPROT
LITERATURE
activated enzyme appears to be stable under anaerobic conditions and eventually returns to the original level of activity in the presence of oxygen. The activated state seems to be stabilized by 1mM cysteine.
-
438069
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
4°C, 50 mM potassium phosphate buffer, pH 7.2, 0.5 mM EDTA, 1% 2-mercaptoethanol, half-life of soluble enzyme is 3 weeks, immobilized enzyme shows large decline at the beginning and almost no further decrease of activity after 3 weeks
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
purification of the major 14C-labeled peptide from a tryptic digestion of labeled mercuric reductase
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recombinant His-tagged MerA from Escherichia coli strain BL21(DE3)Plys by nickel affinity chromatography
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recombinant MerA catalytic core and NmerA proteins from Escherichia coli strain XL-1 Blue by anion exchange chromatography and gel filtreation, and separation by affinity chromatography
recombinant wild-type and mutant N-terminally His6-tagged and maltose-binding protein fusion enzymes from Escherichia coli strain C43 by amylose affinity chromatography, cleavage of the tags by 3C protease, ultrafiltration, and gel filtration
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
gene merA and mer operon, expression of MerA catalytic core and NmerA proteins in Escherichia coli strain XL-1 Blue
gene merA, DNA and amino acid sequence determination and analysis, phylogenetic analysis
gene merA, DNA and amino acid sequence determination and analysis, pylogenetic analysis and tree, recombinant expression in Escherichia coli strain BL21(DE3)
gene merA, expression as wild-type and mutant N-terminally His6-tagged and maltose-binding protein fusion proteins with a 3C protease cleavage site in Escherichia coli strain TOP10 and C43
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gene merA, mer operon located on Tn5041, DNA and amino acid sequence determination and analysis, chromosomal localization, real-time PCR enzyme expression analysis
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gene merA, recombinant expression in transgenoc Nicotiana tabacum cv. Xanthium plants using gene transfer by Agrobacterium tumefaciens. Transgenic tobacco expressing merA volatilizes significantly more mercury than wild-type plants. Subcloning in Escherichia coli strains DH5alpha and BL21(DE3)
gene merA, the MerA protein is encoded by the mer operon on transposon Tn501, DNA and amino acid sequence determination and analysis, sequence comparisons and phylogenetic analysis
merA, DNA and amino acid sequence determination of genes from bacteria isolated from surface and sub-surface floodplain soil, phylogenetic analysis, overview
plasmid transfer to mercury sensitive Escherichia coli strain DH5alpha, overexpression of gene merA as His-tagged protein in Escherichia coli BL21(DE3)Plys cells
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subcloning and expression in strain TG2, bacterial two hybrid assays are performed in strain BTH101
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gene merA, DNA and amino acid sequence determination and analysis, phylogenetic analysis
gene merA, DNA and amino acid sequence determination and analysis, phylogenetic analysis
merA, DNA and amino acid sequence determination of genes from bacteria isolated from surface and sub-surface floodplain soil, phylogenetic analysis, overview
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merA, DNA and amino acid sequence determination of genes from bacteria isolated from surface and sub-surface floodplain soil, phylogenetic analysis, overview
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merA, DNA and amino acid sequence determination of genes from bacteria isolated from surface and sub-surface floodplain soil, phylogenetic analysis, overview
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
the enzyme is induced by Hg
transcriptional level of merA increased 157fold and 255 fold after 30 min after 60 min of incubation with 6 microM HgCl2+, respectively; transcriptional level of merA increased 197fold after incubation with 1 microM CdCl2+
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transcriptional level of merA increased 30fold and 45fold after treatment with 10 microM ZnCl2+ and 30 microM ZnCl2+, respectively
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transcriptional level of merA increased 6, 10, and 20fold after treatment with 5, 10, and 20 microM CdSO4 2+, respectively
transcriptional level of merA increased 6, 10, and 20fold after treatment with 5, 10, and 20 microM CdSO4 2+, respectively
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transcriptional level of merA increased 6, 10, and 20fold after treatment with 5, 10, and 20 microM CdSO4 2+, respectively
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
C628A
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HgX2 substrates with small ligands can rapidly access the redox-active cysteines in the absence of the C-terminal cysteines, but those with large ligands require the C-terminal cysteines for rapid access. The C-terminal cysteines play a critical role in removing the high-affinity ligands before Hg(II) reaches the redox-active cysteines
C629A
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HgX2 substrates with small ligands can rapidly access the redox-active cysteines in the absence of the C-terminal cysteines, but those with large ligands require the C-terminal cysteines for rapid access. The C-terminal cysteines play a critical role in removing the high-affinity ligands before Hg(II) reaches the redox-active cysteines
Y264F
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Km-value for Hg2+ is 5fold lower compared to the Km-value of the wild-type enzyme, turn-over number is reduced by 164fold
Y264F/Y605F
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Km-value for Hg2+ is 5fold lower than the Km-value of the wild-type enzyme, turnover-number is reduced by 1091fold
Y605F
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Km-value for Hg2+ is 1.3fold higher compared to the Km-value of the wild-type enzyme, turnover-number is reduced by 6.3fold
C628A
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HgX2 substrates with small ligands can rapidly access the redox-active cysteines in the absence of the C-terminal cysteines, but those with large ligands require the C-terminal cysteines for rapid access. The C-terminal cysteines play a critical role in removing the high-affinity ligands before Hg(II) reaches the redox-active cysteines
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C629A
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HgX2 substrates with small ligands can rapidly access the redox-active cysteines in the absence of the C-terminal cysteines, but those with large ligands require the C-terminal cysteines for rapid access. The C-terminal cysteines play a critical role in removing the high-affinity ligands before Hg(II) reaches the redox-active cysteines
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Y264F
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Km-value for Hg2+ is 5fold lower compared to the Km-value of the wild-type enzyme, turn-over number is reduced by 164fold
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Y264F/Y605F
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Km-value for Hg2+ is 5fold lower than the Km-value of the wild-type enzyme, turnover-number is reduced by 1091fold
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Y605F
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Km-value for Hg2+ is 1.3fold higher compared to the Km-value of the wild-type enzyme, turnover-number is reduced by 6.3fold
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C558A
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mutation results in a total disruption of the Hg(II) detoxification pathway in vivo, compared to wild-type enzyme the mutant shows a 20fold reduction in turnover number and a 10fold increase in Km
C559A
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mutation results in a total disruption of the Hg(II) detoxification pathway in vivo, compared to wild-type enzyme less than a 2fold reduction in turnover number and an increase in Km-value of 4-5fold
Y605H
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24fold decrease in turnover number and a 15fold decrease in Km-value
C11A
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site-directed mutagenesis of NmerA residue of the metal binding site
C14A
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site-directed mutagenesis of NmerA residue of the metal binding site
Y62F
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site-directed mutagenesis of NmerA residue of the metal binding site
E133G/E134G
site-directed mutagenesis, the mutant shows altered salt and metal resistance and temperature stability compared to the wild-type enzyme
E15A/E16A
site-directed mutagenesis, the mutant shows altered salt and metal resistance and temperature stability compared to the wild-type enzyme
E515A/E516A
site-directed mutagenesis, the mutant shows altered salt and metal resistance and temperature stability compared to the wild-type enzyme
E545A/E546A
site-directed mutagenesis, the mutant shows salt and metal resistance and temperature stability similar to the wild-type enzyme
K432L/P433D/A434L/R435T
site-directed mutagenesis, the mutant shows salt and metal resistance and temperature stability similar to the wild-type enzyme
K432L/P433D/A434L/R435T/K465D/V466S/G467R/K468T/F469L/P470T
site-directed mutagenesis, the mutant shows salt and metal resistance and temperature stability similar to the wild-type enzyme
additional information
additional information
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cloning and expression of catalytic core and N-terminal domain of enzyme as separate proteins. the N-terminal domain NmerA is a stable, soluble protein that binds 1 Hg2+ per domain and delivers it to the catalytic core at kinetically competent rates
additional information
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cloning and expression of catalytic core and N-terminal domain of enzyme as separate proteins. the N-terminal domain NmerA is a stable, soluble protein that binds 1 Hg2+ per domain and delivers it to the catalytic core at kinetically competent rates
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additional information
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constitutive expression of enzyme in Pseudomonas putida results in a broad spectrum mercury resistance
additional information
mutations to substitute residues from the ATII-LCL MerA to their corresponding amino acids in the soil enzyme, overview
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
environmental protection
environmental protection
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application of the immobilized mercuric reductase for continuous treatment of Hg(II)-containing water in a fixed bed reactor
environmental protection
-
detoxification of mercury by immobilized mercuric reductase
environmental protection
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the organism can potentially be used for bioremediation in marine environments
environmental protection
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detoxification of mercury by immobilized mercuric reductase
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environmental protection
-
application of the immobilized mercuric reductase for continuous treatment of Hg(II)-containing water in a fixed bed reactor
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environmental protection
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the organism can potentially be used for bioremediation in marine environments
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LINKS TO OTHER DATABASES (specific for EC-Number 1.16.1.1)
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