ID   MERA_ENTAG              Reviewed;         561 AA.
AC   P94702;
DT   01-NOV-1997, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1997, sequence version 1.
DT   03-AUG-2022, entry version 123.
DE   RecName: Full=Mercuric reductase;
DE            EC=1.16.1.1;
DE   AltName: Full=Hg(II) reductase;
GN   Name=merA;
OS   Enterobacter agglomerans (Erwinia herbicola) (Pantoea agglomerans).
OG   Plasmid pKLH272.
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Erwiniaceae; Pantoea; Pantoea agglomerans group.
OX   NCBI_TaxID=549;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=9159519; DOI=10.1046/j.1365-2958.1997.3261688.x;
RA   Yurieva O., Kholodii G., Minakhin L., Gorlenko Z., Kalyaeva E., Mindlin S.,
RA   Nikiforov V.;
RT   "Intercontinental spread of promiscuous mercury-resistance transposons in
RT   environmental bacteria.";
RL   Mol. Microbiol. 24:321-329(1997).
CC   -!- FUNCTION: Resistance to Hg(2+) in bacteria appears to be governed by a
CC       specialized system which includes mercuric reductase. MerA protein is
CC       responsible for volatilizing mercury as Hg(0).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H(+) + Hg + NADP(+) = Hg(2+) + NADPH; Xref=Rhea:RHEA:23856,
CC         ChEBI:CHEBI:15378, ChEBI:CHEBI:16170, ChEBI:CHEBI:16793,
CC         ChEBI:CHEBI:57783, ChEBI:CHEBI:58349; EC=1.16.1.1;
CC   -!- COFACTOR:
CC       Name=FAD; Xref=ChEBI:CHEBI:57692; Evidence={ECO:0000250};
CC       Note=Binds 1 FAD per subunit. {ECO:0000250};
CC   -!- SUBUNIT: Homodimer. {ECO:0000250}.
CC   -!- MISCELLANEOUS: The active site is a redox-active disulfide bond.
CC   -!- SIMILARITY: Belongs to the class-I pyridine nucleotide-disulfide
CC       oxidoreductase family. {ECO:0000305}.
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DR   EMBL; Y08992; CAA70184.1; -; Genomic_DNA.
DR   AlphaFoldDB; P94702; -.
DR   SMR; P94702; -.
DR   GO; GO:0050660; F:flavin adenine dinucleotide binding; IEA:InterPro.
DR   GO; GO:0016152; F:mercury (II) reductase activity; IEA:UniProtKB-EC.
DR   GO; GO:0045340; F:mercury ion binding; IEA:InterPro.
DR   GO; GO:0050661; F:NADP binding; IEA:InterPro.
DR   GO; GO:0016668; F:oxidoreductase activity, acting on a sulfur group of donors, NAD(P) as acceptor; IEA:InterPro.
DR   GO; GO:0045454; P:cell redox homeostasis; IEA:InterPro.
DR   GO; GO:0050787; P:detoxification of mercury ion; IEA:InterPro.
DR   CDD; cd00371; HMA; 1.
DR   Gene3D; 3.30.390.30; -; 1.
DR   Gene3D; 3.50.50.60; -; 2.
DR   InterPro; IPR036188; FAD/NAD-bd_sf.
DR   InterPro; IPR023753; FAD/NAD-binding_dom.
DR   InterPro; IPR016156; FAD/NAD-linked_Rdtase_dimer_sf.
DR   InterPro; IPR017969; Heavy-metal-associated_CS.
DR   InterPro; IPR006121; HMA_dom.
DR   InterPro; IPR036163; HMA_dom_sf.
DR   InterPro; IPR021179; Mercury_reductase_MerA.
DR   InterPro; IPR001100; Pyr_nuc-diS_OxRdtase.
DR   InterPro; IPR004099; Pyr_nucl-diS_OxRdtase_dimer.
DR   InterPro; IPR012999; Pyr_OxRdtase_I_AS.
DR   Pfam; PF00403; HMA; 1.
DR   Pfam; PF07992; Pyr_redox_2; 1.
DR   Pfam; PF02852; Pyr_redox_dim; 1.
DR   PIRSF; PIRSF000350; Mercury_reductase_MerA; 1.
DR   SUPFAM; SSF51905; SSF51905; 1.
DR   SUPFAM; SSF55008; SSF55008; 1.
DR   SUPFAM; SSF55424; SSF55424; 1.
DR   TIGRFAMs; TIGR02053; MerA; 1.
DR   PROSITE; PS01047; HMA_1; 1.
DR   PROSITE; PS50846; HMA_2; 1.
DR   PROSITE; PS00076; PYRIDINE_REDOX_1; 1.
PE   3: Inferred from homology;
KW   Disulfide bond; FAD; Flavoprotein; Mercuric resistance; Mercury;
KW   Metal-binding; NADP; Oxidoreductase; Plasmid; Redox-active center.
FT   CHAIN           1..561
FT                   /note="Mercuric reductase"
FT                   /id="PRO_0000067996"
FT   DOMAIN          1..65
FT                   /note="HMA"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00280"
FT   BINDING         11
FT                   /ligand="a metal cation"
FT                   /ligand_id="ChEBI:CHEBI:25213"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00280"
FT   BINDING         14
FT                   /ligand="a metal cation"
FT                   /ligand_id="ChEBI:CHEBI:25213"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00280"
FT   BINDING         128..136
FT                   /ligand="FAD"
FT                   /ligand_id="ChEBI:CHEBI:57692"
FT                   /evidence="ECO:0000250"
FT   BINDING         558
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT   BINDING         559
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT   DISULFID        136..141
FT                   /note="Redox-active"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   561 AA;  58785 MW;  FABA07D7EC2F13C8 CRC64;
     MTTLKITGMT CDSCAAHVKE ALEKVPGVQS ALVSYPKGTA QLAIEAGTSS DALTTAVAGL
     GYEATLADAP PTDNRAGLLD KMRGWIGAAD KPSGNERPLQ VVVIGSGGAA MAAALKAVEQ
     GAQVTLIERG TIGGTCVNVG CVPSKIMIRV AHIAHLRRES PFDGGMPPTS PTILRERLLA
     QQQARVEELR HAKYEGILDG NSAITVLHGE ARFKDDQSLI VSLNEGGERV VMFDRCLVAT
     GASPAVPPIP GLKESPYWTS TEALASDTIP ERLAVIGSSV VALELAQAFA RLGSKVTALA
     RNTLFFREDP AIGEAVTAAF RAEGIEVLEH TQASQVAHMD GEFVLTTTHG ELRADKLLVA
     TGRTPNTRSL ALEAAGVAVN AQGAIVIDKG MRTSSPNIYA AGDCTDQPQF VYVAAAAGTR
     AAINMTGGDA ALDLTAMPAV VFTDPQVATV GYSEAEAHHD GIETDSRLLT LDNVPRALAN
     FDTRGFIKLV IEEGSGRLIG VQAVAPEAGE LIQTAVLAIR NRMTVQELAD QLFPYLTMVE
     GLKLAAQTFS KDVKQLSCCA G