ID   MERA_SHEPU              Reviewed;         557 AA.
AC   Q54465;
DT   01-NOV-1997, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   03-AUG-2022, entry version 118.
DE   RecName: Full=Mercuric reductase;
DE            EC=1.16.1.1;
DE   AltName: Full=Hg(II) reductase;
GN   Name=merA;
OS   Shewanella putrefaciens (Pseudomonas putrefaciens).
OG   Plasmid IncJ pMERPH.
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Alteromonadales;
OC   Shewanellaceae; Shewanella.
OX   NCBI_TaxID=24;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=9167257; DOI=10.1111/j.1574-6976.1997.tb00300.x;
RA   Osborn A.M., Bruce K.D., Strike P., Ritchie D.A.;
RT   "Distribution, diversity and evolution of the bacterial mercury resistance
RT   (mer) operon.";
RL   FEMS Microbiol. Rev. 19:239-262(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; Z49196; CAA89057.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q54465; -.
DR   SMR; Q54465; -.
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..557
FT                   /note="Mercuric reductase"
FT                   /id="PRO_0000067999"
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         124..133
FT                   /ligand="FAD"
FT                   /ligand_id="ChEBI:CHEBI:57692"
FT                   /evidence="ECO:0000250"
FT   BINDING         554
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT   BINDING         555
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT   DISULFID        133..138
FT                   /note="Redox-active"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   557 AA;  59336 MW;  EE3D6E1C2ACD473C CRC64;
     MILLSIEGMT CPSCVAHVKE ALDAIEGVNK VEISYENARA TITTNGGVSV TVLIGAIEAL
     GYIAKESTGT AKEITSPNDC CDNENASNTE SNQTQHVAII GTGSGAFACA IKAAEGGAKV
     TLIEGADVIG GCCVNVGCVP SKILIRAAQL AQQQRNNPFT GLENHAPQLS RALLTQQQTA
     RVEELRAAKY QNILETNPAL SLLKGWAQFK NANTLIVRKN DGTEQAVHAD KILIATGSTP
     TIPPIDGLTE TPYWTSTEAL FAQELPQHLV VIGSSVVALE IAQAYRRLGS EVTILARHTL
     LYREDPLLGE KLTGCFEKEG IRVLNSTQAT KVTHDGSQFT LETNAGDLRC DRLLVSTGRH
     ANTCQLNLGA VGVTTNKKGE IVVNERMETN VPGIYAAGDC CNMPQFVYVA AAAGSRSGIN
     MTGGYAKLDL STMPAVIFTD PQVATVGLTE EQANAQDIET DSRVLEMENV PRALANFETD
     GFIKLVTEKA TGRLIGAQIL AHEGGELIQS AALAIRNRMT VTELADQLFP YLTMVEGLKL
     CAQTFNKDVK ELSCCAG