ID   MERA_SERMA              Reviewed;         460 AA.
AC   P08662;
DT   01-JAN-1988, integrated into UniProtKB/Swiss-Prot.
DT   01-JAN-1990, sequence version 2.
DT   03-AUG-2022, entry version 129.
DE   RecName: Full=Mercuric reductase;
DE            EC=1.16.1.1;
DE   AltName: Full=Hg(II) reductase;
DE   Flags: Fragments;
GN   Name=merA;
OS   Serratia marcescens.
OG   Plasmid pDU1358.
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Yersiniaceae; Serratia.
OX   NCBI_TaxID=615;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-342.
RX   PubMed=2666393; DOI=10.1128/jb.171.8.4241-4247.1989;
RA   Nucifora G., Chu L., Silver S., Misra T.K.;
RT   "Mercury operon regulation by the merR gene of the organomercurial
RT   resistance system of plasmid pDU1358.";
RL   J. Bacteriol. 171:4241-4247(1989).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 343-460.
RX   PubMed=3033633; DOI=10.1073/pnas.84.10.3112;
RA   Griffin H.G., Foster T.J., Silver S., Misra T.K.;
RT   "Cloning and DNA sequence of the mercuric- and organomercurial-resistance
RT   determinants of plasmid pDU1358.";
RL   Proc. Natl. Acad. Sci. U.S.A. 84:3112-3116(1987).
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.
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; M24940; AAA98224.1; -; Genomic_DNA.
DR   EMBL; M15049; AAA88368.1; -; Genomic_DNA.
DR   PIR; A29010; A29010.
DR   AlphaFoldDB; P08662; -.
DR   SMR; P08662; -.
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:0046872; F:metal ion binding; IEA:UniProtKB-KW.
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:0046689; P:response to mercury ion; IEA:UniProtKB-KW.
DR   CDD; cd00371; HMA; 1.
DR   Gene3D; 3.30.390.30; -; 1.
DR   Gene3D; 3.50.50.60; -; 1.
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; 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   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..460
FT                   /note="Mercuric reductase"
FT                   /id="PRO_0000068000"
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         457
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT   BINDING         458
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT   DISULFID        136..141
FT                   /note="Redox-active"
FT                   /evidence="ECO:0000250"
FT   NON_CONS        342..343
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   460 AA;  48588 MW;  628466EF3F653F05 CRC64;
     MTHLKITGMT CDSCAAHVKE ALEKVPGVQS AIVSYAKGAA QLALDPGTAP DALTAAVAGL
     GYKAMLADAP PTDNRTGLFD KVRGWMGAAD KGSGAERPLQ VAVIGSGGAA MAAALKAVEQ
     GAQVTLIERG TIGGTCVNVG CVPSKIMIRA AHIAHLRRES PFDGGMPPTP PTILRERLLA
     QQQARVEELR HAKYEGILDG NSAITVRHGE ARFKDDRDLS VSLNEGGERV VMFDRCLVAT
     GASPAMPPIP GLKESPYWTS TEALVSDTIP ERLAVIGSSV VALELAQAFA RLGSQVTILA
     RNTLFFRDDP SIGEAVTAAF RAEGIKVLEH TQASQVAHVN GEDPQVATVG YSEAEAHHDG
     IETDSRTLTL DNVPRALANF DTRGFIKLVI EEGSGRLIGV QVVAPEAGEL IQTAVLAIRN
     RMTVQELADQ LFPYLTMVEG LKLAAQTFTK DVKQLSCCAG