ID   MERA_STRLI              Reviewed;         474 AA.
AC   P30341;
DT   01-APR-1993, integrated into UniProtKB/Swiss-Prot.
DT   01-APR-1993, 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   Streptomyces lividans.
OC   Bacteria; Actinobacteria; Streptomycetales; Streptomycetaceae;
OC   Streptomyces.
OX   NCBI_TaxID=1916;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=66 / 1326;
RX   PubMed=1494353; DOI=10.1007/bf00279645;
RA   Sedlmeier R., Altenbuchner J.;
RT   "Cloning and DNA sequence analysis of the mercury resistance genes of
RT   Streptomyces lividans.";
RL   Mol. Gen. Genet. 236:76-85(1992).
RN   [2]
RP   REGULATION.
RC   STRAIN=66 / 1326;
RX   PubMed=8676873; DOI=10.1007/bf02172521;
RA   Brunker P., Rother D., Sedlmeier R., Klein J., Mattes R., Altenbuchner J.;
RT   "Regulation of the operon responsible for broad-spectrum mercury resistance
RT   in Streptomyces lividans 1326.";
RL   Mol. Gen. Genet. 251:307-315(1996).
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   -!- INDUCTION: By mercuric ions. Negatively regulated by MerR.
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; X65467; CAA46460.1; -; Genomic_DNA.
DR   PIR; S30168; S30168.
DR   AlphaFoldDB; P30341; -.
DR   SMR; P30341; -.
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   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; 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; 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; SSF55424; SSF55424; 1.
DR   TIGRFAMs; TIGR02053; MerA; 1.
DR   PROSITE; PS00076; PYRIDINE_REDOX_1; 1.
PE   2: Evidence at transcript level;
KW   Disulfide bond; FAD; Flavoprotein; Mercuric resistance; Mercury;
KW   Metal-binding; NADP; Oxidoreductase; Redox-active center.
FT   CHAIN           1..474
FT                   /note="Mercuric reductase"
FT                   /id="PRO_0000068004"
FT   BINDING         37..45
FT                   /ligand="FAD"
FT                   /ligand_id="ChEBI:CHEBI:57692"
FT                   /evidence="ECO:0000250"
FT   BINDING         471
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT                   /evidence="ECO:0000255"
FT   BINDING         472
FT                   /ligand="Hg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:16793"
FT                   /evidence="ECO:0000255"
FT   DISULFID        45..50
FT                   /note="Redox-active"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   474 AA;  49671 MW;  3C85E89D0062215E CRC64;
     MLQAHTGYDL AIIGSGAGAF AAAIAARNKG RSVVMVERGT TGGTCVNVGC VPSKALLAAA
     EARHGAQAAS RFPGIQATEP ALDFPALISG KDTLVGQLRA EKYTDLAAEY GWQIVHGTAT
     FADGPMLEVA LNDGGTATVE AAHYLIATGS APTAPHIDGL DQVDYLTSTT AMELQQLPEH
     LLILGGGYVG LEQAQLFARL GSRVTLAVRS RLASREEPEI SAGIENIFRE EGITVHTRTQ
     LRAVRRDGEG ILATLTGPDG DQQVRASHLL IATGRRSVTN GLGLERVGVK TGERGEVVVD
     EYLRTDNPRI WAAGDVTCHP DFVYVAAAHG TLVADNALDG AERTLDYTAL PKVTFTSPAI
     ASVGLTEAQL TEAGIAHQTR TLSLENVPRA LVNRDTRGLV KLIAERGTGK LLAAHVLAEG
     AGDVITAATY AITAGLTVDQ LARTWHPYLT MAEALKLAAQ TFTSDVAKLS CCAG