ID   CYSI_ALKHC              Reviewed;         572 AA.
AC   Q9KF75;
DT   03-NOV-2009, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2000, sequence version 1.
DT   03-AUG-2022, entry version 114.
DE   RecName: Full=Sulfite reductase [NADPH] hemoprotein beta-component {ECO:0000255|HAMAP-Rule:MF_01540};
DE            Short=SiR-HP {ECO:0000255|HAMAP-Rule:MF_01540};
DE            Short=SiRHP {ECO:0000255|HAMAP-Rule:MF_01540};
DE            EC=1.8.1.2 {ECO:0000255|HAMAP-Rule:MF_01540};
GN   Name=cysI {ECO:0000255|HAMAP-Rule:MF_01540}; OrderedLocusNames=BH0610;
OS   Alkalihalobacillus halodurans (strain ATCC BAA-125 / DSM 18197 / FERM 7344
OS   / JCM 9153 / C-125) (Bacillus halodurans).
OC   Bacteria; Firmicutes; Bacilli; Bacillales; Bacillaceae; Alkalihalobacillus.
OX   NCBI_TaxID=272558;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC BAA-125 / DSM 18197 / FERM 7344 / JCM 9153 / C-125;
RX   PubMed=11058132; DOI=10.1093/nar/28.21.4317;
RA   Takami H., Nakasone K., Takaki Y., Maeno G., Sasaki R., Masui N., Fuji F.,
RA   Hirama C., Nakamura Y., Ogasawara N., Kuhara S., Horikoshi K.;
RT   "Complete genome sequence of the alkaliphilic bacterium Bacillus halodurans
RT   and genomic sequence comparison with Bacillus subtilis.";
RL   Nucleic Acids Res. 28:4317-4331(2000).
CC   -!- FUNCTION: Component of the sulfite reductase complex that catalyzes the
CC       6-electron reduction of sulfite to sulfide. This is one of several
CC       activities required for the biosynthesis of L-cysteine from sulfate.
CC       {ECO:0000255|HAMAP-Rule:MF_01540}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=3 H2O + hydrogen sulfide + 3 NADP(+) = 4 H(+) + 3 NADPH +
CC         sulfite; Xref=Rhea:RHEA:13801, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:17359, ChEBI:CHEBI:29919, ChEBI:CHEBI:57783,
CC         ChEBI:CHEBI:58349; EC=1.8.1.2; Evidence={ECO:0000255|HAMAP-
CC         Rule:MF_01540};
CC   -!- COFACTOR:
CC       Name=siroheme; Xref=ChEBI:CHEBI:60052;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01540};
CC       Note=Binds 1 siroheme per subunit. {ECO:0000255|HAMAP-Rule:MF_01540};
CC   -!- COFACTOR:
CC       Name=[4Fe-4S] cluster; Xref=ChEBI:CHEBI:49883;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01540};
CC       Note=Binds 1 [4Fe-4S] cluster per subunit. {ECO:0000255|HAMAP-
CC       Rule:MF_01540};
CC   -!- PATHWAY: Sulfur metabolism; hydrogen sulfide biosynthesis; hydrogen
CC       sulfide from sulfite (NADPH route): step 1/1. {ECO:0000255|HAMAP-
CC       Rule:MF_01540}.
CC   -!- SUBUNIT: Alpha(8)-beta(8). The alpha component is a flavoprotein, the
CC       beta component is a hemoprotein. {ECO:0000255|HAMAP-Rule:MF_01540}.
CC   -!- SIMILARITY: Belongs to the nitrite and sulfite reductase 4Fe-4S domain
CC       family. {ECO:0000255|HAMAP-Rule:MF_01540}.
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DR   EMBL; BA000004; BAB04329.1; -; Genomic_DNA.
DR   PIR; B83726; B83726.
DR   RefSeq; WP_010896787.1; NC_002570.2.
DR   AlphaFoldDB; Q9KF75; -.
DR   SMR; Q9KF75; -.
DR   STRING; 272558.10173224; -.
DR   EnsemblBacteria; BAB04329; BAB04329; BAB04329.
DR   KEGG; bha:BH0610; -.
DR   eggNOG; COG0155; Bacteria.
DR   HOGENOM; CLU_001975_3_2_9; -.
DR   OMA; MGMTHGD; -.
DR   OrthoDB; 1588103at2; -.
DR   UniPathway; UPA00140; UER00207.
DR   Proteomes; UP000001258; Chromosome.
DR   GO; GO:0009337; C:sulfite reductase complex (NADPH); IEA:InterPro.
DR   GO; GO:0051539; F:4 iron, 4 sulfur cluster binding; IEA:UniProtKB-KW.
DR   GO; GO:0020037; F:heme binding; IEA:InterPro.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0050661; F:NADP binding; IEA:InterPro.
DR   GO; GO:0004783; F:sulfite reductase (NADPH) activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0019344; P:cysteine biosynthetic process; IEA:UniProtKB-KW.
DR   GO; GO:0070814; P:hydrogen sulfide biosynthetic process; IEA:UniProtKB-UniRule.
DR   GO; GO:0000103; P:sulfate assimilation; IEA:UniProtKB-UniRule.
DR   Gene3D; 3.30.413.10; -; 2.
DR   HAMAP; MF_01540; CysI; 1.
DR   InterPro; IPR011786; CysI.
DR   InterPro; IPR005117; NiRdtase/SiRdtase_haem-b_fer.
DR   InterPro; IPR036136; Nit/Sulf_reduc_fer-like_dom_sf.
DR   InterPro; IPR006067; NO2/SO3_Rdtase_4Fe4S_dom.
DR   InterPro; IPR045169; NO2/SO3_Rdtase_4Fe4S_prot.
DR   InterPro; IPR045854; NO2/SO3_Rdtase_4Fe4S_sf.
DR   InterPro; IPR006066; NO2/SO3_Rdtase_FeS/sirohaem_BS.
DR   PANTHER; PTHR11493; PTHR11493; 1.
DR   Pfam; PF01077; NIR_SIR; 2.
DR   Pfam; PF03460; NIR_SIR_ferr; 2.
DR   PRINTS; PR00397; SIROHAEM.
DR   SUPFAM; SSF55124; SSF55124; 2.
DR   SUPFAM; SSF56014; SSF56014; 2.
DR   TIGRFAMs; TIGR02041; CysI; 1.
DR   PROSITE; PS00365; NIR_SIR; 1.
PE   3: Inferred from homology;
KW   4Fe-4S; Amino-acid biosynthesis; Cysteine biosynthesis; Heme; Iron;
KW   Iron-sulfur; Metal-binding; NADP; Oxidoreductase; Reference proteome.
FT   CHAIN           1..572
FT                   /note="Sulfite reductase [NADPH] hemoprotein beta-
FT                   component"
FT                   /id="PRO_0000388475"
FT   BINDING         437
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         443
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         482
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         486
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         486
FT                   /ligand="siroheme"
FT                   /ligand_id="ChEBI:CHEBI:60052"
FT                   /ligand_part="Fe"
FT                   /ligand_part_id="ChEBI:CHEBI:18248"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
SQ   SEQUENCE   572 AA;  65004 MW;  7B9C545068D34C8D CRC64;
     MGNERLKAPE GPPSDVERIK EESNYLRGTL KESMLEPISA GISDDDNRLM KHHGSYLQDD
     RDLRNERQKQ KLEPAYQFML RVRMPGGVAT PEQWLVMDEL AQKYGNGTMK LTTRETFQLH
     GILKWNMKKT IQAIHSALLD TIAACGDVNR NVMCTSNPYQ SEIHQEVYEW SKKLSDDLLP
     RTRAYHEIWL DEEKVAGTPE AEEVEPMYGP LYLPRKFKIG IAVPPSNDID VFSQDLGFIA
     IVEDDKLVGF NVAIGGGMGM THGDKATYPQ LAKVIGFCKP EQIYDVAEKI ITIQRDYGNR
     SVRKNARFKY TVDRLGLETV KNELENRLGW SLDEAKPYHF DHNGDRYGWV KGVKGRWHFT
     LFVEGGRVTD YADYKLMTGL REIAKIHTGD IRLTSNQNLI IANVTSQKKK KINELIEQYG
     LTDGKHYTAL RRSSIACVAL PTCGLAMAEA ERYLPKLIDK IDEIIEENGL KNEEITIRMT
     GCPNGCARHA LGEIGFIGKA PGKYNMYLGA AFDGSRLSKM YRENIGEEEI LKELREILPR
     YAKERKEGEH FGDFVIRAGI IKETTDGTNF HD