ID   CYSI_METEP              Reviewed;         612 AA.
AC   A9W4X6;
DT   03-NOV-2009, integrated into UniProtKB/Swiss-Prot.
DT   03-NOV-2009, sequence version 2.
DT   03-AUG-2022, entry version 82.
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=Mext_2237;
OS   Methylorubrum extorquens (strain PA1) (Methylobacterium extorquens).
OC   Bacteria; Proteobacteria; Alphaproteobacteria; Hyphomicrobiales;
OC   Methylobacteriaceae; Methylorubrum.
OX   NCBI_TaxID=419610;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=PA1;
RG   US DOE Joint Genome Institute;
RA   Copeland A., Lucas S., Lapidus A., Barry K., Glavina del Rio T., Dalin E.,
RA   Tice H., Pitluck S., Saunders E., Brettin T., Bruce D., Detter J.C.,
RA   Han C., Schmutz J., Larimer F., Land M., Hauser L., Kyrpides N., Kim E.,
RA   Marx C., Richardson P.;
RT   "Complete sequence of Methylobacterium extorquens PA1.";
RL   Submitted (DEC-2007) to the EMBL/GenBank/DDBJ databases.
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}.
CC   -!- SEQUENCE CAUTION:
CC       Sequence=ABY30632.1; Type=Erroneous initiation; Evidence={ECO:0000305};
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DR   EMBL; CP000908; ABY30632.1; ALT_INIT; Genomic_DNA.
DR   RefSeq; WP_042508826.1; NC_010172.1.
DR   AlphaFoldDB; A9W4X6; -.
DR   SMR; A9W4X6; -.
DR   STRING; 419610.Mext_2237; -.
DR   EnsemblBacteria; ABY30632; ABY30632; Mext_2237.
DR   KEGG; mex:Mext_2237; -.
DR   eggNOG; COG0155; Bacteria.
DR   HOGENOM; CLU_001975_3_2_5; -.
DR   BioCyc; MEXT419610:MEXT_RS11285-MON; -.
DR   UniPathway; UPA00140; UER00207.
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.
FT   CHAIN           1..612
FT                   /note="Sulfite reductase [NADPH] hemoprotein beta-
FT                   component"
FT                   /id="PRO_0000388495"
FT   REGION          1..26
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   BINDING         469
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         475
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         514
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         518
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01540"
FT   BINDING         518
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   612 AA;  66792 MW;  6513311E594FF19D CRC64;
     MDDHKPIETP DGPAVDTPGI GARRYETPPT ELPITEAEAA RAAGLAHNEH LKIASGYLRG
     GLADGLLKHA TGAISEDDGQ LVKFHGMYMQ DDRDIRAERT KKKLEKAYSF MIRLRIAGGV
     VTPKQWLILD NIATTYAGSA LRATTRQTFQ YHGVIKSNLK RTMAAIDSAL LDTIAACGDV
     NRNVMAATNP AQAGAHKIAL QLAKDISDTL LPKTGAWREI WLDGERVVGG EDAAEVEPVY
     GKTYLPRKFK TVVAVPPSNE VDIFAHDLGF IAILDKKNRV TGWNVTVGGG MGMTHGETDT
     FPRTADVLGF VQPEDALKAA EAVMTVQRDW GNRKNRKNAR LKYTIERFGL DAFRAEVEKR
     IGKKLGAPKP FTFDGNGDRY GWVEGDDGRH HLTLYVPSGR IKDIEGGPQF LSGLRRIAEV
     HEGDFRLTGN QNVIIANVPA GKRAEIDALV DEYGLTRGAS ALRRNSMACV ALPTCGLALA
     ESERYLPDLL SELEESLARH GLQDEPITIR STGCPNGCAR PFISEIGLVG RGPERYHLYL
     GAAFDGSRLS KLYREDVTAS EIKGTLDPLF AAYAKDRQPG EHFGDFVIRA GFVAKTSNGP
     DFHERTGPLR AA