FUNCTION: This enzyme catalyzes the 6-electron reduction of sulfite to sulfide. This is one of several activities required for the biosynthesis of L-cysteine from sulfate (By similarity).
CATALYTIC ACTIVITY: H₂S + 3 NADP⁺ + 3 H₂O = sulfite + 3 NADPH.
COFACTOR: Binds 1 siroheme per subunit (By similarity).
COFACTOR: Binds 1 4Fe-4S cluster per subunit (By similarity).
SUBUNIT: Alpha(8)-beta(4). The alpha component is a flavoprotein, the beta component is a hemoprotein (By similarity).
SIMILARITY: Belongs to the nitrite and sulfite reductase 4Fe-4S domain family.

Copyright

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Cross-references

Sequence databases

EMBL

CP000826; ABV39917.1; -; Genomic_DNA.

[EMBL / GenBank / DDBJ] [CoDingSequence]

RefSeq

YP_001477045.1; -.

3D structure databases

ModBase

A8G9X7.

Ontologies

GO:0009337;	Cellular component: sulfite reductase complex (NADPH) (inferred from electronic annotation from InterPro).
GO:0051539;	Molecular function: 4 iron, 4 sulfur cluster binding (inferred from electronic annotation from InterPro).
GO:0009055;	Molecular function: electron carrier activity (inferred from electronic annotation from InterPro).
GO:0020037;	Molecular function: heme binding (inferred from electronic annotation from InterPro).
GO:0005506;	Molecular function: iron ion binding (inferred from electronic annotation from UniProtKB-KW).
GO:0050661;	Molecular function: NADP binding (inferred from electronic annotation from InterPro).
GO:0004783;	Molecular function: sulfite reductase (NADPH) activity (inferred from electronic annotation from HAMAP).
GO:0019344;	Biological process: cysteine biosynthetic process (inferred from electronic annotation from UniProtKB-KW).
GO:0055114;	Biological process: oxidation reduction (inferred from electronic annotation from UniProtKB-KW).
GO:0000103;	Biological process: sulfate assimilation (inferred from electronic annotation from HAMAP).
QuickGo view.

Family and domain databases

HAMAP

MF_01540; -; 1.
PBIL [Tree]

InterPro

IPR011786; CysI.
IPR006066; Nir_Si_BS.
IPR006067; Nir_Sir_4Fe4S.
IPR005117; NiRdtase/SiRdtase_haem-b_fer.
Graphical view of domain structure.

Pfam

PF01077; NIR_SIR; 1.
PF03460; NIR_SIR_ferr; 2.
Pfam graphical view of domain structure.

PR00397; SIROHAEM.

TIGR02041; CysI; 1.

PS00365; NIR_SIR; 1.

Genome annotation databases

GeneID

5603584; -.

GenomeReviews

CP000826_GR; Spro_0811.

KEGG

spe:Spro_0811; -.

CMR

A8G9X7; Spro_0811.

Other

UniRef

View cluster of proteins with at least 50% / 90% / 100% identity.

Keywords

4Fe-4S; Amino-acid biosynthesis; Complete proteome; Cysteine biosynthesis; Heme; Iron; Iron-sulfur; Metal-binding; NADP; Oxidoreductase.

Features

Feature table viewer

`Key`	`From To`	`Length`	`Description`	`FTId`
`CHAIN`	`1 571`	`571`	`Sulfite reductase [NADPH] hemoprotein beta-component.`	`PRO_1000068767`
`METAL`	`435 435`		`Iron-sulfur (4Fe-4S) (By similarity).`
`METAL`	`441 441`		`Iron-sulfur (4Fe-4S) (By similarity).`
`METAL`	`480 480`		`Iron-sulfur (4Fe-4S) (By similarity).`
`METAL`	`484 484`		`Iron (siroheme axial ligand) (By similarity).`
`METAL`	`484 484`		`Iron-sulfur (4Fe-4S) (By similarity).`

Sequence information

Length: 571 AA [This is the length of the unprocessed precursor]

Molecular weight: 63873 Da [This is the MW of the unprocessed precursor]

CRC64: 805C43AF6C8F21AE [This is a checksum on the sequence]

        10         20         30         40         50         60 
MSDKHPGPLV VEGKLADAER LKKESNFLRG TIAEDLKDGL TGGFTGDNFL LIRFHGMYQQ 

        70         80         90        100        110        120 
DDRDIRAERA EQKLEPRHAM MLRCRLPGGI ISPQQWLGID KFAQESTLYG SIRITNRQTF 

       130        140        150        160        170        180 
QFHGILKGNV KPVHQLLGRL GLDALATAND VNRNVLCTSN PVESELHQEA YEWAKKISEH 

       190        200        210        220        230        240 
LLPRTRAYAE VWLDQEKVAT TDEEPILGAT YLPRKFKTTV VIPPQNDVDL HANDMNFVAI 

       250        260        270        280        290        300 
AKNGKLVGFN LLVGGGLSIE HGNKKTYARQ ASEFGYIPLE HTLAVAEAVV TTQRDWGNRT 

       310        320        330        340        350        360 
DRKNAKTKYT LERVGVDTFR AEVEKRAGIT FEPIRPYEFT GRGDRIGWVK GIDNQWHLTL 

       370        380        390        400        410        420 
FIENGRLLDY PGRPLKTGVA EIARIHKGDF RLTANQNLIV AGVPESEKAK IEALARDHGL 

       430        440        450        460        470        480 
IDDGVSVQRQ NSMACVSFPT CPLAMAEAER FLPEFVTKVE GILHRHGVGD EHIVLRITGC 

       490        500        510        520        530        540 
PNGCGRALLA EIGLVGKAVG RYNLHLGGNR EGTRIPRMYR ENINEEEILR EIDQLVGRWA 

       550        560        570 
TERTAGEGFG DFTIRAGVVR PVVDPAQDFW D

A8G9X7 in FASTA format

View entry in original UniProtKB/Swiss-Prot format
View entry in raw text format (no links)
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	BLAST submission on ExPASy/SIB or at NCBI (USA)		Sequence analysis tools: ProtParam, ProtScale, Compute pI/Mw, PeptideMass, PeptideCutter, Dotlet (Java)
	ScanProsite, MotifScan		Submit a homology modeling request to SWISS-MODEL
	NPSA Sequence analysis tools