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

Copyrighted by the UniProt Consortium, see http://www.uniprot.org/terms. Distributed under the Creative Commons Attribution-NoDerivs License.

Cross-references

Sequence databases

EMBL

CR954246; CAI85259.1; -; Genomic_DNA.

[EMBL / GenBank / DDBJ] [CoDingSequence]

RefSeq

YP_338702.1; -.

3D structure databases

ModBase

Q3IFM1.

Enzyme and pathway databases

BioCyc

PHAL326442:PSHAA0155-MON; -.

Ontologies

GO:0005506;	Molecular function: iron ion binding (inferred from electronic annotation from UniProtKB-KW).
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.

PRINTS

PR00397; SIROHAEM.

TIGRFAMs

TIGR02041; CysI; 1.

PROSITE

PS00365; NIR_SIR; FALSE_NEG.

Genome annotation databases

GeneID

3709416; -.

GenomeReviews

CR954246_GR; PSHAa0155.

KEGG

pha:PSHAa0155; -.

NMPDR

fig|326442.4.peg.240; -.

Phylogenomic databases

HOGENOM

Q3IFM1; -.

Genome annotation databases

CMR

Q3IFM1; PSHAa0155.

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`	`1 565`	`565`	`Sulfite reductase [NADPH] hemoprotein beta-component.`	`PRO_0000292962`
`METAL`	`429 429`		`Iron-sulfur (4Fe-4S) (By similarity).`
`METAL`	`435 435`		`Iron-sulfur (4Fe-4S) (By similarity).`
`METAL`	`474 474`		`Iron-sulfur (4Fe-4S) (By similarity).`
`METAL`	`478 478`		`Iron (siroheme axial ligand) (By similarity).`
`METAL`	`478 478`		`Iron-sulfur (4Fe-4S) (By similarity).`

Sequence information

Length: 565 AA [This is the length of the unprocessed precursor]

Molecular weight: 62933 Da [This is the MW of the unprocessed precursor]

CRC64: F622A443A6723502 [This is a checksum on the sequence]

        10         20         30         40         50         60 
MSEQDKNVKL SDNERMKRES NFLRGTIATD LKDEITGGFT ADNFQLIRFH GMYQQDDRDI 

        70         80         90        100        110        120 
RGERAKQKLE PLHNVMLRAR MPGGIIKPEQ WLAIDKFAEE KTSYGSIRLT TRQTFQFHGV 

       130        140        150        160        170        180 
LKPNIKGMHQ LLDSVGIDSI ATAGDVNRNV LCTTNPVESE LHQEAYEWAA KISEHLLPKT 

       190        200        210        220        230        240 
KAYAEIWLNG EKAETTEEPI LGSNYLPRKF KTTVTIPPNN EVDVHANDLN FVAIAENGKL 

       250        260        270        280        290        300 
IGFNVLVGGG LAMTHGDTAT YPRKADDFGF IPLEHTLKIA EHVVSVQRDW GNRSNRKNAK 

       310        320        330        340        350        360 
TKYTLDRVGV DVFKAEVEKR AGVEFASSRP YKFTHRGDRI GWVEGIDGKH HLTLFIQSGR 

       370        380        390        400        410        420 
ILDYPDKPLK TGCRKIAEVH QGDMRMTANQ NLIIAGVAAN QKAVIEEIAR NHGLIDDKDT 

       430        440        450        460        470        480 
EQRKNSMACV ALPTCPLAMA EAERYLPSLV EKIEALLAKH GVPNDSIIMR VVGCPNGCGR 

       490        500        510        520        530        540 
AMLAEAGLVG KGPGKYNVYL GGNLEGTRIP KLYLENVGED VYLAAFDELI GQWVNERNDG 

       550        560 
ECFGDFVIRK GIVAEVKVSV TDFHA

Q3IFM1 in FASTA format

View entry in original UniProtKB/Swiss-Prot format
View entry in raw text format (no links)
Report form for errors/updates in this UniProtKB/Swiss-Prot entry

	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