ExPASy Proteomics Server

Accession	MF_01540
Dates	22-AUG-2005 (Created) 25-NOV-2009 (Last updated, Version 8)

Data class

Protein

Predictors

HAMAP; MF_01540; [distribution of match scores in UniProtKB];[seed alignment for MF_01540]

Names

CysI

Identifier

CYSI

Protein name

RecName: Full=Sulfite reductase [NADPH] hemoprotein beta-component; Short=SiR-HP; Short=SiRHP; EC=1.8.1.2;

Gene name

cysI

FUNCTION: Component of the sulfite reductase complex that 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: H(2)S + 3 NADP(+) + 3 H(2)O = sulfite + 3 NADPH.

COFACTOR: Binds 1 siroheme per subunit (By similarity).

COFACTOR: Binds 1 4Fe-4S cluster per subunit (By similarity).

PATHWAY: Sulfur metabolism; hydrogen sulfide biosynthesis; hydrogen sulfide from sulfite (NADPH route): step 1/1.

SUBUNIT: Alpha(8)-beta(8). 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.

PROSITE	PS00365; NIR_SIR; 1;
Pfam	PF01077; NIR_SIR; 1; PF03460; NIR_SIR_ferr; 2;
PRINTS	PR00397; SIROHAEM; 1;
TIGRFAMs	TIGR02041; CysI; 1;

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

GO:0004783; Molecular function: sulfite reductase (NADPH) activity.
GO:0000103; Biological process: sulfate assimilation.
GO:0070814; Biological process: hydrogen sulfide biosynthetic process.

From: CYSI_ECOLI (P17846)
Key		From		To		Description		Condition		FTGroup
METAL		434		434		Iron-sulfur (4Fe-4S) (By similarity)		C
METAL		440		440		Iron-sulfur (4Fe-4S) (By similarity)		C
METAL		479		479		Iron-sulfur (4Fe-4S) (By similarity)		C
METAL		483		483		Iron (siroheme axial ligand) (By similarity)		C
METAL		483		483		Iron-sulfur (4Fe-4S) (By similarity)		C

Size range:	555-616 amino acids
Related UniRules:	None
Template:	P17846 (CYSI_ECOLI); P17845 (CYSI_SALTY); O32213 (CYSI_BACSU); Q8KQT8 (CYSI_XANOR): [Recover all]
Scope:	Bacteria
Fusion:	Nter: None; Cter: None
Duplicate:	in KLEP3, NEIMB, PECCP
Plasmid encoded:	None