HMM Summary Page: TIGR02041

Functionsulfite reductase (NADPH) hemoprotein, beta-component
Gene SymbolcysI
Trusted Cutoff756.55
Domain Trusted Cutoff756.55
Noise Cutoff707.50
Domain Noise Cutoff707.50
Isology Typeequivalog
EC Number1.8.1.2
HMM Length541
Mainrole CategoryCentral intermediary metabolism
Subrole CategorySulfur metabolism
Gene Ontology TermGO:0000103: sulfate assimilation biological_process
GO:0004783: sulfite reductase (NADPH) activity molecular_function
AuthorBrinkac L
Entry DateOct 28 2003 3:23PM
Last ModifiedFeb 14 2011 3:27PM
CommentSulfite reductase (NADPH) catalyzes a six electron reduction of sulfite to sulfide in prokaryotic organisms. It is a complex oligomeric enzyme composed of two different peptides with a subunit composition of alpha(8)-beta(4) [1]. The alpha component, encoded by cysJ, is a flavoprotein containing both FMN and FAD, while the beta component, encoded by cysI, is a siroheme, iron-sulfur protein [1]. In Salmonella typhimurium and Escherichia coli, both the alpha and beta subunits of sulfite reductase are located in a unidirectional gene cluster along with phosphoadenosine phosphosulfate reductase, which catalyzes a two step reduction of PAPS to give free sulfite [2]. In cyanobacteria and plant species, sulfite reductase ferredoxin (EC catalyzes the reduction of sulfite to sulfide [3].
ReferencesRN [1] RM 7569952 RT Sulfite reductase structure at 1.6 A: evolution and catalysis for reduction of inorganic anions. RA Crane BR, Siegel LM, Getzoff ED. RL Science. 1995 Oct 6;270(5233):59-67. RN [2] RM 2670946 RT Characterization of the cysJIH regions of Salmonella typhimurium and Escherichia coli B. DNA sequences of cysI and cysH and a model for the siroheme-Fe4S4 active center of sulfite reductase hemoprotein based on amino acid homology with spinach nitrite reductase. RA Ostrowski J, Wu JY, Rueger DC, Miller BE, Siegel LM, Kredich NM. RL J Biol Chem. 1989 Sep 15;264(26):15726-37. RN [3] RM 8347657 RT The ferredoxin:sulphite reductase gene from Synechococcus PCC7942. RA Gisselmann G, Klausmeier P, Schwenn JD. RL Biochim Biophys Acta. 1993 Aug 16;1144(1):102-6. DR PFAM; PF01077; Nitrite and sulphite reductase 4Fe-4S domain DR PFAM; PF03460; Nitrite/Sulfite reductase ferredoxin-like half domain DR PROSITE; PS00365; Nitrite and sulfite reductases iron-sulfur/siroheme-binding site. DR EXPERIMENTAL; SP|P17846; Escherichia coli; isolated as a homodimer exhibiting phospho-adenylylsulphate reductase (PAPS reductase) activity DR OUTGROUP; GP|1113082; Plectonema boryanum; nitrite reductase DR HAMAP; MF_01540; 71 of 72
Genome PropertyGenProp0149: sulfate reduction to sulfide, assimilatory (HMM)