PMID:22659143

Citation	Fischer, M, Schmidt, C, Falke, D and Sawers, RG (2012) Terminal reduction reactions of nitrate and sulfate assimilation in Streptomyces coelicolor A3(2): identification of genes encoding nitrite and sulfite reductases. Res. Microbiol. 163:340-8
Abstract	The model actinobacterium Streptomyces coelicolor A3(2) uses nitrate and sulfate as nitrogen and sulfur sources, respectively. The final step prior to assimilation into amino acids is the 6-electron reduction of the nitrite and sulfite anions, catalyzed by siroheme-dependent nitrite (NirBD) and sulfite (SirA) reductases. There are two predicted nitrite/sulfite reductases annotated in the genome of S. coelicolor, but it is unclear which is responsible for nitrite and which for sulfite reduction. Here we demonstrate that a knock-out in the genes SCO2487 and SCO2488 encoding NirBD prevents use of nitrite as a nitrogen source, while a knock-out in SCO6102 encoding SirA prevents sulfate assimilation. Both mutations could be phenotypically complemented by supplementation of the growth medium with ammonium or casamino acids in the case of the nirBD mutants or sulfur-containing amino acids in the case of the sirA mutants. No functional redundancy between the genes was observed and we demonstrate that NirBD is exclusively required for assimilatory nitrite (it does not detoxify nitrite) and SirA exclusively for assimilatory sulfite reduction.
Links	PubMed Online version:10.1016/j.resmic.2012.05.004
Keywords	Culture Media/chemistry; Electron Transport; Gene Knockout Techniques; Nitrite Reductases/genetics; Nitrite Reductases/metabolism; Nitrites/metabolism; Oxidation-Reduction; Oxidoreductases Acting on Sulfur Group Donors/genetics; Oxidoreductases Acting on Sulfur Group Donors/metabolism; Streptomyces coelicolor/enzymology; Streptomyces coelicolor/genetics; Streptomyces coelicolor/metabolism; Sulfates/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STRCO:Q9ADG1	enables	GO:0016002: sulfite reductase activity	ECO:0000315: mutant phenotype evidence used in manual assertion		F		Seeded From UniProt	complete
STRCO:Q9ADG1		GO:0016002: sulfite reductase activity	ECO:0000315:		F		In figure 5, mutant N34 with a deletion in SirA and missing SCO6102 failed to grow in nitrite supplemented media, as seen in B, but grew in supplemented sulfur media, as seen in D.	complete CACAO 7571

References

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