期刊
RESEARCH IN MICROBIOLOGY
卷 163, 期 5, 页码 340-348出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.resmic.2012.05.004
关键词
Nitrate assimilation; Sulfate assimilation; Siroheme enzymes; Nitrite reduction; Sulfite reduction
类别
资金
- Deutsche Forschungsgemeinschaft [SA 494/4-1]
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. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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