Pedro J Pacheco, Juan J Cabrera, Andrea Jiménez-Leiva, María J Torres, Andrew J Gates, Eulogio J Bedmar, David J Richardson, Socorro Mesa, Germán Tortosa, María J Delgado
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引用次数: 0
Abstract
The soybean endosymbiont Bradyrhizobium diazoefficiens harbours the complete denitrification pathway that is catalysed by a periplasmic nitrate reductase (Nap), a copper (Cu)-containing nitrite reductase (NirK), a c-type nitric oxide reductase (cNor), and a nitrous oxide reductase (Nos), encoded by the napEDABC, nirK, norCBQD, and nosRZDFYLX genes, respectively. Induction of denitrification genes requires low oxygen and nitric oxide, both signals integrated into a complex regulatory network comprised by two interconnected cascades, FixLJ-FixK2-NnrR and RegSR-NifA. Copper is a cofactor of NirK and Nos, but it has also a role in denitrification gene expression and protein synthesis. In fact, Cu limitation triggers a substantial down-regulation of nirK, norCBQD, and nosRZDFYLX gene expression under denitrifying conditions. Bradyrhizobium diazoefficiens genome possesses a gene predicted to encode a Cu-responsive repressor of the CsoR family, which is located adjacent to copA, a gene encoding a putative Cu+-ATPase transporter. To investigate the role of CsoR in the control of denitrification gene expression in response to Cu, a csoR deletion mutant was constructed in this work. Mutation of csoR did not affect the capacity of B. diazoefficiens to grow under denitrifying conditions. However, by using qRT-PCR analyses, we showed that nirK and norCBQD expression was much lower in the csoR mutant compared to wild-type levels under Cu-limiting denitrifying conditions. On the contrary, copA expression was significantly increased in the csoR mutant. The results obtained suggest that CsoR acts as a repressor of copA. Under Cu limitation, CsoR has also an indirect role in the expression of nirK and norCBQD genes.
期刊介绍:
FEMS Microbiology Letters gives priority to concise papers that merit rapid publication by virtue of their originality, general interest and contribution to new developments in microbiology. All aspects of microbiology, including virology, are covered.
2019 Impact Factor: 1.987, Journal Citation Reports (Source Clarivate, 2020)
Ranking: 98/135 (Microbiology)
The journal is divided into eight Sections:
Physiology and Biochemistry (including genetics, molecular biology and ‘omic’ studies)
Food Microbiology (from food production and biotechnology to spoilage and food borne pathogens)
Biotechnology and Synthetic Biology
Pathogens and Pathogenicity (including medical, veterinary, plant and insect pathogens – particularly those relating to food security – with the exception of viruses)
Environmental Microbiology (including ecophysiology, ecogenomics and meta-omic studies)
Virology (viruses infecting any organism, including Bacteria and Archaea)
Taxonomy and Systematics (for publication of novel taxa, taxonomic reclassifications and reviews of a taxonomic nature)
Professional Development (including education, training, CPD, research assessment frameworks, research and publication metrics, best-practice, careers and history of microbiology)
If you are unsure which Section is most appropriate for your manuscript, for example in the case of transdisciplinary studies, we recommend that you contact the Editor-In-Chief by email prior to submission. Our scope includes any type of microorganism - all members of the Bacteria and the Archaea and microbial members of the Eukarya (yeasts, filamentous fungi, microbial algae, protozoa, oomycetes, myxomycetes, etc.) as well as all viruses.