NnrA Is Required for Full Virulence and Regulates Several Brucella melitensis Denitrification Genes

ABSTRACT We identified two regulators of denitrification genes in Brucella melitensis 16M: NarR, which regulates the nitrate reductase (nar) operon, and NnrA, which is involved in the expression of the last three reductases of the denitrification pathway (nirK, norB, and nosZ). NnrA is required for virulence in mice and for intracellular resistance to nitric oxide.

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The Nitric Oxide Production in the Moss Physcomitrella patens Is Mediated by Nitrate Reductase

PLoS ONE ◽

10.1371/journal.pone.0119400 ◽

2015 ◽

Vol 10 (3) ◽

pp. e0119400 ◽

Cited By ~ 15

Author(s):

Rigoberto Medina-Andrés ◽

Alejandro Solano-Peralta ◽

Juan Pablo Saucedo-Vázquez ◽

Selene Napsucialy-Mendivil ◽

Jaime Arturo Pimentel-Cabrera ◽

...

Keyword(s):

Nitric Oxide ◽

Nitrate Reductase ◽

Physcomitrella Patens ◽

Nitric Oxide Production ◽

Oxide Production

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Nitrate reductase-mediated nitric oxide generation is essential for fungal elicitor-induced camptothecin accumulation of Camptotheca acuminata suspension cell cultures

Applied Microbiology and Biotechnology ◽

10.1007/s00253-011-3146-1 ◽

2011 ◽

Vol 90 (3) ◽

pp. 1073-1081 ◽

Cited By ~ 18

Author(s):

Dan Lu ◽

Jufang Dong ◽

Haihong Jin ◽

Lina Sun ◽

Xiangbin Xu ◽

...

Keyword(s):

Nitric Oxide ◽

Nitrate Reductase ◽

Cell Cultures ◽

Fungal Elicitor ◽

Suspension Cell ◽

Camptotheca Acuminata ◽

Suspension Cell Cultures

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The complete denitrification pathway of the symbiotic, nitrogen-fixing bacterium Bradyrhizobium japonicum

Biochemical Society Transactions ◽

10.1042/bst0330141 ◽

2005 ◽

Vol 33 (1) ◽

pp. 141-144 ◽

Cited By ~ 102

Author(s):

E.J. Bedmar ◽

E.F. Robles ◽

M.J. Delgado

Keyword(s):

Nitric Oxide ◽

Nitrous Oxide ◽

Bradyrhizobium Japonicum ◽

Mutational Analysis ◽

Control Level ◽

Gene Clusters ◽

Alternative Form ◽

Nitrate Respiration ◽

Regulatory Cascade ◽

Denitrification Genes

Denitrification is an alternative form of respiration in which bacteria sequentially reduce nitrate or nitrite to nitrogen gas by the intermediates nitric oxide and nitrous oxide when oxygen concentrations are limiting. In Bradyrhizobium japonicum, the N2-fixing microsymbiont of soya beans, denitrification depends on the napEDABC, nirK, norCBQD, and nosRZDFYLX gene clusters encoding nitrate-, nitrite-, nitric oxide- and nitrous oxide-reductase respectively. Mutational analysis of the B. japonicum nap genes has demonstrated that the periplasmic nitrate reductase is the only enzyme responsible for nitrate respiration in this bacterium. Regulatory studies using transcriptional lacZ fusions to the nirK, norCBQD and nosRZDFYLX promoter region indicated that microaerobic induction of these promoters is dependent on the fixLJ and fixK2 genes whose products form the FixLJ–FixK2 regulatory cascade. Besides FixK2, another protein, nitrite and nitric oxide respiratory regulator, has been shown to be required for N-oxide regulation of the B. japonicum nirK and norCBQD genes. Thus nitrite and nitric oxide respiratory regulator adds to the FixLJ–FixK2 cascade an additional control level which integrates the N-oxide signal that is critical for maximal induction of the B. japonicum denitrification genes. However, the identity of the signalling molecule and the sensing mechanism remains unknown.

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