Nitrate-responsive NarX-NarL represses arginine-mediated induction of the Pseudomonas aeruginosa arginine fermentation arcDABC operon.
Denitrification and arginine fermentation are major parts of the anaerobic metabolism of Pseudomonas aeruginosa, which is important for biofilm formation and infection. The two-component regulatory system NarX-NarL is part of the underlying network and is required for denitrifying growth. All target promoters identified so far are activated by NarL. In this study the effect of NarL on arginine fermentation was investigated using proteome, Northern blot and lacZ reporter gene analyses. NarL-dependent repression of the arcDABC operon was observed and the corresponding NarL-binding site in the arcD promoter region was functionally localized at -60 bp upstream of the transcriptional start site using site-directed promoter mutagenesis and reporter gene fusion experiments. The results clearly show that in the presence of nitrate NarL represses the arginine-dependent activation of the arcDABC operon mediated by ArgR. It does not influence the oxygen-tension-dependent activation via Anr. Thus, the anaerobic energy metabolism of P. aeruginosa is coordinated via NarX-NarL activity. In the presence of nitrate the highly efficient denitrification is preferred over the less attractive arginine fermentation.
Benkert
Beatrice
B
Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany.
Quäck
Nicole
N
Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany.
Schreiber
Kerstin
K
Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany.
Jaensch
Lothar
L
Division of Cell and Immune Biology, Proteome Research Group, Helmholtz Centre for Infection Research, Inhoffenstr. 7, D-38124 Braunschweig, Germany.
Jahn
Dieter
D
Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany.
Schobert
Max
M
Institute of Microbiology, Technical University Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany.
D026905:Amino Acid Transport Systems / Q000235:genetics / Q000378:metabolism; D000693:Anaerobiosis; D017920:Antiporters / Q000235:genetics / Q000378:metabolism; D001120:Arginine / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D015152:Blotting, Northern; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D017930:Genes, Reporter; D016297:Mutagenesis, Site-Directed; D009566:Nitrates / Q000378:metabolism*; D009876:Operon; D011401:Promoter Regions, Genetic; D020543:Proteome / Q000235:genetics / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins
D026905:Amino Acid Transport Systems; D017920:Antiporters; C063930:ArcD protein, Bacteria; C087018:ArgR protein, Bacteria; D001426:Bacterial Proteins; D009566:Nitrates; D020543:Proteome; D012097:Repressor Proteins; D001120:Arginine