scholarly journals Structure of the puf operon of the obligately aerobic, bacteriochlorophyll alpha-containing bacterium Roseobacter denitrificans OCh114 and its expression in a Rhodobacter capsulatus puf puc deletion mutant.

1997 ◽  
Vol 179 (17) ◽  
pp. 5247-5258 ◽  
Author(s):  
C Kortlüke ◽  
K Breese ◽  
N Gad'on ◽  
A Labahn ◽  
G Drews
Keyword(s):  
Deletion Mutant ◽  
Rhodobacter Capsulatus ◽  
Puf Operon

scholarly journals Role for draTG and rnf Genes in Reduction of 2,4-Dinitrophenol by Rhodobacter capsulatus

2001 ◽  
Vol 183 (5) ◽  
pp. 1780-1783 ◽  
Author(s):  
Lara P. Sáez ◽  
Patricia Garcı́a ◽  
Manuel Martı́nez-Luque ◽  
Werner Klipp ◽  
Rafael Blasco ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Nitrogen Fixation ◽  
Deletion Mutant ◽  
Rhodobacter Capsulatus ◽  
Short Term ◽  
Phototrophic Bacterium ◽  
Reduction System ◽  
Nitroreductase Activity

ABSTRACT The phototrophic bacterium Rhodobacter capsulatus is able to reduce 2,4-dinitrophenol (DNP) to 2-amino-4-nitrophenol enzymatically and thus can grow in the presence of this uncoupler. DNP reduction was switched off by glutamine or ammonium, but this short-term regulation did not take place in a draTGdeletion mutant. Nevertheless, the target of DraTG does not seem to be the nitrophenol reductase itself since the ammonium shock did not inactivate the enzyme. In addition to this short-term regulation, ammonium or glutamine repressed the DNP reduction system. Mutants ofR. capsulatus affected in ntrC orrpoN exhibited a 10-fold decrease in nitroreductase activity in vitro but almost no DNP activity in vivo. In addition, mutants affected in rnfA or rnfC, which are also under NtrC control and encode components involved in electron transfer to nitrogenase, were unable to metabolize DNP. These results indicate that NtrC regulates dinitrophenol reduction in R. capsulatus, either directly or indirectly, by controlling expression of the Rnf proteins. Therefore, the Rnf complex seems to supply electrons for both nitrogen fixation and DNP reduction.

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