Nitrogenase switch-off by ammonium ions in Azospirillum brasilense requires the GlnB nitrogen signal-transducing protein.
Nitrogenase activity in several diazotrophs is switched off by ammonium and reactivated after consumption. The signaling pathway to this system in Azospirillum brasilense is not understood. We show that ammonium-dependent switch-off through ADP-ribosylation of Fe protein was partial in a glnB mutant of A. brasilense but absent in a glnB glnZ double mutant. Triggering of inactivation by anaerobic conditions was not affected in either mutant. The results suggest that glnB is necessary for full ammonium-dependent nitrogenase switch-off in A. brasilense.
Klassen
Giseli
G
Universidade Federal do Paraná, Departamento de Bioquímica e Biologia Molecular, Caixa Postal 19046 CEP-81531-990, Curitiba, Paraná, Brazil.
Souza
Emanuel M
EM
Yates
M Geoffrey
MG
Rigo
Liu Un
LU
Costa
Roberta M
RM
Inaba
Juliana
J
Pedrosa
Fábio O
FO
D015806:Azospirillum brasilense / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D009591:Nitrogenase / Q000235:genetics / Q000378:metabolism*; D051922:PII Nitrogen Regulatory Proteins; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D015398:Signal Transduction
D001426:Bacterial Proteins; D003470:Culture Media; C100965:GlnZ protein, Azospirillum brasilense; D051922:PII Nitrogen Regulatory Proteins; D000644:Quaternary Ammonium Compounds; C404143:PIID regulatory protein, Bacteria; D009591:Nitrogenase