Azorhizobium caulinodans PII and GlnK proteins control nitrogen fixation and ammonia assimilation.
We herein report that Azorhizobium caulinodans PII and GlnK are not necessary for glutamine synthetase (GS) adenylylation whereas both proteins are required for complete GS deadenylylation. The disruption of both glnB and glnK resulted in a high level of GS adenylylation under the condition of nitrogen fixation, leading to ammonium excretion in the free-living state. PII and GlnK also controlled nif gene expression because NifA activated nifH transcription and nitrogenase activity was derepressed in glnB glnK double mutants, but not in wild-type bacteria, grown in the presence of ammonia.
Michel-Reydellet
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N
Unité de Physiologie Cellulaire, Centre National de la Recherche Scientifique, Unité Recherche Associée 1300, Département des Biotechnologies, Institut Pasteur, 75724 Paris Cedex 15, France.
Kaminski
P A
PA
D000249:Adenosine Monophosphate / Q000378:metabolism; D000641:Ammonia / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D009154:Mutation; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000378:metabolism; D051922:PII Nitrogen Regulatory Proteins; D011499:Protein Processing, Post-Translational; D012230:Rhizobiaceae / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; C113488:GlnK protein, Azorhizobium caulinodans; D051922:PII Nitrogen Regulatory Proteins; D000249:Adenosine Monophosphate; C404143:PIID regulatory protein, Bacteria; D000641:Ammonia; D009591:Nitrogenase; D005974:Glutamate-Ammonia Ligase