Regulation of Herbaspirillum seropedicae NifA by the GlnK PII signal transduction protein is mediated by effectors binding to allosteric sites

Publication date: Available online 19 December 2019Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Adriano Alves Stefanello, Marco Aurélio Schuler de Oliveira, Emanuel Maltempi de Souza, Fábio de Oliveira Pedrosa, Leda Satie Chubatsu, Luciano Fernandes Huergo, Ray Dixon, Rose Adele MonteiroAbstractHerbaspirillum seropedicae is a plant growth promoting bacterium that is able to fix nitrogen and to colonize the surface and internal tissues of important crops. Nitrogen fixation in H. seropedicae is regulated at the transcriptional level by the prokaryotic enhancer binding protein NifA. The activity of NifA is negatively affected by oxygen and positively stimulated by interaction with GlnK, a PII signaling protein that monitors intracellular levels of the key metabolite 2-oxoglutarate (2-OG) and functions as an indirect sensor of the intracellular nitrogen status. GlnK is also subjected to a cycle of reversible uridylylation in response to intracellular levels of glutamine. Previous studies have established the role of the N-terminal GAF domain of NifA in intramolecular repression of NifA activity and the role of GlnK in relieving this inhibition under nitrogen-limiting conditions. However, the mechanism of this control of NifA activity is not fully understood. Here, we constructed a series of GlnK variants to elucidate the role of uridylylation and effector binding during the process of NifA activation. Our data support a model whereby GlnK urid...

Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - December 20, 2019 Category: Biochemistry Source Type: research