title: A core of three amino acids at the carboxyl-terminal region of glutamine synthetase defines its regulation in cyanobacteria.
abstract: Glutamine synthetase (GS) type I is a key enzyme in nitrogen metabolism, and its activity is finely controlled by cellular carbon/nitrogen balance. In cyanobacteria, a reversible process that involves protein-protein interaction with two proteins, the inactivating factors IF7 and IF17, regulates GS. Previously, we showed that three arginine residues of IFs are critical for binding and inhibition of GS. In this work, taking advantage of the specificity of GS/IFs interaction in the model cyanobacteria Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120, we have constructed a different chimeric GSs from these two cyanobacteria. Analysis of these proteins, together with a site-directed mutagenesis approach, indicates that a core of three residues (E419, N456 and R459) is essential for the inactivation process. The three residues belong to the last 56 amino acids of the C-terminus of Synechocystis GS. A protein-protein docking modeling of Synechocystis GS in complex with IF7 supports the role of the identified core for GS/IF interaction.
authors: Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Seville, 41092, Spain.
authors: Lorena
authors: L
authors: Saelices
authors: Rocío
authors: R
authors: Robles-Rengel
authors: Francisco J
authors: FJ
authors: Florencio
authors: M Isabel
authors: MI
authors: Muro-Pastor
mesh_terms: D000596:Amino Acids / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D000458:Cyanobacteria / Q000201:enzymology* / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; C120035:IF17 protein, Synechocystis sp.; C120034:IF7 protein, Synechocystis sp.; D011994:Recombinant Proteins; D005974:Glutamate-Ammonia Ligase