CfrA, a Novel Carbon Flow Regulator, Adapts Carbon Metabolism to Nitrogen Deficiency in Cyanobacteria.

Cyanobacteria unable to fix atmospheric nitrogen have evolved sophisticated adaptations to survive to long periods of nitrogen starvation. These genetic programs are still largely unknown-as evidenced by the many proteins whose expression is regulated in response to nitrogen availability, but which belong to unknown or hypothetical categories. In sp.

Redox interference in nitrogen status via oxidative stress is mediated by 2-oxoglutarate in cyanobacteria.

Reactive oxygen species (ROS) are generated naturally in photosynthetic organisms by respiration and photosynthesis. Therefore, detoxification of these compounds, avoiding oxidative stress, is essential for proper cell function. In cyanobacteria, some observations point to a crosstalk between ROS homeostasis, in particular hydrogen peroxide, and nitrogen metabolism by a mechanism independent of known redox regulators.

Dissecting the Binding between Glutamine Synthetase and Its Two Natively Unfolded Protein Inhibitors.

Ammonium is incorporated into carbon skeletons by the sequential action of glutamine synthetase (GS) and glutamate synthase (GOGAT) in cyanobacteria. The activity of Synechocystis sp. PCC 6803 GS type I is controlled by protein-protein interactions with two intrinsically disordered inactivating factors (IFs): the 65-residue (IF7) and the 149-residue one (IF17).

A core of three amino acids at the carboxyl-terminal region of glutamine synthetase defines its regulation in cyanobacteria.

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.