Site-2 Protease Slr1821 Regulates Carbon/Nitrogen Homeostasis during Ammonium Stress Acclimation in Cyanobacterium Synechocystis sp. PCC 6803.

ABSTRACT: Excess ammonium imposes toxicity and stress response in cyanobacteria. How cyanobacteria acclimate to NH₄⁺ stress is so far poorly understood. Here, Synechocystis sp. PCC6803 S2P homolog Slr1821 was identified as the essential regulator through physiological characterization and transcriptomic analysis of its knockout mutant. The proper expression of 60% and 67% of the NH₄⁺ activated and repressed genes, respectively, were actually Slr1821-dependent since they were abolished or reversed in ∆slr1821. Synechocystis 6803 suppressed nitrogen uptake and assimilation, ammonium integration and mobilization of other nitrogen sources upon NH₄⁺ stress. Opposite regulation on genes for assimilation of nitrogen and

SUBMITTER: Lin S 

PROVIDER: S-EPMC10094980 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature