Inorganic carbon levels regulate growth via SigC signaling cascade in cyanobacteria.

ABSTRACT: Cyanobacterial growth depends on inorganic carbon (Ci; CO₂ and bicarbonate) concentration, but mechanism(s) adjusting photosynthesis and growth according to Ci remain unclear. ΔrpoZ cells lacking the ω subunit of the RNA polymerase (RNAP) show a unique high-CO₂ lethal phenotype in Synechocystis sp. PCC 6803. Bioinformatics, biochemical and 3D modeling studies were used to reveal how suppressor mutations rescue ΔrpoZ cells in 3% CO₂. Suppressor mutations were mapped to the ssr1600 gene. Ssr1600 was shown to function as an anti-σ factor antagonist. The Slr1861 protein was identified as an anti-σ factor and as an Ssr1600 kinase. The Slr1861/Ssr1600 pair was shown to control the formation of RNAP-SigC holoenzyme using a phosphorylation-controlled partner-switch

SUBMITTER: Kurkela J 

PROVIDER: S-EPMC12329169 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature