Metabolic crises of c-diAMP free-mutant and its receptor protein SbtB under diurnal rhythms in cyanobacteria

ABSTRACT: As photoautotrophic organisms, cyanobacteria are subjected to the natural diurnal rhythm. Thus, cyanobacteria face strong metabolomic changes that allow photosynthesis and glycogen anabolism throughout the day, while night phases require the adaption to a heterotrophic-like lifestyle, including glycogen catabolism. Previous studies highlighted the importance of both, SbtB and its effector molecule c-diAMP, for the nighttime survivability of Synechocystis through the regulation of glycogen synthesis. However, the extent of the cellular c-diAMP and SbtB impact for day/night survivability remained elusive. To get better understanding of cellular processes under SbtB or c-diAMP regulation, we compared metabolomic and proteomic characterizations of both a SbtB knockout (ΔsbtB) and a c-diAMP free (ΔdacA) mutant of the model strain Synechocystis sp. PCC 6803. While our data indicates that the cellular role of SbtB for nighttime survivability is solely restricted to carbon/glycogen metabolism, the diurnal lethality of ΔdacA seems to be a sum of cellular dysregulations among several metabolic processes. These processes include photosystem assembly and redox regulation, which leads to elevated levels of intracellular ROS and glutathione. Further, we were able to show an impact of c-diAMP on central carbon as well as nitrogen metabolism. The latter can be directly linked to reduced levels of NtcA, the global nitrogen transcription regulator. Thus, dysregulations of NtcA regulated proteins lead to an imbalance of the glutamine to glutamate ratio, reduced amounts of bioproducts of the ornithine pathway, such as arginine, and elevated levels of urea as a degradation product.

INSTRUMENT(S):

ORGANISM(S): Synechocystis Sp. (strain Pcc 6803 / Kazusa) Bacteria

SUBMITTER: Philipp Spaet  

LAB HEAD: Khaled A. Selim

PROVIDER: PXD045008 | Pride | 2025-08-21

REPOSITORIES: Pride