Posttranslationale Regulation des Autotrophie-Heterotrophie-Wechsels in Synechocystis

01/12/2021 to 30/11/2024

Post-translational regulation of autotrophy-to-heterotrophy switch in Synechocystis

Regulatory potential of protein O-phosphorylation is well understood in eukaryotes, but still underexplored in bacteria. The first site-specific protein O phosphorylation event in any bacterium was described in cyanobacteria, and proved to be essential for activity of the key nitrogen regulatory protein PII. Recent phosphoproteome studies in Synechocystis identified O-phosphorylation as a frequent modification of enzymes in the carbon metabolism and photosynthesis. Moreover, our own quantitative studies revealed strong changes in protein phosphorylation levels during stress conditions such as nitrogen and carbon starvation, i.e. conditions that trigger metabolic switches, compared to cells at vegetative conditions. Within the SCyCode consortium, several groups have recently demonstrated regulatory functions of specific phosphorylation events in modulation of key enzymes, such as phosphoglucomutase. We hypothesize that adaptation to autotrophic and heterotrophic conditions, for example during diurnal cycle or changes of carbon or nitrogen availability, will have a strong impact on protein phosphorylation dynamics, especially of metabolic enzymes and proteins involved in photosynthesis that were previously shown to be phosphorylated. We therefore propose to team up with several groups from the SCyCode consortium to a) perform in-depth temporal proteome and phosphoproteome analysis during diurnal cycle of Synechocystis and investigate the influence of the clock components (KaiABC) on global phosphorylation dynamics (with Wilde group); b) identify substrates of specific protein kinases and phosphatases under stress conditions such as carbon and nitrogen limitation (with Hagemann and Forchhammer groups); and c) reannotate the Synechocystis genome using proteogenomics and attempt to identify novel genes and proteins involved in the carbon/nitrogen metabolism (with Hess group). Our results will be made available to a broad scientific community and will represent a valuable resource for further studies on metabolic regulation in bacteria in general, and cyanobacteria in particular.