BBSRC Systems Biology PhD Studentship

The nitrogen and carbon sensing network in cyanobacteria

Project summary

Cyanobacteria sense and respond to their nitrogen supply and their carbon/nitrogen ratio. Long-term acclimation to fluctuations in resource supply involves transcriptional regulation of photosynthesis and nitrogen assimilation enzymes, while responses to short term fluctuations involve rapid metabolic regulation. In the model cyanobacterium Synechocystis, this involves modulation of the ammonia assimilating enzyme glutamine synthetase by 2-oxoglutarate, a metabolite that acts as a sensor of the intracellular C/N ratio.

This project aims to understand the regulatory and metabolic network that balances C and N metabolism in Synechocystis, in particular how short and longer term fluctuations are distinguished. To answer these questions, mathematical models of the known system components will be constructed. Model parameters will be supplied by gene expression measurements (mRNA-seq), quantification of enzymes and regulatory proteins (and post-translational modifications) by LC-MS/MS (SRM quantification) and metabolic fluxes using 15N and 13C labelling coupled with LC-MS/MS detection of label in the relevant metabolites. Components predicted to be important for C/N sensing will be manipulated by targeted knockdowns or over-expression.

Informal enquiries

Please contact Professor Nick Smirnoff (N.Smirnoff@exeter.ac.uk).