Photorespiration pathway for C3 metabolism. The phosphoglycolate, product of photorespiration, is dephosphorylated in the chloroplast. Glycolate is transported to the peroxisome where molecular oxygen further oxidizes it to glyoxylate which is amidated to the amino acid glycine. Glycine is then transported to the mitochondrial matrix where two glycines are converted into serine molecule. The serine is transported into the peroxisome where it is deaminated to glycerate. Finally, the glycerate is transported back to the chloroplast, where it is phosphorylated to 3-phosphoglycerate and reused in the Calvin cycle. Figure taken from http://www.cliffsnotes.com.

The photorespiration cycle is known for decades but not all components are explored and our understanding of interaction with other major metabolic pathways is also limited. In order to improve our knowledge about the photorespiration, extensive collaborating is needed. Our department is employed in the Systems Biology approach of the project which allows integration of multi-level experimental data into a central computational model. There are several main goals of PROMICS in which solving the Systems Biology is involved:

• Construction of the canonical model of photosynthetic-photorespiratory carbon metabolism
• Analysis of photorespiratory metabolism in a range of phylogenetically different organisms
• Identification of unknown components of photorespiratory metabolism with the help of overexpressor and knockout lines
• Model interrogation and validation, formulating of new hypotheses

This research is supported by the German Research Foundation (DFG) as part of PROMICS research group 1186.