Inner cellular CO2 transfer mechanism during photorespiration

• Applicant: Professor Dr. Hans-Peter Braun
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2009 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 91564084

Mitochondria are the site of photorespiratory CO2 and NH3 release. Furthermore, the vast majority of NADH that is oxidized in the mitochondrial electron transport chain (ETC) during the day results from photorespiration. Complex I of the ETC contains a plant-specific domain made up from five proteins with homology to γ-carbonic anhydrases (CA) that is important for complex I assembly. We hypothesize that this domain is involved in transfer of CO2 from mitochondria to chloroplasts. We will characterize function of CA proteins by enzymatic assays with recombinant proteins, generation of double and triple knock-outs, and determination of physiological responses as well as complex I composition. In addition, we will complement CA mutants with CA coding sequences carrying active site mutations. This will allow for discrimination of the structural and the enzymatic function of these proteins. In a second approach, we will analyse composition and structure of the mitochondrial proteome at different CO2 availabilities in order to understand the impact of photorespiratory flux on general mitochondrial metabolism. Finally, we will start efforts to analyse posttranslational modifications of mitochondrial photorespiratory enzymes. Our work will allow new insights into the regulation of photorespiration and the interconnection with other metabolic pathways.

• DFG Programme: Research Units
• Subproject of: FOR 1186: Photorespiration: Origins and Metabolic Integration in Interacting Compartments
• Participating Person: Professor Dr. Christoph Peterhänsel