Manganese Management in Photoautotrophs
The transition metal manganese (Mn) is essential for all life forms. Organisms performing oxygenic photosynthesis have a special need for Mn since they use it as catalyst for the splitting of water to extract electrons and produce oxygen. Thus, Mn basically establishes the very basis of our life. We are interested in understanding the Mn management in photoautotrophs. To identify and characterize different components of the Mn management network, such as transporters, regulators, and Mn-dependent metalloproteins, we are employing two different model organisms representing different stages along the evolutionary trajectory. The cyanobacterium Synechocystis sp. PCC6803 represents the evolutionary ancestor of chloroplasts, and Arabidopsis thaliana serves as model for most recent land plants.
To address the specific function of proteins in Mn management we generate mutants by a targeted genomic engineering approach and perform a detailed physiological characterization of those mutants. Amongst others, photosynthetic parameters are recorded by PAM measurements, subcellular metal distributions are quantified by ICP-MS (in collaboration with the CEPLAS Metabolomics facility at the University of Cologne), and metabolic effects of Mn limitation/excess are analyzed by a metabolomics approach (in collaboration with the CEPLAS Metabolomics facility at the University of Düsseldorf). Additional information about the proteins is obtained by in vitro studies. Computer based approaches allow to search for additional promising candidates of the Mn management network.