Subproject 5

Evolution of photosynthetic membrane biogenesis and protein complex assembly

Project leaders: Dr. Marc Nowaczyk and Dr.-Ing. Sascha Rexroth

The intricate structure of their cellular membranes is one of the distinguishing features of photoautotropic organisms. This feature can be traced back from lateral segregated stroma and grana thylakoids of higher plant chloroplasts via those of green algae to the simpler thylakoid structures of cyanobacteria. In particular, the - from evolutionary perspective - most primitive known cyanobacterium Gloeobacter violaceus is of special interest as it lacks any intracellular thylakoid system. The overall goal of the proposed work is to elucidate the evolutionary progress of photosystem assembly, the conservation and tuning of protein-protein interactions, and its relevance for the progression of a specialized membrane topology. This will be investigated by applying a toolset of quantitative proteome techniques and surface plasmon resonance spectroscopy in combination with advanced confocal fluorescence microscopy, as well as electron microscopy for analysis of the cellular structure. The coordination and chronologic sequence of photosystem and membrane biogenesis will be addressed in MS-based pulse-chase experiments. This will provide the basis for a detailed understanding of the cellular machinery for photosystem and thylakoid biogenesis and define patterns for its evolutionary progression.