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Posted: Apr 09, 2014
Organization of cellular photosystems
(Nanowerk News) A new DFG Research Unit will study the biogenesis of the complex membrane systems in which the light reactions of photosynthesis take place.
Professor Jörg Nickelsen of Ludwig-Maximilians-Universität Munich (LMU)’s Biocenter will act as the official Speaker for the new DFG Research Unit devoted to “Biogenesis of Thylakoid Membranes: Spatiotemporal Organization of Photosynthetic Protein Complex Assembly”. The venture has been approved by the DFG and will receive funding amounting to nearly 2 million euros. The interdisciplinary and multicenter network brings LMU scientists together with colleagues based in Bayreuth, Berlin, Bochum, Kaiserslautern and Potsdam to analyze the assembly of thylakoids. Thylakoids are membrane systems present in certain bacteria and in higher plants, which harbor the photosynthetic apparatus that converts solar radiation into chemical energy. “The new Research Unit represents a unique combination of expertise in molecular genetics, biochemistry, biophysics and structural analysis, allowing us to adopt a systematic approach to the analysis of the molecular details of the photosynthetic process,” Nickelsen explains.
A complex interplay of multiple factors
By utilizing sunlight for the production of molecular oxygen and energy-rich organic compounds, photosynthesis provides the essential basis for all life on earth. Solar energy is captured by photoreactive molecules located in the thylakoids, and converted into a biochemically useful form in the so-called light reactions. Thylakoids are specialized membrane systems found in some bacterial species and in the chloroplasts of plant cells, and they are the most complicated type of biological energy-producing membranes known. Although their structure and function have been extensively investigated, little is known about how they are actually put together.
The assembly of thylakoids requires a complex interplay between proteins, lipids, pigments and inorganic cofactors, which the members of the new Research Unit plan to dissect. Recent findings suggest that the spatial organization of the components involved plays an important, but hitherto poorly understood, role in the whole process. “Thylakoids have become more complex during the course of evolution, so we intend to study their synthesis in different model organisms,” Nickelsen says. “In this way, we hope to be able to reconstruct the evolutionary trajectory that led from the relatively simple photosynthetic membranes of primitive cyanobacteria to the intricately structured thylakoid networks found in higher plants.”
Two projects for LMU groups
LMU’s contribution to the new Research Unit consists primarily of two projects. Nickelsen and his coworkers will study the biogenesis of the thylakoid membrane of cyanobacteria. They will focus in particular on the question of how the metal manganese is incorporated into the reaction centers located in the thylakoids. The metal is an essential component of the photosystem, because it is intimately involved in the generation of chemical energy and catalyzes the synthesis of molecular oxygen.
LMU biologist Professor Dario Leister will investigate the origins of the highly characteristic spatial organization of the thylakoids in plant chloroplasts. In these organelles, thylakoid disks form localized “pillars” that are reminiscent of stacked dinner-plates. But disks and pillars are in fact connected to each other to form a single continuous compartment. In order to maintain contact with their immediate neighbors, the membranes forming the disk margins must be strongly bent. Leister and his group will concentrate on understanding how this localized curvature is imposed.
DFG-funded Research Units enable teams of researchers working together to tackle important problems in their respective fields and to develop innovative and interdisciplinary approaches to their resolution. In addition to LMU researchers, teams based at Bayreuth University, the Humboldt University in Berlin, the University of the Ruhr in Bochum, the Technical University in Kaiserslautern and the Max Planck Institute of Plant Physiology in Potsdam form part of the new Research Unit.