Subproject 1

Assembly of photosystem I in thylakoid membranes

Project leader: Prof. Dr. Ralph Bock

The photosystems in the thylakoid membrane of chloroplasts and photosynthetic bacteria belong to the largest and most complex macromolecular assemblies found in nature. While structure and composition of the photosystems are reasonably well understood, little is known about how these gigantic complexes are put together during thylakoid membrane biogenesis. Recent work has identified a first set of proteins that are involved in the assembly of photosystem I (PSI) in the thylakoid membrane of higher plants. The successful development of in vivo tagging and affinity purification approaches now enables us to structurally and functionally dissect the machinery that assembles PSI from its many subunits and co-factors. The goals of the research proposed here will be to: (i) elucidate the molecular structure of the PSI assembly machinery and determine the functions of all of its components, (ii) establish an assembly map for PSI that provides a complete picture of the spatial and temporal sequence of events in the assembly process, (iii) elucidate the evolution of the assembly machinery in relation to the evolution of thylakoid structure and morphology, and, in the long run, (iv) reconstitute the PSI assembly process in vitro.