FOR 2092:  Biogenesis of Thylakoid Membranes: Spatiotemporal Organisation of Photosynthetic Protein Complex Assembly

• Subject Area: Biology
• Term: from 2014 to 2022
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 239484859

Photosynthetic electron transport is mediated by multi-subunit pigment-protein complexes which are situated in a specialized membrane system, named thylakoids. Despite a detailed knowledge on the structure and function of these complexes, little is known on their assembly during thylakoid membrane biogenesis. The emerging picture of this process depicts a highly-ordered scaffold of assembly factors that integrates the incorporation of proteins and organic as well as inorganic co-factors in a step-wise manner. Recent work has also indicated that the production line for photosynthetic complexes is initiated at biogenic membrane sub-compartments from where it proceeds via discrete and conserved assembly intermediates to generate a functional energy converting apparatus. The FOR2092 Research Unit has set out to disentangle the molecular principles of the spatiotemporal organization of thylakoid membrane biogenesis by applying a multidisciplinary, systematic approach combining unique expertise in molecular genetics, biochemistry, biophysics and ultrastructural analyses. The concept includes the comparative investigation of a set of suitable model organisms that enables one to follow the complete evolutionary path for the development of thylakoid complexity from primordial cyanobacteria to chloroplasts of vascular plants. By focusing on distinct assembly factors and the spatiotemporal organization of their working mode, the joined forces of FOR2092 members have recently discovered a variety of new molecular aspects of thylakoid biogenesis. The findings include details of photosystem II and photosystem I assembly, membrane insertion of thylakoid proteins, organic and inorganic co-factor incorporation and formation of biogenic membrane structures. In addition, both genetic and biochemical approaches have identified several new components of the intricate assembly factor network for thylakoid biogenesis. In sum, this obtained body of evidence now forms the solid basis for a proceeding comprehensive study of the biogenesis process which will be complemented by comparative analysis of the pigment-free ATPase complex as well as state-of-the-art studies on thylakoid ultrastructure in situ. The consortium envisions that by answering the questions how, where and when the different assembly processes take place and are integrated during thylakoid maturation, the development of knowledge-based strategies for the targeted modification of the biogenesis process in a broad set of photosynthetic model organisms will become feasible in the future.

• DFG Programme: Research Units

Projects

• Assembly of photosystem I in thylakoid membranes (Applicant Bock, Ralph )
• Auxiliary factors for chlorophyll biosynthesis and their potential contribution to the assembly of chlorophyll into chlorophyll-binding proteins (Applicant Grimm, Bernhard )
• Auxiliary factors required for the accumulation and functioning of the thylakoid ATP Synthase (Applicant Rühle, Ph.D., Thilo Fabian )
• Biogenesis and molecular architecture of native thylakoid membranes investigated by in situ cryo-electron tomography (Applicant Engel, Ph.D., Benjamin )
• Biogenesis of thylakoid membranes in cyanobacteria (Applicant Nickelsen, Ph.D., Jörg )
• Central task (Applicants Geimer, Stefan ;  Nickelsen, Ph.D., Jörg ;  Schroda, Michael )
• Coordination Funds (Applicant Nickelsen, Ph.D., Jörg )
• Electron Microscopy (Applicant Geimer, Stefan )
• Elucidating VIPP function in thylakoid biogenesis with VIPPaccumulating mutants as entry point (Applicant Schroda, Michael )
• Evolution of photosynthetic membrane biogenesis and protein complex assembly (Applicant Nowaczyk, Marc )
• Functions of CURT1 proteins in thylakoid grana formation (Applicant Leister, Dario )
• Transport and insertion mechanisms of plastid-encoded thylakoid membrane proteins (Applicant Schünemann, Danja )

• Spokesperson: Professor Jörg Nickelsen, Ph.D.