FOR 5573:  Dynamic Regulation of the Proton Motive Force in Photosynthesis

• Subject Area: Biology ; Medicine
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 507704013

The proton motive force (PMF) is at the heart of energy metabolism and fuels most cellular functions. It is universal as the genetic code and has been shaping evolution. The PMF is an electrochemical gradient across a membrane, usually generated by the concerted activity of multiple membrane protein complexes. It separates energy transformation from molecular identities and stochiometric constraints and freely connects and integrates otherwise unrelated cellular processes. This feature has been key for the success of the PMF. While being particularly flexible, the PMF must also be strictly reliable to fuel biochemical reactions and to maintain the cell. To guarantee energy supply, environmental and physiological stimuli must be integrated into PMF regulation. Even though the PMF has been studied intensely, regulatory strategies remain insufficiently understood. Recently, functional imaging and biosensing techniques have uncovered novel, fundamental features of the mitochondrial PMF. While those insights have started to shift the paradigms of our understanding of bioenergetic dynamics, similar insights are lacking for oxygenic photosynthesis. Yet, studying PMF in the context of photosynthesis is particularly well suited as an approach to understand the principles underpinning PMF dynamics, because it is particularly prone to rapid external changes due to fluctuating light in natural habitats. This Research Group (GoPMF) will develop concepts of how the generation and modulation of the PMF is regulated to optimize photosynthetic output in changeable natural environments. Driven by recent discoveries and enabling methodological developments by members of this initiative, we will assess photosynthetic bioenergetics within its context of subcellular organization and physiology. We will make use of cyanobacteria and chloroplasts as in vivo models to dissect mechanisms of rapid PMF adjustment at the posttranslational and physiological level. These insights will be linked with mechanistic and structural analyses of the molecular machines that generate and modulate the PMF. Combining state-of-the-art imaging techniques, with the development of in situ biosensing techniques to monitor bioenergetic characteristics of the PMF live in individual cells, organelles and thylakoids will take our understanding of PMF management into a novel cell biological context. Mechanistic molecular detail into the mechanisms driving PMF dynamics will be gained through fast time-resolved spectroscopy, mass spectrometry and structural biology including cryo-EM and cryo-ET. Extensive genetic engineering will take advantage of the mechanistic conservation and diversity in PMF regulation by cyanobacteria, algae and plants. These functional studies will be flanked by mathematical modeling of the PMF. We expect to establish an understanding of the PMF as a dynamic, responsive and integrated hub that shapes photosynthesis and its adjustment to rapid external changes.

• DFG Programme: Research Units
• International Connection: Japan, Switzerland, USA

Projects

• Adaptive spatiotemporal organization of chloroplast ATP synthase in Chlamydomonas reinhardtii (Applicants Buchert, Felix ;  Busch, Karin )
• Coordination Funds (Applicant Hippler, Michael )
• Cross-species computational analysis of the PMF and its key characteristics (Applicant Matuszynska, Anna )
• Developing functional and structural imaging of PMF determinants (Applicants Busch, Karin ;  Schwarzländer, Markus )
• Elucidating the interplay of PMF determinants in mitochondria and chloroplasts in folio (Applicant Schwarzländer, Markus )
• Molecular insights into cytochrome b6f driven PMF tuning (Applicant Hippler, Michael )
• P05 –Comparative exploration of KEA3 function in PMF partitioning and photoprotection (Applicant Armbruster, Ute )
• Structural and functional analysis of NDH-1 supercomplexes (Applicants Nowaczyk, Marc ;  Schuller, Jan Michael )
• Studies of the proton motif force (PMF) in the cyanobacterium Synechocystis with the the aim to maximize photosynthetic hydrogen production (Applicant Gutekunst, Kirstin )
• Studying the functional significance of the putative Na+/H+ carrier AtNHD1 in the thylakoid membrane for proton motive force dynamic and partitioning (Applicant Kunz, Hans-Henning )
• The effects of proton motive force on thylakoid architecture and function (Applicant Engel, Ph.D., Benjamin )
• The role of protein acetylation in the regulation of photosynthetic light reactions. (Applicant Finkemeier, Iris )

• Spokesperson: Professor Dr. Michael Hippler