Regulation of photosynthesis by thylakoid K+/H+ antiport

• Applicant: Professorin Dr. Ute Armbruster
• Subject Area: Plant Biochemistry and Biophysics ; Plant Physiology
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 366065941

• Final Report Year: 2021

Final Report Abstract

Solar energy drives life on earth. This is facilitated by the photosynthetic process. Light availability for photosynthesis, however, often fluctuates immensely. My research group seeks to understand the molecular mechanisms which underpin photosynthesis in dynamic light conditions. We have previously uncovered that the thylakoid K+/H+ exchange protein plays a key role in the regulation of photosynthesis in response to light intensity. KEA3-mediated proton export from the lumen downregulates a pH- dependent photoprotective mechanism, which dissipates absorbed light energy as heat. During the current funding period we could show that KEA3 activity is downregulated via a C-terminal element in high light to avoid photosystem damage. The analysis of long-term acclimation effects on dynamic photosynthesis revealed that KEA3 downregulation in high light is linked to limitations in downstream metabolism. Furthermore, we demonstrated that the KEA3 regulatory C-terminus binds ATP and ADP and undergoes conformational changes in response. These results propose the phosphorylation potential as signal for downstream metabolism regulating KEA3 activity and thereby altering energy flux. In summary, by taking multiple approaches, we were able to advance our understanding of dynamic photosynthesis by characterizing its regulatory network and defining the function of KEA3.

Publications

• (2017) The regulation of the chloroplast proton motive force plays a key role for photosynthesis in fluctuating light. Current Opinion in Plant Biology 37, 56-62
  Armbruster, U., Correa Galvis, V., Kunz, H.H., Strand, D.D.
  
• (2019) Efficient photosynthesis in dynamic light environments: a chloroplast's perspective. Biochemical Journal 476, 2725-2741
  Kaiser, E., Correa Galvis, V. and Armbruster, U.
  
• (2019) Photosynthesis in Arabidopsis is unaffected by the function of vacuolar K+ channel TPK3. Plant Physiology 180, 1322-1335
  Höhner, R., Correa Galvis, V., Strand, D.D., Völkner, C., Krämer, M., Messer, M., Dinc, F., Sjuts, I., Bölter, B., Kramer, D.M., Armbruster, U. and Kunz, H.H.
  
• (2020) Editorial: Regulation of chloroplast primary metabolism. Photosynthesis Research 145 (1):1-3
  Armbruster, U., Strand D.D.
  
• (2020) H+ transport by K+ EXCHANGE ANTIPORTER3 promotes photosynthesis and growth in chloroplast ATP synthase mutants. Plant Physiology 182, 2126-2142
  Correa Galvis, V., Strand, D.D., Messer, M., Thiele W., Hübner, D., Uflewski, M., Kaiser, E., Siemiatkowska, B., Morris, B.A., Tóth, S.Z., Watanabe, M., Brückner, F., Höfgen, R., Jahns, P., Schöttler, M.A. and Armbruster, U.
  
• (2021) Functional characterization of proton antiport regulation in the thylakoid membrane. Plant Physiology
  Uflewski, M., Miehlke, S., Correa Galvis, V., von Bismarck, T, Chen, X., Tietz, E., Ruß, J., Luzarowski, M., Sokolowska, E., Skirycz, A., Eirich, J., Finkemeier, I., Schöttler, M.A. and Armbruster, U.
  
• (2021) Stromal NADH supplied by Phosphoglycerate Dehydrogenase 3 is crucial for photosynthetic performance. Plant Physiology 186, 142-67
  Höhner, R., Krämer, M., Day, P.M., Zimmermann, S.E., Lopez, L.S., Giavalisco, P., Correa Galvis, V., Armbruster, U., Schöttler, M.A., Jahns, P., Krüger, S. and Kunz, H.H.
  
• Light acclimation interacts with thylakoid ion transport to govern the dynamics of photosynthesis
  von Bismarck, T., Korkmaz, K., Ruß, J., Skurk, K., Kaiser, E., Correa Galvis, V., Cruz, J.A., Strand, D.D., Köhl, K., Eirich, J., Finkemeier, I., Jahns, P., Kramer, D.M. and Armbruster, U.