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Molecular structure of two enzymes, FBPase (left) and SBPase (right), of Physcomitrella. © University of Freiburg, Université de Lorraine, Oliver Einsle, Thomas Roret

Unexpected origins of photosynthesis

The conversion of light solar energy into chemical energy, a process named photosynthesis, is one of the most important biological reactions on earth. An international team of researchers associating Université de Lorraine and INRA, together with the Universities of Freiburg (Germany) UPMC (France) and California Berkeley (United States), has obtained evidence for unexpected origins of photosynthesis. Using the moss Physcomitrella patens as an experimental model, the researchers have shown that along evolution, organisms belonging to two different biological domains have contributed to the elaboration of modern photosynthetic organisms able to fix CO2. This result, published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), is the completion of research initiated more than forty years ago.

Updated on 06/30/2017
Published on 06/13/2016

Oxygenic photosynthesis occurs in land plants, algae and some photosynthetic bacteria called cyanobacteria. In this process, oxygen becomes liberated from water molecules and CO2 incorporated into organic molecules as sugars. Photosynthesis is the origin of the fossil energy and organic matter available on earth today. It also plays a key role at maintaining a constant oxygen level in the atmosphere and at reducing CO2 levels, thereby minimizing the greenhouse effect.

In plant cells, CO2 fixation involves several enzymes of the Calvin-Benson cycle. The efficiency of CO2 fixation conditions notably the agronomical yields. Two of these enzymes, fructose-1,6-bisphosphatase (FBPase) and sedoheptulose-bisphosphatase (SBPase), have been studied since more than forty years. By performing biochemical and genetic analyses in the moss Physcomitrella patens, the researchers have gained access to the molecular structures and catalytic and regulatory properties of these enzymes and they have been able to trace back the evolution of the photosynthetic systems.

Surprisingly, the two moss enzymes are rather similar in structure and catalysis but they differ in their regulatory properties and phylogenetic origins. They were found to derive likely from two different biological domains. Indeed, one of the sequences is predicted to derive from alpha proteobacteria while the other one is closer to Archaea. These results bring unexpected  hypotheses  concerning the origin of photosynthetic organisms which seem to consist of a patchwork of genes inherited from more primitive non-photosynthetic organisms which have become later adapted to the constraints linked to the functioning of oxygenic photosynthesis. This work is a step further in understanding the functioning and regulation of photosynthesis and gaining further control on plant yield.

Molecular structure of two enzymes, FBPase (left) and SBPase (right), of Physcomitrella. © University of Freiburg, Université de Lorraine, Oliver Einsle, Thomas Roret
Molecular structure of two enzymes, FBPase (left) and SBPase (right), of Physcomitrella © University of Freiburg, Université de Lorraine, Oliver Einsle, Thomas Roret

The results presented in this study have been obtained primarily during a cooperation between the Unité mixte de recherche Inra-Université de Lorraine « Interactions Arbres-Microorganismes » and the laboratories of Plant Biotechnology in the Biology Faculty, and Biochemistry in the Chemistry and Pharmacy Faculty of Freiburg University. Additional cooperation involved laboratories at Institut de Biologie Physico-chimique (IBPC) in Paris and the department of Plant and Microbial Biology from University of California at Berkeley.

This article corresponds largely to the doctoral work of Désirée Gütle in a co-tutelle between Nancy and Freiburg with help on the French side of a doctoral grant from MENRT and from Labex ARBRE and on the German side of funding from Excellence Initiative of the Bundes Republik Deutschland including the structures SGCBM, BIOSS, FRIAS from Freiburg and also from the Université franco-allemande on both sides.

Contact(s)
Scientific contact(s):

  • Jean-Pierre Jacquot (33 (0)6 80 72 40 29) Unité mixte de recherche Inra-Université de Lorraine « Interactions Arbres/micro-organismes »
Press Relations:
INRA News Office ( 33 (0)1 42 75 91 86 ), Fanny Lienhardt / Press relations Université de Lorraine (33 (0)6 75 04 85 65 )
Associated Division(s):
Forest, Grassland and Freshwater Ecology
Associated Centre(s):
Grand Est - Nancy

Reference

Desirée D. Gütle, Thomas Roret, Stefanie J. Mueller, Jérémy Couturier, Stéphane D. Lemaire, Arnaud Hecker, Tiphaine Dhalleine, Bob B. Buchanan, Ralf Reski, Oliver Einsle, Jean-Pierre Jacquot (2016): Chloroplast FBPase and SPBase are thioredoxin-linked enzymes with similar architecture but different evolutionary histories. Proceedings of the National Academy of Sciences (USA), DOI: 10.1073/pnas.1606241113.