Solene Moulin

All Publications

• What do photosynthetic organisms need to thrive in all circumstances? The Plant cell Moulin, S. 2023

  View details for DOI 10.1093/plcell/koad213

  View details for PubMedID 37536272

• The way out: TPT3 allows triose-P export from the chloroplast. The Plant cell Moulin, S. 2023

  View details for DOI 10.1093/plcell/koad106

  View details for PubMedID 37052933

• The endosymbiont of Epithemia clementina is specialized for nitrogen fixation within a photosynthetic eukaryote. bioRxiv : the preprint server for biology Moulin, S. L., Frail, S., Doenier, J., Braukmann, T., Yeh, E. 2023

  Abstract

  Epithemia spp. diatoms contain obligate, nitrogen-fixing endosymbionts, or "diazoplasts", derived from cyanobacteria. These algae are a rare example of photosynthetic eukaryotes that have successfully coupled oxygenic photosynthesis with oxygen-sensitive nitrogenase activity. Here, we report a newly-isolated species, E. clementina , as a model to investigate endosymbiotic acquisition of nitrogen fixation. To detect the metabolic changes associated with endosymbiotic specialization, we compared nitrogen fixation, associated carbon and nitrogen metabolism, and their regulatory pathways in the Epithemia diazoplast with its close, free-living cyanobacterial relative, Crocosphaera subtropica . Unlike C. subtropica , we show that nitrogenase activity in the diazoplast is concurrent with, and even dependent on, host photosynthesis and no longer associated with cyanobacterial glycogen storage suggesting carbohydrates are imported from the host diatom. Carbohydrate catabolism in the diazoplast indicates that the oxidative pentose pathway and oxidative phosphorylation, in concert, generates reducing equivalents and ATP and consumes oxygen to support nitrogenase activity. In contrast to expanded nitrogenase activity, the diazoplast has diminished ability to utilize alternative nitrogen sources. Upon ammonium repletion, negative feedback regulation of nitrogen fixation was conserved, however ammonia assimilation showed paradoxical responses in the diazoplast compared with C. subtropica . The altered nitrogen regulation likely favors nitrogen transfer to the host. Our results suggest that the diazoplast is specialized for endosymbiotic nitrogen fixation. Altogether, we establish a new model for studying endosymbiosis, perform the first functional characterization of this diazotroph endosymbiosis, and identify metabolic adaptations for endosymbiotic acquisition of a critical biological function.

  View details for DOI 10.1101/2023.03.08.531752

  View details for PubMedID 37066385

• Crop plants move up a gear: Switching for a faster Rubisco in tobacco. The Plant cell Moulin, S. 2022

  View details for DOI 10.1093/plcell/koac355

  View details for PubMedID 36502854

• From the archives: Oxidative stress tolerance in Chlamydomonas and herbicide resistance in the weedy species Eleusine indica. The Plant cell Moulin, S. 2022

  View details for DOI 10.1093/plcell/koac356

  View details for PubMedID 36478194

• Get connected to the fungal network for improved transfer of nitrogen: the role of ZmAMT3;1 in ammonium transport in maize-arbuscular mycorrhizal symbiosis. The Plant cell Moulin, S. 2022

  View details for DOI 10.1093/plcell/koac221

  View details for PubMedID 35929506

• The big guy keeps the gate: The largest chloroplast-encoded protein, Orf2971, serves for translocation and quality control of chloroplast-imported proteins. The Plant cell Moulin, S. L. 2022

  View details for DOI 10.1093/plcell/koac181

  View details for PubMedID 35762462

• With a little help from my friends: mitochondria maintain redox balance for the endoplasmic reticulum. The Plant cell Moulin, S. L. 2022

  View details for DOI 10.1093/plcell/koac018

  View details for PubMedID 35234937

• Fatty acid photodecarboxylase is an ancient photoenzyme that forms hydrocarbons in the thylakoids of algae. Plant physiology Moulin, S. L., Beyly-Adriano, A. n., Cuiné, S. n., Blangy, S. n., Légeret, B. n., Floriani, M. n., Burlacot, A. n., Sorigué, D. n., Samire, P. P., Li-Beisson, Y. n., Peltier, G. n., Beisson, F. n. 2021

  Abstract

  Fatty acid photodecarboxylase (FAP) is one of the few enzymes that require light for their catalytic cycle (photoenzymes). FAP was first identified in the microalga Chlorella variabilis NC64A, and belongs to an algae-specific subgroup of the glucose-methanol-choline oxidoreductase family. While the FAP from C. variabilis and its Chlamydomonas reinhardtii homolog CrFAP have demonstrated in vitro activities, their activities and physiological functions have not been studied in vivo. Furthermore, the conservation of FAP activity beyond green microalgae remains hypothetical. Here, using a C. reinhardtii FAP knockout line (fap), we showed that CrFAP is responsible for the formation of 7-heptadecene, the only hydrocarbon of this alga. We further showed that CrFAP was predominantly membrane-associated and that >90% of 7-heptadecene was recovered in the thylakoid fraction. In the fap mutant, photosynthetic activity was not affected under standard growth conditions, but was reduced after cold acclimation when light intensity varied. A phylogenetic analysis that included sequences from Tara Ocean identified almost 200 putative FAPs and indicated that FAP was acquired early after primary endosymbiosis. Within Bikonta, FAP was retained in secondary photosynthetic endosymbiosis lineages but absent from those that lost the plastid. Characterization of recombinant FAPs from various algal genera (Nannochloropsis, Ectocarpus, Galdieria, Chondrus) provided experimental evidence that FAP photochemical activity was present in red and brown algae, and was not limited to unicellular species. These results thus indicate that FAP was conserved during the evolution of most algal lineages where photosynthesis was retained, and suggest that its function is linked to photosynthetic membranes.

  View details for DOI 10.1093/plphys/kiab168

  View details for PubMedID 33856460

• Mechanism and dynamics of fatty acid photodecarboxylase. Science (New York, N.Y.) Sorigué, D. n., Hadjidemetriou, K. n., Blangy, S. n., Gotthard, G. n., Bonvalet, A. n., Coquelle, N. n., Samire, P. n., Aleksandrov, A. n., Antonucci, L. n., Benachir, A. n., Boutet, S. n., Byrdin, M. n., Cammarata, M. n., Carbajo, S. n., Cuiné, S. n., Doak, R. B., Foucar, L. n., Gorel, A. n., Grünbein, M. n., Hartmann, E. n., Hienerwadel, R. n., Hilpert, M. n., Kloos, M. n., Lane, T. J., Légeret, B. n., Legrand, P. n., Li-Beisson, Y. n., Moulin, S. L., Nurizzo, D. n., Peltier, G. n., Schirò, G. n., Shoeman, R. L., Sliwa, M. n., Solinas, X. n., Zhuang, B. n., Barends, T. R., Colletier, J. P., Joffre, M. n., Royant, A. n., Berthomieu, C. n., Weik, M. n., Domratcheva, T. n., Brettel, K. n., Vos, M. H., Schlichting, I. n., Arnoux, P. n., Müller, P. n., Beisson, F. n. 2021; 372 (6538)

  Abstract

  Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.

  View details for DOI 10.1126/science.abd5687

  View details for PubMedID 33833098

• Continuous photoproduction of hydrocarbon drop-in fuel by microbial cell factories SCIENTIFIC REPORTS Moulin, S., Legeret, B., Blangy, S., Sorigue, D., Burlacot, A., Auroy, P., Li-Beisson, Y., Peltier, G., Beisson, F. 2019; 9: 13713

  Abstract

  Use of microbes to produce liquid transportation fuels is not yet economically viable. A key point to reduce production costs is the design a cell factory that combines the continuous production of drop-in fuel molecules with the ability to recover products from the cell culture at low cost. Medium-chain hydrocarbons seem ideal targets because they can be produced from abundant fatty acids and, due to their volatility, can be easily collected in gas phase. However, pathways used to produce hydrocarbons from fatty acids require two steps, low efficient enzymes and/or complex electron donors. Recently, a new hydrocarbon-forming route involving a single enzyme called fatty acid photodecarboxylase (FAP) was discovered in microalgae. Here, we show that in illuminated E. coli cultures coexpression of FAP and a medium-chain fatty acid thioesterase results in continuous release of volatile hydrocarbons. Maximum hydrocarbon productivity was reached under low/medium light while higher irradiance resulted in decreased amounts of FAP. It was also found that the production rate of hydrocarbons was constant for at least 5 days and that 30% of total hydrocarbons could be collected in the gas phase of the culture. This work thus demonstrates that the photochemistry of the FAP can be harnessed to design a simple cell factory that continuously produces hydrocarbons easy to recover and in pure form.

  View details for DOI 10.1038/s41598-019-50261-6

  View details for Web of Science ID 000487217200006

  View details for PubMedID 31548626

  View details for PubMedCentralID PMC6757031

• An algal photoenzyme converts fatty acids to hydrocarbons SCIENCE Sorigue, D., Legeret, B., Cuine, S., Blangy, S., Moulin, S., Billon, E., Richaud, P., Brugiere, S., Coute, Y., Nurizzo, D., Mueller, P., Brettel, K., Pignol, D., Arnoux, P., Li-Beisson, Y., Peltier, G., Beisson, F. 2017; 357 (6354): 903–7

  Abstract

  Although many organisms capture or respond to sunlight, few enzymes are known to be driven by light. Among these are DNA photolyases and the photosynthetic reaction centers. Here, we show that the microalga Chlorella variabilis NC64A harbors a photoenzyme that acts in lipid metabolism. This enzyme belongs to an algae-specific clade of the glucose-methanol-choline oxidoreductase family and catalyzes the decarboxylation of free fatty acids to n-alkanes or -alkenes in response to blue light. Crystal structure of the protein reveals a fatty acid-binding site in a hydrophobic tunnel leading to the light-capturing flavin adenine dinucleotide (FAD) cofactor. The decarboxylation is initiated through electron abstraction from the fatty acid by the photoexcited FAD with a quantum yield >80%. This photoenzyme, which we name fatty acid photodecarboxylase, may be useful in light-driven, bio-based production of hydrocarbons.

  View details for DOI 10.1126/science.aan6349

  View details for Web of Science ID 000408734900039

  View details for PubMedID 28860382

• A Selaginella moellendorffii Ortholog of KARRIKIN INSENSITIVE2 Functions in Arabidopsis Development but Cannot Mediate Responses to Karrikins or Strigolactones PLANT CELL Waters, M. T., Scaffidi, A., Moulin, S. Y., Sun, Y. K., Flematti, G. R., Smith, S. M. 2015; 27 (7): 1925–44

  Abstract

  In Arabidopsis thaliana, the α/β-fold hydrolase KARRIKIN INSENSITIVE2 (KAI2) is essential for normal seed germination, seedling development, and leaf morphogenesis, as well as for responses to karrikins. KAI2 is a paralog of DWARF14 (D14), the proposed strigolactone receptor, but the evolutionary timing of functional divergence between the KAI2 and D14 clades has not been established. By swapping gene promoters, we show that Arabidopsis KAI2 and D14 proteins are functionally distinct. We show that the catalytic serine of KAI2 is essential for function in plants and for biochemical activity in vitro. We identified two KAI2 homologs from Selaginella moellendorffii and two from Marchantia polymorpha. One from each species could hydrolyze the strigolactone analog GR24 in vitro, but when tested for their ability to complement Arabidopsis d14 and kai2 mutants, neither of these homologs was effective. However, the second KAI2 homolog from S. moellendorffii was able to complement the seedling and leaf development phenotypes of Arabidopsis kai2. This homolog could not transduce signals from exogenous karrikins, strigolactone analogs, or carlactone, but its activity did depend on the conserved catalytic serine. We conclude that KAI2, and most likely the endogenous signal to which it responds, has been conserved since the divergence of lycophytes and angiosperm lineages, despite their major developmental and morphogenic differences.

  View details for DOI 10.1105/tpc.15.00146

  View details for Web of Science ID 000359358600012

  View details for PubMedID 26175507

  View details for PubMedCentralID PMC4531350