Rangées de graines.. © INRA, Elena Schweitzer © Fotolia

Our results

Contents
  1. Introduction
  2. Human milk digestion in the preterm infant: impact of technological treatments
  3. Research & Innovation 2017 - For Food and Biobased Products
  4. The way in which proteins aggregate when heated may change their sensitising potency
  5. Enhancing the viability of spray-dried probiotic bacteria by stimulating their stress tolerance
  6. To stick or not to stick? Pulling pili sheds new light on biofilm formation
  7. When biopolymers selfassemble: a balance between energy and entropy.
  8. Mimicking the gastrointestinal digestion in a lab-on-a-chip:the microdigester
  9. How a milk droplet becomes a powder grain
  10. Research & Innovation 2016 - For Food and Bioproducts
  11. A new process for the biorefining of plants
  12. Under the UV light : the bacterial membrane
  13. Reverse engineering or how to rebuild ... bread!
  14. Green Chemistry: a step towards lipid production in yeast
  15. Individually designed neo-enzymes for antibacterial vaccines
  16. Multi-scale mechanical modelling: from the nanometric scale to the macroscopic properties of bread crumb
  17. Minimill: 500 g to assess the milling value of soft wheats
  18. Microbial production of lipids for energy or chemical purposes
  19. The discrete role of ferulic acid in the assembly of lignified cell wall
  20. Eco-design of composites made from wood co-products
  21. Analysis of volatile compounds enables the authentication of a poultry production system
  22. Nanoparticles as capping agents for biopolymers microscopy
  23. Pasteurisation, UHT, microfiltration...All the processes don't affect the nutritional quality of milk in the same way
  24. Integration of expert knowledge applied to cheese ripening
  25. Controlling cheese mass loss during ripening
  26. The shape memory of starch
  27. Research & Innovation 2015 - For Food & Biobased Products
  28. Behaviour of casein micelles during milk filtering operations
  29. Overaccumulation of lipids by the yeast S. cerevisiae for the production of biokerosine
  30. Sequential ventilation in cheese ripening rooms: 50% electrical energy savings
  31. An innovative process to extract bioactive compounds from wheat
  32. Diffusion weighted MRI: a generic tool for the microimaging of lipids in food matrices
  33. Characterization of a major gene of anthocyanin biosynthesis in grape berry
  34. New enzyme activity detectors made from semi-reflective biopolymer nanolayers
  35. Improving our knowledge about the structure of the casein micelle
  36. Heating milk seems to favour the development of allergy in infants
  37. Fun with Shape
  38. Using volatile metabolites in meat products to detect livestock contamination by environmental micropollutants
  39. SensinMouth, when taste makes sense
  40. A decision support system for the fresh fruit and vegetable chain based on a knowledge engineering approach
  41. SOLEIL casts light on the 3D structure of proteins responsible for the stabilisation of storage lipids in oilseed plants
  42. A close-up view of the multi-scale protein assembly process
  43. Controlling the drying of infant dairy products by taking water-constituent interactions into account
  44. Polysccharide nanocrystals to stabilise pickering emulsions
  45. Discovery of new degradative enzymes of plant polysaccharides in the human intestinal microbiome
  46. A durum wheat flour adapted for the production of traditional baguettes
  47. Virtual modelling to guide the construction of « tailored-made » enzymes
  48. How far can we reduce the salt content of cooked meat products?
  49. Diffusion of organic substances in polymer materials: beyond existing scaling laws
  50. Smart Foams : various ways to destroy foams on demand !
  51. Dates, rich in tannins and yet neither bitter nor astringent
  52. Sodium content reduction in food
  53. Research & Innovation 2014

SOLEIL casts light on the 3D structure of proteins responsible for the stabilisation of storage lipids in oilseed plants

Oil extraction from oleaginous plant seeds uses organic solvent and steam, which are damaging for environment and expensive. Within seeds cells, storage lipids are present in organelles called lipid bodies or oleosomes. At the water/oil interface one can find proteins that are oleosins and caleosin. These proteins stabilise lipid bodies but hamper efficient yield in oil extraction. To do so, these proteins have a hydrophilic surface toward water and an hydrophobic core toward oil.

Schéma de fonctionnement du synchrotron SOLEIL © J-F. Santarelli, Synchrotron SOLEIL

Understanding the structure of oleosins in oil bodies is a challenge within the agronomic and economic, as well as the medical context

In the current climate of the depletion of the earth's fossil fuel resources, rising oil prices and environmental protection, the recovery of energy from biomass oil and green chemistry has become increasingly important.  This requires the implementation of more effective and more environmentally-friendly oil extraction processes.  The aim of the French National Research Agency's (ANR) Chemistry for Sustainable Development SOPol programme is to increase our knowledge about the structure of proteins (oleosins) that stabilise fat bodies in the seeds of the major oilseed crops.
Moreover, the oleosins in peanuts are allergenic proteins.  In a broader sense, the fat bodies that are also present in mammals play an important role in highly prevalent diseases today such as obesity and diabetes.  

In order to understand the folding of these proteins we used beam light produced by the particles accelerator SOLEIL (Saint-Aubin, 91)

Circular dichroïsm experiments performed at SOLEIL allowed us to propose a model for the folding of the central domain of three of these proteins in agreement with a very hydrophobic domain.
After having produced S3 and S5 oleosins, as well as the caleosin of Arabidopsis thaliana recombinantly in Escherichia coli, different classes of surface-active agents were tested in order to maintain these proteins in an aqueous solution without denaturing them.  Only anionic detergents such as SDS (sodium dodecyl sulphate) and surface-active polymers known as amphipols (APols) proved capable of maintaining more than 60% of these proteins in solution after ultracentrifugation.  These are the surface-active agents used to maintain membrane proteins in their native form in aqueous solutions.   
Within the framework of a partnership with the SOLEIL synchrotron, we obtained circular dichroism spectra of proteins maintained in solution in SDS and APols. These data (Fig. 1A) allowed us to propose a model of oleosin and caleosin folding in an aqueous solution (Fig. 1B).  We thus hypothesize that the hydrophobic central part of these proteins consists primarily of beta-sheets.  The hydrophilic extremities would then have a secondary structure content that would change depending on the surface-active agent used.  The oleosins would therefore have a partially flexible structure.

  Figure 1 A Circular dichroism spectra by synchrotron radiation (SRCD). Caleosin (Clo) on the right and oleosin S3 (S3) on the left are maintained in aqueous solution by a detergent (SDS, in red) and different amphipols (A12-xxx), in blue.  Measurements are represented by points; adjustments that make it possible to determine the percentage of the secondary structure are represented by lines. Figure 1B: Folding models of these two proteins.  At the top, the breakdown of the primary sequence with the triblock distribution of amino acids: in blue, the hydrophilic extremities; in yellow, the hydrophobic central part.  At the bottom, the folding models proposed with beta-sheets in the form of arrows and alpha helixes in the form of cylinders.. © INRA
Figure 1 A Circular dichroism spectra by synchrotron radiation (SRCD). Caleosin (Clo) on the right and oleosin S3 (S3) on the left are maintained in aqueous solution by a detergent (SDS, in red) and different amphipols (A12-xxx), in blue. Measurements are represented by points; adjustments that make it possible to determine the percentage of the secondary structure are represented by lines. Figure 1B: Folding models of these two proteins. At the top, the breakdown of the primary sequence with the triblock distribution of amino acids: in blue, the hydrophilic extremities; in yellow, the hydrophobic central part. At the bottom, the folding models proposed with beta-sheets in the form of arrows and alpha helixes in the form of cylinders. © INRA

Parts whose secondary structure is undetermined are represented by a black line.  The size of structural elements is proportional to the quantity of the structure determined by SRCD

Our results show that oleosins can be maintained in solution by different surface-active agents and with a low level of dispersal.
Oleosins present secondary structures that are variable at the level of their hydrophilic extremities.  Even if amphipols are known for their ability to maintain membrane proteins in their native state, the following step consists of studying the secondary structure of these proteins in their native environment – lipid bodies. The vegetative yeasts designed should make it possible to overcome the technological obstacles in the way of obtaining a dichroic signal in a turbid environment consisting of aqueous solutions of lipid bodies.  Moreover, we now have access to tools that allow us to obtain data on three-dimensional structures, either by nuclear magnetic resonance or by x-ray crystallography of these purified proteins.
Understanding oleosins folding will allow breakthroughs in agronomic field but also in healthcare, some of these proteins being allergens. Moreover lipid bodies are also present in human blood. So, these structural data could help to better apprehend formation of certain diseases such as obesity and diabetes.

Partnership

Synchrotron SOLEIL (Saint-Aubin, 91)

Références

See also

  • Gohon, Y., Vindigni, JD., Pallier, A., Celia, H., Giuliani, A., Wien, F., Tribet, C., Chardot T., Pierre Briozzo, (2011)
  • "High water solubility and folding in amphipols of integral proteins with large hydrophobic regions: oleosin and caleosin from seed lipid bodies." BBA, 1088: 707-716
  • Popot, J.-L., Althoff, T., Bagnard, D., Banères, J.-L., Bazzacco, P., Billon-Denis, E., Catoire, L. J., Champeil, P., Charvolin, D.,
  • Cocco, M. J., Crémel, G., Dahmane, T., de la Maza, L. M., Ebel, C., Gabel, F., Giusti, F., Gohon, Y., Goormaghtigh, E.,
  • Guittet, E., Kleinschmidt, J. H., Kühlbrandt, W., Le Bon, C., Martinez, K. L., Picard, M., Pucci, B., Rappaport, F., Sachs, J. N.,
  • Tribet, C., van Heijenoort, C., Wien, F., Zito, F. & Zoonens, M. (2011). "Amphipols from A to Z." Annu. Rev. Biophys. 40, 379-408.