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Les oléosines, de nouveaux émulsifiants d'origine végétale. Comparaison des globules lipidiques extraits de végétaux (A. thaliana) et de levures (Y. lipolytica)

Abstract : Plants submitted to desiccation store lipids in bodies of spherical shapes: oleosoms.
These are composed of a core of triacylglycerols surrounded by a single layer of
phospholipids (PLs) in which are embedded proteins of low molecular weight, mostly
oleosins. These proteins comprise three domains: amphiphilic N- and C- terminal and an
hydrophobic central domain of 72 amino acids very well conserved. Oleosins have a
structural role. Due to their presence, oleosoms do not coalesce even during seed reimbibition
upon germination. Although yeasts have storage organits similar to those of plants,
the protein pattern is very different. We cloned and expressed two isoforms of Arabidopsis
thaliana oleosins in E. coli and Yarrowia lipolytica. Oleosins expressed in yeasts are
addressed to the oil bodies. Furthermore oleosins expressed in bacteria were purified under
denaturing conditions. By experimental and model studies, we postulate an α-helix
organisation of the central domain. Surface tension studies showed that purified recombined
oleosins were inserted at water / oil interfaces and decrease efficiently the interfacial tension
(better than β-casein). They were also inserted in PLs monolayer on water / air interface.
Therefore, plant oleosins have properties of an oil / water emulsifier.
Keywords: oleosin, Arabidopsis thaliana, Yarrowia lipolytica, oil body, emulsifier.
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Submitted on : Monday, November 29, 2004 - 4:55:25 PM
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  • HAL Id : tel-00007548, version 1
  • PRODINRA : 330889

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Emeline Roux. Les oléosines, de nouveaux émulsifiants d'origine végétale. Comparaison des globules lipidiques extraits de végétaux (A. thaliana) et de levures (Y. lipolytica). Biologie végétale. Institut national agronomique paris-grignon - INA P-G, 2003. Français. ⟨tel-00007548⟩

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