title: High water solubility and fold in amphipols of proteins with large hydrophobic regions: oleosins and caleosin from seed lipid bodies.
abstract: Seed lipid bodies constitute natural emulsions stabilized by specialized integral membrane proteins, among which the most abundant are oleosins, followed by the calcium binding caleosin. These proteins exhibit a triblock structure, with a highly hydrophobic central region comprising up to 71 residues. Little is known on their three-dimensional structure. Here we report the solubilization of caleosin and of two oleosins in aqueous solution, using various detergents or original amphiphilic polymers, amphipols. All three proteins, insoluble in water buffers, were maintained soluble either by anionic detergents or amphipols. Neutral detergents were ineffective. In complex with amphipols the oleosins and caleosin contain more beta and less alpha secondary structures than in the SDS detergent, as evaluated by synchrotron radiation circular dichroism. These are the first reported structural results on lipid bodies proteins maintained in solution with amphipols, a promising alternative to notoriously denaturing detergents.
authors.affiliation: INRA, AgroParisTech, UMR 1318 Institut Jean-Pierre Bourgin, Dynamic and Structure of Lipid Bodies, F-78850 Thiverval Grignon, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Gohon
authors.forename: Jean-David
authors.initials: JD
authors.lastname: Vindigni
authors.forename: Agnès
authors.initials: A
authors.lastname: Pallier
authors.forename: Frank
authors.initials: F
authors.lastname: Wien
authors.forename: Hervé
authors.initials: H
authors.lastname: Celia
authors.forename: Alexandre
authors.initials: A
authors.lastname: Giuliani
authors.forename: Christophe
authors.initials: C
authors.lastname: Tribet
authors.forename: Thierry
authors.initials: T
authors.lastname: Chardot
authors.forename: Pierre
authors.initials: P
authors.lastname: Briozzo
mesh_terms: D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D002942:Circular Dichroism; D057927:Hydrophobic and Hydrophilic Interactions; D008055:Lipids / Q000032:analysis*; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012639:Seeds / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry*
chemical_list: D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; D008055:Lipids; D010940:Plant Proteins; D011108:Polymers; C402836:caleosin protein, Sesamum indicum; C079353:oleosin protein, Arabidopsis; D014867:Water