title: Fold of an oleosin targeted to cellular oil bodies.
abstract: In cells, from bacteria to plants or mammals, lipids are stored in natural emulsions called oil bodies (OBs). This organelle is surrounded by a phospholipid monolayer which is thought to contain integral proteins involved in its stabilization. The insertion and fold of these proteins into the phospholipid monolayer are poorly understood. In seed OBs, the most abundant integral proteins are oleosins, which contain a 70-residue central hydrophobic domain. The secondary structure of solubilized oleosins varies greatly from mainly alpha helices to a predominantly beta sheets depending on the detergent used. To study the fold of integral membrane proteins inserted in a cellular OB environment, S3 protein, the major Arabidopsis thaliana seed oleosin, was targeted to Saccharomyces cerevisiae OBs. The diameter of purified yeast OBs harboring S3 or S3 fused with the Green Fluorescent Protein (GFP) was smaller and more homogeneous than plant OBs. Comparison of the secondary structure of S3 and S3-GFP was used to validate the structure of folded S3. Circular dichroism using synchrotron radiation indicated that S3 and S3-GFP in yeast OBs contain mainly beta secondary structures. While yeast OBs are chemically different to A. thaliana seed OBs, this approach allowed the secondary structure of S3 in OB particles to be determined for the first time.
authors.affiliation: INRA, UMR 1318 Institut Jean-Pierre Bourgin, Dynamics and Structure of Lipid Bodies, Versailles, France.
authors.forename: Jean-David
authors.initials: JD
authors.lastname: Vindigni
authors.forename: Frank
authors.initials: F
authors.lastname: Wien
authors.forename: Alexandre
authors.initials: A
authors.lastname: Giuliani
authors.forename: Zoi
authors.initials: Z
authors.lastname: Erpapazoglou
authors.forename: Roselyne
authors.initials: R
authors.lastname: Tache
authors.forename: Franjo
authors.initials: F
authors.lastname: Jagic
authors.forename: Thierry
authors.initials: T
authors.lastname: Chardot
authors.forename: Yann
authors.initials: Y
authors.lastname: Gohon
authors.forename: Marine
authors.initials: M
authors.lastname: Froissard
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D015151:Immunoblotting; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009821:Oils / Q000737:chemistry* / Q000378:metabolism; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D009821:Oils; D011993:Recombinant Fusion Proteins; C079353:oleosin protein, Arabidopsis; D010767:Phosphorylcholine; D049452:Green Fluorescent Proteins; C028810:dodecylphosphocholine