title: Dual targeting of a mature plastoglobulin/fibrillin fusion protein to chloroplast plastoglobules and thylakoids in transplastomic tobacco plants.
abstract: Plastoglobules (PG) are lipid droplets in chloroplasts and other plastid types having important functions in lipid metabolism. Plastoglobulins (PGL) also known as fibrillins (FBN) are evolutionary conserved proteins present at the PG surface but also to various extents at the thylakoid membrane. PGLs are thought to have structural functions in PG formation and maintenance. The targeting of an Arabidopsis PGL (PGL34) to PG required the full protein sequence with the exception of a short C-terminal stretch. This indicated that PGL targeting relies on correct folding rather than a discrete sequence. PGLs lack strongly hydrophic regions and may therefore extrinsically associate with PG and thylakoid membranes via interaction with hydrophilic headgroups of surface lipids. Here, we report on the expression of the Arabidopsis plastoglobulin of 35kD (PGL35 or FBN1a) expressed as a mature protein fused to HIVp24 (human immunodeficiency virus capsid particle p24) or HCV (hepatitis C virus core protein) in transplastomic tobacco. A PGL35-HIVp24 fusion targeted in part to plastoglobules but a larger proportion was recovered in the thylakoid fraction. The findings indicate that transplastomic PGL35-HIVp24 folded correctly after its synthesis inside the chloroplast and then dually targeted to plastoglobules as well as thylakoid membranes.
authors.affiliation: Department of Plant Biology, University of Geneva, 30, Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Venkatasalam
authors.initials: V
authors.lastname: Shanmugabalaji
authors.forename: Céline
authors.initials: C
authors.lastname: Besagni
authors.forename: Lucia Eugeni
authors.initials: LE
authors.lastname: Piller
authors.forename: Veronique
authors.initials: V
authors.lastname: Douet
authors.forename: Stephanie
authors.initials: S
authors.lastname: Ruf
authors.forename: Ralph
authors.initials: R
authors.lastname: Bock
authors.forename: Felix
authors.initials: F
authors.lastname: Kessler
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism / Q000648:ultrastructure; D018745:Genome, Plant; D016655:HIV Core Protein p24 / Q000235:genetics / Q000378:metabolism; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism; D050356:Lipid Metabolism; D046529:Microscopy, Electron, Transmission; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism / Q000648:ultrastructure; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D014758:Viral Core Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D016655:HIV Core Protein p24; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014758:Viral Core Proteins; C514799:p24 protein, Human Immunodeficiency Virus Type 1