title: The Induction of Recombinant Protein Bodies in Different Subcellular Compartments Reveals a Cryptic Plastid-Targeting Signal in the 27-kDa γ-Zein Sequence.
abstract: Naturally occurring storage proteins such as zeins are used as fusion partners for recombinant proteins because they induce the formation of ectopic storage organelles known as protein bodies (PBs) where the proteins are stabilized by intermolecular interactions and the formation of disulfide bonds. Endogenous PBs are derived from the endoplasmic reticulum (ER). Here, we have used different targeting sequences to determine whether ectopic PBs composed of the N-terminal portion of mature 27 kDa γ-zein added to a fluorescent protein could be induced to form elsewhere in the cell. The addition of a transit peptide for targeting to plastids causes PB formation in the stroma, whereas in the absence of any added targeting sequence PBs were typically associated with the plastid envelope, revealing the presence of a cryptic plastid-targeting signal within the γ-zein cysteine-rich domain. The subcellular localization of the PBs influences their morphology and the solubility of the stored recombinant fusion protein. Our results indicate that the biogenesis and budding of PBs does not require ER-specific factors and therefore, confirm that γ-zein is a versatile fusion partner for recombinant proteins offering unique opportunities for the accumulation and bioencapsulation of recombinant proteins in different subcellular compartments.
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences , Vienna , Austria.
authors.forename: Anna
authors.initials: A
authors.lastname: Hofbauer
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences , Vienna , Austria.
authors.forename: Jenny
authors.initials: J
authors.lastname: Peters
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences , Vienna , Austria.
authors.forename: Elsa
authors.initials: E
authors.lastname: Arcalis
authors.affiliation: Institute of Molecular Biotechnology, RWTH Aachen University , Aachen , Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rademacher
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences , Vienna , Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Lampel
authors.affiliation: Agriculture and Agri-Food Canada , Lethbridge, AB , Canada.
authors.forename: François
authors.initials: F
authors.lastname: Eudes
authors.affiliation: Institute of Agricultural Biology and Biotechnology, National Research Council (CNR) , Milan , Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vitale
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences , Vienna , Austria.
authors.forename: Eva
authors.initials: E
authors.lastname: Stoger
keywords: intermembrane space; molecular farming; plastid import; protein bodies; recombinant protein; subcellular targeting