title: The intracellular fate of a recombinant protein is tissue dependent.
abstract: Recombinant proteins directed to the secretory pathway in plants require a signal peptide for entry into the endoplasmic reticulum. In the absence of further targeting information, such proteins are generally secreted via the default pathway to the apoplast. This has been well documented in protoplasts and leaf tissue, but the trafficking of recombinant proteins in seeds and other storage tissues has rarely been investigated. We used Aspergillus niger phytase as a model glycoprotein to compare the intracellular fate of a recombinant protein in the leaves and seeds of rice (Oryza sativa). Using fluorescence and electron microscopy we showed that the recombinant protein was efficiently secreted from leaf cells as expected. In contrast, within endosperm cells it was retained in endoplasmic reticulum-derived prolamin bodies and protein storage vacuoles. Consistent with our immunolocalization data, the phytase produced in endosperm cells possessed oligomannose and vacuolar-type N-glycans [Man(3)(Xyl)(Fuc)GlcNAc(2)], whereas the phytase produced in leaves contained predominantly secretion-type N-glycans [GlcNAc(2)Man(3)(Xyl)(Fuc)GlcNAc(2)]. The latter could not be detected in preparations of the endosperm-derived phytase. Our results show that the intracellular deposition and modification of a recombinant protein is tissue dependent.
authors.affiliation: Institute for Molecular Biotechnology, Biology VII, Aachen University, 52074 Aachen, Germany.
authors.forename: Georgia
authors.initials: G
authors.lastname: Drakakaki
authors.forename: Sylvain
authors.initials: S
authors.lastname: Marcel
authors.forename: Elsa
authors.initials: E
authors.lastname: Arcalis
authors.forename: Friedrich
authors.initials: F
authors.lastname: Altmann
authors.forename: Pablo
authors.initials: P
authors.lastname: Gonzalez-Melendi
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
authors.forename: Paul
authors.initials: P
authors.lastname: Christou
authors.forename: Eva
authors.initials: E
authors.lastname: Stoger
mesh_terms: D010832:6-Phytase / Q000737:chemistry / Q000235:genetics; D001483:Base Sequence; D017931:DNA Primers; D004721:Endoplasmic Reticulum / Q000378:metabolism; D017403:In Situ Hybridization; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008970:Molecular Weight; D012275:Oryza / Q000201:enzymology / Q000235:genetics; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism*; D012639:Seeds / Q000378:metabolism
chemical_list: D017931:DNA Primers; D010940:Plant Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D010832:6-Phytase