Proteomic characterisation of endoplasmic reticulum-derived protein bodies in tobacco leaves.

Background: The N-terminal proline-rich domain (Zera) of the maize storage protein γ-zein, is able to induce the formation of endoplasmic reticulum (ER)-derived protein bodies (PBs) when fused to proteins of interest. This encapsulation enables a recombinant fused protein to escape from degradation and facilitates its recovery from plant biomass by gradient purification. The aim of the present work was to evaluate if induced PBs encapsulate additional proteins jointly with the recombinant protein.

The expression of a xylanase targeted to ER-protein bodies provides a simple strategy to produce active insoluble enzyme polymers in tobacco plants.

Background: Xylanases deserve particular attention due to their potential application in the feed, pulp bleaching and paper industries. We have developed here an efficient system for the production of an active xylanase in tobacco plants fused to a proline-rich domain (Zera) of the maize storage protein γ-zein. Zera is a self-assembling domain able to form protein aggregates in vivo packed in newly formed endoplasmic reticulum-derived organelles known as protein bodies (PBs).

Protein body induction: a new tool to produce and recover recombinant proteins in plants.

Stable accumulation of storage proteins, lipids and carbohydrates is a hallmark of the plant seed, and is a characteristic that is typically deficient in existing platforms for recombinant protein manufacture. One of the biological sequestration mechanisms that facilitate the folding, assembly and stabilization of plant seed storage proteins involve the de novo formation of unique intracellular organelles, the endoplasmic reticulum (ER)-derived protein bodies (PBs). In cereals, such as maize, PBs are formed directly in the lumen of the ER of endosperm cells and contain zeins, a group of polypeptides, which account for more than half of the total seed protein mass.

Eukaryotic protein production in designed storage organelles.

Background: Protein bodies (PBs) are natural endoplasmic reticulum (ER) or vacuole plant-derived organelles that stably accumulate large amounts of storage proteins in seeds. The proline-rich N-terminal domain derived from the maize storage protein gamma zein (Zera) is sufficient to induce PBs in non-seed tissues of Arabidopsis and tobacco. This Zera property opens up new routes for high-level accumulation of recombinant proteins by fusion of Zera with proteins of interest.

The maize Dof protein PBF activates transcription of gamma-zein during maize seed development.

Maize PBF (prolamin-box binding factor) belongs to the Dof class of plant specific transcription factors containing one highly conserved zinc finger DNA-binding domain, called Dof (DNA binding with one finger) domain. Maize PBF trans-activates the gamma-zein gene (gammaZ) promoter in developing maize seeds as shown by transient expression in maize endosperms. Co-transfection of a gammaZ:GUS construct with 35S:PBF resulted in a sevenfold increase in GUS expression, however, PBF mutation in Cys residues within the Dof domain abolishes both, binding to DNA and the capacity to activate gammaZ promoter.

The fuc1 gene product (20 kDa FUC1) of Pisum sativum has no alpha-L-fucosidase activity.

An alpha-L-fucosidase purified from pea (Pisum sativum L. cv Alaska) epicotyl was previously described as a cell wall enzyme of 20 kDa that hydrolyses terminal alpha-L-fucosidic linkages from oligosaccharide fragments of xyloglucan. cDNA and genomic copies were further isolated and sequenced.