Deposition of foreign proteins in plant vacuoles: a unique characteristic of Plant Based Platforms

PETRUCCELLI, SILVANA*

Advances in Medicine and Biology

Nova Publishers

Año: 2019; p. 215 - 262

The global demand for biological andindustrial enzymes is growing driven by the increasing world population and theexpansion of their biotechnological applications. To be active and soluble,many of these proteins require post-translational modifications that aretypical of the secretory pathway. Accordingly, in most expression systems,these proteins are introduced in the endomembrane system and finish their wayin the extracellular space. However, vacuolar deposition is an alternativefinal destination in plant cells. Compartments specialized in the storage ofenormous amounts of proteins are unique in plant cells. Many heterologousproteins sorted to vacuoles accumulate at high yields in leaves and othervegetative tissue, among them, human glucocerebrosidase, collagen,transglutaminase, complement factor C5a as well as cell wall degrading enzymesand avidin. To reach vacuoles, the foreign proteins must be fused to a plantvacuolar sorting signals (VSS). In seeds, proteins are stored within theProtein Storage Vacuoles (PSV) or inside the ER-derived Protein Bodies (PB).Secretory heterologous proteins accumulate in PSV or PB even when they lack intheir sequences a plant VSS. This unexpected localization of secretory proteinsin seed storage compartments is frequently observed in reproductive tissues.Plant cells differ from other eukaryotic cells in that they have severalvacuolar trafficking routes: proteins travel to the vacuoles following theclassic route through the Golgi apparatus, or alternative they go directly fromthe ER to the vacuole avoiding Golgi. The trafficking path and finalsubcellular destination are essential for foreign protein activity andstability. In fact, several plant-based-platforms (PBPs) benefit of vacuolardeposition to increase protein yields. This chapter focuses on examples inwhich foreign protein accumulation in vacuoles proved to be a fruitfulproduction strategy