Delivering of proteins to the plant vacuole--an update.

Cláudia Pereira,Susana Pereira,José Pissarra

doi:10.3390/ijms15057611

Cláudia Pereira, Susana Pereira + Show 1 more

Open Access

https://doi.org/10.3390/ijms15057611

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Abstract

Trafficking of soluble cargo to the vacuole is far from being a closed issue as it can occur by different routes and involve different intermediates. The textbook view of proteins being sorted at the post-Golgi level to the lytic vacuole via the pre-vacuole or to the protein storage vacuole mediated by dense vesicles is now challenged as novel routes are being disclosed and vacuoles with intermediate characteristics described. The identification of Vacuolar Sorting Determinants is a key signature to understand protein trafficking to the vacuole. Despite the long established vacuolar signals, some others have been described in the last few years, with different properties that can be specific for some cells or some types of vacuoles. There are also reports of proteins having two different vacuolar signals and their significance is questionable: a way to increase the efficiency of the sorting or different sorting depending on the protein roles in a specific context? Along came the idea of differential vacuolar sorting, suggesting a possible specialization of the trafficking pathways according to the type of cell and specific needs. In this review, we show the recent advances in the field and focus on different aspects of protein trafficking to the vacuoles.

Highlights

Plants play an important role in the world economy as they represent the major source of food, and of textiles, building materials, bio-fuels and medicinal products
It was observed that the same protein can be either secreted to the apoplast or directed to the vacuole, or accumulate in protein storage vacuoles (PSVs) or lytic vacuoles (LV) traveling though different routes, depending on the cell type and developmental stage suggesting a tight mechanism of regulation of trafficking
Because of the variety in plant models, cell types and experimental approaches used to decipher vacuolar targeting processes, protein trafficking to the vacuole is far from being a closed issue

Summary

Introduction

Plants play an important role in the world economy as they represent the major source of food, and of textiles, building materials, bio-fuels and medicinal products. Identifying the molecules (proteins and enzymes), their biogenesis and their functions is fundamental to understand their role in plant cell homeostasis and to develop rational crop improvement strategies. The plant cell is effectively an integrated community of membrane-delimited compartments, each of which has evolved to optimize and separate specific biochemical functions. Functional organization of the endomembranes is a key cellular infrastructure allowing the cell the continuous adaptation needed for the metabolic and structural changes occurring in vegetative and reproductive tissues. The major production line of the cell biosynthetic factory is made by distinct organelles constitutive of the cell secretory pathway: Endoplasmic Reticulum, Golgi Apparatus, Endosomes, Pre-vacuolar and Vacuolar compartments. The specificities of plant endomembrane biology, notably the Endoplasmic Reticulum-Golgi complex or the endosomal and vacuolar organization, outline the amazing ability of plant cells to re-organize its membrane system according to the cell needs. Any protein trafficking within the endomembrane system is orchestrated by all the events, permitting to reach the right compartment, by the right route, at the right time

Plant Vacuoles

Routes to the Vacuole

Sorting Signals

A Role for Glycosylation

Specialization of Vacuolar Trafficking Pathways

Conclusions