Current Progress in Tonoplast Proteomics Reveals Insights into the Function of the Large Central Vacuole

Abstract

Vacuoles of plants fulfill various biologically important functions, like turgor generation and maintenance, detoxification, solute sequestration, or protein storage. Different types of plant vacuoles (lytic versus protein storage) are characterized by different functional properties apparently caused by a different composition/abundance and regulation of transport proteins in the surrounding membrane, the tonoplast. Proteome analyses allow the identification of vacuolar proteins and provide an informative basis for assigning observed transport processes to specific carriers or channels. This review summarizes techniques required for vacuolar proteome analyses, like e.g., isolation of the large central vacuole or tonoplast membrane purification. Moreover, an overview about diverse published vacuolar proteome studies is provided. It becomes evident that qualitative proteomes from different plant species represent just the tip of the iceberg. During the past few years, mass spectrometry achieved immense improvement concerning its accuracy, sensitivity, and application. As a consequence, modern tonoplast proteome approaches are suited for detecting alterations in membrane protein abundance in response to changing environmental/physiological conditions and help to clarify the regulation of tonoplast transport processes.

Membrane Transporters in Citrus clementina Fruit Juice-Derived Nanovesicles

“…In fact, tonoplast has been shown to be highly enriched in V-ATPases. Proteomics revealed the presence of prominent V-type ATPase subunits in tonoplast vesicle preparations [20]. One reasonable explanation of the high expression of V-ATPases in our C. clementina juice sac cells-derived vesicle sample, therefore, could be the presence of tonoplast vesicles.…”

Molecular Composition of Plant Vacuoles: Important but Less Understood Regulations and Roles of Tonoplast Lipids

“…Some vacuolar transporters and channels have been characterized and their regulation of transport across tonoplast has been discussed [ 2 , 31 , 32 , 33 ]. In order to identify tonoplast proteins profiles, proteomic analysis of tonoplast preparations from different cell types has been carried out and has revealed similar groups of proteins such as vacuolar ATPases, transporters and proteins involved in membrane fusion [ 24 , 34 , 35 , 36 , 37 , 38 , 39 ]. However, nearly 50% of proteins identified from each of these experiments were unidentified in others.…”

Identification of Chloroplast Envelope Proteins with Critical Importance for Cold Acclimation

“…It is important to mention that the label-free approach has its specific limitations. However, these limitations can be minimized using more biological replicates and extensive statistical analyses (Trentmann and Haferkamp, 2013).…”