Endomembrane System

Overview

Overview

Degradation of plasma membrane proteins, ESCRT, Ubiquitin, Intracellular transport of proteins

Leader: Mag. Dr. Barbara Korbei

Orientation

Endosomal vesicular transport is of central importance in many vital aspects in higher plant cells. Although these pathways are quite well defined on a molecular level in yeast and animal cells, only recently the focus has shifted to plants, with a special emphasis on plant-specific trafficking routes and unique functions of molecular players in the plant endosomal trafficking system.

This research project aims to increase the understanding of the endosomal trafficking in the model plant Arabidopsis thaliana by examining the potential role of the nine different plant specific VHS-GAT domain proteins in post-Golgi vesicular transport. VHS-GAT domain proteins are present in all eukaryotic kingdoms. In higher plants, there is one highly extended family of VHS-GAT domain proteins - the TOL proteins. We have recently managed to show, that TOL protein substitute for the missing ESCRT-0 proteins (VHS-GAT domain subfamily in yeast and mammals), acting as principal gating factors for recognition of ubiquitinated cargo at the plasma membrane. Yet, while some TOL proteins function analogous to the ESCRT-0, others might perform diverse functions characteristic for other VHS-GAT domain proteins, or even plant-specific unique functions. 

Specifically, the proposed work should clarify aspects of endosomal trafficking in plants that require TOLs and also how this involvement is achieved. To this end we will characterize TOL interacting proteins in order to identify pathways and signaling events modulated by TOLs. Furthermore, structural and functional analysis of conserved TOL protein domains should result in insights into redundant and unique functions of the different TOLs. Finally we intend to address the dynamics of TOL expression and localization in response to diverse intrinsic and environmental stimuli.

The outcome of this project will provide us with novel insights into the different roles of TOL proteins in vesicular trafficking in Arabidopsis thaliana and therefore into membrane protein trafficking and sorting pathways in higher plants at a molecular level. Furthermore it should represent the cornerstone for further studies, addressing the control of protein trafficking in the endosomal system of higher plants.

Figure: Vacuolar Degradation of a Plasma Membrane Protein.  PIN2p::PIN2:VENUS (green) in root tips (left)

Figure: Vacuolar Degradation of a Plasma Membrane Protein. PIN2p::PIN2:VENUS (green) in root tips (left)

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Funding Agencies