The structure and dynamics of the plant endoplasmic reticulum - WCUB, ENWW

The endoplasmic reticulum (ER) acts as a subcellular \superhighway" that connects membrane compartments [1]. The ER connects to the plasma membrane (PM) at stable ER-PM contact sites (EPCSs) [2] [3] which have been implicated in lipid transport, infection response and may act as \organizational hubs" for the cytoskeleton (reviewed in [4]). Two components of the plant EPCSs have been identified: NET3C, an actin binding protein which connects EPCSs to the actin cytoskeleton, and VAP27 a member of the vesicle-associated membrane protein (VAMP)-associated protein (VAP) family [5]. The role of these EPCS components in controlling ER structure will be assessed using dominant-negative mutants and over-expression mutants, and the effect on ER dynamics analysed using novel ER network analysis software. Using a novel molecular toolbox it is now possible to transiently modify ER structure. The ER is composed of two morphologically distinct domains { sheets and tubules, that are joined at three-way junctions (reviewed in [6]). These structures are present in different relative proportions in different cell types depending on the cells secretory requirements [7]. Transient over-expression of Arabidopsis thaliana reticulon proteins has been shown to induce tubular structures within the ER [8, 9], whilst transient over-expression of the A. thaliana Lunapark proteins induces sheet-like structures. Changes to ER dynamics caused by over-expression of these proteins will be analysed using the aforementioned software and with single-particle tracking technology. The movement of the ER is controlled by the underlying actin cytoskeleton [10]. As such the dynamics and structure of the actin cytoskeleton will be analysed in modified ER and EPCS backgrounds compared to wild-types.