The Role of Lipid Phosphatase Sac1 in the Organization of the Cortical/Tubular Endoplasmic Reticulum in Yeast
EMSL Project ID
39971
Abstract
The endoplasmic reticulum (ER) is a continuous membrane system but consists of various domains that perform different functions. Distinct ER regions are composed of sheets and tubules, which differ in their characteristic membrane curvature. The physiological significance of tubulated ER membranes is unknown. Key proteins involved in tubule architecture have been identified but the factors required for regulation of tubule dynamics and for assembly into an interconnected network remain largely undiscovered. Our recent work showed that the lipid phosphatase Sac1 is highly enriched at cortical ER tubules in yeast. Sac1 plays a well-characterized role in coordinating cell growth and Golgi traffic but its function in the ER has not been resolved. Our preliminary work now indicates that Sac1 may be an important regulator of ER tubule dynamics and organization. Our current analysis of cortical ER organization is handicapped by the resolution limit of conventional microscopy, which cannot sufficiently resolve localization patterns of individual proteins at tubular ER structures. This proposal aims at characterizing the cortical/tubular ER network in yeast cells using super-resolution photo-activated localization microscopy (PALM). To this end we will use a collection of yeast strains co-expressing fluorescently-tagged proteins at the tubular ER. We will also analyze the tubular ER in mutants lacking Sac1 or the known factors involved in tubular ER structure. The planned experiments will address whether the shape of the cortical ER responds to environmental stimuli such as changes in nutrient levels and whether this control involves lipid phosphatase Sac1. In addition, we will probe structural changes in Sac1 that may trigger partitioning of this enzyme in tubular membranes using FRET. The high-resolution techniques available at EMSL will be of paramount importance to elucidate the role of Sac1 in organizing the intricate structure of the tubular ER network.
Project Details
Project type
Exploratory Research
Start Date
2010-09-29
End Date
2011-10-03
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members