Regulation of the Yeast Triacylglycerol Lipase Tgl3p by Formation of Nonpolar Lipids

Abstract

Background: Tgl3p from yeast serves as the major triacylglycerol lipase but also as lysophospholipid acyltransferase. Results: Formation of nonpolar lipids strongly affects subcellular localization and function of Tgl3p. Conclusion: Tgl3p activity is mainly regulated by the presence/absence of lipid droplets. Significance: The yeast lipase/acyltransferase Tgl3p is an important player in lipid homeostasis.

Modifications of the C terminus Affect Functionality and Stability of Yeast Triacylglycerol Lipase Tgl3p

“…This situation is unique insofar as, despite correct targeting, the lipase activity of this Tgl3p variant was severely compromised. Comparable results were obtained previously in our laboratory by Schmidt et al (17) who showed that Tgl3p mutants inactivated by site-directed mutagenesis in the GXSXG motif targeted normally to lipid droplets. Thus, it appears that activity of Tgl3p is not required for correct targeting.…”

“…In a previous study from our laboratory Schmidt et al (17) showed that the half-life of Tgl3p is dramatically reduced when the protein was located to the ER. Experiments described in the present study enabled us to explain this effect at the molecular level.…”

“…5C). (17) showed that a small portion of Tgl3p is found in the ER of wild type cells. In the absence of LD, i.e.…”

“…Thus, our knowledge of targeting and anchoring of proteins to LD is still limited. Interestingly, several LD proteins including Tgl3p show a dual localization in LD and in the ER (15)(16)(17). This is surprising on one hand, because these proteins have to assemble in two different membrane environments, namely a phospholipid monolayer in LD and a phospholipid bilayer in the ER.…”

Screening for Hydrolytic Enzymes Reveals Ayr1p as a Novel Triacylglycerol Lipase in Saccharomyces cerevisiae

“…Regulatory mechanisms governing localization and function of proteins in different compartments have to be taken into account. One recent example for such aspects is the stability, gene expression, and localization of Tgl3p, depending on the availability and the presence of its substrate TG (52).…”