title: Regulation of the yeast triacylglycerol lipases Tgl4p and Tgl5p by the presence/absence of nonpolar lipids.
abstract: Tgl3p, Tgl4p, and Tgl5p are the major triacylglycerol lipases of the yeast Saccharomyces cerevisiae Recently we demonstrated that properties of Tgl3p are regulated by the formation of nonpolar lipids. The present study extends these investigations to the two other yeast triacylglycerol lipases, Tgl4p and Tgl5p. We show that Tgl4p and Tgl5p, which are localized to lipid droplets in wild type, are partially retained in the endoplasmic reticulum in cells lacking triacylglycerols and localize exclusively to the endoplasmic reticulum in a mutant devoid of lipid droplets. In cells lacking steryl esters, the subcellular distribution of Tgl4p and Tgl5p is unaffected, but Tgl5p becomes unstable, whereas the stability of Tgl4p increases. In cells lacking nonpolar lipids, Tgl4p and Tgl5p lose their lipolytic activity but retain their side activity as lysophospholipid acyltransferases. To investigate the regulatory network of yeast triacylglycerol lipases in more detail, we also examined properties of Tgl3p, Tgl4p, and Tgl5p, respectively, in the absence of the other lipases. Surprisingly, lack of two lipases did not affect expression, localization, and stability of the remaining Tgl protein. These results suggest that Tgl3p, Tgl4p, and Tgl5p, although they exhibit similar functions, act as independent entities.
authors.affiliation: Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria.
authors.forename: Isabella
authors.initials: I
authors.lastname: Klein
authors.affiliation: Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria.
authors.forename: Lisa
authors.initials: L
authors.lastname: Klug
authors.affiliation: Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Schmidt
authors.affiliation: Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria.
authors.forename: Martina
authors.initials: M
authors.lastname: Zandl
authors.affiliation: Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria.
authors.forename: Martina
authors.initials: M
authors.lastname: Korber
authors.affiliation: Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria karin.athenstaedt@tugraz.at guenther.daum@tugraz.at.
authors.forename: Günther
authors.initials: G
authors.lastname: Daum
authors.affiliation: Institute of Biochemistry, Graz University of Technology, A-8010 Graz, Austria karin.athenstaedt@tugraz.at guenther.daum@tugraz.at.
authors.forename: Karin
authors.initials: K
authors.lastname: Athenstaedt
mesh_terms: D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D066292:Lipid Droplets / Q000378:metabolism; D050356:Lipid Metabolism; D008055:Lipids / Q000502:physiology; D008066:Lipolysis; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D008055:Lipids; D029701:Saccharomyces cerevisiae Proteins; D014280:Triglycerides; D008243:1-Acylglycerophosphocholine O-Acyltransferase; D008049:Lipase; C506904:Tgl4 protein, S cerevisiae; C506905:Tgl5 protein, S cerevisiae