A Yeast Strain Lacking Lipid Particles Bears a Defect in Ergosterol Formation

摘要: Lipid particles of the yeast Saccharomyces cerevisiae are storage compartments for triacylglycerols (TAG) and steryl esters (STE). Four gene products, namely TAG synthases Dga1p Lro1p, STE Are1p Are2p contribute to lipid synthesis. A strain lacking four respective genes is devoid thus providing a valuable tool study physiological role lipids particles. Using dga1lro1are1are2 quadruple mutant transformed with plasmids bearing inducible DGA1, LRO1, or ARE2 we demonstrate that synthesis contributes more efficiently particle proliferation than STE. Moreover, show proteins typically located in wild type such as Erg1p, Erg6p, Erg7p, Ayr1p refined microsomal fractions mutant. This result confirms close relationship between endoplasmic reticulum. Most interestingly, amount squalene epoxidase which dually reticulum type, decreased mutant, whereas amounts other tested were not reduced. decrease caused by down-regulation ERG1 transcription but low stability Erg1p Because similar effect was also observed are1are2 mutants this finding can be mainly attributed lack The however, sensitive terbinafine, an inhibitor suggesting presence and/or intact has additional protective effect. In two synthases, Are2p, incorporation ergosterol into plasma membrane reduced, although total cellular free higher type. Thus, esterification/deacylation mechanism appears supply membrane.