Van Heusden G P, Nebohâcovâ M, Overbeeke T L, Steensma H Y
Institute of Molecular Plant Sciences, Section Yeast Genetics, Leiden University, The Netherlands.
Yeast. 1998 Feb;14(3):225-32. doi: 10.1002/(SICI)1097-0061(199802)14:3<225::AID-YEA215>3.0.CO;2-#.
Escherichia coli cells with a disrupted diacylglycerol kinase gene are unable to grow on media containing arbutin due to a lethal accumulation of diacylglycerol. In order to isolate genes from the yeast Saccharomyces cerevisiae involved in diacylglycerol metabolism we complemented an E. coli diacylglycerol kinase disruptant with a yeast genomic library and transformants were selected capable of growing in the presence of arbutin. Using this method, a gene (TGL2) was isolated coding for a protein resembling lipases from Pseudomonas. After expression of the TGL2 gene in E. coli, lipolytic activity towards triacylglycerols and diacylglycerols with short-chain fatty acids could be measured. Therefore, it is very likely that the TGL2 gene can complement the E. coli diacylglycerol kinase disruptant, because it encodes a protein that degrades the diacylglycerol accumulated after growth in the presence of arbutin. Disruption of the TGL2 gene in S. cerevisiae did not result in a detectable phenotype. The role of the Tgl2 protein in lipid degradation in yeast is still unclear.
由于二酰基甘油的致死性积累,二酰基甘油激酶基因被破坏的大肠杆菌细胞无法在含有熊果苷的培养基上生长。为了从酿酒酵母中分离出参与二酰基甘油代谢的基因,我们用酵母基因组文库对大肠杆菌二酰基甘油激酶破坏株进行了互补,并筛选出了能够在熊果苷存在下生长的转化体。利用这种方法,分离出了一个基因(TGL2),其编码的蛋白质类似于假单胞菌的脂肪酶。在大肠杆菌中表达TGL2基因后,可以检测到对含短链脂肪酸的三酰基甘油和二酰基甘油的脂解活性。因此,TGL2基因很可能能够互补大肠杆菌二酰基甘油激酶破坏株,因为它编码一种蛋白质,该蛋白质可降解在熊果苷存在下生长后积累的二酰基甘油。酿酒酵母中TGL2基因的破坏并未导致可检测到的表型。Tgl2蛋白在酵母脂质降解中的作用仍不清楚。