Selvaraju Kandasamy, Rajakumar Selvaraj, Nachiappan Vasanthi
Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620024, Tamilnadu, India.
Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620024, Tamilnadu, India.
Biochim Biophys Acta. 2014 Oct;1842(10):1383-92. doi: 10.1016/j.bbalip.2014.06.013. Epub 2014 Jul 8.
Phospholipids also play a major role in maintaining the lipid droplet (LD) morphology. In our current study, deletion of LPL1 resulted in altered morphology of LDs and was confirmed by microscopic analysis. LPL1/YOR059c contains lipase specific motif GXSXG and acetate labeling in the LPL1 overexpressed strains depicted a decrease in glycerophospholipids and an increase in free fatty acids. The purified Lpl1p showed phospholipase activity with broader substrate specificity, acting on all glycerophospholipids primarily at sn-2 position and later at sn-1 position. Localization studies precisely revealed that Lpl1 is exclusively localized in the LD at the stationary phase. Site directed mutagenesis experiments clearly demonstrated that the lipase motif is vital for the phospholipase activity. In summary, our results demonstrate that yeast Lpl1 exerts phospholipase activity, plays a vital role in LD morphology, and its absence results in altered LD size. Based on the localization and enzyme activity we renamed YOR059c as LPL1 (LD phospholipase 1).
磷脂在维持脂滴（LD）形态方面也起着重要作用。在我们目前的研究中，LPL1的缺失导致了脂滴形态的改变，这通过显微镜分析得到了证实。LPL1/YOR059c包含脂肪酶特异性基序GXSXG，在LPL1过表达菌株中的乙酸盐标记显示甘油磷脂减少，游离脂肪酸增加。纯化的Lpl1p表现出具有更广泛底物特异性的磷脂酶活性，主要作用于所有甘油磷脂的sn-2位，随后作用于sn-1位。定位研究精确地揭示Lpl1仅在稳定期定位于脂滴。定点诱变实验清楚地表明脂肪酶基序对磷脂酶活性至关重要。总之，我们的结果表明酵母Lpl1发挥磷脂酶活性，在脂滴形态中起重要作用，其缺失会导致脂滴大小改变。基于其定位和酶活性，我们将YOR059c重新命名为LPL1（脂滴磷脂酶1）。
