绿潮浒苔具有广泛底物特异性的二酰基甘油酰基转移酶1的功能研究

三酰基甘油(甘油三酯)是生物体内主要的碳和能量储存形式，也是细胞膜和信号分子的重要组成部分，它们在多种生理过程和环境胁迫响应中发挥重要作用。酰基辅酶A:二酰基甘油酰基转移酶(DGAT)催化真核生物甘油三酯合成途径中最后一步和唯一的酰基化步骤。本研究从绿潮浒苔中鉴定并获得了一个新的二酰基甘油酰基转移酶UpDGAT1基因，并在酿酒酵母甘油三酯缺失合成四重突变体中通过异源表达验证了该基因的功能。薄层色谱和BODIPY染色结果表明，浒苔UpDGAT1基因能够恢复酵母中甘油三酯的合成和脂质体的形成。酵母细胞的脂肪酸组成分析显示，浒苔UpDGAT1具有广泛的底物特异性，可接受饱和、单不饱和和多不饱和酰基辅酶A作为底物。高盐度和高温胁迫增加了浒苔UpDGAT1基因的表达和浒苔甘油三酯的积累。本研究为进一步解析UpDGAT1在浒苔甘油三酯积累和胁迫响应中的作用提供了基础。

Characterization of a broad substrates specificity acyl-CoA: diacylglycerol acyltransferase 1 from the green tide alga Ulva prolifera

Triacylglycerols (triglycerides, TAGs) are the major carbon and energy storage forms in various organisms, and important components of cellular membranes and signaling molecules; they have essential functions in multiple physiological processes and stress regulation. Acyl-CoA: diacylglycerol acyltransferase (DGAT) catalyzes the final and only committed acylation step in the synthesis of TAGs in eukaryotes. The present work identified and isolated a novel gene, UpDGAT1, from the green tide alga Ulva prolifera. The activity of UpDGAT1 was confirmed by heterologous expression in a Saccharomyces cerevisiae TAG-deficient quadruple mutant. Results of thin-layer chromatography and BODIPY staining indicated that UpDGAT1 was able to restore TAG synthesis and lipid body formation in the yeast. Lipid analysis of yeast cells revealed that UpDGAT1 showed broad substrate specificity, accepting saturated as well as mono- and polyunsaturated acyl-CoAs as substrates. High salinity and high temperature stresses increased UpDGAT1 expression and TAG accumulation in U. prolifera. The present study provides clues to the functions of UpDGAT1 in TAG accumulation in, and stress adaptation of, U. prolifera.