Phospholipid:diacylglycerol acyltransferase:: An enzyme that catalyzes the acyl-CoA-independent formation of triacylglycerol in yeast and plants
Phospholipid:diacylglycerol acyltransferase:: An enzyme that catalyzes the acyl-CoA-independent formation of triacylglycerol in yeast and plants
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DOI：
10.1073/pnas.120067297
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发表时间：
2000-06-06
影响因子：
11.1
通讯作者：
Stymne, H
中科院分区：
文献类型：
--
作者：
Dahlqvist, A;St책hl, U;Stymne, H
已知三酰基甘油（TAG）在使用酰基-CoA作为酰基供体和二酰基甘油（DAG）作为受体的反应中合成，并且其由酶酰基-toA：二酰基甘油酰基转移酶催化。我们已经发现，一些植物和酵母也有一个酰基辅酶A-独立的TAG合成机制，它使用磷脂作为酰基供体和DAG作为受体。这种反应是由一种酶催化的，我们称之为磷脂：二酰基甘油酰基转移酶，或PDAT，PDAT的特点是在微粒体制剂从三种不同的油料种子：向日葵，蓖麻子，Crepis palaestina，我们发现，特异性的酶的酰基在磷脂中的这些物种之间的变化。因此，C. palaestina PDAT优先将vernoloyl基团并入TAG中，而来自蓖麻子的PDAT并入蓖麻油酰基和vernoloyl基团两者。进一步发现酵母微粒体中也存在PDAT活性，其底物特异性取决于酰基供体的头基、转移的酰基和受体DAG的酰基链。PDAT蛋白与卵磷脂：胆固醇酰基转移酶相关，后者催化胆固醇酯的酰基辅酶A非依赖性合成。然而，芽殖酵母PDAT及其在裂殖酵母和拟南芥中的近亲在该蛋白超家族中形成了一个独特的分支。这表明在进化的早期出现了一种单独的PDAT酶。
Triacylglycerol (TAG) is known to be synthesized in a reaction that uses acyl-CoA as acyl donor and diacylglycerol (DAG) as acceptor, and which is catalyzed by the enzyme acyl-toA:diacylglycerol acyltransferase. We have found that some plants and yeast also have an acyl-CoA-independent mechanism for TAG synthesis, which uses phospholipids as acyl donors and DAG as acceptor. This reaction is catalyzed by an enzyme that we call phospholipid:diacylglycerol acyltransferase, or PDAT, PDAT was characterized in microsomal preparations from three different oil seeds: sunflower, castor bean, and Crepis palaestina, We found that the specificity of the enzyme for the acyl group in the phospholipid varies between these species. Thus, C. palaestina PDAT preferentially incorporates vernoloyl groups into TAG, whereas PDAT from castor bean incorporates both ricinoleoyl and vernoloyl groups. We further found that PDAT activity also is present in yeast microsomes, The substrate specificity of this PDAT depends on the head group of the acyl donor, the acyl group transferred, and the acyl chains of the acceptor DAG, The gene encoding the enzyme was identified. The encoded PDAT protein is related to lecithin:cholesterol acyltransferase, which catalyzes the acyl-CoA-independent synthesis of cholesterol esters, However, budding yeast PDAT and its relatives in fission yeast and Arabidopsis form a distinct branch within this protein superfamily. indicating that a separate PDAT enzyme arose at an early point in evolution.