Arroyo-Caro José María, Chileh Tarik, Alonso Diego López, García-Maroto Federico
Centro de Investigación en Biotecnología Agroalimentaria, Universidad de Almería, Campus de Excelencia Internacional Agroalimentario (CeiA3), CITE-II B, Almería, Spain.
Lipids. 2013 Jul;48(7):663-74. doi: 10.1007/s11745-013-3797-z. Epub 2013 May 23.
Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT, EC 2.3.1.23) catalyzes acylation of lysophosphatidylcholine (lysoPtdCho) to produce phosphatidylcholine (PtdCho), the main phospholipid in cellular membranes. This reaction is a key component of the acyl-editing process, involving recycling of the fatty acids (FA) mainly at the sn-2 position of PtdCho. Growing evidences indicate that the LPCAT reaction controls the direct entry of newly synthesized FA into PtdCho and, at least in some plant species, it has an important impact on the synthesis and composition of triacylglycerols. Here we describe the molecular characterization of the single LPCAT gene found in the genome of Ricinus communis (RcLPCAT) that is homologous to LPCAT genes of the MBOAT family previously described in Arabidopsis and Brassica. RcLPCAT is ubiquitously expressed in all organs of the castor plant. Biochemical properties have been studied by heterologous expression of RcLPCAT in the ale1 yeast mutant, defective in lysophospholipid acyltransferase activity. RcLPCAT preferentially acylates lysoPtdCho against other lysophospholipids (lysoPL) and does not discriminates the acyl chain in the acceptor, displaying a strong activity with alkyl lysoPL. Regarding the acyl-CoA donor, RcLPCAT uses monounsaturated fatty acid thioesters, such as oleoyl-CoA (18:1-CoA), as preferred donors, while it has a low activity with saturated fatty acids and shows a poor utilization of ricinoleoyl-CoA (18:1-OH-CoA). These characteristics are discussed in terms of a possible role of RcLPCAT in regulating the entry of FA into PtdCho and the exclusion from the membranes of the hydroxylated FA.
酰基辅酶A：溶血磷脂酰胆碱酰基转移酶（LPCAT，EC 2.3.1.23）催化溶血磷脂酰胆碱（lysoPtdCho）的酰化反应，生成磷脂酰胆碱（PtdCho），即细胞膜中的主要磷脂。该反应是酰基编辑过程的关键组成部分，主要涉及脂肪酸（FA）在PtdCho的sn-2位上的循环利用。越来越多的证据表明，LPCAT反应控制新合成的FA直接进入PtdCho，并且至少在某些植物物种中，它对三酰甘油的合成和组成具有重要影响。在这里，我们描述了在蓖麻基因组中发现的单个LPCAT基因（RcLPCAT）的分子特征，该基因与先前在拟南芥和油菜中描述的MBOAT家族的LPCAT基因同源。RcLPCAT在蓖麻植株的所有器官中普遍表达。通过在缺乏溶血磷脂酰转移酶活性的ale1酵母突变体中异源表达RcLPCAT来研究其生化特性。与其他溶血磷脂（lysoPL）相比，RcLPCAT优先酰化lysoPtdCho，并且在受体中不区分酰基链，对烷基lysoPL表现出很强的活性。关于酰基辅酶A供体，RcLPCAT使用单不饱和脂肪酸硫酯，如油酰辅酶A（18:1-CoA）作为首选供体，而它对饱和脂肪酸的活性较低，对蓖麻油酸辅酶A（18:1-OH-CoA）的利用率较差。本文根据RcLPCAT在调节FA进入PtdCho以及将羟基化FA排除在膜外的可能作用对这些特性进行了讨论。
