Functional Characterization of Lysophosphatidylcholine: Acyl-CoA Acyltransferase Genes From Sunflower (Helianthus annuus L.)
Functional Characterization of Lysophosphatidylcholine: Acyl-CoA Acyltransferase Genes From Sunflower (Helianthus annuus L.)
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DOI：
10.3389/fpls.2020.00403
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发表时间：
2020-04-15
影响因子：
5.6
通讯作者：
Venegas-Caleron, Monica
中科院分区：
文献类型：
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作者：
Mapelli-Brahm, Ana;Sanchez, Rosario;Venegas-Caleron, Monica
溶血磷脂酰胆碱酰基转移酶（LPCAT，EC 2.3.1.23）是Lands循环中进化上保守的关键酶，其催化溶血磷脂酰胆碱（LPC）的酰化以产生磷脂酰胆碱（PC），磷脂酰胆碱是细胞膜中的主要磷脂。在这项研究中，三个LPCAT基因从向日葵进行了鉴定和相应的蛋白质特征。这些HaLPCAT基因编码的功能活性酶能够补充缺陷的酵母突变体。此外，使用酵母细胞的微粒体制备物进行酶测定。当在正向反应中测量酰基特异性时，这些酶表现出对不饱和酰基-CoA的底物偏好，尤其是对亚麻酰-CoA，而在反向反应中，亚油酰或亚麻酰酰基从PC转移到酰基-CoA，达到类似的程度。研究了LPCAT基因的表达水平，揭示了不同的组织特异性表达模式。总之，本研究表明，向日葵LPCAT催化的组合正向和反向反应促进PC的sn-2位和酰基辅酶A池之间的酰基交换。向日葵的LPCAT表现出不同的特征，这可能指向不同的功能，有利于富集种子三酰甘油（TAG）与多不饱和脂肪酸（PUFA）。
Lysophosphatidylcholine acyltransferase (LPCAT, EC 2.3.1.23) is an evolutionarily conserved key enzyme in the Lands cycle that catalyzes acylation of lysophosphatidylcholine (LPC) to produce phosphatidylcholine (PC), the main phospholipid in cellular membranes. In this study, three LPCAT genes from sunflower were identified and the corresponding proteins characterized. These HaLPCAT genes encoded functionally active enzymes that were able to complement a deficient yeast mutant. Moreover, enzymatic assays were carried out using microsomal preparations of the yeast cells. When acyl specificities were measured in the forward reaction, these enzymes exhibited a substrate preference for unsaturated acyl-CoAs, especially for linolenoyl-CoA, while in the reverse reaction, linoleoyl or linolenoyl acyl groups were transferred from PC to acyl-CoA to a similar extent. Expression levels of LPCAT genes were studied revealing distinct tissue-specific expression patterns. In summary, this study suggests that the combined forward and reverse reactions catalyzed by sunflower LPCATs facilitate acyl-exchange between the sn-2 position of PC and the acyl-CoA pool. Sunflower LPCATs displayed different characteristics, which could point to different functionalities, favoring the enrichment of seed triacylglycerols (TAGs) with polyunsaturated fatty acid (PUFA).