Sidorov Roman, Kazakov Giorgi, Kotsuba Vasily, Tyurina Tatiana
K. A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow 127276, Russia.
Federal Research Center "Fundamentals of Biotechnology", Russian Academy of Sciences, Leninsky Prospect, 33, Build. 2, Moscow 119334, Russia.
Plants (Basel). 2025 Feb 18;14(4):612. doi: 10.3390/plants14040612.
This article represents the first consideration of the peculiarities of the fatty acid (FAs) composition and structure of storage triacylglycerols (TAGs) of the relict plant L. The composition of storage TAGs was found to comprise 21 individual FAs, with an unsaturated FA content of 96.8%. Additionally, monounsaturated acids with a very long chain (VLCFAs), specifically C20:1-C24:1, constituted over 60% of the total FAs. The ethylene bond position isomers of unsaturated FAs were accurately identified and the presence of unusual isomers, including 20:1Δ13, 22:1Δ15, and 24:1Δ17 acids. Furthermore, the unusual minor 24:2Δ15,18 acid was identified and characterised for the first time. The pathways of the mentioned VLCFA's biosynthesis have been proposed. The distribution of FA acyls between the positions of triacylglycerols was found to be highly specific. Thus, VLCFAs exclusively acylate the α positions of the carbon atoms of the glycerol residue of the TAG molecule (-1 and -3 positions), while unsaturated C18 acids exclusively acylate the β-carbon atom (-2 position). The composition of the molecular species of TAGs was analysed using a calculation method based on the Vander Wal model and by RP-HPLC-ESI-MS. A significant discrepancy from the statistical model was observed, indicating a preference for the formation of symmetrical TAGs, such as -1,3-dierucoyl-2-oleoyl-glycerol and related molecular species. This observation led to the formulation of a hypothesis regarding the potential existence of at least two specialised enzyme isoforms involved in the biosynthesis of such TAGs via the Kennedy pathway, exhibiting unusual substrate specificity. Consequently, this plant can be regarded not only as a producer of unusual molecular types of triacylglycerols but also as a source of genetic material for the search of genes encoding the aforementioned enzymes with unusual substrate specificity.
本文首次探讨了残遗植物L储存三酰甘油(TAGs)的脂肪酸(FAs)组成和结构特点。研究发现,储存TAGs的组成包含21种单个脂肪酸,不饱和脂肪酸含量为96.8%。此外,具有超长链(VLCFAs)的单不饱和酸,特别是C20:1 - C24:1,占总脂肪酸的60%以上。准确鉴定了不饱和脂肪酸的乙烯键位置异构体,包括不寻常的异构体,如20:1Δ13、22:1Δ15和24:1Δ17酸。此外,首次鉴定并表征了不寻常的微量24:2Δ15,18酸。提出了上述超长链脂肪酸生物合成的途径。发现脂肪酸酰基在三酰甘油的位置之间的分布具有高度特异性。因此,超长链脂肪酸专门酰化TAG分子甘油残基碳原子的α位(-1和-3位),而不饱和C18酸专门酰化β碳原子(-2位)。使用基于范德瓦尔模型的计算方法以及反相高效液相色谱-电喷雾电离质谱(RP-HPLC-ESI-MS)分析了TAGs分子种类的组成。观察到与统计模型存在显著差异,表明倾向于形成对称的TAGs,如-1,3-二芥酰基-2-油酰基甘油及相关分子种类。这一观察结果导致提出一个假设,即通过肯尼迪途径参与此类TAGs生物合成的至少存在两种具有不寻常底物特异性的专门酶异构体。因此,这种植物不仅可被视为不寻常分子类型三酰甘油的生产者,还可作为寻找编码上述具有不寻常底物特异性酶的基因的遗传物质来源。
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