Elevating the lipid content in high-biomass forage crops has emerged as a new research platform for increasing energy density and improving livestock production efficiency associated with improved human health beneficial meat and milk quality. To gain insights of triacylglycerol (TAG) biosynthesis in forage sorghum, two type-1 diacylglycerol acyltransferase (designated as SbDGAT1-1 and SbDGAT1-2) were characterized for its in vivo function. SbDGAT1-2 is more abundantly expressed in embryo and bran during the early stage of the grain development in comparison to SbDGAT1-1. Heterologous expression of SbDGAT1 genes in TAG deficient H1246 strain restored the TAG accumulation capability with high substrate predilection towards 16:0, 16:1 and 18:1 fatty acids (FA). In parallel, we have identified N-terminal intrinsically disordered region (IDR) in SbDGAT1 proteins. To test the efficacy of the N-terminal region, truncated variants of SbDGAT1-1 (designated as SbDGAT1-1(39-515) and SbDGAT1-1(89-515)) were generated and expressed in yeast H1246 strain. Deletion in the N-terminal region resulted in decreased accumulation of TAG and FA (16:0 and 18:0) when compared to the SbDGAT1-1 variant expressed in yeast H1246 strain. The present study provides significant insight in forage sorghum DGAT1 gene function, useful for enhancing the green-forage TAG content through metabolic engineering.

中文翻译：

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来自高粱（Sorghum bicolor）胚胎的两个酰基辅酶A：二酰基甘油酰基转移酶1（DGAT1）基因的鉴定和功能表征

提高高生物量饲料作物中的脂质含量已成为一个新的研究平台，用于增加能量密度和提高牲畜生产效率，从而改善人类健康有益的肉类和牛奶质量。为了深入了解高粱中三酰甘油 (TAG) 的生物合成，对两种 1 型二酰甘油酰基转移酶（称为 SbDGAT1-1 和 SbDGAT1-2）的体内功能进行了表征。与 SbDGAT1-1 相比，SbDGAT1-2 在谷物发育的早期阶段在胚和麸中表达更丰富。SbDGAT1 基因在 TAG 缺陷 H1246 菌株中的异源表达恢复了 TAG 积累能力，对 16:0、16:1 和 18:1 脂肪酸 (FA) 的底物具有高偏好。在平行下，我们已经在 SbDGAT1 蛋白中鉴定了 N 端固有无序区域 (IDR)。为了测试 N 端区域的功效，在酵母 H1246 菌株中生成并表达了 SbDGAT1-1 的截短变体（指定为 SbDGAT1-1(39-515) 和 SbDGAT1-1(89-515)）。与酵母 H1246 菌株中表达的 SbDGAT1-1 变体相比，N 末端区域的缺失导致 TAG 和 FA（16:0 和 18:0）的积累减少。本研究提供了对饲草高粱 DGAT1 基因功能的重要见解，有助于通过代谢工程提高绿色饲草 TAG 含量。与酵母 H1246 菌株中表达的 SbDGAT1-1 变体相比，N 末端区域的缺失导致 TAG 和 FA（16:0 和 18:0）的积累减少。本研究提供了对饲草高粱 DGAT1 基因功能的重要见解，有助于通过代谢工程提高绿色饲草 TAG 含量。与酵母 H1246 菌株中表达的 SbDGAT1-1 变体相比，N 末端区域的缺失导致 TAG 和 FA（16:0 和 18:0）的积累减少。本研究提供了对饲草高粱 DGAT1 基因功能的重要见解，有助于通过代谢工程提高绿色饲草 TAG 含量。