Key Laboratory of Applied Marine Biotechnology, Department of Marine Sciences, Ningbo University, Ministry of Education of China, Ningbo, Zhejiang315211, People's Republic of China.
Collaborative Innovation Center for Zhejiang Marine High-efficiency and Healthy Aquaculture, Ningbo University, Ningbo, Zhejiang315211, People's Republic of China.
Br J Nutr. 2020 Nov 14;124(9):881-889. doi: 10.1017/S0007114520002068. Epub 2020 Jun 10.
The razor clam, Sinonovacula constricta, contains high levels of long-chain PUFA (LC-PUFA), which are critical for human health. In addition, S. constricta is the first marine mollusc demonstrated to possess Δ6 fatty acyl desaturase (Fad) and complete LC-PUFA biosynthetic ability, providing a good representative to investigate the molecular mechanism of sterol regulatory element binding proteins (SREBP) in regulating Δ6 Fad for LC-PUFA biosynthesis in marine molluscs. Herein, S. constricta SREBP and Δ6 Fad promoter were cloned and characterised. Subsequently, dual luciferase and electrophoretic mobility shift assays were conducted to explore the SREBP binding elements in the core regulatory region of S. constricta Δ6 Fad promoter. Results showed that S. constricta SREBP had a very conservative basic helix-loop-helix-leucine zipper motif, while S. constricta Δ6 Fad promoter exhibited very poor identity with teleost Fads2 promoters, indicating their differentiation during evolution. A 454 bp region harbouring a core sequence in S. constricta Δ6 Fad promoter was predicted to be essential for the transcriptional activation by SREBP. This was the first report on the regulatory mechanism of LC-PUFA biosynthesis in marine molluscs, which would facilitate optimising the LC-PUFA biosynthetic pathway of bivalves in further studies.
刀蛏含有高水平的长链多不饱和脂肪酸（LC-PUFA），这些脂肪酸对人类健康至关重要。此外，刀蛏是第一个被证明具有Δ6 脂肪酸去饱和酶（Fad）和完整 LC-PUFA 生物合成能力的海洋软体动物，为研究甾醇调节元件结合蛋白（SREBP）在调节海洋软体动物 LC-PUFA 生物合成中Δ6 Fad 的分子机制提供了一个很好的代表。本文克隆并鉴定了刀蛏 SREBP 和 Δ6 Fad 启动子。随后，进行了双荧光素酶和电泳迁移率变动分析，以探讨刀蛏 Δ6 Fad 启动子核心调控区中 SREBP 的结合元件。结果表明，刀蛏 SREBP 具有非常保守的基本螺旋-环-螺旋-亮氨酸拉链基序，而刀蛏 Δ6 Fad 启动子与硬骨鱼 Fads2 启动子的同源性很差，表明它们在进化过程中发生了分化。预测刀蛏 Δ6 Fad 启动子中含有一个 454bp 的核心序列区域，对于 SREBP 的转录激活是必需的。这是首次报道海洋软体动物 LC-PUFA 生物合成的调控机制，这将有助于在进一步的研究中优化双壳类动物的 LC-PUFA 生物合成途径。
