曼氏无针乌贼(Sepiella maindroni)SCD基因全长cDNA的克隆和序列分析

CLONING AND ANALYSIS OF THE FULL-LENGTH cDNA SEQUENCE OF SEPIELLA MAINDRONI SCD GENE

硬脂酰辅酶A去饱和酶(SCD)是脂肪代谢的关键酶。本研究采用RT-PCR和RACE技术克隆了曼氏无针乌贼(Sepiella maindroni)SCDcDNA的全序列,序列全长1513bp,由261bp的5′非翻译区、编码306个氨基酸的921bp开放阅读框和331bp的3′非翻译区组成。在线翻译所得多肽理论分子量为34.92kDa,等电点为8.95,是疏水性蛋白,含有丰富的螺旋结构(45.10%),存在4个跨膜区。其氨基酸序列与真蛸(Octopus vulgaris)和长牡蛎(Crassostrea gigas)相似性达到91%,与其它非软体动物也表现为50%以上的相似性,说明SCD结构相对保守;系统进化树结果表明曼氏无针乌贼和真蛸及牡蛎进化关系最近,与鱼类稍远,与人及大鼠等哺乳动物亲缘关系最远。SCD基因是改善曼氏无针乌贼肉质的重要候选基因,其成功克隆及相关分析对于深入探讨软体动物脂肪酸代谢相关基因在生物体内作用机制及调控机理具有重要意义。

Strearyl coenzyme A desaturation enzyme is the key enzyme of fatty acid desaturation. In this paper, a 1513bp full-length cDNA of SCD gene from Sepiella maindroni was obtained with RT-PCR and rapid amplification of cDNA ends （RACE） techniques, which consisted of a 261bp 5＇untranslated region （UTR）, a 921bp open reading frame （ORF）, and a 349bp 3＇UTR. The molecular weight of deduced protein was 34.92kDa and its pI was 8.95. The SCD protein was hydrophobic protein and contained four transmembrane regions with rich spiral structures （45.10%）. The deduced amino acid sequence aligned with those of SCD genes from different species showed high degree of sequence homology. The similarity of amino acid sequence of SCD protein was 91% among S. maindroni, Octopus vulgaris and Crassostrea gigas, and the homology was also more than 50% between S. maindroni and other animals. The result indicated that the structure of SCD protein was conserved. The SCD in S. maindroni was clustered with O. vulgaris and C. gigas, and further grouped with fish, then fell into a neighboring branch with human, mouse and other mammals. The SCD gene was the main candidate gene for improving the meat quality of S. maindroni, and its cloning and related analysis were of great signifi-cance to explore mollusks fatty acidr metabolism related genes in the biological and regulation mechanisms.