Abstract: Black porgy (Acanthopagrus schlegelii) is a marine economic fish with strong resistance to stress. However, it is impossible to overwinter outdoors in the north of Yangtze River, and it is time-consuming and labor-intensive to overwinter indoors every year. The structure and function of  the protein encoded by fatty acid elongase (ELO) gene of A. schlegelii were studied in order to cultivate the strain of A. schlegelii with low temperature tolerance and explore its molecular mechanism. Firstly, the ELO amino acids of five kinds of fish, such as A. schlegelii, Sparus aurata, Siniperca chuatsi, Epinephelus coioides, Cyprinus carpio, were sequenced by DNAman 8 software, and their homology and evolutionary relationship were analyzed. Then, the physicochemical properties, subcellular localization, signal peptide, transmembrane region, splicing site, protein phosphorylation, glycosylation, secondary structure, domain, molecular function and protein interaction of ELO protein of A. schlegelii were analyzed by bioinformatics tools, and homologous modeling and three-dimensional structure prediction were carried out. The results of amino acid sequence alignment showed that the sequence homology between A. schlegelii and other fishes was high. Among the five fishes analyzed, A. schlegelii had the closest genetic relationship with Sparus aurata and the farthest genetic relationship with Cyprinidae fishes. Bioinformatics analysis showed that ELO protein was a basic, small molecule, stable and non-secretory hydrophilic protein, and subcellular localization was in cytoplasm, nucleus and mitochondria. There were 22 splicing sites, 19 phosphorylation sites and 9 lysine saccharification sites in the protein, but there were no glycosylation sites and signal peptides. It contained a variety of secondary structures, among which α-helix was the main one, with one domain and seven transmembrane regions; ELO protein may have direct interaction with other 10 protein, which may affect estrogen synthesis. Through bioinformatics analysis of the structure and function of the protein encoded by ELO gene of A. schlegelii, it was preliminarily determined that it was related to low temperature tolerance. The research results provided a basic theoretical basis for breeding low-temperature resistant strains of A. schlegelii.

Key words: Acanthopagrus schlegelii, fatty acid elongase (ELO) gene, bioinformatics

摘要： 黑鲷是一种抗逆性强的海水经济鱼类，但在长江以北无法在室外自然越冬，每年进行室内越冬又耗时耗力。为了培育黑鲷耐低温品系，探究黑鲷低温耐受的分子机制，研究了黑鲷脂肪酸延长酶（fatty acid elongase，ELO）基因编码蛋白的结构和功能。首先，运用DNAman 8软件对黑鲷、金头鲷、鱖鱼、斜带石斑鱼、鲤鱼等5种鱼类的ELO蛋白进行氨基酸序列比对，分析其同源性和进化关系；随后，利用生物信息学工具对黑鲷ELO蛋白的理化性质、亚细胞定位、信号肽、跨膜区、剪切位点、蛋白磷酸化、糖基化、二级结构、结构域、分子功能及蛋白质相互作用等进行分析，并进行同源建模与三维结构预测。氨基酸序列比对结果显示，黑鲷与其他鱼类之间序列的同源性较高，在所分析的5种鱼类中，黑鲷与金头鲷亲缘关系最近，与鲤科鱼类亲缘关系最远。生物信息学分析结果表明，ELO蛋白为碱性、小分子、稳定、非分泌型亲水蛋白质，亚细胞定位于细胞质、细胞核和线粒体；该蛋白质中存在22个剪切位点、19个磷酸化位点和 9个赖氨酸糖化作用位点，没有糖基化位点和信号肽；其包含多种二级结构，其中以α-螺旋为主，存在1个结构域及7个跨膜区域；ELO蛋白与其他10个蛋白质可能存在直接的相互作用关系，有可能影响雌激素合成。通过对黑鲷ELO基因编码蛋白结构与功能的生物信息学分析，初步判定其与低温耐受相关。研究结果为黑鲷耐低温品系选育提供了基础理论依据。

关键词: 黑鲷, 脂肪酸延长酶基因, 生物信息学