文蛤MmASS基因克隆及生物信息学分析

利用RACE技术克隆获得文蛤精氨酸琥珀酸合成酶基因(MmASS)的cDNA序列全长,该基因全长为1 588 bp,共编码415个氨基酸,分子量为46.81 kD,理论等电点pI为5.51。预测蛋白序列包含6个保守区域,主要集中了ATP结合位点、天门冬氨酸L-Asp结合位点以及瓜氨酸L-Cit结合位点。氨基酸序列比对结果显示,MmASS蛋白序列的保守功能域与其他物种具有较高的相似度,说明该基因高度保守,可能与其他物种的ASS基因具有相似的功能。系统进化树分析结果表明,MmASS的预测蛋白序列与缢蛏、贻贝、牡蛎等双壳贝类的亲缘关系最近,符合进化规律。亚细胞定位预测结果显示,MmASS定位于细胞质的可能性最大。MmASS不同组织的表达特征结果显示,该基因在各个组织中广泛存在,在文蛤鳃组织中的表达量最高(P<0.05),其次是肝胰腺组织,由此推测MmASS参与调节文蛤各个组织的生理活动,可能在文蛤的免疫防御机制中发挥重要功能。

Moleculor cloning and bioinformatics analysis of argininosuccinate synthetase in Meretrix meretrix

In this study, the complete cDNA sequence of argininosuccinate synthetasewas cloned in the saltwater clam Meretrix meretrixusing the rapid amplification of cDNA ends (RACE) approach. The complete MmASS cDNA measures 1588 bp in length with an open reading frame encoding 415 amino acids. The molecular weight of MmASSwas 46.81 kD and the theoretical isoelectric point was 5.51. The deduced MmASSprotein comprises six conserved sequences, containing the substrate-binding residues for ATP, aspartate and citrulline. The results of the multiple amino acid alignment and the phylogenetic analysis showed that MmASSexhibited high amino acid sequence identity with other species. MmASSalso had a close phylogenetic relationship with Sinonovacula constricta. Overall,similar functions might exist in M.meretrixand other species. Predicted subcellular localization suggested that MmASS is a cytosolic enzyme. The expression levels of MmASS were distributed in all of the examined tissues. MmASSwas most highly expressed in the gill (P<0.05), followed by the hepatopancreas. These results indicated that MmASSwas involved in various physiological activities of different tissues and may play an important role in the immune mechanisms.