海湾扇贝组织蛋白酶L基因编码区的克隆和分析

Cloning and sequence analysis of cathepsin L gene from bay scallop Argopecten irradians

通过cDNA末端快速扩增技术(RACE),从海湾扇贝(Argopecten irradians)中克隆得到了组织蛋白酶L基因(AiCL)的编码区全长,为1 095 bp,推测编码364个氨基酸。经比对与分析发现蛋白序列中存在4个组织蛋白酶L活性位点保守氨基酸:Q164,C170,H309,N329;6个极为保守的半胱氨酸残基:C167,C201,C210,C243,C302,C351。预测其N端17个氨基酸为信号肽序列,C端ASYPTV可能也是分泌信号。AiCL成熟蛋白分子由219个氨基酸构成,前体肽的切割位点预计在A145和M146之间。序列同源性分析中,AiCL蛋白序列与软体动物同源蛋白最为相似,序列一致性在50%以上,在系统进化树中与其它无脊椎动物组织蛋白酶L聚合到一起。通过SWISS-MODEL构建的AiCL成熟蛋白三维模型表明该蛋白空间结构高度保守。根据其序列特征,推测AiCL可能具有水解多种肌蛋白的活性。

The complete open reading frame（ORF） of cathepsin L was obtained from bay scallop（Argopecten irradians） by RACE technique.The ORF was of 1 095 bp,encoding 364 amino acids.Four conserved residues for enzyme activity（Q164,C170,H309,N329） and six preserved cysteines were found in the protein sequence.17 amino acids of N terminal were predicted to be the signal peptide and the sequence ASYPTV at C terminal was found to be a possible signal sequence.The mature protein of AICL contained 219 amino acids and the potential cleavage site was between A145 and M146.Analysis indicated AiCL shared the highest identities（50%） with molluscan cathepsin Ls.It clustered with other invertebrate cathepsin Ls in the phylogenetic tree.The 3D-model predicted by SWISS-MODEL demonstrated that cathepsin L was conserved in tertiary structure.Collectively,data showed that AiCL was likely to catalyze the hydrolysis of multiple muscle related proteins.