生物信息学分析亚洲牛带绦虫乳酸脱氢酶基因及其蛋白的结构与特性

目的分析和预测亚洲牛带绦虫(Taeniasaginata asiatica,Ta)乳酸脱氢酶(lactate dehydrogenase,LDH)基因及其编码蛋白的结构和特性,以指导其生物学功能的实验研究。方法利用生物信息网站如美国国家生物技术信息中心(NC-BI,http://www.ncbi.nlm.nih.gov/)和瑞士生物信息学研究所的蛋白分析专家系统(ExPASY,http://ca.expasy.org/)中有关基因和蛋白序列、结构信息分析的各种工具,结合其它生物信息学分析软件包,如DNAman和Vector NTI suite,从亚洲牛带绦虫全长cDNA质粒文库中识别乳酸脱氢酶(TaLDH)基因及其编码区,分析、预测该基因编码的蛋白质的理化特性、抗原表位、翻译后的修饰位点、功能域、亚细胞定位、拓扑结构、二级结构、三维空间构象,酶的活性中心在拓扑结构和空间构象中的位置分布等。结果该基因全长1285bp,编码区为92bp-1084bp,编码331个氨基酸,其推导氨基酸序列与其它物种乳酸脱氢酶氨基酸序列一致性达50%左右,具有乳酸脱氢酶保守结构域。其编码的蛋白相对分子量理论预测值和等电点分别是35268.9Da和8.03。其编码的蛋白有3个跨膜区、没有其它亚细胞定位序列。α螺旋(H)、β折叠(E)和无规卷曲(L)的比例分别是36.56:22.96:40.48,L-乳酸脱氢酶活化位点,位于189-195aa,TaLDH氨基酸序列中有16个潜在抗原表位,酶催化位点的关键氨基酸在不同物种中保守,在空间结构中3个关键氨基酸相互靠近。结论应用生物信息方法从亚洲牛带绦虫成虫cDNA文库中筛选出了TaLDH的cDNA全长序列并预测得到其结构与功能方面的信息。

Bioinformatics analysis on the structures and properties of gene and the encoding protein of lactate dehydrogenase from Taeniasaginata asiatica

To analyze and predict the structure and properties of gene and the encoding protein of lactate dehydrogenase.(LDH) from Taeniasaginata asiatuca(TaLDH),the full-length cDNA encoding TaLDH was identified from the cDNA plasmid library by Blast X and rpsblast programs provided by NCBI The physico-chemical properties,modification sites after translation,subcellular location,topological structure,secondary and 3D structures of Ta LDH were analyzed by tools provided by ExPaSy,and the potential epitopes of Ta LDH were predicted by the software of DNAman.It was demonstrated that the amino acid sequence translated from the cDNA sequence had identity with that of TaLDH from other species.There was a conserved LDH-domain in the deduced amino acid sequence.The full-length cDNA sequence encoding TaLDH included a complete open reading frame(ORF) of 1285 bp coding to a putative protein with 331 amino acids with a coding region of 92-1084 bp.Molecular weight of Ta LDH was predicted to be 35268.9 Da and its isoelectric point was 8.03.The coding protein was demonstrated to have 3 trans-membrane regions,but had no sequence of subcellular localization.Meanwhile,the proportions of the helix(H),β-sheet(E) and random coil(L) were 36.56,22.96 and 40.48 respectively.The active site of L-lactate dehydrogenase located at 189-195 position of amino acids.There were 16 potential epitopes in the sequence of amino acids of TaLDH.The 3 key residues in the catalytic site of enzyme were conserved in different species and they located near to each other in the spatial structure.It is clear that the full-length cDNA sequence encoding TaLDH can be screened from the cDNA library of adult Taniasaginata asiatica by bioinformatics analysis and it can be used to investigate the structure and properties of gene and the encoding protein of TaLDH.