【摘要】 目的为明了偶蹄动物PrP基因的结构特征及其变异与结构、功能和朊粒病传染种间屏障的关系以及系统发生关系;方法利用DNAstar和Clustalx程序及treev32软件进行了22种偶蹄动物的43个完整PrP基因序列的同源性分析、多重排比和进化树构建;结果不同种属偶蹄动物的PrP基因完整ORF大小有所差异,范围为768～795bp,可编码255～264个氨基酸的朊蛋白。核苷酸和氨基酸序列的同源性,偶蹄动物间≥88.6%和≥93.3%,反刍动物间≥95.4%和≥96.5%。共发现40个点突变和2个突变区。在N-端柔韧无序“尾”区(25～135)以八肽重复缺失为主,球形结构域区(136～241)以点突变为主,点突变主要簇聚在S1β-折叠前的柔韧无规卷曲区的C-端部分和HCα-螺旋内。氨基酸104～135区和球形结构域区存在有8个高突变位点。已知PrP肽基元和功能位点如芳烃回文序列基元、2个N-连接糖基化位点、2个苏氨酸磷酸化位点、1个酪氨酸硫化位点、形成二硫键的2个半胱氨酸以及GPI锚锚着点丝氨酸为偶蹄动物所共有,各种间变异体的各结构模式非常一致。进化关系分析,可将偶蹄动物PrP基因区分为3大类,反刍动物PrP基因分为3小类。令人意外的是,2个双峰驼PrP基因的进化关系与牛属动物基因同源。结论偶蹄动物的PrP基因是一个保守基因,氨基酸104～135区和球形结构域区内的8个高突变位点可能是影响分子间相互作用、形成朊粒病传染种间屏障的主要位点,物种间各氨基酸变异并不影响PrP的主要结构和功能。更多还原

【Abstract】 【Objective】 The purpose of this study is to clarify the structural features of artiodactyl PrP gene,relationships of the sequence variations with its structure-function and the species barrier of prion disease transmission,and molecular phylogeny among the PrP genes.【Method】 The identity analysis and multiple alignment of 43 complete PrP gene sequences of 22 artiodactyls were undertaken,and phylogenetic trees were reconstructed,respectively,by using the DNAstar and Clustalx packages,and treev32 program.【Results】PrP gene sequences in different artiodactyls showed the entire ORFs size range from 768 bp to 795 bp,which could encode PrPs with 255 to 264 amino acids.The homology of these nucleotide and amino acid sequences were greater than or equal to 88.6% and greater than or equal to 93.3% among artiodactyls,and were greater than or equal to 95.4% and greater than or equal to 96.5% between ruminants,respectively.A total of 40 point mutations and two variable regions were found.The major mutations in the N-terminal flexible disordered“tail”region(25～135) were the octarepeat deletion,while those in the globular domain region(136～241) were the point mutations.The most of point mutations clustered in the C-terminal portion of the flexible disordered region before S1 β-sheet and within HC α-helix.There were eight high-frequency mutation positions in the regions of amino acid residues 104～135 and the globular domain.The known motifs and functional positions of PrP,such as the aromatic hydrocarbon palindrome motif,the two N-linked glycosylation sites,the two threonine residues phosphorylation sites,the tyrosine residue sulfurization site,the two cysteine residues forming the disulfide bond,and the serine residue at position 242 where the GPI anchor is attached,were mutual for all interspecies variations of artiodactyls.It was showed that the interspecies variations were in good agreement with structural model.According to the phylogenetic relationship analysis of PrP genes,the PrP genes of artiodactyls could be obviously separated into three super-kinds,the PrP genes of ruminants could be further divided into three distinct kinds of genes.It was surprised that the PrP gene phylogenesis of two bactrian camels was homologous with the bovine genus animals.【Conclusion】PrP gene in artiodactyls is a conservative gene.The eight high-frequency mutation positions within the regions of amino acid residues 104-135 and the globular domain seem to be the major positions affecting intermolecular interactions and forming the species barrier of prion disease transmission,and the amino acid variations in these species do not affect the key structures and functions of PrPs.更多还原