固有无序蛋白质无序与有序接点处的氨基酸序列分析

The Sequence Analysis of the Junction between Disordered and Ordered Region for Intrinsically Disordered Proteins

近几年发现的固有无序蛋白质数量不断增加,但目前的研究主要集中于无序区域的序列分析,预测软件的开发也主要基于无序区域的序列和结构特征。目前,尚没有针对无序区域与有序区域接点处氨基酸序列分析的报道,也未发现比较不同功能固有无序蛋白质的无序区域序列特征的研究。本文将目前所发现的固有无序蛋白质按功能划分为分子伴侣、分子组装等8组,建立其二级数据库;然后,运用ProtParam软件对固有无序蛋白质无序与有序接点处的氨基酸序列进行相关特征分析,这些特征参数包括氨基酸组成、净电荷、芳香族氨基酸含量和疏水性。基于数据库和分析统计工具的考虑,文章在每组序列的接点两侧,分别选择了1～5个氨基酸作为研究对象。结果表明,不同功能的固有无序蛋白质接点处无序区域和有序区域的氨基酸种类、净电荷含量、芳香族氨基酸含量,以及疏水性,都存在不同程度的差异;但是就整体而言,固有无序蛋白质接点处无序区域的亲水氨基酸(D、E、K、G)含量比较高,而接点处有序区域的疏水氨基酸(C、W、L、I、F)含量比较高;接点处无序区域的净电荷高于有序区域的净电荷,无序区域的芳香族氨基酸含量低于有序区域。本研究揭示了固有无序蛋白质有序与无序接点处的序列特征,将为无序蛋白质的预测添加新的输入信息,有助于开发和改进固有无序蛋白质预测软件。

There has been a significant increase in the number of intrinsically disordered proteins（IDPs） research in recent years,while most of researchers focused on the disordered regions of IDPs.The exploitation of prediction software of IDPs is also based on the structure and sequence characteristics of disordered regions.However,there is no research that analyzes the sequence character of the junction between ordered and disordered regions until now.In this work,we classified all of the IDPs into eight groups by function such as Chaperones,Molecular assembly and so on.In order to obtain more statistical result,we cut one to five amino acids separately from the ordered and disordered regions that close to the IDPs junction.ProtParam software was used to analyze the sequence features of IDPs junctions,including the composition of amino acid,content of net charge and aromatic amino acid and hydrophobicity distribution.The results show that these characteristics are diverse among different functional proteins.Overall,the content of hydrophilic amino acids（D,E,K,G） is higher in the disordered region than ordered region of the junction,but the ordered region has higher level of hydrophobic amino acids（C,W,L,I,F） than disordered region of the junction.In addition,the net charges of disordered region are higher than the ordered region of the junction,but the content of aromatic amino acids of disordered region is less than ordered region of the junction.We hope that the analysis of the sequence characteristics of the junction between the ordered and disordered regions will promote the development of IDPs prediction software.