基于序列比对分析木聚糖1,4-β-木糖苷酶结构差异和分子进化规律

Analysis of Structure Difference and Molecular Evolution of Xylan 1,4-β-Xylosidase Based on Sequence Alignment

摘要:

木聚糖1,4-β-木糖苷酶（EC 3.2.1.37）是一种外切水解酶，近年来该酶在工业上的使用越来越广泛，目前对于木聚糖1,4-β-木糖苷酶结构的研究相对缺少。为了分析木聚糖1,4-β-木糖苷酶的进化关系以及结构差异，利用MEGA X 10.1.8进行木聚糖1,4-β-木糖苷酶基因序列多序列比对，构建系统进化树，结果分析显示木聚糖1,4-β木糖苷酶可分为两大类，从中筛选出12条代表性序列进行氨基酸序列多序列比对，发现只有15个较保守位点，在进化上呈现不保守的特点。利用生物信息学工具预测分析12条序列对应的酶的理化性质、信号肽，预测结果表明所有酶都表现为亲水性，有胞内与胞外两种分泌方式。利用Modeller 9.24以及Phyre 2进行三级结构建模，根据建模结果木聚糖1,4-β-木糖苷酶分为β-折叠桶、碗状结构、（α/β）8桶状结构三种代表性结构，利用分子对接辅助结合口袋大小计算，推测底物的大小对其特征结构的形态存在一定程度的影响。基于木聚糖1,4-β-木糖苷酶结构规律的研究，可以精确设计点突变，降低盲目性，获得需要的理化性质，为木聚糖1,4-β-木糖苷酶的改造提供生物信息学指导，其次为进一步的木聚糖1,4-β-木糖苷酶结构与功能关系研究提供基础，进一步拓宽对木聚糖1,4-β-木糖苷酶在食品、医药等领域应用。

Abstract:

Xylan 1,4-β-xylosidase (EC 3.2.1.37) is an exohydrolase that has become more widely used in industry in recent years. At present, there has been a relative lack of research on the structure of xylan 1,4-β-xylosidase.In order to analyze the evolutionary relationship and structural differences of xylan 1,4-β-xylosidase, MEGAX10.1.8 was used to compare the multiple sequences of xylan 1,4-β-xylosidase gene sequences and construct a phylogenetic evolutiontree. The analysis of results showed that xylan 1,4-β-xylosidase could be divided into two categories, from which 12 representative sequences were screen and selected for the comparison and alignment of multiple amino acid sequences. Only 15 relatively conserved sites were found, showing non-conservative characteristics. The physicochemical properties and signal peptides of the enzymes corresponding to the 12 sequences were predicted and analyzed by bioinformatics tools. The prediction results showed that all enzymes were hydrophilic, and possessed intracellular and extracellular secretion modes. Modell 9.24 and Phyre2 were used to construct models for the tertiary structure. According to the modeling results, xylan 1,4-β-xylosidase was divided into three representative structures: β-folded barrel, bowl-like structure, and (α/β)8 barrel structure. Molecular docking was used to assist the calculation of the size of the binding pocket, and it was speculated that the size of substrate has a certain degree of effect on the morphology of its characteristic structure. Based on the study of the structural pattern of xylan 1,4-β-xylosidase, point mutations can be precisely designed, blindness can be reduced, and desired physicochemical properties can be obtained, to provide bioinformatics guidance for further research on the modification of xylan 1,4-β-xylosidase, then offers a basis for further study on the relationship between the structure and function of xylan 1,4-β-xylosidase, thereby further broadening the application of xylan 1,4-β-xylosidase in food, medicine and other fields.