Three-dimensional structures of thermophilic β-1,4-xylanases from Chaetomium thermophilum and Nonomuraea flexuosa -: Comparison of twelve xylanases in relation to their thermal stability
Three-dimensional structures of thermophilic β-1,4-xylanases from Chaetomium thermophilum and Nonomuraea flexuosa -: Comparison of twelve xylanases in relation to their thermal stability
复制标题
DOI：
10.1046/j.1432-1033.2003.03496.x
复制
发表时间：
2003-04-01
期刊：
影响因子：
--
通讯作者：
Rouvinen, J
中科院分区：
文献类型：
--
作者：
Hakulinen, N;Turunen, O;Rouvinen, J
分别在1.75和2.1埃分辨率下测定了来自Chaetomium thermophilum和Nonomuraea flexuosa的耐热木聚糖酶的晶体结构。两种酶都具有家族11木聚糖酶典型的整体折叠，其中两个高度扭曲的β-折叠形成大裂缝。对来自嗜温和嗜热生物的第11家族木聚糖酶的12种晶体结构的比较表明，不同木聚糖酶的结构非常相似。序列同一性差异与结构差异相关。几个微小的修饰似乎是家族11木聚糖酶的热稳定性增加的原因：（a）较高的Thr：Ser比率（B）增加了带电残基的数量，特别是Arg，导致增强的极性相互作用，以及（c）二级结构的改善的稳定性涉及β链中的较高数量的残基和α-螺旋区域的稳定。家族11木聚糖酶的一些成员具有独特的策略来提高其稳定性，例如蛋白质表面上更多的离子对或芳香残基，更紧凑的结构，更紧密的包装，以及在某些区域的插入导致增强的相互作用。
The crystal structures of thermophilic xylanases from Chaetomium thermophilum and Nonomuraea flexuosa were determined at 1.75 and 2.1 Angstrom resolution, respectively. Both enzymes have the overall fold typical to family 11 xylanases with two highly twisted beta-sheets forming a large cleft. The comparison of 12 crystal structures of family 11 xylanases from both mesophilic and thermophilic organisms showed that the structures of different xylanases are very similar. The sequence identity differences correlated well with the structural differences. Several minor modifications appeared to be responsible for the increased thermal stability of family 11 xylanases: (a) higher Thr : Ser ratio (b) increased number of charged residues, especially Arg, resulting in enhanced polar interactions, and (c) improved stabilization of secondary structures involved the higher number of residues in the beta-strands and stabilization of the alpha-helix region. Some members of family 11 xylanases have a unique strategy to improve their stability, such as a higher number of ion pairs or aromatic residues on protein surface, a more compact structure, a tighter packing, and insertions at some regions resulting in enhanced interactions.