• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Molecular Biology >Crystal structure of inulosucrase from Lactobacillus: insights into the substrate specificity and product specificity of GH68 fructansucrases.
【24h】

Crystal structure of inulosucrase from Lactobacillus: insights into the substrate specificity and product specificity of GH68 fructansucrases.

机译：乳酸杆菌的inulosucrase的晶体结构：深入了解GH68果糖蔗糖酶的底物特异性和产物特异性。

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Fructansucrases (FSs) catalyze a transfructosylation reaction with sucrose as substrate to produce fructo-oligosaccharides and fructan polymers that contain either beta-2,1 glycosidic linkages (inulin) or beta-2,6 linkages (levan). Levan-synthesizing FSs (levansucrases) have been most extensively investigated, while detailed information on inulosucrases is limited. Importantly, the molecular basis of the different product specificities of levansucrases and inulosucrases is poorly understood. We have elucidated the three-dimensional structure of a truncated active bacterial GH68 inulosucrase, InuJ of Lactobacillus johnsonii NCC533 (residues 145-708), in its apo form, with a bound substrate (sucrose), and with a transfructosylation product. The sucrose binding pocket and the sucrose binding mode are virtually identical with those of GH68 levansucrases, confirming that both enzyme types use the same fully conserved structural framework for the binding and cleavage of the donor substrate sucrose in the active site. The binding mode of the first transfructosylation product 1-kestose (Fru-beta(2-1)-Fru-alpha(2-1)-Glc, where Fru=fructose and Glc=glucose) in subsites -1 to +2 shows for the first time how inulin-type fructo-oligosaccharide bind in GH68 FS and how an inulin-type linkage can be formed. Surprisingly, observed interactions with the sugar in subsites +1 and +2 are provided by residues that are also present in levansucrases. The binding mode of 1-kestose and the presence of a more distant sucrose binding site suggest that residues beyond the +2 subsite, in particular residues from the nonconserved 1B-1C loop, determine product linkage type specificity in GH68 FSs.
机译：果糖蔗糖酶（FSs）以蔗糖为底物催化反果糖基化反应，生成果糖寡糖和含有β-2,1糖苷键（菊粉）或β-2,6键（levan）的果聚糖聚合物。合成左聚糖的FS（糖蔗糖酶）已得到最广泛的研究，而有关蔗糖的详细信息有限。重要的是，人们对糖蔗糖酶和inulosucrases不同产品特异性的分子基础知之甚少。我们已经阐明了截短的活性细菌GH68 inulosucrase，约翰逊乳杆菌NCC533的InuJ的三维结构（残基145-708），其载脂蛋白形式具有结合的底物（蔗糖）和果糖基化产物。蔗糖结合口袋和蔗糖结合模式实际上与GH68糖蔗糖酶相同，这证实了两种酶类型均使用相同的完全保守的结构框架来结合和裂解供体底物蔗糖在活性位点。在位点-1至+2中第一个果糖基化产物1-koseose（Fru-beta（2-1）-Fru-alpha（2-1）-Glc，其中Fru =果糖和Glc =葡萄糖）的结合模式显示为菊粉型低聚果糖如何在GH68 FS中结合，以及如何形成菊粉型连接。出乎意料的是，观察到的与亚基+1和+2中糖的相互作用是由糖蔗糖酶中也存在的残基提供的。 1-Koseose的结合模式和更远的蔗糖结合位点的存在表明，+ 2亚位点以外的残基，特别是来自非保守1B-1C环的残基，决定了GH68 FS中产物连锁类型的特异性。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号