...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Glucoxylation of Ras by Clostridium sordellii Lethal Toxin:Consequences for Effector Loop Conformations Observed by NMR Spectroscopy
【24h】

Glucoxylation of Ras by Clostridium sordellii Lethal Toxin:Consequences for Effector Loop Conformations Observed by NMR Spectroscopy

机译：梭状芽胞杆菌致死性毒素对Ras的葡萄糖氧化作用：核磁共振波谱观察效应环构象的结果

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

The lethal toxin (LT) from Clostridium sordellii,which belongs to the family of large clostridial cytotoxins,acts as a monoglucosyltransferase for the Rho subfamily GTPase Rac and also modifies Ras.In the present study we investigated structural changes of H-Ras in its di- adn triphosphate form that occur upon glucosylation of the enzymatic glucosylation process,using UDP-glucose as a cosubstrate,show that the modification of the threonine side chain influences the chemicla shifts of the phosphate groups of th ebound nucleotides.In the diphosphate-bound form (Ras centre dot GDP) glucosylation of Thr35 induces only small changes in the chemicla environment of the active center.In the triphosphate form with th eGTP analogue GppNHp bound (Ras centre dot GppNHp) Ras shows at least two different conformations in the active cneter that exchange on a medium-range time scale (10 to 0.1 ms).Glucoxylation selectively stabilizes one distinct conformation of the effector loop(state1) with tyrosine-32 probably apart from the nucleotide and threonine-35 not involved in magnesium on coordinaton.This conformaion is known to have a low affinity to effector proteins such as Raf-1,AF-6,or Byr2 and thus prevents the transduction of the activation signal in the Ras-mediated pathway.NMR correlation spectra of Ras(T35glc) centre dot GDP and denaturation experiments with urea indicate that the glucose is bound in the alpha-anomeric form to the hydroxyl group of the threonine-35 side chain.Inhibition of the glucoxylaton reaction by 1,5-gluconolactone suggests a stereospecific reaction mechanism with a glucoxyl oxonium ion transition state for the enzymatc activity of LT.
机译：梭状芽胞杆菌的致死毒素（LT）属于大梭菌细胞毒素家族，它作为Rho亚家族GTPase Rac的单葡糖基转移酶，也修饰Ras。在本研究中，我们研究了H-Ras在其双链中的结构变化-使用UDP-葡萄糖作为共底物，在酶促糖基化过程进行糖基化时出现的三磷酸和三磷酸形式显示，苏氨酸侧链的修饰会影响到核苷酸的磷酸基团的化学位移。 （Ras中心点GDP）Thr35的糖基化仅引起活性中心化学环境的细微变化。在结合有eGTP类似物GppNHp（Ras中心点GppNHp）的三磷酸形式中，Ras在活性中心存在至少两个不同构象在中等范围的时间尺度（10到0.1 ms）上进行交换。葡萄糖氧化选择性地稳定了酪氨酸对效应子环（state1）的一种独特构象-32可能与协作蛋白中不涉及镁的核苷酸和苏氨酸-35分开。已知这种构象与效应蛋白（如Raf-1，AF-6或Byr2）具有低亲和力，因此阻止了激活的转导Ras（T35glc）中心点GDP的NMR相关光谱和尿素的变性实验表明，葡萄糖以α-异头异构体形式结合在苏氨酸35侧链的羟基上。 1,5-葡糖酸内酯的葡糖吡喃酮反应提示了对LT的酶活性具有葡糖基氧鎓离子过渡态的立体定向反应机制。

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