...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Controlling Conformational Flexibility of an O2-Binding H-NOX Domain
【24h】

Controlling Conformational Flexibility of an O2-Binding H-NOX Domain

机译：控制O2绑定H-NOX域的构象灵活性

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

Heme Nitric oxide/OXygen binding (H-NOX) domains have provided a novel scaffold to probe ligand affinity in hemoproteins. Mutation of isoleucine 5, a conserved residue located in the heme-binding pocket of the H-NOX domain from Thermoanaerobacter tengcongensis (Tt H-NOX), was carried out to examine changes in oxygen (O2)-binding properties. A series of I5 mutants (I5F, I5F/I75F, I5F/L144F, I5F/I75F/L144F) were investigated to probe the role of steric bulk within the heme pocket. The mutations significantly increased O2 association rates (1.5–2.5-fold) and dissociation rates (8–190-fold) as compared to wild-type Tt H-NOX. Structural changes that accompanied the I5F mutation were characterized using X-ray crystallography and resonance Raman spectroscopy. A 1.67 Å crystal structure of the I5F mutant indicated that introducing a phenylalanine at position 5 resulted in a significant shift of the N-terminal domain of the protein, causing an opening of the heme pocket. This movement also resulted in an increased amount of flexibility at the N-terminus and the loop covering the N-terminal helix as indicated by the two conformations of the first six N-terminal amino acids, high B-factors in this region of the protein, and partially discontinuous electron density. In addition, introduction of a phenylalanine at position 5 resulted in increased flexibility of the heme within the pocket and weakened hydrogen bonding to the bound O2 as measured by resonance Raman spectroscopy. This study provides insight into the critical role of I5 in controlling conformational flexibility and ligand affinity in H-NOX proteins.
机译：血红素一氧化氮/氧结合（H-NOX）域提供了一种新颖的支架来探测血红蛋白中的配体亲和力。进行了异亮氨酸5（位于腾科嗜热厌氧菌（Tt H-NOX）的H-NOX结构域的血红素结合口袋中的保守残基）的突变，以检测氧的变化（O 2 ）绑定属性。研究了一系列的I5突变体（I5F，I5F / I75F，I5F / L144F，I5F / I75F / L144F），以探测血红素袋内空间位阻的作用。与野生型Tt H-NOX相比，该突变显着提高了O 2 缔合速率（1.5-2.5倍）和解离速率（8-190倍）。使用X射线晶体学和共振拉曼光谱表征伴随I5F突变的结构变化。 I5F突变体的1.67Å晶体结构表明，在位置5引入苯丙氨酸会导致蛋白质N端结构域发生明显移位，从而导致血红素囊袋打开。这种运动还导致N末端和覆盖N末端螺旋的环增加了柔韧性，如前六个N末端氨基酸的两个构象所示，蛋白质的该区域中的高B因子和部分不连续的电子密度。此外，通过共振拉曼光谱法测量，在位置5引入苯丙氨酸会导致血红素在袋中的柔韧性增加，并削弱氢键结合到结合的O 2 上。这项研究提供了对I5在控制H-NOX蛋白中构象柔韧性和配体亲和力中的关键作用的见解。

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