• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Molecular Biology >Rearrangement of charge-charge interactions in variant ubiquitins as detected by double-mutant cycles and NMR.
【24h】

Rearrangement of charge-charge interactions in variant ubiquitins as detected by double-mutant cycles and NMR.

机译：通过双突变循环和NMR检测到，泛素中的电荷-电荷相互作用重排。

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

Previous studies of ubiquitin disclosed numerous charge-charge interactions on the protein's surface. To investigate how neighboring residues influence the strength of these interactions, double-mutant cycles are combined with pK(a) determinations by 2D NMR. More specifically, the environment around the Asp21-Lys29 ion pair has been altered through mutations at position 25, which is an asparagine in mammalian ubiquitin and a positively-charged residue in many other ubiquitin-like proteins. The pK(a) value of Asp21 decreases by 0.4 to 0.7 pH unit when Asn25 is substituted with a positively charged residue, suggesting a new and favorable ion pair interaction between positions 21 and 25. However, analysis of double mutants reveals that the favorable interaction between Asp21 and Lys29 is weakened when position 25 is a positively charged residue. Interestingly, while the pK(a) value of His25 in the N25H variant agrees with model compound values, additional mutants reveal that this agreement is fortuitous, resulting from a balance of favorable and unfavorable interactions; similar results were observed previously for Glu34 in ubiquitin and His8 in staphylococcal nuclease. Ionizable groups may thus have pK(a) values similar to model compound values and yet still be involved in significant interactions with other protein groups. One surprising result of introducing positively charged residues at position 25 is a new interaction between Lys29 and Glu18, an interaction not present in wild-type ubiquitin. This unanticipated result illustrates a key advantage of using NMR to determine pK(a) values for many residues simultaneously in the variant proteins. Overall, the strength of an interaction between two residues at the surface of ubiquitin is sensitive to the identity of neighboring residues. The results also demonstrate that relatively conservative and common point mutations such as substitutions of polar with charged residues and vice versa can have effects on interactions beyond the site of mutation per se.
机译：泛素的先前研究揭示了蛋白质表面上的许多电荷-电荷相互作用。为了研究相邻残基如何影响这些相互作用的强度，将双突变循环与通过2D NMR测定的pK（a）相结合。更具体地说，Asp21-Lys29离子对周围的环境已经通过位置25处的突变而改变，该位置是哺乳动物泛素中的天冬酰胺和许多其他泛素样蛋白中带正电荷的残基。当Asn25被带正电荷的残基取代时，Asp21的pK（a）值降低0.4至0.7 pH单位，这表明21位和25位之间出现了新的有利的离子对相互作用。但是，对双突变体的分析表明，有利的相互作用当第25位为带正电荷的残基时，Asp21和Lys29之间的差变弱。有趣的是，尽管N25H变体中His25的pK（a）值与模型化合物的值一致，但另外的突变体表明，这种协议是偶然的，是由于有利的相互作用和不利的相互作用之间的平衡所致。以前在泛素中的Glu34和在葡萄球菌核酸酶中的His8观察到了相似的结果。因此，可电离基团的pK（a）值与模型化合物的值相似，但仍与其他蛋白质基团发生显着相互作用。在位置25引入带正电荷的残基的一个令人惊讶的结果是Lys29和Glu18之间的新相互作用，这种相互作用在野生型泛素中不存在。这一出乎意料的结果说明了使用NMR同时确定变异蛋白中许多残基的pK（a）值的关键优势。总的来说，遍在蛋白表面上两个残基之间相互作用的强度对相邻残基的身份很敏感。结果还表明，相对保守和常见的点突变，例如用带电残基取代极性，反之亦然，可能会对超出突变位点本身的相互作用产生影响。

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