• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Molecular Biology >Dynamic allostery controls coat protein conformer switching during MS2 phage assembly.
【24h】

Dynamic allostery controls coat protein conformer switching during MS2 phage assembly.

机译：动态变构可控制MS2噬菌体组装过程中外壳蛋白构象异构体的转换。

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

Previously, an RNA stem-loop (TR) encompassing 19 nt of the genome of bacteriophage MS2 was shown to act as an allosteric effector of conformational switching in the coat protein during in vitro capsid assembly. TR RNA binding to symmetric coat protein dimers results in conformational changes, principally at the FG-loop connecting the F and G beta-strands in each subunit, yielding an asymmetric structure. The FG-loops define the quasi-equivalent conformers of the coat protein subunit (A, B, and C) in the T=3 capsid. Efficient assembly of this capsid in vitro requires that both symmetrical and asymmetrical forms of the coat protein dimer be present in solution, implying that they closely resemble the quasi-equivalent dimers (A/B and C/C) seen in the final capsid. Experiments show that assembly can be triggered by a number of RNA stem-loops unrelated to TR in sequence and detailed secondary structure, suggesting that there is little sequence specificity to the allosteric effect. Since the stem-loop binding site on the coat protein dimer is distal to the FG-loops the mechanism of this switching effect needs to be investigated. We have analyzed the vibrational modes of both TR-bound and RNA-free coat protein dimers using an all-atom normal-mode analysis. The results suggest that asymmetric contacts between the A-duplex RNA phosphodiester backbone and the EF-loop in one coat protein subunit result in the FG-loop of that subunit becoming more dynamic, whilst the equivalent loop on the other monomer decreases its mobility. The increased dynamic behaviour occurs in the FG-loop of the subunit required to undergo the largest conformational change when adopting the quasi-equivalent B conformation. The free energy barrier on the pathway to form this new structure would consequently be reduced compared to the unbound subunit. Our results also imply that the allosteric effect should be independent of the base sequence of the bound stem-loop, as observed experimentally. As a test of this model, we also examined the vibrational modes of a known assembly mutant, W82R, which cannot assemble beyond dimer. This mutation leads to an increased mobility of the DE-loop rather than the FG-loop after TR binding, consistent with the non-assembling phenotype of this mutant protein.
机译：以前，在体外衣壳装配过程中，包含噬菌体MS2基因组19 nt的RNA茎环（TR）在外壳蛋白中起构象转换构象效应。 TR RNA结合到对称的外壳蛋白二聚体上导致构象变化，主要在连接每个亚基中F和Gβ链的FG环处，产生不对称结构。 FG环定义了T = 3衣壳中外壳蛋白亚基（A，B和C）的准等同构象。这种衣壳的高效体外组装要求溶液中存在外壳蛋白二聚体的对称形式和不对称形式，这意味着它们与最终衣壳中的准等效二聚体（A / B和C / C）非常相似。实验表明装配可以由序列中与TR不相关的许多RNA茎环和详细的二级结构触发，这表明对变构作用的序列特异性很小。由于外壳蛋白二聚体上的茎环结合位点位于FG环的远端，因此需要研究这种转换效应的机制。我们已经使用全原子正常模式分析了TR绑定和无RNA外壳蛋白二聚体的振动模式。结果表明，一个外壳蛋白亚基中A-双链RNA磷酸二酯主链与EF环之间的不对称接触导致该亚基的FG环变得更加动态，而另一单体上的等效环降低了其迁移率。当采用准等效的B构象时，增加的动态行为发生在需要经历最大构象变化的亚基的FG环中。因此，与未结合的亚基相比，形成这种新结构的途径中的自由能垒将减少。我们的结果还暗示，如实验观察到的，变构效应应独立于结合的茎环的碱基序列。作为对该模型的测试，我们还检查了已知的装配突变体W82R的振动模式，该装配体无法装配成二聚体。这种突变导致TR结合后DE环而不是FG环的迁移率增加，这与该突变蛋白的非组装表型一致。

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