Comparison of membrane insertion pathways of the apoptotic regulator Bcl-xL and the diphtheria toxin translocation domain.
Comparison of membrane insertion pathways of the apoptotic regulator Bcl-xL and the diphtheria toxin translocation domain.
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DOI：
10.1021/bi400926k
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发表时间：
2013-11-12
期刊：
影响因子：
2.9
通讯作者：
Ladokhin, Alexey S.
中科院分区：
文献类型：
--
作者：
Vargas-Uribe, Mauricio;Rodnin, Mykola V.;Ladokhin, Alexey S.
白喉毒素t结构域和凋亡抑制因子Bcl-xL是通过将折叠从水溶性切换到膜插入状态而采用最终拓扑结构的膜蛋白。虽然这种转变的确切分子机制在这两种情况下都不清楚，但t结构域和Bcl-xL的可溶性态结构的相似性导致他们的膜插入途径也将是相似的。以前，我们已经应用了一系列光谱方法来表征ph触发的白喉毒素t结构域的重折叠和膜插入。在这里，我们使用相同的方法来描述Bcl-xL的膜插入途径，这使我们能够直接比较两种体系在溶液中的热力学稳定性，ph依赖的膜结合和跨膜插入。CD测量的热变性表明，与t结构域不同，Bcl-xL不会经历ph依赖的结构不稳定。FRET测量表明，Bcl-xL在阴离子脂质存在的调节下经历了可逆的膜结合，这表明膜态形式的形成发生在膜界面附近。采用环境敏感染料NBD对Bcl-xL主要疏水螺旋发夹α5 -α6的膜插入进行了研究。与相应的TH8-TH9发夹在t结构域的插入相反，α5 -α6的插入并不强烈依赖于阴离子脂质的存在。综上所述，我们的研究结果表明，虽然Bcl-xL和t结构域具有结构相似性，但它们的构象切换模式和膜插入途径明显不同。
The diphtheria toxin T-domain and the apoptotic repressor Bcl-xL are membrane proteins that adopt their final topology by switching folds from a water-soluble to a membrane-inserted state. While the exact molecular mechanisms of this transition are not clearly understood in either case, the similarity in the structures of soluble states of T-domain and Bcl-xL led to the suggestion that their membrane-insertion pathways will be similar as well. Previously we have applied an array of spectroscopic methods to characterize the pH-triggered refolding and membrane insertion of the diphtheria toxin T-domain. Here, we use the same set of methods to describe the membrane insertion pathway of Bcl-xL, which allows us to make a direct comparison between both systems with respect to thermodynamic stability in solution, pH-dependent membrane association and transmembrane insertion. Thermal denaturation measured by CD indicates that, unlike the T-domain, Bcl-xL does not undergo a pH-dependent destabilization of the structure. FRET measurements demonstrate that Bcl-xL undergoes reversible membrane association modulated by the presence of anionic lipids, suggesting that formation of the membrane-competent form occurs close to membrane interface. Membrane insertion of the main hydrophobic helical hairpin of Bcl-xL, α5–α6, was studied by site-selective attachment of environment-sensitive dye NBD. In contrast to the insertion of the corresponding TH8–TH9 hairpin in T-domain, insertion of α5–α6 was found not to depend strongly on the presence of anionic lipids. Taken together our results indicate that while Bcl-xL and the T-domain share structural similarities, their mode of conformational switching and membrane insertion pathways are distinctly different.
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影响因子：
4.2
作者：
Murphy JR
通讯作者：
Murphy JR
影响因子：
16.8
作者：
Garcia-Saez, Ana J.;Ries, Jonas;Schwille, Petra
通讯作者：
Schwille, Petra
DOI：
10.1073/pnas.94.8.3668
发表时间：
1997-04-15
影响因子：
11.1
作者：
Hsu, YT;Wolter, KG;Youle, RJ
通讯作者：
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影响因子：
3.4
作者：
HOPE, MJ;BALLY, MB;CULLIS, PR
通讯作者：
CULLIS, PR
影响因子：
2.9
作者：
Oh, KJ;Zhan, HJ;Collier, RJ
通讯作者：
Collier, RJ