Proline isomerization in the C-terminal region of HSP27.
Proline isomerization in the C-terminal region of HSP27.
复制标题
DOI：
10.1007/s12192-017-0791-z
复制
发表时间：
2017-07
影响因子：
3.8
通讯作者：
Baldwin AJ
中科院分区：
文献类型：
--
作者：
Alderson TR;Benesch JLP;Baldwin AJ
在哺乳动物中，小热休克蛋白 (sHSP) 通常组装成相互转化的多分散寡聚物。 sHSP 寡聚物的动态交换至少部分受到 α-晶状体蛋白结构域和 C 末端区域 (CTR) 之间的分子相互作用的调节。在此，我们报告了对人 HSP27（一种系统表达的 sHSP）无序且灵活的 CTR 的构象和动力学的溶液态核磁共振 (NMR) 波谱研究。我们观察到脯氨酸 194 附近残基的多个 NMR 信号，并且我们确定，虽然所有观察到的形式都是高度无序的，但额外的共振来自于 G193-P194 肽键的顺反肽基-脯氨酰异构化。在生理温度下，顺式 P194 状态接近 15%，并且，尽管 CTR 的顺式和反式 P194 形式都是灵活且动态的，但这两种状态都显示出采用 β 链构象的残余但不同的倾向。在分离的 CTR 肽的 NMR 谱中，我们观察到涉及脯氨酸 182 的异构化的类似证据，该异构化在 IPI/V 基序中发现。总的来说，这些数据表明顺反脯氨酸异构化在调节 sHSP 寡聚化中的潜在作用。本文的在线版本 (doi:10.1007/s12192-017-0791-z) 包含补充材料，可供授权用户使用。
In mammals, small heat-shock proteins (sHSPs) typically assemble into interconverting, polydisperse oligomers. The dynamic exchange of sHSP oligomers is regulated, at least in part, by molecular interactions between the α-crystallin domain and the C-terminal region (CTR). Here we report solution-state nuclear magnetic resonance (NMR) spectroscopy investigations of the conformation and dynamics of the disordered and flexible CTR of human HSP27, a systemically expressed sHSP. We observed multiple NMR signals for residues in the vicinity of proline 194, and we determined that, while all observed forms are highly disordered, the extra resonances arise from cis-trans peptidyl-prolyl isomerization about the G193-P194 peptide bond. The cis-P194 state is populated to near 15% at physiological temperatures, and, although both cis- and trans-P194 forms of the CTR are flexible and dynamic, both states show a residual but differing tendency to adopt β-strand conformations. In NMR spectra of an isolated CTR peptide, we observed similar evidence for isomerization involving proline 182, found within the IPI/V motif. Collectively, these data indicate a potential role for cis-trans proline isomerization in regulating the oligomerization of sHSPs. The online version of this article (doi:10.1007/s12192-017-0791-z) contains supplementary material, which is available to authorized users.