Characterizing the residue level folding of the intrinsically unstructured IA3
Characterizing the residue level folding of the intrinsically unstructured IA3
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DOI：
10.1021/bi061358w
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发表时间：
2006-11-14
期刊：
影响因子：
2.9
通讯作者：
Hagen, Stephen J.
中科院分区：
文献类型：
--
作者：
Ganesh, Omjoy K.;Green, Terry B.;Hagen, Stephen J.
残基水平的简单蛋白质的折叠分析可能持有的关键，了解折叠途径，并在结构预测援助。IA（3）是酵母天冬氨酸蛋白酶A（YPrA）的内源性抑制剂，在溶液中是一种非结构蛋白。IA 3在水和23%2，2，2-三氟乙醇（TFE）中的2D N-15-HSQC光谱的比较表明，在TFE存在下，IA 3的各个残基交叉峰变得更加分散，表明在TFE存在下，蛋白质经历非结构化到结构化的转变。这种转变可以通过交叉峰的移动来监测。然而，跟踪各个交叉峰是复杂的，并且不能确定在序列中是否全局地发生单个跃迁。在这个平衡研究中，我们应用奇异值分解（SVD）来阐明TFE驱动的转变和剩余水平偏离平均行为的主要特征。该分析产生了双态折叠描述以及单个残基的NMR频移的细节，表明IA 3的N-末端具有比C-末端更高的螺旋倾向。此外，我们还讨论了观察到的偏离两态折叠跃迁的可能机制.当与传统的生物化学理解单个残基之间的相互作用相结合时，这种方法可以更好地理解蛋白质折叠。
Residue level analysis of the folding of simple proteins may hold the key to understanding folding pathways and aid in structure prediction. IA(3), the endogenous inhibitor of yeast aspartic proteinase A ( YPrA), is an unstructured protein in solution. Comparison of the 2D N-15-HSQC spectra of IA3 in water and in 23% 2,2,2- trifluoroethanol (TFE) shows that the individual residue cross peaks of IA3 become more dispersed in the presence of TFE, indicating that the protein undergoes an unstructured to structured transition in the presence of TFE. This transition can be monitored by the movements of the cross peaks. Following the individual cross peaks, however, is complicated and does not establish whether a single transition occurs globally in the sequence. In this equilibrium study, we apply singular value decomposition (SVD) to elucidate both the main features of the TFE- driven transition and the residue-level deviations from the average behavior. This analysis has yielded a two-state folding description as well as specifics of NMR frequency shifts of individual residues, indicating that the N- terminus of IA3 has a higher helical propensity than the C- terminus. Additionally, we discuss possible mechanisms for observed deviations from a two- state folding transition. When combined with a traditional biochemical understanding of interactions between individual residues, this approach leads to a better understanding of protein folding.