State Key Laboratory for Supramolecular Structure and Materials, Jilin University, Changchun, China.
J Phys Chem B. 2011 Jun 2;115(21):7038-44. doi: 10.1021/jp200060q. Epub 2011 May 4.
Survivin exists as a homodimeric conformation to act as a suppressor of apoptosis in organisms. Previously, we found that the deletants with truncations of N-terminal residues up to Arg18 lost the binding ability to Smac/DIABLO but not the binding force of homodimers. In order to establish the relationship between function and structural stability, thermal unfolding of SurF and its deletants in buffer have been studied in the present paper. The fluorescent results indicated that with the removal of the N-terminus, the thermal stability of the tertiary structure dropped vigorously, especially for SurΔN18. However, using circular dichroism (CD) spectroscopy, we observed that the main unfolding of the secondary structures was not affected very much with N-terminus deletion. Fourier transform infrared (FT-IR) spectroscopy and two-dimensional (2D) correlation analysis were further used to provide structural information that occurred in the main transitions, which were associated with conformational changes of several β-components and α-helix, followed by the gain of some aggregations and random coils at high temperature. In addition, more aggregates were found to form for the longer N-terminal deletants during the main unfolding.
Survivin 以同源二聚体的形式存在，作为生物体内凋亡的抑制剂。先前，我们发现截短到 Arg18 的 N 端残基的缺失体丧失了与 Smac/DIABLO 的结合能力，但同源二聚体的结合力并未丧失。为了确定功能与结构稳定性之间的关系，本文研究了 SurF 及其缺失体在缓冲液中的热变性。荧光结果表明，随着 N 端的去除，三级结构的热稳定性急剧下降，尤其是对于 SurΔN18。然而，使用圆二色性（CD）光谱，我们观察到二级结构的主要展开并没有受到 N 端缺失的很大影响。傅里叶变换红外（FT-IR）光谱和二维（2D）相关分析进一步提供了发生在主转变中的结构信息，这些信息与几个β-成分和α-螺旋的构象变化有关，随后在高温下获得了一些聚集和无规卷曲。此外，在主展开过程中，发现更长的 N 端缺失体形成了更多的聚集物。
