Crystal and solution structures of human protein-disulfide isomerase-like protein of the testis (PDILT) provide insight into its chaperone activity
Crystal and solution structures of human protein-disulfide isomerase-like protein of the testis (PDILT) provide insight into its chaperone activity
复制标题
人类睾丸蛋白二硫键异构酶样蛋白 (PDILT) 的晶体和溶液结构提供了对其分子伴侣活性的深入了解。
DOI：
10.1074/jbc.m117.797290
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发表时间：
2018-01-26
影响因子：
4.8
通讯作者：
Liang, Huanhuan
中科院分区：
文献类型：
--
作者：
Li, Huanhuan;Yang, Kai;Liang, Huanhuan
睾丸蛋白二硫键异构酶样蛋白(PDILT)是蛋白质二硫键异构酶家族的成员之一，是男性生殖细胞减数分裂后精子发生特异性蛋白折叠所必需的伴侣蛋白。然而，调节PDILT伴侣功能的结构机制尚不清楚。在这里，我们报道了用2.4Å分辨率的X射线结晶学和小角X射线散射(SAXS)测定的人PDILT的结构。与以前报道的PDI家族相关蛋白的U型结构不同，我们的结构表明hPDILT在晶体中折叠成致密的L样结构，在溶液中折叠成延伸的链状结构。HPDILT中的疏水区域和疏水口袋在晶体结构中被清楚地描绘出来，这对底物识别是重要的。此外，我们的SAXS分析以及基于结构的取代和截断的结果表明，hPDILT的C-末端尾部是抑制变性蛋白质聚集所必需的，这表明尾部对PDILT的伴侣活性至关重要。综上所述，我们的发现已经确定了启动和控制PDILT活性的关键区域和构象变化。这些结果促进了我们对PDILT分子伴侣活性的结构机制的理解。
Protein-disulfide isomerase-like protein of the testis (PDILT), a member of the protein-disulfide isomerase family, is a chaperone essential for the folding of spermatogenesis-specific proteins in male postmeiotic germ cells. However, the structural mechanisms that regulate the chaperone function of PDILTs are unknown. Here, we report the structures of human PDILT (hPDILT) determined by X-ray crystallography to 2.4 Å resolution and small-angle X-ray scattering (SAXS). Distinct from previously reported U-like structures of related PDI family proteins, our structures revealed that hPDILT folds into a compact L-like structure in crystals and into an extended chain-like structure in solution. The hydrophobic regions and the hydrophobic pockets in hPDILT, which are important for substrate recognition, were clearly delineated in the crystal structure. Moreover, our results of the SAXS analysis and of structure-based substitutions and truncations indicated that the C-terminal tail in hPDILT is required for suppression of aggregation of denatured proteins, suggesting that the tail is crucial for the chaperone activity of PDILT. Taken together, our findings have identified the critical regions and conformational changes of PDILT that enable and control its activity. These results advance our understanding of the structural mechanisms involved in the chaperone activity of PDILT.