The b′ domain provides the principal peptide-binding site of protein disulfide isomerase but all domains contribute to binding of misfolded proteins
The b′ domain provides the principal peptide-binding site of protein disulfide isomerase but all domains contribute to binding of misfolded proteins
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DOI：
10.1093/emboj/17.4.927
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发表时间：
1998-02-16
期刊：
影响因子：
11.4
通讯作者：
Freedman, RB
中科院分区：
文献类型：
--
作者：
Klappa, P;Ruddock, LW;Freedman, RB
蛋白质二硫键异构酶（proteins disulfide isomerase，PDI）是许多二硫键蛋白质折叠的有效催化剂，目前对PDI的催化功能了解较多，但对它与底物的结合知之甚少。为了表征PDI的底物结合位点，我们研究了在大肠杆菌中表达的人PDI的各种重组片段与不同放射性标记的模型肽的相互作用。我们观察到人PDI的B'结构域对于小肽的结合是必需的和足够的。在较大肽的情况下，特别是衍生自牛胰腺胰蛋白酶抑制剂的28个氨基酸片段，或错误折叠的蛋白质，B'结构域是必需的，但不足以有效结合，表明需要额外结构域的贡献。因此，我们提出PDI的不同结构域都有助于结合位点，其中B'结构域形成必需的核心。
Protein disulfide isomerase (PDI) is a very efficient catalyst of folding of many disulfide-bonded proteins, A great deal is known about the catalytic functions of PDI, while little is known about its substrate binding, We recently demonstrated by cross-linking that PDI binds peptides and misfolded proteins, with high affinity but broad specificity. To characterize the substrate-binding site of PDI, we investigated the interactions of various recombinant fragments of human PDI, expressed in Escherichia coli, with different radiolabelled model peptides, We observed that the b' domain of human PDI is essential and sufficient for the binding of small peptides, In the case of larger peptides, specifically a 28 amino acid fragment derived from bovine pancreatic trypsin inhibitor, or misfolded proteins, the b' domain is essential but not sufficient for efficient binding, indicating that contributions from additional domains are required, Hence we propose that the different domains of PDI all contribute to the binding site, with the b' domain forming the essential core.