Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel.
The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel.
Chemistry. 2022 Mar 16;28(16):e202200279. doi: 10.1002/chem.202200279. Epub 2022 Feb 19.
Human SELENOF is an endoplasmic reticulum (ER) selenoprotein that contains the redox active motif CXU (C is cysteine and U is selenocysteine), resembling the redox motif of thiol-disulfide oxidoreductases (CXXC). Like other selenoproteins, the challenge in accessing SELENOF has somewhat limited its full biological characterization thus far. Here we present the one-pot chemical synthesis of the thioredoxin-like domain of SELENOF, highlighted by the use of Fmoc-protected selenazolidine, native chemical ligations and deselenization reactions. The redox potential of the CXU motif, together with insulin turbidimetric assay suggested that SELENOF may catalyze the reduction of disulfides in misfolded proteins. Furthermore, we demonstrate that SELENOF is not a protein disulfide isomerase (PDI)-like enzyme, as it did not enhance the folding of the two protein models; bovine pancreatic trypsin inhibitor and hirudin. These studies suggest that SELENOF may be responsible for reducing the non-native disulfide bonds of misfolded glycoproteins as part of the quality control system in the ER.
人 SELENOF 是内质网 (ER) 中的一种硒蛋白，其包含氧化还原活性基序 CXU（C 为半胱氨酸，U 为硒代半胱氨酸），类似于硫醇-二硫键氧化还原酶（CXXC）的氧化还原基序。与其他硒蛋白一样，由于难以获得 SELENOF，因此到目前为止，对其进行全面的生物学特征分析有些受限。在此，我们提出了一种通过一锅化学合成方法制备 SELENOF 的硫氧还蛋白样结构域的方法，其突出特点是使用 Fmoc 保护的硒唑烷、天然化学连接和去硒化反应。该方法制备的 CXU 基序的氧化还原电位，以及胰岛素浊度测定实验表明，SELENOF 可能催化错误折叠蛋白中二硫键的还原。此外，我们证明 SELENOF 不是一种蛋白二硫键异构酶（PDI）样酶，因为它不能增强两种蛋白模型（牛胰蛋白酶抑制剂和水蛭素）的折叠。这些研究表明，SELENOF 可能负责还原内质网中错误折叠糖蛋白的非天然二硫键，作为质量控制系统的一部分。
