For secreted proteins, proper protein folding is essential not only for biological function but also for secretion itself. Proteins with folding problems are trapped in the endoplasmic reticulum (ER) and are eventually degraded in the cytoplasm. In this study, we exploited co-expression of an artificial fusion protein, based on the sequence of a DnaJ protein, which could interact as co-chaperones in the Hsp70-based protein-folding system, with target recombinant secreted proteins to enhance their production and secretion. The J-domain sequence or a fragment thereof was conjugated to a target protein-binding domain that was capable of binding to a portion of the target-protein sequence. Production of many of the target proteins was significantly upregulated when co-expressed with the J-domain fusion protein. Surprisingly, the enhancement of secretion was observed even when the J-domain had a mutation in the HPD motif, which is necessary for J-protein-Hsp70 interactions, suggesting the phenomenon observed is independent on functional J-protein-Hsp70 interactions. This technology has great potential for not only enhancing the production of recombinant proteins, but also to treat conformational diseases such as cystic fibrosis, and Alpha-1 antitrypsin deficiency.

中文翻译：

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人造DnaJ蛋白质，用于蛋白质生产和构象疾病。

对于分泌的蛋白质，适当的蛋白质折叠不仅对于生物学功能至关重要，而且对于分泌本身也是必不可少的。具有折叠问题的蛋白质被困在内质网（ER）中，并最终在细胞质中降解。在这项研究中，我们基于DnaJ蛋白质的序列开发了一种人工融合蛋白的共表达，该蛋白可以在基于Hsp70的蛋白折叠系统中作为伴侣分子相互作用，并与目标重组分泌蛋白相互作用，从而提高其产量和分泌物。将J结构域序列或其片段缀合至能够结合靶蛋白序列的一部分的靶蛋白结合结构域。当与J结构域融合蛋白共表达时，许多靶蛋白的产生显着上调。出奇，即使J结构域在HPD基序中发生突变（这是J蛋白与Hsp70相互作用所必需的），也观察到了分泌的增强，这表明观察到的现象与功能性J蛋白与Hsp70的相互作用无关。该技术不仅具有增强重组蛋白生产的潜力，而且还具有治疗诸如囊性纤维化和Alpha-1抗胰蛋白酶缺乏症等构象疾病的巨大潜力。