Silk sericin is a natural polymer with potential utility in biomedical and biotechnological applications. Recombinantly expressed sericin ensures a source of pure protein with no contamination and with multiple properties when expressed as a fusion protein. Hence, the present paper aims to recombinantly express a functional silk sericin fusion protein. In order to develop a more effective sericin protein, we have attempted to recombinantly express a part of sericin sequence, which represents a highly conserved and internally repetitive unit of the sericin1 protein, and its fusion with cecropin B, a potent antimicrobial peptide. Both difficult-to-express proteins were expressed in Escherichia coli and purified by nickel-charged affinity resin. Further, functional assay demonstrated that both proteins were individually active against Gram-positive and negative bacteria, with enhanced bactericidal activity observed in sericin-cecropin B fusion protein. To our knowledge, this is the first report not only on the recombinant expression of sericin as a fusion protein but also the bactericidal possibility of the 38-amino acid serine-rich motif of sericin protein. We also discuss the potential biomedical and biotechnological applications of this sericin hybrid protein.

中文翻译：

---

丝胶蛋白-天蚕素融合蛋白的重组表达及其功能活性

丝胶是一种天然聚合物，在生物医学和生物技术应用中具有潜在用途。重组表达的丝胶可确保作为融合蛋白表达时无污染且具有多种特性的纯蛋白质来源。因此，本论文旨在重组表达功能性丝胶融合蛋白。为了开发更有效的丝胶蛋白，我们尝试重组表达丝胶蛋白序列的一部分，该序列代表丝胶蛋白1蛋白的高度保守和内部重复单元，并与天蚕素B（一种有效的抗菌肽）融合。两种难以表达的蛋白质都在大肠杆菌中表达，并通过带镍的亲和树脂进行纯化。更多，功能测定表明，这两种蛋白质对革兰氏阳性和阴性细菌均具有单独的活性，在丝胶-天蚕素 B 融合蛋白中观察到增强的杀菌活性。据我们所知，这是首次报道丝胶蛋白作为融合蛋白的重组表达，以及丝胶蛋白的 38 个氨基酸的富含丝氨酸基序的杀菌可能性。我们还讨论了这种丝胶杂交蛋白的潜在生物医学和生物技术应用。