State Key Laboratory of Silkworm Genome Biology, Biological Science Research Center, Southwest University, Chongqing 400716, China; Chongqing Engineering and Technology Research Center for Novel Silk Materials, Chongqing Key Laboratory of Sericulture, Southwest University, Chongqing 400716, China; Sericulture Genome and Biotechnology Engineering Laboratory, Chongqing 400716, China.
State Key Laboratory of Silkworm Genome Biology, Biological Science Research Center, Southwest University, Chongqing 400716, China; Chongqing Engineering and Technology Research Center for Novel Silk Materials, Chongqing Key Laboratory of Sericulture, Southwest University, Chongqing 400716, China.
Acta Biomater. 2022 Sep 15;150:96-110. doi: 10.1016/j.actbio.2022.07.021. Epub 2022 Jul 25.
Sericins are glue proteins on the surface of silk fibers. Four sericins have been characterized in silkworm, namely sericin1 (Ser1), sericin2 (Ser2), sericin3 (Ser3), and sericin4 (Ser4). In this study, we report a novel sericin, sericin5 (Ser5), which exists only in non-cocoon silk. We describe the sequence, exon-intron structure, and translation products of Ser5 in Bombyx mori. The Ser5 gene is approximately 22-kb long and comprises 16 exons. Ser5 protein has a size of 260 kDa, as determined by SDS-PAGE, western blot, and LC-MS/MS. Immunofluorescence analysis revealed that Ser5 co-localizes with Ser1 in the sericin layer. The expression pattern of Ser5 was detected at the transcriptional and translational levels. We systematically analyzed and compared the amino acid composition, repeat regions, and hydrophilicity of silkworm sericins. Morphological observations showed that non-cocoon silk had more sericin than cocoon silk. Circular dichroism spectra revealed that non-cocoon silk sericin contained more β-sheet structures than cocoon silk sericin. In addition, we found that the hydrophilicity and adhesive strength of native sericin increases gradually from the inner layer to the outer layer. This research enhances our understanding of various sericins from cocoon silk and non-cocoon silk with regard to their expression patterns, hydrophilicity, secondary structure and adhesive performances. STATEMENT OF SIGNIFICANCE: Sericin is a natural biomaterial with diverse biological properties, which has long been used as tissue engineering and biomedical applications. However, the composition and distribution of sericins in different kinds of silk are still uncertain, and the properties difference between sericins have not yet been reported. Our study makes a significant contribution to the literature as it identifies the sequence, composition, hydrophilicity and adhesive property of sericins. Moreover, it provides key insights into the structure-function and function-distribution relationships associated with sericins. We believe that this study will arouse the interest to the readership of your journal as it identifies the new complete sequence of sericin and revealed the composition and properties of sericin, thus highlighting their future potentials applications in both the biomaterial and technical fields.
丝胶蛋白是蚕丝表面的胶状蛋白。在蚕中已经鉴定出四种丝胶蛋白，即丝胶 1（Ser1）、丝胶 2（Ser2）、丝胶 3（Ser3）和丝胶 4（Ser4）。在本研究中，我们报告了一种新型丝胶蛋白，丝胶 5（Ser5），它仅存在于非茧丝中。我们描述了家蚕中 Ser5 的序列、外显子-内含子结构和翻译产物。Ser5 基因约 22kb 长，包含 16 个外显子。SDS-PAGE、western blot 和 LC-MS/MS 测定 Ser5 蛋白大小为 260kDa。免疫荧光分析显示 Ser5 与丝胶层中的 Ser1 共定位。在转录和翻译水平检测到 Ser5 的表达模式。我们系统地分析和比较了家蚕丝胶蛋白的氨基酸组成、重复区和亲水性。形态学观察表明，非茧丝的丝胶含量多于茧丝。圆二色光谱表明，非茧丝丝胶的β-折叠结构含量高于茧丝丝胶。此外，我们发现天然丝胶的亲水性和粘附强度从内层到外层逐渐增加。这项研究增强了我们对茧丝和非茧丝中各种丝胶的表达模式、亲水性、二级结构和粘附性能的理解。研究意义：丝胶是一种具有多种生物学特性的天然生物材料，长期以来一直被用于组织工程和生物医学应用。然而，不同种类丝胶中的丝胶组成和分布仍不确定，丝胶的性能差异也尚未报道。我们的研究对文献做出了重要贡献，因为它确定了丝胶的序列、组成、亲水性和粘附特性。此外，它为丝胶的结构-功能和功能-分布关系提供了关键见解。我们相信，这项研究将引起您的期刊读者的兴趣，因为它确定了丝胶的全新完整序列，并揭示了丝胶的组成和性质，从而突出了它们在生物材料和技术领域的未来应用潜力。
