Recombinant Silk Proteins with Additional Polyalanine Have Excellent Mechanical Properties.

Shuo Zhao,Xiaogang Ye,Xiaoli Tang,Jinghua Ruan,Boxiong Zhong,Meiyu Wu,Xiaoxiao Wang

doi:10.3390/ijms22041513

Shuo Zhao, Xiaogang Ye + Show 5 more

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https://doi.org/10.3390/ijms22041513

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Abstract

This paper explores the structures of exogenous protein molecules that can effectively improve the mechanical properties of silkworm silk. Several transgenic vectors fused with the silkworm fibroin light chain and type 3 repeats in different multiples of the ampullate dragline silk protein 1 (MaSp1) from black widow spider with different lengths of the polyalanine motifs were constructed for this study. Transgenic silkworms were successfully obtained by piggyBac-mediated microinjection. Molecular detection showed that foreign proteins were successfully secreted and contained within the cocoon shells. According to the prediction of PONDR® VSL2 and PONDR® VL-XT, the type 3 repeats and the polyalanine motif of the MaSp1 protein were amorphous. The results of FTIR analysis showed that the content of β-sheets in the silk of transgenic silkworms engineered with transgenic vectors with additional polyalanine was significantly higher than that of wild-type silkworm silk. Additionally, silk with a higher β-sheet content had better fracture strength and Young’s modulus. The mechanical properties of silk with longer chains of exogenous proteins were improved. In general, our results provide theoretical guidance and technical support for the large-scale production of excellent bionic silk.

Highlights

IntroductionThe mechanical properties of silk with longer chains of exogenous proteins were improved
Silkworm (Bombyx mori) silk has been used in the textile industry for thousands of years, and it is the only natural silk fiber that can be produced on a large scale [1]
Fibroin is a hydrophobic protein that consists of a fibroin light (FL) chain (26 kDa), a fibroin heavy (FH) chain (350 kDa), and a glycoprotein called the P25 protein (30 kDa) [2,3,4]

Summary

Introduction

The mechanical properties of silk with longer chains of exogenous proteins were improved. Silkworm (Bombyx mori) silk has been used in the textile industry for thousands of years, and it is the only natural silk fiber that can be produced on a large scale [1]. It is generally believed that the mechanical properties of silk are mainly dependent on the FH chain in silk [5]. Molecular structure analysis shows that the FH chain has a large molecular weight and a large number of (GA)N GX repeat motifs, which can form a large crystal/semicrystal domain in the silk fiber and could be the molecular basis of the mechanical properties of the silk fibroin heavy chain [7,8]. The dragline silk fiber predominantly contains two types of conserved spidroins: ampullate dragline silk protein 1 (MaSp1) and major ampullate dragline silk protein 2 (MaSp2) [11,12]

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Conclusion