News from this site (correspondent Wu Xuan) Natural spider silk has excellent mechanical properties. They are usually composed of a variety of spider silk proteins, including major and minor component proteins. Because spiders live alone and feed each other, large-scale high-density breeding cannot be achieved. Therefore, artificial spinning is an important means to obtain large amounts of high-strength silk fibers. The study of the structure and function of spider silk proteins is the basis for the production of silk fibers. Although the structure and function of the main components of various spider silk proteins have been extensively studied, the molecular mechanism of the secondary components of spider silk in the process of self-assembly and fiber formation of spider silk proteins is poorly understood, which seriously hinders Design and preparation of high-performance artificial spider silk protein.
On September 21, 2021, the team of Professor Lin Zhi from the School of Life Sciences of Tianjin University published a titled Critical role of minor eggcase silk component in promoting spidroin chain alignment and strong fiber formation in , the journal PNAS of the American Academy of Sciences research paper. This research carried out research on the structure and filament formation mechanism of the minor component protein TuSp2 of spider egg sheath silk through nuclear magnetic resonance (NMR) and combined with materials science technology, and found that artificially spun from the major and minor component proteins. The strength of silk is better than that of natural egg sheath silk, which provides a new direction for rational design of high mechanical properties of silk protein material.
The main points of this article:
1) This study firstly found that the minor component protein of spider egg sheath silk TuSp2 can not only accelerate the self-assembly of the main component protein TuSp1, but also significantly promote the production of silk protein in the fiber under the action of mechanical shearing force. Sequence arrangement, which indicates that TuSp2 plays a key role in the formation of oocyst filaments.
2) TuSp2 is composed of multiple repetitive domains (RP), but does not have the typical non-repetitive domains at the end of silk protein. In order to explore its mechanism of action in filament formation, the authors analyzed the solution structure of TuSp2 repeat domains through multi-dimensional NMR spectroscopy.Structural studies have shown that TuSp2-RP forms a dimer mainly through hydrophobic interaction in solution. The dimer structure has two unique negatively charged surface blocks, which can then recruit the positively charged TuSp1 repeating domains on the surface. At the same time, it can also bind to the end domain of TuSp1. The docking structure shows that one molecule of TuSp2-RP dimer can bind at least three molecules of TuSp1 repeat domain. Based on the above research, the author proposed the micelle model of TuSp1:TuSp2. This model explains why silk fibers formed from TuSp1:TuSp2 composites have a higher birefringence effect than those formed from TuSp1 alone (Figure 1).
Figure 1. The structural basis and micellar model of the interaction between TuSp2-RP and TuSp1-RP
3) The author further designed a miniature silk protein containing TuSp1 and TuSp2 based on structural mechanism research to explore minor component pairs The influence of silk fiber mechanical properties. Studies have found that artificial spider silk fibers spun from TuSp1 and TuSp2 micro-silk protein complexes have fewer surface and internal structural defects than fibers formed by TuSp1 alone, and thus have better physical properties. Under the optimal ratio of TuSp1 and TuSp2, its strength and Young's modulus even surpass that of natural egg sheath filaments (Figure 2).
Figure 2. SEM characterization and mechanical properties of recombinant egg sheath filament fibers
In summary, this work clarifies the key role of TuSp2 in the formation of egg sheath filaments and reveals that TuSp2 promotes egg sheath filament protein autonomy The structural mechanism of assembly and orderly arrangement of molecules; in addition, the co-spinning strategy developed in this research also provides new inspiration for the production of other types of artificial spider silk fibers with predictable physical properties.
The first author of this paper is Fan Tiantian, a doctoral student in the School of Life Sciences, Tianjin University; Qin Ruiqi, Zhang Yan, Wang Jingxia and Fan Jinsong are the co-first authors; the corresponding author is Professor Lin Zhi from the School of Life Sciences, Tianjin University. The cooperative unit is National University of Singapore Professor Yang Daiwen team and Ningxia Medical University Professor Huang Weidong team. Nankai University Professor Xuncheng Su's team provided great support for this work.This research was supported by the first-class funding of Tianjin University .
Original link:
(edited by Zhang Hua Wang Haoen)
[Source: Tianjin University News Network]
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