Decoding silkworm spinning programmed by pH and metal ions

Kai Song ¹Yejing Wang ²Wenjie Dong ³Zhenzhen Li ²Qingyou Xia ⁴Ping Zhu ⁵Huawei He⁶

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作者信息

1. Integrative Science Center of Germplasm Creation in Western China(CHONGQING)Science City,Biological Science Research Center,Southwest University,Chongqing 400715,China;National Laboratory of Biomacromolecules,CAS Center for Excellence in Biomacromolecules,Institute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China
2. Integrative Science Center of Germplasm Creation in Western China(Chongqing)Science City,Biological Science Research Center,Southwest University,Chongqing 400715,China
3. National Laboratory of Biomacromolecules,CAS Center for Excellence in Biomacromolecules,Institute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China
4. Integrative Science Center of Germplasm Creation in Western China(CHONGQING)Science City,Biological Science Research Center,Southwest University,Chongqing 400715,China;Chongqing Key Laboratory of Sericultural Science,Chongqing Engineering and Technology Research Center for Novel Silk Materials,Southwest University,Chongqing 400715,China
5. National Laboratory of Biomacromolecules,CAS Center for Excellence in Biomacromolecules,Institute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China
6. Integrative Science Center of Germplasm Creation in Western China(CHONGQING)Science City,Biological Science Research Center,Southwest University,Chongqing 400715,China;Chongqing Key Laboratory of Sericultural Science,Chongqing Engineering and Technology Research Center for Novel Silk Materials,Southwest University,Chongqing 400715,China;Chongqing Key Laboratory of Soft-Matter Material Chemistry and Function Manufacturing,Chongqing 400715,China
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Abstract

Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent.It is a great challenge to reproduce high-performance artificial fibers comparable to natural silk by bionic for the incomplete understanding of silkworm spinning in vivo.Here,we found that amphipol and digitonin stabilized the structure of natural silk fibroin(NSF)by a large-scale screen-ing in vitro,and then studied the close-to-native ultrastructure and hierarchical assembly of NSF in the silk gland lumen.Our study showed that NSF formed reversible flexible nanofibrils mainly composed of random coils with a sedimentation coefficient of 5.8 S and a diameter of about 4 nm,rather than a micellar or rod-like structure assembled by the aggregation of globular NSF molecules.Metal ions were required for NSF nanofibril formation.The successive pH decrease from posterior silk gland(PSG)to ante-rior silk gland(ASG)resulted in a gradual increase in NSF hydrophobicity,thus inducing the sol-gelation transition of NSF nanofibrils.NSF nanofibrils were randomly dispersed from PSG to ASG-1,and self-assembled into anisotropic herringbone patterns at ASG-2 near the spinneret ready for silkworm spinning.Our findings reveal the controlled self-assembly mechanism of the multi-scale hierarchical architecture of NSF from nanofibrils to herringbone patterns programmed by metal ions and pH gradient,which provides novel insights into the spinning mechanism of silk-secreting animals and bioinspired design of high-performance fibers.

Key words

Natural silk fibroin/Nanofibril/Self-assembly/Silkworm/Cryo-EM

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基金项目

国家重点研发计划(2022YFD1201600)

国家重点研发计划(2021YFA1300100)

国家重点研发计划(2018YFE0203300)

国家自然科学基金(31972622)

国家自然科学基金(32241029)

国家自然科学基金重点项目(32030103)

重庆市自然科学基金(CSTB2022NSCQ-LZX0302)

重庆市自然科学基金(CSTB2022NSCQ-MSX0761)

重庆市自然科学基金(cstc2020jcyjcxttX0001)

中央高校基本科研业务费专项(XDJK2020TJ001)

Key Project of Science and Technology Research Program of Chongqing Municipal Education Commission,China(KJZD-K202200205)

Chinese Academy of Sciences(CAS)Strategic Priority Research Program(XDB37010100)

Shennong Youth Talent Program(Ministry of Agriculture and Rural Affairs,China)()

Chongqing Innovation Supporting Program for Oversea Returned Talents(CX2023069)

出版年

2024

科学通报(英文版)

中国科学院

科学通报(英文版)

CSTPCD

ISSN：1001-6538

参考文献量57

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