Comparing the rheology of native spider and silkworm spinning dope

Holland, Chris; Terry, Ann E.; Porter, David; Vollrath, Fritz

doi:10.1038/nmat1762

Cited by 160 publications

(219 citation statements)

References 26 publications

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“…The results show that the two domains in NRP and RPC undergo structural changes cooperatively, implying that the two domains interact with each other at high temperature. At Ն37°C, both NRP and RPC could self-assemble and polymerize into macroscopic fibers within a couple of hours without physical shear when the concentrations of NRP and RPC were only 0.1-0.2 wt%, which are much lower than 25-30 wt%, the fibroin concentration in spider glands (20). During the polymerization, structural transition from mainly ␣-conformation to ␤-conformation occurs because the protein molecule adopts a mainly ␤-conformation in silk fibers (13).…”

Section: Fig 2 Solution Structures Of Tusp1 Domains Ribbon Drawingmentioning

confidence: 94%

Solution structure of eggcase silk protein and its implications for silk fiber formation

Lin

Huang

Zhang

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

104

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Spider silks are renowned for their excellent mechanical properties and biomimetic and industrial potentials. They are formed from the natural refolding of water-soluble fibroins with ␣-helical and random coil structures in silk glands into insoluble fibers with mainly ␤-structures. The structures of the fibroins at atomic resolution and silk formation mechanism remain largely unknown. Here, we report the 3D structures of individual domains of a Ϸ366-kDa eggcase silk protein that consists of 20 identical type 1 repetitive domains, one type 2 repetitive domain, and conserved nonrepetitive N-and C-terminal domains. The structures of the individual domains in solution were determined by using NMR techniques. The domain interactions were investigated by NMR and dynamic light-scattering techniques. The formation of micelles and macroscopic fibers from the domains was examined by electron microscopy. We find that either of the terminal domains covalently linked with at least one repetitive domain spontaneously forms micelle-like structures and can be further transformed into fibers at >37°C and a protein concentration of >0.1 wt%. Our biophysical and biochemical experiments indicate that the less hydrophilic terminal domains initiate the assembly of the proteins and form the outer layer of the micelles whereas the more hydrophilic repetitive domains are embedded inside to ensure the formation of the micelle-like structures that are the essential intermediates in silk formation. Our results establish the roles of individual silk protein domains in fiber formation and provide the basis for designing miniature fibroins for producing artificial silks.NMR ͉ spider silk ͉ structural transition ͉ TuSp1 S pider silks are renowned for their excellent mechanical properties and biomimetic and industrial potentials. The orb-web spiders employ up to seven types of abdominal glands to produce silks for various purposes, ranging from prey capture to offspring protection in egg cases (1). Among seven different types of silks, tubuliform silk (eggcase silk) is unique because of its high serine and low glycine content (2, 3). Eggcase silk fibroins are synthesized only in female tubuliform (cylindrical) silk glands for the construction of protective egg cases, where eggs undergo development. A number of eggcase silk cDNA clones from orb-weaver superfamilies have recently been isolated (4-8). The length of eggcase silk cDNA varies from 10 to 13 kb in different species. The sequence of the inferred protein, tubuliform spidroin 1 (TuSp1) accounts for the amino acid (aa) composition of tubuliform silk very well, indicating that TuSp1 is the major component of eggcase silk (4-8). Both in situ hybridization and immunoblot analyses show that TuSp1 is expressed specifically in the tubuliform gland (4). Eggcase silk must be sufficiently robust to resist different threats, such as predator/parasitoid invasion or temperature fluctuations. Compared with the widely studied spider dragline silk, eggcase silk is slightly less tough but more resistant ...

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Section: Fig 2 Solution Structures Of Tusp1 Domains Ribbon Drawingmentioning

confidence: 94%

Solution structure of eggcase silk protein and its implications for silk fiber formation

Lin

Huang

Zhang

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

104

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“…The excellent mechanical properties of spider silk have received intense scrutiny over the years [1][2][3]. Transgenic and recombinant protein routes have been investigated to produce engineered spider silk fibres [4,5].…”

Section: Introductionmentioning

confidence: 99%

Intrinsic tensile properties of cocoon silk fibres can be estimated by removing flaws through repeated tensile tests

Rajkhowa

Kaur

Wang

et al. 2015

J. R. Soc. Interface.

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Silk fibres from silkworm cocoons have lower strength than spider silk and have received less attention as a source of high-performance fibres. In this work, we have used an innovative procedure to eliminate the flaws gradually of a single fibre specimen by retesting the unbroken portion of the fibre, after each fracture test. This was done multiple times so that the final test may provide the intrinsic fibre strength. During each retest, the fibre specimen began to yield once the failure load of the preceding test was exceeded. For each fibre specimen, a composite curve was constructed from multiple tests. , which is used as a benchmark for developing high-performance fibres. This retesting approach is likely to provide useful insights into discrete flaw distributions and intrinsic mechanical properties of other fatigue-resistant materials.

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“…19,20 Moreover, despite the differences in primary sequences between silk from spiders and silkworms, both have been suggested to exhibit similar secondary structural features. 21 Hexafluoro-isopropanol (HFIP) is an organic solvent employed in artificial spinning and the regeneration of the silk fiber, and results in fibers with similar structural and mechanical features as the native fiber. [22][23][24][25][26] Moreover, the difficulties associated with solubilizing hydrophobic sequences at concentrations relevant for NMR measurements are diminished by low polarity solvents such as HFIP.…”

Section: Introductionmentioning

confidence: 99%

High‐resolution NMR characterization of a spider‐silk mimetic composed of 15 tandem repeats and a CRGD motif

McLachlan¹,

Mantz²,

Kaplan³

et al. 2008

Protein Science

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Multidimensional solution NMR spectroscopic techniques have been used to obtain atomic level information about a recombinant spider silk construct in hexafluoro-isopropanol (HFIP). The synthetic 49 kDa silk-like protein mimics authentic silk from Nephila clavipes, with the inclusion of an extracellular matrix recognition motif. 2D 1 H-15 N HSQC NMR spectroscopy reveals 33 cross peaks, which were assigned to amino acid residues in the semicrystalline repeat units. Signals from the amorphous segments in the primary sequence were weak and broad, suggesting that this region is highly dynamic and undergoing conformational exchange. An analysis of the deviations of the 13 C a , 13 C b , and 13 CO chemical shifts relative to the expected random coil values reveals two highly a-helical regions from amino acid 12-19 and 26-32, which comprise the polyalanine track and a GGLGSQ sequence. This finding is further supported by /-value analysis and sequential and medium-range NOE interactions. Pulsed field gradient NMR measurements indicate that the topology of the silk mimetic in HFIP is nonglobular. Moreover, the 3D 15 N-NOESY HSQC spectrum exhibits few long-range NOEs. Similar spectral features have been observed for repeat modules in other polypeptides and are characteristic of an elongated conformation. The results provide a residue-specific description of a silk sequence in nonaqueous solution and may be insightful for understanding the fold and topology of highly concentrated, stable silk before spinning. Additionally, the insights obtained may find application in future design and large-scale production and storage of synthetic silks in organic solvents.

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Comparing the rheology of native spider and silkworm spinning dope

Cited by 160 publications

References 26 publications

Solution structure of eggcase silk protein and its implications for silk fiber formation

Solution structure of eggcase silk protein and its implications for silk fiber formation

Intrinsic tensile properties of cocoon silk fibres can be estimated by removing flaws through repeated tensile tests

High‐resolution NMR characterization of a spider‐silk mimetic composed of 15 tandem repeats and a CRGD motif

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