Quantitative Correlation between the Protein Primary Sequences and Secondary Structures in Spider Dragline Silks

Jenkins, Janelle E.; Creager, Melinda S.; Lewis, Randolph V.; Holland, Gregory P.; Yarger, Jeffery L.

doi:10.1021/bm9010672

Cited by 109 publications

(148 citation statements)

References 62 publications

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“…The GPGXX motif likely forms -turns, and in the case of successive repetition a spiral is formed, as suggested for elastin [27,28]. NMR studies have shown that a fraction of (GA) n and GGX motifs in major ampullate silk are in -sheet as well as less ordered helical structures [23,27]. Table 1.…”

Section: Silk Structurementioning

confidence: 86%

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Recombinant Spider Silks—Biopolymers with Potential for Future Applications

2011

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Nature has evolved a range of materials that compete with man-made materials in physical properties; one of these is spider silk. Silk is a fibrous material that exhibits extremely high strength and toughness with regard to its low density. In this review we discuss the molecular structure of spider silk and how this understanding has allowed the development of recombinant silk proteins that mimic the properties of natural spider silks. Additionally, we will explore the material morphologies and the applications of these proteins. Finally, we will look at attempts to combine the silk structure with chemical polymers and how the structure of silk has inspired the engineering of novel polymers.

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Section: Silk Structurementioning

confidence: 86%

“…However, only 40% of poly-alanine -sheets in silk fibers are highly ordered while the other 60% exist as poorly aligned -sheet regions [22,23]. The GPGXX and GGX sequences form an amorphous region of protein folds that surrounds the crystalline regions of β-sheets ( Figure 1) [24].…”

Section: Silk Structurementioning

confidence: 99%

Recombinant Spider Silks—Biopolymers with Potential for Future Applications

2011

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“…However, the precise β-sheet content reported varies according to the measurement technique used. Analysis by solid state NMR spectroscopy or Raman microspectroscopy suggests levels of 30 -40%, [29][30][31] as opposed to about 20% identified by XRD. 32 Computer simulations of the crystalline components of silk suggest that the poly-alanine sections align anti-parallel in the H-bonding direction with parallel stacking in the side-chain direction to stabilize the β-sheets.…”

Section: Silk Structure After Spinningmentioning

confidence: 91%

Secondary Structure Transition and Critical Stress for a Model of Spider Silk Assembly

2016

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Spiders spin their silk from an aqueous solution to a solid fiber in ambient conditions. However, to date the assembly mechanism in the spider silk gland has not been satisfactorily explained. In this paper, we use molecular dynamics simulations to model N. clavipes MaSp1 dragline silk formation under shear flow and determine the secondary structure transitions leading to the experimentally observed fiber structures. While no experiments are performed on the silk fiber itself, insights from this polypeptide model can be transferred to the fiber scale. The novelty of this study lies in the calculation of the shear stress (300-700 MPa) required for fiber formation and identification of the amino acid residues involved in the transition. This is the first time that the shear stress has been quantified in connection with a secondary structure transition. By study of molecules containing varying numbers of contiguous MaSp1 repeats we identified the smallest molecule size that gives rise to a 'silk-like' structure contains six poly-alanine repeats.Through a probability analysis of the secondary structure we identify specific amino acids that transition from α-helix to β-sheet. In addition to portions of the poly-alanine section these amino acids include glycine, leucine and glutamine. Stability of β-sheet structures appears to arise from a close proximity in space of helices in the initial spidroin state. Our results are in agreement with the forces exerted by spiders in the silking process and the experimentally determined global secondary structure of spidroin and pulled MaSp1 silk. Our study emphasizes the role of shear in the assembly process of silk and can guide the design of microfluidic devices that attempt to mimic the natural spinning process and predict molecular requirements for the next generation of silk-based functional materials.

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“…In fact, this model first identified the secondary structure composition of the amorphous regions, showing a lack of alpha-helix conformations, but rather a disorderly mixture of structures resembling 3 1 helices and beta-turns, supporting a series of earlier experimental investigations. 26,[28][29][30] Silk's extraordinary properties on the macroscopic scale ultimately stem from the balance of strength and extensibility at the molecular scale. To assess the function of different protein domains, molecular-level deformation mechanisms of the protein composite were examined.…”

Section: Molecular Structure and Mechanics Of Silkmentioning

confidence: 99%

A Materiomics Approach to Spider Silk: Protein Molecules to Webs

Tarakanova

Buehler

2012

JOM

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The exceptional mechanical properties of hierarchical self-assembling silk biopolymers have been extensively studied experimentally and in computational investigations. A series of recent studies has been conducted to examine structure-function relationships across different length scales in silk, ranging from atomistic models of protein constituents to the spider web architecture. Silk is an exemplary natural material because its superior properties stem intrinsically from the synergistic cooperativity of hierarchically organized components, rather than from the superior properties of the building blocks themselves. It is composed of beta-sheet nanocrystals interspersed within less orderly amorphous domains, where the underlying molecular structure is dominated by weak hydrogen bonding. Protein chains are organized into fibrils, which pack together to form threads of a spider web. In this article we survey multiscale studies spanning length scales from angstroms to centimeters, from the amino acid sequence defining silk components to an atomistically derived spider web model, with the aim to bridge varying levels of hierarchy to elucidate the mechanisms by which structure at each composite level contributes to organization and material phenomena at subsequent levels. The work demonstrates that the web is a highly adapted system where both material and hierarchical structure across all length scales is critical for its functional properties.

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Quantitative Correlation between the Protein Primary Sequences and Secondary Structures in Spider Dragline Silks

Cited by 109 publications

References 62 publications

Recombinant Spider Silks—Biopolymers with Potential for Future Applications

Recombinant Spider Silks—Biopolymers with Potential for Future Applications

Secondary Structure Transition and Critical Stress for a Model of Spider Silk Assembly

A Materiomics Approach to Spider Silk: Protein Molecules to Webs

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