Diversity of Molecular Transformations Involved in the Formation of Spider Silks

Lefèvre, Thierry; Boudreault, Simon; Cloutier, Conrad; Pézolet, Michel

doi:10.1016/j.jmb.2010.10.052

Cited by 81 publications

(119 citation statements)

References 69 publications

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“…Raman measurements have shown that this filament basically shares the same structural pattern than the Ac silk in terms of molecular orientation and protein conformation. 60 The Raman results thus suggest that the Pyr silk would be relatively extensible with a relatively large strength, possibly conferring to it a resistance comparable to that of the Ac silk fiber.…”

Section: Structure Of Silk By Raman Spectromicroscopy 329mentioning

confidence: 92%

“…60 An example is given in Figure 9 where the spectrum of the dope of the Ac gland is compared with the orientation-insensitive spectrum of the wrapping silk fiber calculated from the polarized spectra. The fact that the amide I band is initially located at 1657 cm 21 , that the amide III band is weak and located at 1276 cm 21 , and the presence of a small band at 522 cm 21 lead to the conclusion that the proteins mainly adopt an a-helix conformation in the sac of the gland.…”

Section: Conformation Of the Other Spider Silks Before Spinningmentioning

confidence: 99%

“…This is the case for the Cyl and Pyr glands. 60 Despite the similarity of their protein conformations before spinning, the corresponding fibers are not necessarily made of proteins that adopt similar conformations, although this can also happen. 57 The Flag silk is peculiar in that, as opposed to the other types of silk, the FIGURE 9 Spectrum of the spinning dope contained in the ampulla of the Ac gland of N. clavipes compared with the orientation-insensitive spectrum of the fiber calculated from the polarized spectra.…”

Section: Conformation Of the Other Spider Silks Before Spinningmentioning

confidence: 99%

“…60 The first class corresponds to more primitive silks: they are not constituted of the small repetitive motifs which are considered as the hallmark of silk proteins, they are predominantly folded into ahelices and they have a strong b-aggregation propensity. The proteins belonging to the second class, forming more recent silks, are basically constituted of small repetitive motifs, they are natively unfolded and they have a weak b-aggregation propensity.…”

Section: Structure Of Silk By Raman Spectromicroscopy 333mentioning

confidence: 99%

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Structure of silk by raman spectromicroscopy: From the spinning glands to the fibers

et al. 2011

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Raman spectroscopy has long been proved to be a useful tool to study the conformation of protein‐based materials such as silk. Thanks to recent developments, linearly polarized Raman spectromicroscopy has appeared very efficient to characterize the molecular structure of native single silk fibers and spinning dopes because it can provide information relative to the protein secondary structure, molecular orientation, and amino acid composition. This review will describe recent advances in the study of the structure of silk by Raman spectromicroscopy. A particular emphasis is put on the spider dragline and silkworm cocoon threads, other fibers spun by orb‐weaving spiders, the spinning dope contained in their silk glands and the effect of mechanical deformation. Taken together, the results of the literature show that Raman spectromicroscopy is particularly efficient to investigate all aspects of silk structure and production. The data provided can lead to a better understanding of the structure of the silk dope, transformations occurring during the spinning process, and structure and mechanical properties of native fibers. © 2011 Wiley Periodicals, Inc. Biopolymers 97: 322–336, 2012.

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Section: Structure Of Silk By Raman Spectromicroscopy 329mentioning

confidence: 92%

Section: Conformation Of the Other Spider Silks Before Spinningmentioning

confidence: 99%

Section: Conformation Of the Other Spider Silks Before Spinningmentioning

confidence: 99%

Section: Structure Of Silk By Raman Spectromicroscopy 333mentioning

confidence: 99%

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Structure of silk by raman spectromicroscopy: From the spinning glands to the fibers

et al. 2011

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“…Importantly, pH drops from 7.2 in the storage region to 6.3 in the first 0.5 mm of the duct and reaches an unknown value by the end of the ϳ20-mm duct (8). Collectively, these chemical and physical forces induce the spidroin molecules to align with the direction of flow, form ␤-sheets, and partition out of the aqueous phase to form a solid fiber (9,10). The fiber produced from the major ampullate gland is called dragline silk, and it is used in the main structural elements of an orb web and also as a hanging lifeline.…”

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confidence: 99%

Spidroin N-terminal Domain Promotes a pH-dependent Association of Silk Proteins during Self-assembly

Gaines

Sehorn

Marcotte

2010

Journal of Biological Chemistry

102

126

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Spider silks are spun from concentrated solutions of spidroin proteins. The appropriate timing of spidroin assembly into organized fibers must be highly regulated to avoid premature fiber formation. Chemical and physical signals presented to the silk proteins as they pass from the ampulle and through the tapered duct include changes in ionic environment and pH as well as the introduction of shear forces. Here, we show that the N-terminal domain of spidroins from the major ampullate gland (MaSp-NTDs) for both Nephila and Latrodectus spiders associate noncovalently as homodimers. The MaSp-NTDs are highly pH-responsive and undergo a structural transition in the physiological pH range of the spider duct. Tryptophan fluorescence of the MaSp-NTDs reveals a change in conformation when pH is decreased, and the pH at which the transition occurs is determined by the amount and type of salt present. Size exclusion chromatography and pulldown assays both indicate that the lower pH conformation is associated with a significantly increased MaSp-NTD homodimer stability. By transducing the duct pH signal into specific protein-protein interactions, this conserved spidroin domain likely contributes significantly to the silk-spinning process. Based on these results, we propose a model of spider silk assembly dynamics as mediated through the MaSp-NTD.

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Hydration‐Induced β‐Sheet Crosslinking of α‐Helical‐Rich Spider Prey‐Wrapping Silk

Stengel

Addison

Onofrei

et al. 2021

Adv Funct Materials

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Due to its moderate strength (≈700 MPa) and impressive extensibility before breaking (≈60–80%), orb‐weaving spider aciniform (AC) prey‐wrapping silks are actually the toughest of the spider silks but are remarkably understudied. The previous results indicate that native AC silk fibers are an α‐helix rich coiled‐coil/β‐sheet hybrid nanofiber, and that conversion of disordered or helical domains to β‐sheet aggregates is surprisingly minimal and overall β‐sheet content is low (≈15%). In this work, it is demonstrated through scanning electron microscopy that native AC silk fibers undergo matted cross‐linking upon exposure to moisture that increases silk stiffness. The unique molecular mechanism of water‐induced cross‐linking is revealed with solid‐state NMR (SSNMR) methods; water‐induced morphological changes are correlated with an increase in AC silk protein β‐sheet content, and additionally a minor unfolding of coiled‐coil regions is observed. Continued and increased β‐sheet cross‐linking is observed upon application of mechanical shear. The size of these β‐sheet domains to be 4–6 nm using Wide‐Line Separation SSNMR is determined. The observation that merely water treatment can be used to convert a protein‐based material from a flexible/extensible α‐helix‐rich fiber to a rigid crossed‐linked β‐sheet mat is a novel observation that should provide new avenues in bioinspired materials design.

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Diversity of Molecular Transformations Involved in the Formation of Spider Silks

Cited by 81 publications

References 69 publications

Structure of silk by raman spectromicroscopy: From the spinning glands to the fibers

Structure of silk by raman spectromicroscopy: From the spinning glands to the fibers

Spidroin N-terminal Domain Promotes a pH-dependent Association of Silk Proteins during Self-assembly

Hydration‐Induced β‐Sheet Crosslinking of α‐Helical‐Rich Spider Prey‐Wrapping Silk

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