Orientational order of Australian spider silks as determined by solid‐state NMR

Bonev, Boyan B.; Grieve, Stuart M.; Herberstein, Marie E.; Kishore, A. I.; Watts, Anthony; Separovic, Frances

doi:10.1002/bip.20471

Cited by 32 publications

(28 citation statements)

References 47 publications

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“…While this is a widely used technique and adequate for making standardized across and between treatment intra- and inter-specific comparisons [2], [8], [32], any comparison with other studies should consider that other methods with different levels of precision may have been used to derive amino acid composition. Nuclear magnetic resonance (NMR) and other spectroscopic methods are becoming more widely used in silk research [14], [19], [25], [62] as these methods have lower amino acid compositional variability associated with their analyses compared to traditional methods [14], [62], [63]. We therefore cannot rule out MaSp expression as a means by which the MA silks of the spiders examined here vary with protein intake until adequate comparable NMR studies are done.…”

Section: Resultsmentioning

confidence: 99%

Variation in Protein Intake Induces Variation in Spider Silk Expression

Blamires

Tso

2012

PLoS ONE

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BackgroundIt is energetically expensive to synthesize certain amino acids. The proteins (spidroins) of spider major ampullate (MA) silk, MaSp1 and MaSp2, differ in amino acid composition. Glutamine and proline are prevalent in MaSp2 and are expensive to synthesize. Since most orb web spiders express high proline silk they might preferentially attain the amino acids needed for silk from food and shift toward expressing more MaSp1 in their MA silk when starved.Methodology/Principal FindingsWe fed three spiders; Argiope aetherea, Cyrtophora moluccensis and Leucauge blanda, high protein, low protein or no protein solutions. A. aetherea and L. blanda MA silks are high in proline, while C. moluccesnsis MA silks are low in proline. After 10 days of feeding we determined the amino acid compositions and mechanical properties of each species' MA silk and compared them between species and treatments with pre-treatment samples, accounting for ancestry. We found that the proline and glutamine of A. aetherea and L. blanda silks were affected by protein intake; significantly decreasing under the low and no protein intake treatments. Glutmaine composition in C. moluccensis silk was likewise affected by protein intake. However, the composition of proline in their MA silk was not significantly affected by protein intake.ConclusionsOur results suggest that protein limitation induces a shift toward different silk proteins with lower glutamine and/or proline content. Contradictions to the MaSp model lie in the findings that C. moluccensis MA silks did not experience a significant reduction in proline and A. aetherea did not experience a significant reduction in serine on low/no protein. The mechanical properties of the silks could not be explained by a MaSp1 expressional shift. Factors other than MaSp expression, such as the expression of spidroin-like orthologues, may impact on silk amino acid composition and spinning and glandular processes may impact mechanics.

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Section: Resultsmentioning

confidence: 99%

Variation in Protein Intake Induces Variation in Spider Silk Expression

Blamires

Tso

2012

PLoS ONE

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“…The presence of multiple populations in fibrous proteins is a recurring theme, as the proportions of crystalline and amorphous domains were used to explain the differences in physical properties of Australian spider silks, for example. 35,36 In contrast to the spider silks, there are crystalline domains in neither the native protein elastin nor the mimetics of its hydrophobic domain. Instead, the proportions in the various conformations are thought to shift with physical changes, such as solvent and stretching.…”

Section: Discussionmentioning

confidence: 99%

Structural insights into the elastin mimetic (LGGVG)₆ using solid‐state ¹³C NMR experiments and statistical analysis of the PDB

Kumashiro¹,

Ohgo²,

Niemczura³

et al. 2008

Biopolymers

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Elastin is a crosslinked hydrophobic protein found in abundance in vertebrate tissue and is the source of elasticity in connective tissues and blood vessels. The repeating polypeptide sequences found in the hydrophobic domains of elastin have been the focus of many studies that attempt to understand the function of the native protein on a molecular scale. In this study, the central residues of the (LGGVG)(6) elastin mimetic are targeted. Using a combination of a statistical analysis based on structures in the Brookhaven Protein Data Bank (PDB), 1D cross-polarization magic-angle-spinning (CPMAS) NMR spectroscopy, and 2D off-magic-angle-spinning (OMAS) spin-diffusion experiments, it is determined that none of the residues are found in a singular regular, highly ordered structure. Instead, like the poly(VPGVG) elastin mimetics, there are multiple conformations and significant disorder. Furthermore, the conformational ensembles are not reflective of proteins generally, as in the PDB, suggesting that the structure distributions in elastin mimetics are unique to these peptides and are a salient feature of the functional model of the native protein.

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“…The large chemical shift anisotropies of 15 N and 13 C in the amide and carbonyl regions can be exploited to establish the relative orientation of peptide planes with respect to the fiber axis (89)(90)(91)(93)(94)(95). The values of the interaction tensor in its PAS are extracted from a powder spectrum measured on an unoriented sample (89,90).…”

Section: Measurement Of Interaction Tensors In Oriented Samplesmentioning

confidence: 99%

Studying natural structural protein fibers by solid‐state nuclear magnetic resonance

Arnold

Marcotte

2009

Concepts Magnetic Resonance

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As a consequence of evolutionary pressure, various organisms have developed structural fibers displaying a range of exceptional mechanical properties adapted specifically to their functions. An understanding of these properties at the molecular level requires a detailed description of local structure, orientation with respect to the fiber and size of constitutive units, and dynamics on various timescales. The size and lack of long-range order in these protein systems constitute an important challenge to classical structural techniques such as high-resolution NMR and X-ray diffraction. Solidstate NMR overcomes these constraints and is uniquely suited to the study of these inherently disordered systems. Solid-state NMR experiments developed or applied to determine structure, orientation, and dynamics of these complex proteins will be reviewed and illustrated through examples of their applications to fibers such as spider and silkworm silks, collagen, elastin, and keratin.

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Orientational order of Australian spider silks as determined by solid‐state NMR

Cited by 32 publications

References 47 publications

Variation in Protein Intake Induces Variation in Spider Silk Expression

Variation in Protein Intake Induces Variation in Spider Silk Expression

Structural insights into the elastin mimetic (LGGVG)₆ using solid‐state ¹³C NMR experiments and statistical analysis of the PDB

Studying natural structural protein fibers by solid‐state nuclear magnetic resonance

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Orientational order of Australian spider silks as determined by solid‐state NMR

Cited by 32 publications

References 47 publications

Variation in Protein Intake Induces Variation in Spider Silk Expression

Variation in Protein Intake Induces Variation in Spider Silk Expression

Structural insights into the elastin mimetic (LGGVG)6 using solid‐state 13C NMR experiments and statistical analysis of the PDB

Studying natural structural protein fibers by solid‐state nuclear magnetic resonance

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Product

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Structural insights into the elastin mimetic (LGGVG)₆ using solid‐state ¹³C NMR experiments and statistical analysis of the PDB