The other prey-capture silk: fibres made by glow-worms (Diptera: Keroplatidae) comprise cross-β-sheet crystallites in an abundant amorphous fraction

Walker, Andrew A., Weisman, Sarah, Trueman, Holly E., Merritt, David J. and Sutherland, Tara D. (2015) The other prey-capture silk: fibres made by glow-worms (Diptera: Keroplatidae) comprise cross-β-sheet crystallites in an abundant amorphous fraction. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 187 78-84. doi:10.1016/j.cbpb.2015.05.008

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Author Walker, Andrew A.
Weisman, Sarah
Trueman, Holly E.
Merritt, David J.
Sutherland, Tara D.
Title The other prey-capture silk: fibres made by glow-worms (Diptera: Keroplatidae) comprise cross-β-sheet crystallites in an abundant amorphous fraction
Journal name Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology   Check publisher's open access policy
ISSN 1879-1107
1096-4959
Publication date 2015-09-01
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.cbpb.2015.05.008
Open Access Status File (Author Post-print)
Volume 187
Start page 78
End page 84
Total pages 7
Place of publication Philadelphia, PA United States
Publisher Elsevier
Collection year 2016
Language eng
Formatted abstract
Glow-worms (larvae of dipteran genus Arachnocampa) are restricted to moist habitats where they capture flying prey using snares composed of highly extensible silk fibres and sticky mucus droplets. Little is known about the composition or structure of glow-worm snares, or the extent of possible convergence between glow-worm and arachnid capture silks. We characterised Arachnocampa richardsae silk and mucus using X-ray scattering, Fourier transform infrared spectroscopy and amino acid analysis. Silk but not mucus contained crystallites of the cross-β-sheet type, which occur in unrelated insect silks but have not been reported previously in fibres used for prey capture. Mucus proteins were rich in Gly (28.5%) and existed in predominantly a random coil structure, typical of many adhesive proteins. In contrast, the silk fibres were unusually rich in charged and polar residues, particularly Lys (18.1%), which we propose is related to their use in a highly hydrated state. Comparison of X-ray scattering, infrared spectroscopy and amino acid analysis data suggests that silk fibres contain a high fraction of disordered protein. We suggest that in the native hydrated state, silk fibres are capable of extension via deformation of both disordered regions and cross-β-sheet crystallites, and that high extensibility is an adaptation promoting successful prey capture. This study illustrates the rich variety of protein motifs that are available for recruitment into biopolymers, and how convergently evolved materials can nevertheless be based on fundamentally different protein structures.
Keyword Silk
Arachnocampa
Glow-worm
Cross-β-sheet
Flagelliform
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Biological Sciences Publications
 
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