title: Fifty years later: the sequence, structure and function of lacewing cross-beta silk.
abstract: Classic studies of protein structure in the 1950s and 1960s demonstrated that green lacewing egg stalk silk possesses a rare native cross-beta sheet conformation. We have identified and sequenced the silk genes expressed by adult females of a green lacewing species. The two encoded silk proteins are 109 and 67 kDa in size and rich in serine, glycine and alanine. Over 70% of each protein sequence consists of highly repetitive regions with 16-residue periodicity. The repetitive sequences can be fitted to an elegant cross-beta sheet structural model with protein chains folded into regular 8-residue long beta strands. This model is supported by wide-angle X-ray scattering data and tensile testing from both our work and the original papers. We suggest that the silk proteins assemble into stacked beta sheet crystallites bound together by a network of cystine cross-links. This hierarchical structure gives the lacewing silk high lateral stiffness nearly threefold that of silkworm silk, enabling the egg stalks to effectively suspend eggs and protect them from predators.
authors: CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia.
authors: Sarah
authors: S
authors: Weisman
authors: Shoko
authors: S
authors: Okada
authors: Stephen T
authors: ST
authors: Mudie
authors: Mickey G
authors: MG
authors: Huson
authors: Holly E
authors: HE
authors: Trueman
authors: Alagacone
authors: A
authors: Sriskantha
authors: Victoria S
authors: VS
authors: Haritos
authors: Tara D
authors: TD
authors: Sutherland
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D012831:Bombyx / Q000378:metabolism; D002853:Chromatography, Liquid; D005260:Female; D007313:Insecta / Q000378:metabolism*; D013058:Mass Spectrometry; D020527:Microscopy, Scanning Probe; D017433:Protein Structure, Secondary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D047011:Silk / Q000737:chemistry* / Q000502:physiology*
chemical_list: D047011:Silk