Amyloidogenic nature of spider silk.
In spiders soluble proteins are converted to form insoluble silk fibres, stronger than steel. The final fibre product has long been the subject of study; however, little is known about the conversion process in the silk-producing gland of the spider. Here we describe a study of the conversion of the soluble form of the major spider-silk protein, spidroin, directly extracted from the silk gland, to a beta-sheet enriched state using circular dichroism (CD) spectroscopy. Combined with electron microscopy (EM) data showing fibril formation in the beta-sheet rich region of the gland and amino-acid sequence analyses linking spidroin and amyloids, these results lead us to suggest that the refolding conversion is amyloid like. We also propose that spider silk could be a valuable model system for testing hypotheses concerning beta-sheet formation in other fibrilogenic systems, including amyloids.
Kenney
John M
JM
Institute for Storage Ring Facilities, University of Aarhus, Denmark. kenney@ifa.au.dk
Knight
David
D
Wise
Michael J
MJ
Vollrath
Fritz
F
D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry*; D000818:Animals; D002942:Circular Dichroism; D005088:Exocrine Glands / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D005349:Fibroins; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000648:ultrastructure; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D013112:Spiders / Q000737:chemistry*; D013696:Temperature
D000682:Amyloid; D011506:Proteins; C076815:spidroin 2; D005349:Fibroins