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Variations in major and minor ampullate silk proteins from Araneus gemmoides

Posted on:2002-06-28Degree:Ph.DType:Dissertation
University:University of WyomingCandidate:Contento, Anthony LouisFull Text:PDF
GTID:1461390011495242Subject:Biology
Abstract/Summary:
Spider silk proteins are the subject of scientific study because of their mechanical properties. Araneoid major ampullate dragline silk has incredible toughness and moderate elasticity. Araneoid minor ampullate silk is strong, but not elastic. The focus of this project was to determine the necessary protein sequence motifs and the tolerance for variation in araneoid and non-araneoid major and minor ampullate silks to maintain mechanical properties. Two species of spiders were chosen for this study: the araneoid orb-weaving spider, Araneus gemmoides; and the non-araneoid funnel/sheet web-weaver, Agelenopsis aperata.; Results from this study have provided a better understanding of the necessary motifs in araneoid silk proteins and the tolerance for variation within their sequence. Araneus gemmoides MaSp1 contains a GQ-GGY-GGL-GSA-GA peptide that is conserved across the higher araneoids, all though there is variation of its placement within the repeat between species. A. gemmoides MaSp2 contains a heptameric Gly-Pro peptide (GPGSGQQ) followed by three GPGXX pentamers. This repeat sequence matches more closely with the heptamer-pentamer-octamer-pentamer sequence used by the Argiope and Gasterancantha spider, rather than the multiple pentamers used by species of Nephila. One MiSp protein was found for A. gemmoides, but when compared with minor ampullate silk sequences for Araneus diadematus (ADF-1) and Nephila clavipes (MiSp1 and MiSp2), it appears that ADF-1 and Araneus gemmoides MiSp are two similar, but different proteins. C-terminal sequences for major and minor ampullate proteins in all studied species of spiders show strong conservation. The sequences SXLXSP and QALLE are conserved across all species and the sequence: SRLSSPxAxSRVSSAVLVAAGxPxxTxxAALSxxISxxVS QISA SNPGLSGCDVLxAQLLExVSALAxILxSSIGQVN This sequence is conserved amongst the araneoid species, within this region. Since the mechanical properties of the araneoid silks are the same, this study has identified the necessary motifs and the allowable sequence variation in Araneus gemmoides and other araneoid spiders to maintain the specific structural and physical properties within these silks.
Keywords/Search Tags:Silk, Araneusgemmoides, Ampullate, Araneoid, Variation, Major, Mechanicalproperties
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