title: An investigation of the divergence of major ampullate silk fibers from Nephila clavipes and Argiope aurantia.
abstract: The major ampullate fiber of both Nephila clavipes and Argiope aurantia is composed of two different proteins, MaSp1 and MaSp2. Each of these proteins has a highly conserved pattern of silk-associated amino acid motifs. The GPGXX motif is the only source of proline and is unique to MaSp2. On the basis of the percent of proline, Nephila clavipes major ampullate silk was calculated to consist of 19% MaSp2 and 81% MaSp1, while Argiope aurantia was calculated to have a significantly higher MaSp2 content of 59% with MaSp1 comprising the remaining 41%. To investigate the functional implications of the difference in protein composition, major ampullate silk fibers from Nephila clavipes and Argiope aurantia were mechanically tested and compared. Stress-strain curves produced from polynomial regression show that the two significant differences between major ampullate silk fibers from Nephila clavipes and Argiope aurantia are the average peak load stress and Young's modulus, with Argiope higher for both.
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071, USA. abrooks@uwyo.edu
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Brooks
authors.forename: Holly B
authors.initials: HB
authors.lastname: Steinkraus
authors.forename: Shane R
authors.initials: SR
authors.lastname: Nelson
authors.forename: Randolph V
authors.initials: RV
authors.lastname: Lewis
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D017124:Conserved Sequence; D019143:Evolution, Molecular; D005260:Female; D005349:Fibroins / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D015233:Models, Statistical; D008969:Molecular Sequence Data; D011392:Proline / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D012044:Regression Analysis; D047011:Silk / Q000737:chemistry*; D013045:Species Specificity; D013112:Spiders; D013314:Stress, Mechanical
chemical_list: D001672:Biocompatible Materials; D046911:Macromolecular Substances; D011506:Proteins; D047011:Silk; D005349:Fibroins; D011392:Proline