title: Spider wrapping silk fibre architecture arising from its modular soluble protein precursor.
abstract: Spiders store spidroins in their silk glands as high concentration aqueous solutions, spinning these dopes into fibres with outstanding mechanical properties. Aciniform (or wrapping) silk is the toughest spider silk and is devoid of the short amino acid sequence motifs characteristic of the other spidroins. Using solution-state NMR spectroscopy, we demonstrate that the 200 amino acid Argiope trifasciata AcSp1 repeat unit contrasts with previously characterized spidroins, adopting a globular 5-helix bundle flanked by intrinsically disordered N- and C-terminal tails. Split-intein-mediated segmental NMR-active isotope-enrichment allowed unambiguous demonstration of modular and malleable "beads-on-a-string" concatemeric behaviour. Concatemers form fibres upon manual drawing with silk-like morphology and mechanical properties, alongside secondary structuring and orientation consistent with native AcSp1 fibres. AcSp1 structural stability varies locally, with the fifth helix denaturing most readily. The structural transition of aciniform spidroin from a mostly α-helical dope to a mixed α-helix/β-sheet-containing fibre can be directly related to spidroin architecture and stability.
authors.affiliation: Department of Biochemistry &Molecular Biology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Marie-Laurence
authors.initials: ML
authors.lastname: Tremblay
authors.affiliation: 1] Department of Biochemistry &Molecular Biology, Dalhousie University, Halifax, NS, Canada [2] Institute of Biological Sciences and Biotechnology, Donghua University, Shanghai, P.R. China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Xu
authors.affiliation: Département de Chimie, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA) Université Laval, Québec, QC, Canada.
authors.forename: Thierry
authors.initials: T
authors.lastname: Lefèvre
authors.affiliation: Department of Biochemistry &Molecular Biology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Muzaddid
authors.initials: M
authors.lastname: Sarker
authors.affiliation: Department of Biochemistry &Molecular Biology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Orrell
authors.affiliation: Département de Chimie, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA) Université Laval, Québec, QC, Canada.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Leclerc
authors.affiliation: Institute of Biological Sciences and Biotechnology, Donghua University, Shanghai, P.R. China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Meng
authors.affiliation: Département de Chimie, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA) Université Laval, Québec, QC, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Pézolet
authors.affiliation: Département de Chimie, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA) Université Laval, Québec, QC, Canada.
authors.forename: Michèle
authors.initials: M
authors.lastname: Auger
authors.affiliation: Department of Biochemistry &Molecular Biology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Xiang-Qin
authors.initials: XQ
authors.lastname: Liu
authors.affiliation: 1] Department of Biochemistry &Molecular Biology, Dalhousie University, Halifax, NS, Canada [2] Department of Chemistry, Dalhousie University, Halifax, NS, Canada.
authors.forename: Jan K
authors.initials: JK
authors.lastname: Rainey
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D000067493:Dynamic Light Scattering; D005349:Fibroins / Q000737:chemistry; D057446:Hydrodynamics; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D011498:Protein Precursors / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D047011:Silk / Q000737:chemistry*; D013112:Spiders / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D047011:Silk; D005349:Fibroins