3LRD

Self-assembly of spider silk proteins is controlled by a pH-sensitive relay


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.173 

Starting Model: experimental
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This is version 1.4 of the entry. See complete history


Literature

Self-assembly of spider silk proteins is controlled by a pH-sensitive relay.

Askarieh, G.Hedhammar, M.Nordling, K.Saenz, A.Casals, C.Rising, A.Johansson, J.Knight, S.D.

(2010) Nature 465: 236-238

  • DOI: https://doi.org/10.1038/nature08962
  • Primary Citation of Related Structures:  
    3LR2, 3LR6, 3LR8, 3LRD

  • PubMed Abstract: 

    Nature's high-performance polymer, spider silk, consists of specific proteins, spidroins, with repetitive segments flanked by conserved non-repetitive domains. Spidroins are stored as a highly concentrated fluid dope. On silk formation, intermolecular interactions between repeat regions are established that provide strength and elasticity. How spiders manage to avoid premature spidroin aggregation before self-assembly is not yet established. A pH drop to 6.3 along the spider's spinning apparatus, altered salt composition and shear forces are believed to trigger the conversion to solid silk, but no molecular details are known. Miniature spidroins consisting of a few repetitive spidroin segments capped by the carboxy-terminal domain form metre-long silk-like fibres irrespective of pH. We discovered that incorporation of the amino-terminal domain of major ampullate spidroin 1 from the dragline of the nursery web spider Euprosthenops australis (NT) into mini-spidroins enables immediate, charge-dependent self-assembly at pH values around 6.3, but delays aggregation above pH 7. The X-ray structure of NT, determined to 1.7 A resolution, shows a homodimer of dipolar, antiparallel five-helix bundle subunits that lack homologues. The overall dimeric structure and observed charge distribution of NT is expected to be conserved through spider evolution and in all types of spidroins. Our results indicate a relay-like mechanism through which the N-terminal domain regulates spidroin assembly by inhibiting precocious aggregation during storage, and accelerating and directing self-assembly as the pH is lowered along the spider's silk extrusion duct.


  • Organizational Affiliation

    Department of Chemistry, Oslo University, 1033 Blindern, 0315 Oslo, Norway.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Major ampullate spidroin 1
A, B
137Euprosthenops australisMutation(s): 2 
Gene Names: MaSp1
UniProt
Find proteins for Q05H60 (Euprosthenops australis)
Explore Q05H60 
Go to UniProtKB:  Q05H60
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ05H60
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.228 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.173 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 68.383α = 90
b = 68.383β = 90
c = 97.781γ = 120
Software Package:
Software NamePurpose
REFMACrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-05-12
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-13
    Changes: Database references, Derived calculations
  • Version 1.3: 2024-02-21
    Changes: Data collection
  • Version 1.4: 2024-04-03
    Changes: Refinement description