3LR2

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.160 

wwPDB Validation 3D Report Full Report


This is version 1.1 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: 10.1038/nature08962
  • Primary Citation of Related Structures:  

  • 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, intermolecula ...

    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

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Major ampullate spidroin 1
A, B
137Euprosthenops australisMutation(s): 0 
Gene Names: MaSp1
Find proteins for Q05H60 (Euprosthenops australis)
Go to UniProtKB:  Q05H60
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
EDO
Query on EDO

Download SDF File 
Download CCD File 
A
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
PEG
Query on PEG

Download SDF File 
Download CCD File 
B
DI(HYDROXYETHYL)ETHER
C4 H10 O3
MTHSVFCYNBDYFN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.160 
  • Space Group: P 32 2 1
Unit Cell:
Length (Å)Angle (°)
a = 68.379α = 90.00
b = 68.379β = 90.00
c = 97.857γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-05-12
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance