Diversified Structural Basis of a Conserved Molecular Mechanism for pH-Dependent Dimerization in Spider Silk N-Terminal Domains

Abstract

Conversion of spider silk proteins from soluble dope to insoluble fibers involves pH-dependent dimerization of the N-terminal domain (NT). This conversion is tightly regulated to prevent premature precipitation and enable rapid silk formation at the end of the duct. Three glutamic acid residues that mediate this process in the NT from Euprosthenops australis major ampullate spidroin 1 are well conserved among spidroins. However, NTs of minor ampullate spidroins from several species, including Araneus ventricosus ((Av)MiSp NT), lack one of the glutamic acids. Here we investigate the pH-dependent structural changes of (Av)MiSp NT, revealing that it uses the same mechanism but involves a non-conserved glutamic acid residue instead. Homology modeling of the structures of other MiSp NTs suggests that these harbor different compensatory residues. This indicates that, despite sequence variations, the molecular mechanism underlying pH-dependent dimerization of NT is conserved among different silk types.

Keywords

NMR structure; pH sensitivity; protein conformation; spidroins

Published in

ChemBioChem
2015, Volume: 16, number: 12, pages: 1720-1724 Publisher: WILEY-V C H VERLAG GMBH

SLU Authors

• Rising, Anna

  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    
  • Karolinska Institute

• Johansson, Jan

  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    
  • Karolinska Institute
  • Tallinn University

UKÄ Subject classification

Cell and Molecular Biology


Publication identifier

DOI: https://doi.org/10.1002/cbic.201500263

Permanent link to this page (URI)

https://res.slu.se/id/publ/68644