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Diversified Structural Basis of a Conserved Molecular Mechanism for pH‐Dependent Dimerization in Spider Silk N‐Terminal Domains
Author(s) -
Otikovs Martins,
Chen Gefei,
Nordling Kerstin,
Landreh Michael,
Meng Qing,
Jörnvall Hans,
Kronqvist Nina,
Rising Anna,
Johansson Jan,
Jaudzems Kristaps
Publication year - 2015
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201500263
Subject(s) - silk , spider silk , glutamic acid , spider , biophysics , biochemistry , biology , residue (chemistry) , concerted evolution , homology (biology) , peptide sequence , conserved sequence , amino acid , chemistry , phylogenetics , materials science , zoology , gene , composite material
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.