Unraveling A Trap-and-Trigger Mechanism in the pH-Sensitive Self-Assembly of Spider Silk Proteins.

ABSTRACT: When the major ampulate spidroins (MaSp1) are called upon to form spider dragline silk, one of nature's most amazing materials, a small drop in pH must occur. Using a state-of-the-art simulation technique, constant pH molecular dynamics, we discovered a few residues that respond to the pH signal in the dimerization of the N-terminal domain (NTD) of MaSp1 which is an integral step in the fiber assembly. At neutral pH the deprotonation of Glu79 and Glu119 leads to water penetration and structural changes at the monomer-monomer binding interface. At strongly acidic pH, the protonation of Asp39 and Asp40 weakens the electrostatic attraction between the monomers. Thus, we propose a "trap-and-trigger" mechanism whereby the intermolecular salt-bridges at physiologically relevant pH conditions alw

SUBMITTER: Wallace JA 

PROVIDER: S-EPMC3410443 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature