Open AccessBiP mutants that are unable to interact with endoplasmic reticulum DnaJ proteins provide insights into interdomain interactions in BiP
Author(s) -
Walid Awad,
Isaac Estrada,
Ying Shen,
Linda M. Hendershot
Publication year - 2008
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0702132105
Subject(s) - endoplasmic reticulum , atp hydrolysis , cyclic nucleotide binding domain , microbiology and biotechnology , atpase , nucleotide , biology , mutant , biochemistry , plasma protein binding , heat shock protein , chemistry , enzyme , gene
The heat shock protein (Hsp)70 family of molecular chaperones interacts with unfolded proteins through a C-terminal substrate-binding domain (SBD) that is controlled by nucleotide binding to the N-terminal domain. The ATPase cycle is regulated by cochaperones, including DnaJ proteins that accelerate ATP hydrolysis to stabilize the Hsp70–substrate complex. We found that R197 in hamster BiP, which resides at the surface of the nucleotide-binding domain, is critical for both association with endoplasmic reticulum DnaJ proteins and interaction with the SBD. Decreasing the positive charge at this residue enhanced basal ATPase activity, destabilized interaction with the SBD, and reduced substrate release bothin vitro andin vivo . Mutation of three glutamic acids in the SBD mimicked many of these effects. Our data provide insights into communications between the two domains and suggest a mechanism by which DnaJ proteins increase ATP hydrolysis.