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A multipronged approach to the mechanism of allostery in Hsp70 chaperones
Author(s) -
Gierasch Lila M,
Swain Joanna F,
Smock Robert G,
Dinler Gizem
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a964
Subject(s) - allosteric regulation , cyclic nucleotide binding domain , atp hydrolysis , linker , chemistry , docking (animal) , allosteric enzyme , nucleotide , biophysics , stereochemistry , biochemistry , biology , atpase , enzyme , medicine , nursing , computer science , gene , operating system
Hsp70 chaperones bind and release non‐native proteins in a process that relies on allosteric signaling between the nucleotide binding domain (NBD) and substrate binding domain (SBD): ATP‐binding/hydrolysis by the N‐terminal NBD regulates the affinity of the SBD for substrates, and conversely, binding of substrates enhances the NBD ATPase activity Taking advantage of the phylogenetic prevalence of Hsp70s, we identified clusters of evolutionarily co‐dependent residues in continuous structural pathways that suggest elements of an allosteric mechanism (R. Smock, J. Swain, W. Russ, R. Ranganathan, and L. Gierasch, submitted). We are testing the resulting model for allostery and interdomain docking using a complementary experimental approach. NMR study of a new stable construct of the DnaK SBD showed that the empty state is overall quite similar to the peptide‐bound state (J. Swain, E. Schulz, and L. Gierasch, J. Biol. Chem., paper in press 11/7/05). Moreover, the chemical shifts of the DnaK SBD and the NBD do not change in a two‐domain construct in the absence of ligands. Strikingly, ATP binding leads to a profound change in the SBD as well as the NBD. Thus, the two domains actively dock in the presence of ATP. We have discovered that an NBD construct retaining four conserved hydrophobic residues of the interdomain linker mimics the substrate‐activated NBD, arguing that the linker mediates allosteric communication. All of our results are converging on a model for the elusive and essential mode of interaction and allosteric signal transmission between the two domains of Hsp70s. [Supported by NIH grant GM027616]