The solution structure of the 21 kDa substrate-binding domain of the Escherichia
coli Hsp70-chaperone protein DnaK (DnaK 386-561) has been determined to a
precision of 1.00 A (backbone of the beta-domain) from 1075 experimental
restraints obtained from multinuclear, multidimensional NMR experiments. The
domain is observed to bind to its own C-terminus and offers a preview of the
interaction of this chaperone with other proteins. The bound protein region is
tightly held at a single amino acid position (a leucyl residue) that is buried
in a deep pocket lined with conserved hydrophobic residues. A second hydrophobic
binding site was identified using paramagnetically labeled peptides. It is
located in a region close to the N-terminus of the domain and may constitute the
allosteric region that links substrate-binding affinity with nucleotide binding
in the Hsp70 chaperones.
