NMR SOLUTION STRUCTURE OF THE 21 KDA CHAPERONE PROTEIN DNAK SUBSTRATE-BINDING DOMAIN - A PREVIEW OF CHAPERONE-PROTEIN INTERACTION

The solution structure of the 21 kDa substrate-binding domain of the E scherichia coli Hsp70-chaperone protein DnaK (DnaK 386-561) has been d etermined to a precision of 1.00 Angstrom (backbone of the beta-domain ) from 1075 experimental restraints obtained from multinuclear, multid imensional NMR experiments. The domain is observed to bind to its own C-terminus and offers a preview of the interaction of this chaperone w ith other proteins. The bound protein region is tightly held at a sing le amino acid position (a leucyl residue) that is buried in a deep poc ket lined with conserved hydrophobic residues. A second hydrophobic bi nding site was identified using paramagnetically labeled peptides. It is located in a region close to the N-terminus of the domain and may c onstitute the allosteric region that links substrate-binding affinity with nucleotide binding in the Hsp70 chaperones.