Specificity of DnaK-peptide binding.

The sequence specificity of DnaK substrate binding has been studied using a peptide display library. Based on the amino acid patterns that appeared in this selection, short peptides were synthesized for direct measurements of DnaK affinity. The results show that peptides enriched in internal hydrophobic residues are preferential DnaK substrates, and negatively charged peptides have poor affinity. The isolated C-terminal domain of DnaK binds peptides. Peptide dissociation studies indicate that bound peptides are released from the C-terminal fragment and from DnaK at identical rates. ATP stimulates peptide dissociation from DnaK but not from the C-terminal fragment.