Mapping of Hsp70-binding sites on protein antigens.

Hsp70-binding sites were mapped on three antigens, the 16-, 19- and 38-kDa proteins of Mycobacterium tuberculosis, using overlapping synthetic peptides in a competitive-binding assay. In each protein, two or three prominent hsp70-binding sites were identified when peptides 20-amino-acid long were used, predominantly in regions containing clusters of aliphatic amino acids. Although there was an overall concordance in the pattern of peptide binding to hsp70 from bacterial (M. tuberculosis) and mammalian sources (immunoglobulin heavy-chain-binding protein), some differences in the specificity of polypeptide binding and the effect of peptides on ATPase activity were observed.