DETERMINATION OF THE BINDING FRAME WITHIN A PHYSIOLOGICAL LIGAND FOR THE CHAPERONE SECB

The hallmark of the class of proteins called chaperones is the amazing ability to bind tightly to a wide array of polypeptide ligands that h ave no consensus in sequence; chaperones recognize non-native structur e. As a step in the elucidation of the molecular mechanism of such rem arkable binding, we have characterized complexes between the bacterial chaperone SecB and a series of ligands related to maltose-binding pro tein. SecB interacts at multiple sites on its polypeptide ligand. The entire binding region covers approximately half of the primary sequenc e of maltose-binding protein and comprises contiguous sites positioned around the center of the sequence.