DEMONSTRATION OF PROTEIN-PROTEIN INTERACTION SPECIFICITY BY NMR CHEMICAL-SHIFT MAPPING

Chemical shift mapping is becoming a popular method for studying prote in-protein interactions in solution. The technique is used to identify putative sites of interaction on a protein surface by detecting chemi cal shift perturbations in simple (H-1, N-15)-HSQC NMR spectra of a un iformly labeled protein as a function of added (unlabeled) target prot ein. The high concentrations required for these experiments raise ques tions concerning the possibility for non-specific interactions being d etected, thereby compromising the information obtained, We demonstrate here that the simple chemical shift mapping approach faithfully repro duces the known functional specificities among pairs of closely relate d proteins from the phosphoenolpyruvate:sugar phosphotransferase syste ms of Escherichia coli and Bacillus Subtilis.