Prolypeptide binding by the prokaryotic SH3-like domain of the diphtheria toxin repressor: A regulatory switch

A study was carried out to determine the solution structure of the intramolecular complex formed between the proline-rich segment and the SH3-like domain by using the NMR spectroscopy. The structural and biophysical studies suggest that the proline-rich peptide segment of diphtheria toxin repressor functions as a switch that modulates the activation of repressor activity.