Determinants of Ugand Specificity in Groups I and IV WW domains

摘要

We have applied surface plasmon resonance to determine the ligand specificity of several WW domains containing Arg-14. Among these WW domains, Rsp5.2 and mNedd4.3 bound only to the Group I ligand containing Pro-Pro-Xaa-Tyr with K_D values of 11 and 55μM, respectively. The WW domains of hPinl, C. elegans Pinl homologue (Y110), PinA and Sspl bound to Group IV ligands with K_D values ranging from 22 to 700 μM. PinA and Sspl do not have Argl7, unlike Pinl and Y110. The modeled structures of PinA and Sspl revealed that they conserve the structure and network of hydrogen bonds of Loop I, which are also formed in Pinl and Y110. We propose that this configuration of Loop I (referred to as the "p patch") is necessary for binding Group IV ligands, and that it can be used to predict the specificity and functions of other WW domains, hi addition, we have completed the back bone assignment of the WW domain of PinA.