Crystallographic study of in transglycosylase suggests pharmacophore for virtual hibitors of tRNA-guanine a new structure-based screening

The enzyme tRNA-guanine transglycosylase (TGT) is involved in the pathogenicity of Shigellae. As the crystal structure of this protein is known, it is a putative target for the structure-based design of inhibitors. Here we report a crystallographic study of several new ligands exhibiting a 2,6-diamino-3H-quinazolin-4-one scaffold, which has been shown recently to be a promising template for TGT-inhibitors. Crystal structure analysis of these complexes has revealed an unexpected movement of the side-chain of Asp102. A detailed analysis of the water network disrupted by this rotation has lead to the derivation of a new composite pharmacophore. A virtual screening has been performed based on this pharmacophore hypothesis and several new inhibitors of micromolar binding affinity with new skeletons have been discovered. (C) 2004 Elsevier Ltd. All rights reserved.