75650-93-0

Species-specific antimicrobial therapy has the potential to combat the increasing threat of antibiotic resistance and alteration of the human microbiome. We therefore set out to demonstrate the beginning of a pathogen-selective drug discovery method using the periodontal pathogen Porphyromonas gingivalis as a model. Through our knowledge of metabolic networks and essential genes we identified a "druggable" essential target, meso-diaminopimelate dehydrogenase, which is found in a limited number of species. We adopted a highthroughput virtual screen method on the ZINC chemical library to select a group of potential small-molecule inhibitors. Meso-diaminopimelate dehydrogenase from P. gingivalis was first expressed and purified in Escherichia coli then characterized for enzymatic inhibitor screening studies. Several inhibitors with similar structural scaffolds containing a sulfonamide core and aromatic substituents showed dose-dependent inhibition. These compounds were further assayed showing reasonable whole-cell activity and the inhibition mechanism was determined. We conclude that the establishment of this target and screening strategy provides a model for the future development of new antimicrobials.

meso-Diaminopimelate dehydrogenase (EC 1.4.1.16) was purified to homogeneity from Corynebacterium glutamicum ATCC 13032.The enzyme had a molecular weight of about 70,000 and consisted of two subunits identical in molecular weight.The enzyme was highly specific for meso-2,6-diaminopimelate.The pH optima for deamination and amination were about 9.8 and 7.9, respectively.The Michaelis contants were 3.1 mM for meso-2,6-diaminopimelate, 0.12 mM for NADP+, 0.28mM for L-2-amino-6-ketopimelate, 36 mM for ammonia, and 0.13 mM for NADPH.D and L isomers of 2,6-diaminopimelate competitively inhibited the oxidative deamination of meso-2,6-diaminopimelate.The enzyme was distributed in a wider range of bacterial species than reported previously when assayed by a sensitive formazan formation method.