National Center for
4N9A: E. Coli Sliding Clamp In Complex With (r)-6-chloro-2,3,4,9-tetrahydro- 1h-carbazole-1-carboxylic Acid
J. Med. Chem. (2014) 57 p.2799-2806
The bacterial sliding clamp (SC), also known as the DNA polymerase III beta subunit, is an emerging antibacterial target that plays a central role in DNA replication, serving as a protein-protein interaction hub with a common binding pocket to recognize linear motifs in the partner proteins. Here, fragment-based screening using X-ray crystallography produced four hits bound in the linear-motif-binding pocket of the Escherichia coli SC. Compounds structurally related to the hits were identified that inhibited the E. coli SC and SC-mediated DNA replication in vitro. A tetrahydrocarbazole derivative emerged as a promising lead whose methyl and ethyl ester prodrug forms showed minimum inhibitory concentrations in the range of 21-43 mug/mL against representative Gram-negative and Gram-positive bacteria species. The work demonstrates the utility of a fragment-based approach for identifying bacterial sliding clamp inhibitors as lead compounds with broad-spectrum antibacterial activity.