Inhibitors of bacterial transcription initiation complex formation.

Antibiotic resistance is a growing global problem, with very few new compounds in development. Bacterial transcription is an underutilized target for antibiotics, which has been attributed to the similarity of the active site of RNA polymerases (RNAPs) across all domains of life and the ease with which resistance can arise through point mutation at multiple sites within this conserved region. In this study we have taken a rational approach to design a novel set of compounds that specifically target the formation of transcription initiation complexes by preventing the unique bacterial σ initiation factor from binding to RNAP. We have identified the region of RNAP to which these compounds bind and demonstrate that one compound, GKL003, has an inhibition constant in the low nanomolar range. This compound has activity against both Gram-positive and -negative organisms, including a community acquired methicillin-resistant strain of the major pathogen Staphylococcus aureus.