Screening for Inhibitors of DNA Replication in Gram-Positive Bacteria

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DESCRIPTION (provided by applicant): Using a model Gram (+) organism, Bacillus subtilis, we propose to transfer to the MLPCN, a robust high throughput screening assay targeting the DNA Polymerase III holoenzyme. Small molecules discovered via screening of this target will be prioritized using appropriate biochemical specificity and microbiological activity assays to select inhibitors that have the potential to be developed into antibacterial and step-specific perturbants of DNA replication pathways. This model organism is closely related to most common Gram (+) human pathogens such as S. aureus, S. pyogenes and the biodefense category A organism, Bacillus anthracis. Over the last three decades only 2 new chemical classes of antibiotics have been approved by the FDA and it is widely recognized that bacterial resistance to existing classes of antibiotics is increasing. Presently there are no antibacterial targeting the essential process of DNA replication in bacteria. Bacterial DNA replication is performed by the cellular replicase, DNA polymerase III holoenzyme that has the processivity to replicate the entire chromosome without dissociation. This process employs at least 5 different essential proteins and enzymatic activities. These protein targets and the essential interactions that occur between them provide attractive targets for the development of antibacterial, and will also serve as an ideal system for developing chemical genetic approaches to perturb the various interactions and reaction stages. PUBLIC HEALTH RELEVANCE: Bacterial pathogens are increasingly becoming resistant to commonly used antibiotics in both community and hospital settings, representing a growing public health problem. This has driven the need for research to discover new antibacterial that affect unexploited targets for which resistance is absent. This work will explore a variety of such unexploited targets, essential for bacterial DNA replication in a model organism closely related to many common human pathogenic bacteria, which will aid the discovery of such new antibacterial compounds.