ABSTRACT
Antibiotic drug resistance among hospital and community acquired methicillin resistant Staphylococcus aureus (MRSA) has dramatically eroded the efficacy of current therapeutics. We describe a chemical genetic strategy using antisense interference to broadly identify new drug targets that potentiate the effects of existing antibiotics against both etiological classes of MRSA infection. Further, we describe the resulting chemical genetic interaction networks and highlight the prominent and overlapping target sets that restore MRSA susceptibility to penicillin, cephalosporins, and carbapenems. Pharmacological validation of this approach is the potent synergy between a known inhibitor to a member of this genetic potentiation network (GlmS) and a broad set of ß-lactam antibiotics against methicillin resistant Staphylococci. Developing drug-like leads to these targets may serve as rational and effective combination agents when paired with existing ß-lactam antibiotics to restore their efficacy against MRSA.
Subject(s)
Anti-Bacterial Agents/pharmacology , Methicillin-Resistant Staphylococcus aureus/drug effects , beta-Lactams/pharmacology , Anti-Bacterial Agents/chemistry , DNA, Antisense/chemistry , DNA, Antisense/metabolism , Drug Resistance, Bacterial , Peptidoglycan/biosynthesis , beta-Lactams/chemistryABSTRACT
The emergence of drug-resistant bacteria coupled with the limited discovery of novel chemical scaffolds and druggable targets inspires new approaches to antibiotic development. Here we describe a chemical genomics strategy based on 245 Staphylococcus aureus antisense RNA strains, each engineered for reduced expression of target genes essential for S. aureus growth. Attenuation of gene expression can sensitize cells to compounds that inhibit the activity of a gene product or associated process. Pools of strains grown competitively in the presence of bioactive compounds generate characteristic profiles of strain sensitivities reflecting compound mechanism of action. Here, we validate this approach with a structurally and mechanistically diverse set of reference antibiotics and, in the accompanying paper in this issue of Chemistry & Biology (Huber et al., 2009), demonstrate its use in the discovery of new cell wall inhibitors.
Subject(s)
Anti-Bacterial Agents/pharmacology , RNA, Antisense/metabolism , Staphylococcus aureus/metabolism , Anti-Bacterial Agents/chemistry , Cluster Analysis , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Phenotype , RNA Interference , Staphylococcus aureus/geneticsABSTRACT
Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial and community-acquired pathogen for which few existing antibiotics are efficacious. Here we describe two structurally related synthetic compounds that potentiate beta-lactam activity against MRSA. Genetic studies indicate that these agents target SAV1754 based on the following observations: (i) it has a unique chemical hypersensitivity profile, (ii) overexpression or point mutations are sufficient to confer resistance, and (iii) genetic inactivation phenocopies the potentiating effect of these agents in combination with beta-lactams. Further, we demonstrate these agents inhibit peptidoglycan synthesis. Because SAV1754 is essential for growth and structurally related to the recently reported peptidoglycan flippase of Escherichia coli, we speculate it performs an analogous function in S. aureus. These results suggest that SAV1754 inhibitors might possess therapeutic potential alone, or in combination with beta-lactams to restore MRSA efficacy.
