The evolution of antibacterial chemotherapy: targeting RecA to sabotage antibiotic tolerance and resistance mechanisms Public Deposited

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  • March 22, 2019
Creator
  • Wigle, Tim J.
    • Affiliation: Eshelman School of Pharmacy
Abstract
  • Antibiotic resistant bacteria are rendering the current supply of available antibacterial drugs ineffective at an alarming rate and there is a dearth of novel drug targets for the treatment of bacterial infectious diseases. New strategies are required to combat pathogenic bacteria and in this context RecA has emerged as an intriguing candidate for inhibition studies. In the bacterial kingdom, the RecA protein is a highly conserved recombinase enzyme that mediates DNA repair and horizontal gene transfer and across all species it almost uniformly regulates the SOS response to DNA damage. Recent evidence suggests that these RecA-controlled processes are responsible for an increased tolerance to antibiotic chemotherapy and they up-regulate pathways which ultimately lead to full-fledged antibiotic resistance. We propose targeting RecA with small molecules to sabotage the molecular mechanisms which are believed to cause antibiotic chemotherapy to fail. Towards the goal of validating RecA as an important and novel target for the chemotherapeutic treatment of bacterial infectious diseases we have studied the interaction of metal-dithiols, nucleotide analogs and drug-like small molecules with the RecA protein. Upon activation RecA binds ssDNA and performs ATP hydrolysis, therefore we observed either a reduction of RecA-ssDNA binding or ATP hydrolysis in the presence of potential inhibitors using fast and efficient screening assays. As the size and complexity of the compound libraries increased in our studies, the methods we employed to identify inhibitors evolved to meet the demand they imposed. In all, more than 64,000 compounds were assayed against RecA and we identified several lead structures which were active against RecA in Escherichia coli cell cultures. We demonstrate that cell-permeable inhibitors of RecA are capable of abrogating the SOS response and potentiate the toxicity of bactericidal antibiotics, e.g. ciprofloxacin. The results of this study suggests that RecA may serve as a novel antibacterial drug target not belonging to any class of currently prescribed antibiotics, and which has not previously been examined in this regard.
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  • Singleton, Scott
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