Ferrer-González, Edgar F.. Insights into FtsZ inhibitors and their use against antibiotic-resistant bacterial pathogens. Retrieved from https://doi.org/doi:10.7282/t3-xhe8-7p46
DescriptionAntibiotic resistance is one of the biggest public health challenges of our time. The emergence and spread of drug-resistant pathogens threatens our ability to treat common infections. This problem is exacerbated by the dwindling pipeline of new antimicrobial agents. This dissertation explores the mechanism by which FtsZ inhibitors overcome the resistance properties of methicillin-resistant Staphylococcus aureus (MRSA). MRSA resistance to β-lactam antibiotics is predominantly driven by the acquisition of a fifth penicillin binding protein (PBP), termed PBP2a. β-lactam antibiotics have a low binding affinity for PBP2a, allowing MRSA to survive in the presence of these drugs. When β-lactam antibiotics are used in combination with a FtsZ inhibitor they become active against MRSA. To probe the mechanism underlying this behavior, we first determined the relative binding affinities of various β-lactam antibiotics for S. aureus PBP1, PBP2, PBP3, and PBP4. Using this information, we explored the relationship between PBP targeting selectivity and the extent of antibacterial synergy observed when combining different β-lactam antibiotics with a FtsZ inhibitor. Our findings indicate that β-lactam antibiotics with a high binding affinity for PBP2 exhibit the greatest extent of synergistic activity with FtsZ inhibitors. To further understand the nature of this synergistic relationship, we analyzed the impact of FtsZ inhibition on the relative localization of FtsZ and the five PBPs present in MRSA using fluorescence microscopy. Our results suggest that PBP2 plays a major role in the cell wall remodeling and repair necessitated by FtsZ inhibition and that PBP2a does not complement this function. Without a complementary contribution from PBP2a, PBP2 becomes highly vulnerable to PBP2-selective β-lactam antibiotics, thereby underscoring the high degree of synergistic activity between these drugs and FtsZ inhibitors. In addition to these findings, the development and validation of a fluorescent FtsZ inhibitor (BOFP) is also presented. Our results show that BOFP can be utilized to visualize and study FtsZ in a broad range of both Gram-negative and Gram-positive bacterial pathogens of acute clinical importance. This powerful tool will enable us to identify new broad-spectrum FtsZ inhibitors and understand their mechanisms of action, while expedite the knowledge on FtsZ.