Loss of β-Ketoacyl Acyl Carrier Protein Synthase III Activity Restores Multidrug-Resistant Escherichia coli Sensitivity to Previously Ineffective Antibiotics

• Published in: mSphere 2022-06, Vol.7 (3), p.e0011722-e0011722
• Main Authors: Hong, Yaoqin, Qin, Jilong, Verderosa, Anthony D, Hawas, Sophia, Zhang, Bing, Blaskovich, Mark A T, Cronan, Jr, John E, Totsika, Makrina
• Format: Article
• Language: English
• Subjects: Acyl carrier protein; Acyl carrier protein synthase; antibiotic potentiation; Antibiotic resistance; Antibiotics; Antimicrobial agents; Bacteria; Bacteriology; Biofilms; Biological activity; Biosynthesis; Carbapenemase; Clinical isolates; E coli; Escherichia coli; fatty acid biosynthesis; Fatty acids; Gene deletion; Gram-negative bacteria; Gram-positive bacteria; Homeostasis; Lipids; Membrane permeability; Multidrug resistance; Multidrug resistant organisms; outer membrane permeability; Pathogens; Prokaryotes; Public health; Research Article
• ISSN: 2379-5042; 2379-5042
• DOI: 10.1128/msphere.00117-22

Antibiotic resistance is one of the most prominent threats to modern medicine. In the latest World Health Organization list of bacterial pathogens that urgently require new antibiotics, 9 out of 12 are Gram-negative, with four being of "critical priority." One crucial barrier restricting antibiotic efficacy against Gram-negative bacteria is their unique cell envelope. While fatty acids are a shared constituent of all structural membrane lipids, their biosynthesis pathway in bacteria is distinct from eukaryotes, making it an attractive target for new antibiotic development that remains less explored. Here, we interrogated the redundant components of the bacterial type II atty cid ynthesis (FAS II) pathway, showing that disrupting FAS II homeostasis in Escherichia coli through deletion of the gene damages the cell envelope of antibiotic-susceptible and antibiotic-resistant clinical isolates. The gene encodes the β-ketoacyl acyl carrier protein synthase III (KAS III), which catalyzes the initial condensation reactions during fatty acid biosynthesis. We show that null mutation potentiated the killing of multidrug-resistant E. coli by a broad panel of previously ineffective antibiotics, despite the presence of relevant antibiotic resistance determinants, for example, carbapenemase . Enhanced antibiotic sensitivity was additionally demonstrated in the context of eradicating established biofilms and treating established human cell infection . Our findings showcase the potential of FabH as a promising target that could be further explored in the development of therapies that may repurpose currently ineffective antibiotics or rescue failing last-resort antibiotics against Gram-negative pathogens. Gram-negative pathogens are a major concern for global public health due to increasing rates of antibiotic resistance and the lack of new drugs. A major contributing factor toward antibiotic resistance in Gram-negative bacteria is their formidable outer membrane, which acts as a permeability barrier preventing many biologically active antimicrobials from reaching the intracellular targets and thus limiting their efficacy. Fatty acids are the fundamental building blocks of structural membrane lipids, and their synthesis constitutes an attractive antimicrobial target, as it follows distinct pathways in prokaryotes and eukaryotes. Here, we identified a component of fatty acid synthesis, FabH, as a gate-keeper of outer membrane barrier function. Without FabH, Gram-negative bac