PMID- 35574679 OWN - NLM STAT- MEDLINE DCOM- 20220701 LR - 20220722 IS - 2379-5042 (Electronic) IS - 2379-5042 (Linking) VI - 7 IP - 3 DP - 2022 Jun 29 TI - Loss of beta-Ketoacyl Acyl Carrier Protein Synthase III Activity Restores Multidrug-Resistant Escherichia coli Sensitivity to Previously Ineffective Antibiotics. PG - e0011722 LID - 10.1128/msphere.00117-22 [doi] LID - e00117-22 AB - 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 fatty acid synthesis (FAS II) pathway, showing that disrupting FAS II homeostasis in Escherichia coli through deletion of the fabH gene damages the cell envelope of antibiotic-susceptible and antibiotic-resistant clinical isolates. The fabH gene encodes the beta-ketoacyl acyl carrier protein synthase III (KAS III), which catalyzes the initial condensation reactions during fatty acid biosynthesis. We show that fabH 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 kpc2. Enhanced antibiotic sensitivity was additionally demonstrated in the context of eradicating established biofilms and treating established human cell infection in vitro. 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. IMPORTANCE 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 bacteria become susceptible to otherwise impermeable antibiotics and are resensitized to killing by last-resort antibiotics. This study supports FabH as a promising target for inhibition in future antimicrobial therapies. FAU - Hong, Yaoqin AU - Hong Y AUID- ORCID: 0000-0002-4408-2648 AD - Centre of Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia. FAU - Qin, Jilong AU - Qin J AUID- ORCID: 0000-0002-5867-6332 AD - Centre of Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia. FAU - Verderosa, Anthony D AU - Verderosa AD AUID- ORCID: 0000-0002-0549-6565 AD - Centre of Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia. FAU - Hawas, Sophia AU - Hawas S AD - Centre of Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia. FAU - Zhang, Bing AU - Zhang B AUID- ORCID: 0000-0001-8405-9242 AD - Centre for Superbug Solutions, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia. FAU - Blaskovich, Mark A T AU - Blaskovich MAT AUID- ORCID: 0000-0001-9447-2292 AD - Centre for Superbug Solutions, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia. FAU - Cronan, John E Jr AU - Cronan JE Jr AUID- ORCID: 0000-0002-7064-312X AD - Department of Microbiology, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. AD - Department of Biochemistry, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. FAU - Totsika, Makrina AU - Totsika M AUID- ORCID: 0000-0003-2468-0293 AD - Centre of Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia. LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20220516 PL - United States TA - mSphere JT - mSphere JID - 101674533 RN - 0 (Anti-Bacterial Agents) RN - 0 (Fatty Acids) RN - 0 (Membrane Lipids) RN - EC 2.7.8.- (Transferases (Other Substituted Phosphate Groups)) RN - EC 2.7.8.7 (holo-(acyl-carrier-protein) synthase) SB - IM MH - *Anti-Bacterial Agents/metabolism/pharmacology MH - Bacteria MH - *Escherichia coli MH - Fatty Acids/metabolism MH - Gram-Negative Bacteria MH - Humans MH - Membrane Lipids/metabolism/pharmacology MH - Transferases (Other Substituted Phosphate Groups) PMC - PMC9241538 OTO - NOTNLM OT - antibiotic potentiation OT - fatty acid biosynthesis OT - multidrug resistance OT - outer membrane permeability COIS- The authors declare no conflict of interest. EDAT- 2022/05/17 06:00 MHDA- 2022/07/02 06:00 PMCR- 2022/05/16 CRDT- 2022/05/16 05:22 PHST- 2022/05/17 06:00 [pubmed] PHST- 2022/07/02 06:00 [medline] PHST- 2022/05/16 05:22 [entrez] PHST- 2022/05/16 00:00 [pmc-release] AID - 00117-22 [pii] AID - msphere.00117-22 [pii] AID - 10.1128/msphere.00117-22 [doi] PST - ppublish SO - mSphere. 2022 Jun 29;7(3):e0011722. doi: 10.1128/msphere.00117-22. Epub 2022 May 16.