title: Antibiotic Capture by Bacterial Lipocalins Uncovers an Extracellular Mechanism of Intrinsic Antibiotic Resistance.
abstract: The potential for microbes to overcome antibiotics of different classes before they reach bacterial cells is largely unexplored. Here we show that a soluble bacterial lipocalin produced byBurkholderia cenocepaciaupon exposure to sublethal antibiotic concentrations increases resistance to diverse antibioticsin vitroandin vivoThese phenotypes were recapitulated by heterologous expression inB. cenocepaciaof lipocalin genes fromPseudomonas aeruginosa,Mycobacterium tuberculosis, and methicillin-resistantStaphylococcus aureusPurified lipocalin bound different classes of bactericidal antibiotics and contributed to bacterial survivalin vivoExperimental and X-ray crystal structure-guided computational studies revealed that lipocalins counteract antibiotic action by capturing antibiotics in the extracellular space. We also demonstrated that fat-soluble vitamins prevent antibiotic capture by binding bacterial lipocalin with higher affinity than antibiotics. Therefore, bacterial lipocalins contribute to antimicrobial resistance by capturing diverse antibiotics in the extracellular space at the site of infection, which can be counteracted by known vitamins.IMPORTANCECurrent research on antibiotic action and resistance focuses on targeting essential functions within bacterial cells. We discovered a previously unrecognized mode of general bacterial antibiotic resistance operating in the extracellular space, which depends on bacterial protein molecules called lipocalins. These molecules are highly conserved in most bacteria and have the ability to capture different classes of antibiotics outside bacterial cells. We also discovered that liposoluble vitamins, such as vitamin E, overcomein vitroandin vivoantibiotic resistance mediated by bacterial lipocalins, providing an unexpected new alternative to combat resistance by using this vitamin or its derivatives as antibiotic adjuvants.
authors.affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada.|Microbiology and Immunology Department, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt.
authors.forename: Omar M
authors.initials: OM
authors.lastname: El-Halfawy
authors.affiliation: Department of Chemical and Physical Biology, Centre for Biological Research, CIB, CSIC, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Klett
authors.affiliation: The Wellcome-Wolfson Institute of Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Ingram
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Slade A
authors.initials: SA
authors.lastname: Loutet
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Michael E P
authors.initials: ME
authors.lastname: Murphy
authors.affiliation: Department of Chemical and Physical Biology, Centre for Biological Research, CIB, CSIC, Madrid, Spain.
authors.forename: Sonsoles
authors.initials: S
authors.lastname: Martín-Santamaría
authors.affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada m.valvano@qub.ac.uk.|The Wellcome-Wolfson Institute of Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom.
authors.forename: Miguel A
authors.identifier: 0000-0001-8229-3641
authors.initials: MA
authors.lastname: Valvano
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D057508:Burkholderia cenocepacia / Q000187:drug effects* / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D015870:Gene Expression; D054834:Lipocalins / Q000378:metabolism*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D054834:Lipocalins