OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesicles
ABSTRACT β-lactamases from Gram-negative bacteria are generally regarded as soluble, periplasmic enzymes. NDMs have been exceptionally characterized as lipoproteins anchored to the outer membrane. A bioinformatics study on all sequenced β-lactamases was performed that revealed a predominance of puta...
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American Society for Microbiology
2025-02-01
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| Online Access: | https://journals.asm.org/doi/10.1128/mbio.03343-24 |
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| author | Lucia Capodimonte Fernando Teixeira Pinto Meireles Guillermo Bahr Robert A. Bonomo Matteo Dal Peraro Carolina López Alejandro J. Vila |
| author_facet | Lucia Capodimonte Fernando Teixeira Pinto Meireles Guillermo Bahr Robert A. Bonomo Matteo Dal Peraro Carolina López Alejandro J. Vila |
| author_sort | Lucia Capodimonte |
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| description | ABSTRACT β-lactamases from Gram-negative bacteria are generally regarded as soluble, periplasmic enzymes. NDMs have been exceptionally characterized as lipoproteins anchored to the outer membrane. A bioinformatics study on all sequenced β-lactamases was performed that revealed a predominance of putative lipidated enzymes in the Class D OXAs. Namely, 60% of the OXA Class D enzymes contain a lipobox sequence in their signal peptide, that is expected to trigger lipidation and membrane anchoring. This contrasts with β-lactamases from other classes, which are predicted to be mostly soluble proteins. Almost all (>99%) putative lipidated OXAs are present in Acinetobacter spp. Importantly, we further demonstrate that OXA-23 and OXA-24/40 are lipidated, membrane-bound proteins in Acinetobacter baumannii. In contrast, OXA-48 (commonly produced by Enterobacterales) lacks a lipobox and is a soluble protein. Outer membrane vesicles (OMVs) from A. baumannii cells expressing OXA-23 and OXA-24/40 contain these enzymes in their active form. Moreover, OXA-loaded OMVs were able to protect A. baumannii, Escherichia coli, and Pseudomonas aeruginosa cells susceptible to piperacillin and imipenem. These results permit us to conclude that membrane binding is a bacterial host-specific phenomenon in OXA enzymes. These findings reveal that membrane-bound β-lactamases are more common than expected and support the hypothesis that OMVs loaded with lipidated β-lactamases are vehicles for antimicrobial resistance and its dissemination. This advantage could be crucial in polymicrobial infections, in which Acinetobacter spp. are usually involved, and underscore the relevance of identifying the cellular localization of lactamases to better understand their physiology and target them.IMPORTANCEβ-lactamases represent the main mechanism of antimicrobial resistance in Gram-negative pathogens. Their catalytic function (cleaving β-lactam antibiotics) occurs in the bacterial periplasm, where they are commonly reported as soluble proteins. A bioinformatic analysis reveals a significant number of putative lipidated β-lactamases, expected to be attached to the outer bacterial membrane. Notably, 60% of Class D OXA β-lactamases (all from Acinetobacter spp.) are predicted as membrane-anchored proteins. We demonstrate that two clinically relevant carbapenemases, OXA-23 and OXA-24/40, are membrane-bound proteins in A. baumannii. This cellular localization favors the secretion of these enzymes into outer membrane vesicles that transport them outside the boundaries of the cell. β-lactamase-loaded vesicles can protect populations of antibiotic-susceptible bacteria, enabling them to thrive in the presence of β-lactam antibiotics. The ubiquity of this phenomenon suggests that it may have influenced the dissemination of resistance mediated by Acinetobacter spp., particularly in polymicrobial infections, being a potent evolutionary advantage. |
| format | Article |
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| institution | Kabale University |
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| publishDate | 2025-02-01 |
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| spelling | doaj-art-e9fa0e15cfe14a05b0af4059f9105eea2025-02-05T14:00:48ZengAmerican Society for MicrobiologymBio2150-75112025-02-0116210.1128/mbio.03343-24OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesiclesLucia Capodimonte0Fernando Teixeira Pinto Meireles1Guillermo Bahr2Robert A. Bonomo3Matteo Dal Peraro4Carolina López5Alejandro J. Vila6Instituto de Biología Molecular y Celular de Rosario (CONICET IBR -UNR), Rosario, ArgentinaInstitute of Bioengineering, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, SwitzerlandInstituto de Biología Molecular y Celular de Rosario (CONICET IBR -UNR), Rosario, ArgentinaDepartment of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USAInstitute of Bioengineering, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, SwitzerlandInstituto de Biología Molecular y Celular de Rosario (CONICET IBR -UNR), Rosario, ArgentinaInstituto de Biología Molecular y Celular de Rosario (CONICET IBR -UNR), Rosario, ArgentinaABSTRACT β-lactamases from Gram-negative bacteria are generally regarded as soluble, periplasmic enzymes. NDMs have been exceptionally characterized as lipoproteins anchored to the outer membrane. A bioinformatics study on all sequenced β-lactamases was performed that revealed a predominance of putative lipidated enzymes in the Class D OXAs. Namely, 60% of the OXA Class D enzymes contain a lipobox sequence in their signal peptide, that is expected to trigger lipidation and membrane anchoring. This contrasts with β-lactamases from other classes, which are predicted to be mostly soluble proteins. Almost all (>99%) putative lipidated OXAs are present in Acinetobacter spp. Importantly, we further demonstrate that OXA-23 and OXA-24/40 are lipidated, membrane-bound proteins in Acinetobacter baumannii. In contrast, OXA-48 (commonly produced by Enterobacterales) lacks a lipobox and is a soluble protein. Outer membrane vesicles (OMVs) from A. baumannii cells expressing OXA-23 and OXA-24/40 contain these enzymes in their active form. Moreover, OXA-loaded OMVs were able to protect A. baumannii, Escherichia coli, and Pseudomonas aeruginosa cells susceptible to piperacillin and imipenem. These results permit us to conclude that membrane binding is a bacterial host-specific phenomenon in OXA enzymes. These findings reveal that membrane-bound β-lactamases are more common than expected and support the hypothesis that OMVs loaded with lipidated β-lactamases are vehicles for antimicrobial resistance and its dissemination. This advantage could be crucial in polymicrobial infections, in which Acinetobacter spp. are usually involved, and underscore the relevance of identifying the cellular localization of lactamases to better understand their physiology and target them.IMPORTANCEβ-lactamases represent the main mechanism of antimicrobial resistance in Gram-negative pathogens. Their catalytic function (cleaving β-lactam antibiotics) occurs in the bacterial periplasm, where they are commonly reported as soluble proteins. A bioinformatic analysis reveals a significant number of putative lipidated β-lactamases, expected to be attached to the outer bacterial membrane. Notably, 60% of Class D OXA β-lactamases (all from Acinetobacter spp.) are predicted as membrane-anchored proteins. We demonstrate that two clinically relevant carbapenemases, OXA-23 and OXA-24/40, are membrane-bound proteins in A. baumannii. This cellular localization favors the secretion of these enzymes into outer membrane vesicles that transport them outside the boundaries of the cell. β-lactamase-loaded vesicles can protect populations of antibiotic-susceptible bacteria, enabling them to thrive in the presence of β-lactam antibiotics. The ubiquity of this phenomenon suggests that it may have influenced the dissemination of resistance mediated by Acinetobacter spp., particularly in polymicrobial infections, being a potent evolutionary advantage.https://journals.asm.org/doi/10.1128/mbio.03343-24lipidated β-lactamasesOXA β-lactamasesAcinetobacter spp.outer membrane vesiclesdissemination of antimicrobial resistance |
| spellingShingle | Lucia Capodimonte Fernando Teixeira Pinto Meireles Guillermo Bahr Robert A. Bonomo Matteo Dal Peraro Carolina López Alejandro J. Vila OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesicles mBio lipidated β-lactamases OXA β-lactamases Acinetobacter spp. outer membrane vesicles dissemination of antimicrobial resistance |
| title | OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesicles |
| title_full | OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesicles |
| title_fullStr | OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesicles |
| title_full_unstemmed | OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesicles |
| title_short | OXA β-lactamases from Acinetobacter spp. are membrane bound and secreted into outer membrane vesicles |
| title_sort | oxa β lactamases from acinetobacter spp are membrane bound and secreted into outer membrane vesicles |
| topic | lipidated β-lactamases OXA β-lactamases Acinetobacter spp. outer membrane vesicles dissemination of antimicrobial resistance |
| url | https://journals.asm.org/doi/10.1128/mbio.03343-24 |
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