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Liu M, Wang M, Huang M, Gao Q, Zhu D, Wang M, Jia R, Chen S, Zhao X, Yang Q, Wu Y, Zhang S, Huang J, Ou X, Mao S, Tian B, Sun D, Cheng A. Iron efflux by IetA enhances β-lactam aztreonam resistance and is linked to oxidative stress through cellular respiration in Riemerella anatipestifer. J Antimicrob Chemother 2024; 79:1385-1396. [PMID: 38629469 DOI: 10.1093/jac/dkae114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 03/20/2024] [Indexed: 06/04/2024] Open
Abstract
BACKGROUND Riemerella anatipestifer encodes an iron acquisition system, but whether it encodes the iron efflux pump and its role in antibiotic resistance are largely unknown. OBJECTIVES To screen and identify an iron efflux gene in R. anatipestifer and determine whether and how the iron efflux gene is involved in antibiotic resistance. METHODS In this study, gene knockout, streptonigrin susceptibility assay and inductively coupled plasma mass spectrometry were used to screen for the iron efflux gene ietA. The MIC measurements, scanning electron microscopy and reactive oxygen species (ROS) detection were used to verify the role of IetA in aztreonam resistance and its mechanism. Mortality and colonization assay were used to investigate the role of IetA in virulence. RESULTS The deletion mutant ΔietA showed heightened susceptibility to streptonigrin, and prominent intracellular iron accumulation was observed in ΔfurΔietA under excess iron conditions. Additionally, ΔietA exhibited increased sensitivity to H2O2-produced oxidative stress. Under aerobic conditions with abundant iron, ΔietA displayed increased susceptibility to the β-lactam antibiotic aztreonam due to heightened ROS production. However, the killing efficacy of aztreonam was diminished in both WT and ΔietA under anaerobic or iron restriction conditions. Further experiments demonstrated that the efficiency of aztreonam against ΔietA was dependent on respiratory complexes Ⅰ and Ⅱ. Finally, in a duckling model, ΔietA had reduced virulence compared with the WT. CONCLUSION Iron efflux is critical to alleviate oxidative stress damage and β-lactam aztreonam killing in R. anatipestifer, which is linked by cellular respiration.
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Affiliation(s)
- Mafeng Liu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Mengying Wang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Mi Huang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Qun Gao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Dekang Zhu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Mingshu Wang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Renyong Jia
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Shun Chen
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Xinxin Zhao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Qiao Yang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Ying Wu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Shaqiu Zhang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Juan Huang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Xumin Ou
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Sai Mao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Bin Tian
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Di Sun
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Anchun Cheng
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu 611130, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 611130, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu 611130, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
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Yang M, Du D, Zhu F, Qin H. Metabolic network and proteomic expression perturbed by cyclosporine A to model microbe Escherichia coli. JOURNAL OF HAZARDOUS MATERIALS 2024; 464:132975. [PMID: 38044020 DOI: 10.1016/j.jhazmat.2023.132975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/06/2023] [Accepted: 11/08/2023] [Indexed: 12/05/2023]
Abstract
Cyclosporine A (CsA) is a model drug that has caused great concern due to its widespread use and abuse in the environment. However, the potential harm of CsA to organisms also remains largely unknown, and this issue is exceptionally important for the health risk assessment of antibiotics. To address this concern, the crosstalk between CsA stress and cellular metabolism at the proteomic level in Escherichia coli was investigated and dissected in this study. The results showed that CsA inhibited E. coli growth in a time-dependent manner. CsA induced reactive oxygen species (ROS) overproduction in a dose- and time-dependent manner, leading to membrane depolarization followed by cell apoptosis. In addition, translation, the citric acid cycle, amino acid biosynthesis, glycolysis and responses to oxidative stress and heat were the central metabolic pathways induced by CsA stress. The upregulated proteins, including PotD, PotF and PotG, controlled cell growth. The downregulated proteins, including SspA, SspB, CstA and DpS, were regulators of self-feedback during the starvation process. And the up- and downregulated proteins, including AtpD, Adk, GroS, GroL and DnaK, controlled energy production. These results provide an important reference for the environmental health risk assessment of CsA.
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Affiliation(s)
- Meng Yang
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Daolin Du
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Fang Zhu
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Huaming Qin
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China.
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Schmidt JJ, Remme DCLE, Eisfeld J, Brandenburg VB, Bille H, Narberhaus F. The LysR-type transcription factor LsrB regulates beta-lactam resistance in Agrobacterium tumefaciens. Mol Microbiol 2024; 121:26-39. [PMID: 37985428 DOI: 10.1111/mmi.15191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/20/2023] [Accepted: 10/28/2023] [Indexed: 11/22/2023]
Abstract
Agrobacterium tumefaciens is a plant pathogen, broadly known as the causal agent of the crown gall disease. The soil bacterium is naturally resistant to beta-lactam antibiotics by utilizing the inducible beta-lactamase AmpC. Our picture on the condition-dependent regulation of ampC expression is incomplete. A known regulator is AmpR controlling the transcription of ampC in response to unrecycled muropeptides as a signal for cell wall stress. In our study, we uncovered the global transcriptional regulator LsrB as a critical player acting upstream of AmpR. Deletion of lsrB led to severe ampicillin and penicillin sensitivity, which could be restored to wild-type levels by lsrB complementation. By transcriptome profiling via RNA-Seq and qRT-PCR and by electrophoretic mobility shift assays, we show that ampD coding for an anhydroamidase involved in peptidoglycan recycling is under direct negative control by LsrB. Controlling AmpD levels by the LysR-type regulator in turn impacts the cytoplasmic concentration of cell wall degradation products and thereby the AmpR-mediated regulation of ampC. Our results substantially expand the existing model of inducible beta-lactam resistance in A. tumefaciens by establishing LsrB as higher-level transcriptional regulator.
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Affiliation(s)
| | | | - Jessica Eisfeld
- Medical Microbiology, Ruhr University Bochum, Bochum, Germany
| | | | - Hannah Bille
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
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4
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Harper CE, Zhang W, Lee J, Shin JH, Keller MR, van Wijngaarden E, Chou E, Wang Z, Dörr T, Chen P, Hernandez CJ. Mechanical stimuli activate gene expression via a cell envelope stress sensing pathway. Sci Rep 2023; 13:13979. [PMID: 37633922 PMCID: PMC10460444 DOI: 10.1038/s41598-023-40897-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/17/2023] [Indexed: 08/28/2023] Open
Abstract
Mechanosensitive mechanisms are often used to sense damage to tissue structure, stimulating matrix synthesis and repair. While this kind of mechanoregulatory process is well recognized in eukaryotic systems, it is not known whether such a process occurs in bacteria. In Vibrio cholerae, antibiotic-induced damage to the load-bearing cell wall promotes increased signaling by the two-component system VxrAB, which stimulates cell wall synthesis. Here we show that changes in mechanical stress within the cell envelope are sufficient to stimulate VxrAB signaling in the absence of antibiotics. We applied mechanical forces to individual bacteria using three distinct loading modalities: extrusion loading within a microfluidic device, direct compression and hydrostatic pressure. In all cases, VxrAB signaling, as indicated by a fluorescent protein reporter, was increased in cells submitted to greater magnitudes of mechanical loading, hence diverse forms of mechanical stimuli activate VxrAB signaling. Reduction in cell envelope stiffness following removal of the endopeptidase ShyA led to large increases in cell envelope deformation and substantially increased VxrAB response, further supporting the responsiveness of VxrAB. Our findings demonstrate a mechanosensitive gene regulatory system in bacteria and suggest that mechanical signals may contribute to the regulation of cell wall homeostasis.
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Affiliation(s)
- Christine E Harper
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Wenyao Zhang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Junsung Lee
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Jung-Ho Shin
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Microbiology, Cornell University, Ithaca, NY, 14853, USA
| | - Megan R Keller
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Ellen van Wijngaarden
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Emily Chou
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Zhaohong Wang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA.
- Department of Microbiology, Cornell University, Ithaca, NY, 14853, USA.
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, NY, 14853, USA.
| | - Peng Chen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
| | - Christopher J Hernandez
- Department of Bioengineering and Therapeutic Sciences and Orthopaedic Surgery, University of California, San Francisco, CA, 94143, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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5
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Kawai Y, Kawai M, Mackenzie ES, Dashti Y, Kepplinger B, Waldron KJ, Errington J. On the mechanisms of lysis triggered by perturbations of bacterial cell wall biosynthesis. Nat Commun 2023; 14:4123. [PMID: 37433811 DOI: 10.1038/s41467-023-39723-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 06/20/2023] [Indexed: 07/13/2023] Open
Abstract
Inhibition of bacterial cell wall synthesis by antibiotics such as β-lactams is thought to cause explosive lysis through loss of cell wall integrity. However, recent studies on a wide range of bacteria have suggested that these antibiotics also perturb central carbon metabolism, contributing to death via oxidative damage. Here, we genetically dissect this connection in Bacillus subtilis perturbed for cell wall synthesis, and identify key enzymatic steps in upstream and downstream pathways that stimulate the generation of reactive oxygen species through cellular respiration. Our results also reveal the critical role of iron homeostasis for the oxidative damage-mediated lethal effects. We show that protection of cells from oxygen radicals via a recently discovered siderophore-like compound uncouples changes in cell morphology normally associated with cell death, from lysis as usually judged by a phase pale microscopic appearance. Phase paling appears to be closely associated with lipid peroxidation.
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Affiliation(s)
- Yoshikazu Kawai
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK.
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, 2006, Australia.
| | - Maki Kawai
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, 2006, Australia
| | - Eilidh Sohini Mackenzie
- Bioscience Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Yousef Dashti
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, 2006, Australia
| | - Bernhard Kepplinger
- Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, 50-383, Wrocław, Poland
| | - Kevin John Waldron
- Bioscience Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, 02-106, Poland
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK.
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, 2006, Australia.
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Keller MR, Dörr T. Bacterial metabolism and susceptibility to cell wall-active antibiotics. Adv Microb Physiol 2023; 83:181-219. [PMID: 37507159 PMCID: PMC11024984 DOI: 10.1016/bs.ampbs.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
Bacterial infections are increasingly resistant to antimicrobial therapy. Intense research focus has thus been placed on identifying the mechanisms that bacteria use to resist killing or growth inhibition by antibiotics and the ways in which bacteria share these traits with one another. This work has led to the advancement of new drugs, combination therapy regimens, and a deeper appreciation for the adaptability seen in microorganisms. However, while the primary mechanisms of action of most antibiotics are well understood, the more subtle contributions of bacterial metabolic state to repairing or preventing damage caused by antimicrobials (thereby promoting survival) are still understudied. Here, we review a modern viewpoint on a classical system: examining bacterial metabolism's connection to antibiotic susceptibility. We dive into the relationship between metabolism and antibiotic efficacy through the lens of growth rate, energy state, resource allocation, and the infection environment, focusing on cell wall-active antibiotics.
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Affiliation(s)
- Megan Renee Keller
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States; Department of Microbiology, Cornell University, Ithaca, NY, United States; Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, NY, United States.
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7
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Proutière A, Drebes Dörr NC, Bader L, Stutzmann S, Metzger LC, Isaac S, Chiaruttini N, Blokesch M. Sporadic type VI secretion in seventh pandemic Vibrio cholerae. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 37134007 DOI: 10.1099/mic.0.001329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Vibrio cholerae is a pathogen that causes disease in millions of people every year by colonizing the small intestine and then secreting the potent cholera toxin. How the pathogen overcomes the colonization barrier created by the host's natural microbiota is, however, still not well understood. In this context, the type VI secretion system (T6SS) has gained considerable attention given its ability to mediate interbacterial killing. Interestingly, and in contrast to non-pandemic or environmental V. cholerae isolates, strains that are causing the ongoing cholera pandemic (7PET clade) are considered T6SS-silent under laboratory conditions. Since this idea was recently challenged, we performed a comparative in vitro study on T6SS activity using diverse strains or regulatory mutants. We show that modest T6SS activity is detectable in most of the tested strains under interbacterial competition conditions. The system's activity was also observed through immunodetection of the T6SS tube protein Hcp in culture supernatants, a phenotype that can be masked by the strains' haemagglutinin/protease. We further investigated the low T6SS activity within the bacterial populations by imaging 7PET V. cholerae at the single-cell level. The micrographs showed the production of the machinery in only a small fraction of cells within the population. This sporadic T6SS production was higher at 30 °C than at 37 °C and occurred independently of the known regulators TfoX and TfoY but was dependent on the VxrAB two-component system. Overall, our work provides new insight into the heterogeneity of T6SS production in populations of 7PET V. cholerae strains in vitro and provides a possible explanation of the system's low activity in bulk measurements.
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Affiliation(s)
- Alexis Proutière
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Natália C Drebes Dörr
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Loriane Bader
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sandrine Stutzmann
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lisa C Metzger
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sandrine Isaac
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nicolas Chiaruttini
- Bioimaging and Optics Platform (PT-BIOP), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Kitts G, Rogers A, Teschler JK, Park JH, Trebino MA, Chaudry I, Erill I, Yildiz FH. The Rvv two-component regulatory system regulates biofilm formation and colonization in Vibrio cholerae. PLoS Pathog 2023; 19:e1011415. [PMID: 37216386 PMCID: PMC10237652 DOI: 10.1371/journal.ppat.1011415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 06/02/2023] [Accepted: 05/10/2023] [Indexed: 05/24/2023] Open
Abstract
The facultative human pathogen, Vibrio cholerae, employs two-component signal transduction systems (TCS) to sense and respond to environmental signals encountered during its infection cycle. TCSs consist of a sensor histidine kinase (HK) and a response regulator (RR); the V. cholerae genome encodes 43 HKs and 49 RRs, of which 25 are predicted to be cognate pairs. Using deletion mutants of each HK gene, we analyzed the transcription of vpsL, a biofilm gene required for Vibrio polysaccharide and biofilm formation. We found that a V. cholerae TCS that had not been studied before, now termed Rvv, controls biofilm gene transcription. The Rvv TCS is part of a three-gene operon that is present in 30% of Vibrionales species. The rvv operon encodes RvvA, the HK; RvvB, the cognate RR; and RvvC, a protein of unknown function. Deletion of rvvA increased transcription of biofilm genes and altered biofilm formation, while deletion of rvvB or rvvC lead to no changes in biofilm gene transcription. The phenotypes observed in ΔrvvA depend on RvvB. Mutating RvvB to mimic constitutively active and inactive versions of the RR only impacted phenotypes in the ΔrvvA genetic background. Mutating the conserved residue required for kinase activity in RvvA did not affect phenotypes, whereas mutation of the conserved residue required for phosphatase activity mimicked the phenotype of the rvvA mutant. Furthermore, ΔrvvA displayed a significant colonization defect which was dependent on RvvB and RvvB phosphorylation state, but not on VPS production. We found that RvvA's phosphatase activity regulates biofilm gene transcription, biofilm formation, and colonization phenotypes. This is the first systematic analysis of the role of V. cholerae HKs in biofilm gene transcription and resulted in the identification of a new regulator of biofilm formation and virulence, advancing our understanding of the role TCSs play in regulating these critical cellular processes in V. cholerae.
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Affiliation(s)
- Giordan Kitts
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Andrew Rogers
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Jennifer K. Teschler
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Jin Hwan Park
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Michael A. Trebino
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Issac Chaudry
- Department of Biological Sciences, University of Maryland Baltimore County (UMBC), Baltimore, Maryland, United States of America
| | - Ivan Erill
- Department of Biological Sciences, University of Maryland Baltimore County (UMBC), Baltimore, Maryland, United States of America
| | - Fitnat H. Yildiz
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California, United States of America
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9
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Keller M, Han X, Dörr T. Disrupting Central Carbon Metabolism Increases β-Lactam Antibiotic Susceptibility in Vibrio cholerae. J Bacteriol 2023; 205:e0047622. [PMID: 36840595 PMCID: PMC10029711 DOI: 10.1128/jb.00476-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 01/31/2023] [Indexed: 02/24/2023] Open
Abstract
Antibiotic tolerance, the ability of bacteria to sustain viability in the presence of typically bactericidal antibiotics for extended time periods, is an understudied contributor to treatment failure. The Gram-negative pathogen Vibrio cholerae, the causative agent of cholera, becomes highly tolerant to β-lactam antibiotics (penicillin and related compounds) in a process requiring the two-component system VxrAB. VxrAB is induced by exposure to cell wall damaging conditions, which results in the differential regulation of >100 genes. While the effectors of VxrAB are relatively well known, VxrAB environment-sensing and activation mechanisms remain a mystery. Here, we used transposon mutagenesis to screen for mutants that spontaneously upregulate VxrAB signaling. This screen was answered by genes known to be required for proper cell envelope homeostasis, validating the approach. Unexpectedly, we also uncovered a new connection between central carbon metabolism and antibiotic tolerance in Vibrio cholerae. Inactivation of pgi (vc0374, coding for glucose-6-phosphate isomerase) resulted in an intracellular accumulation of glucose-6-phosphate and fructose-6-phosphate, concomitant with a marked cell envelope defect, resulting in VxrAB induction. Deletion of pgi also increased sensitivity to β-lactams and conferred a growth defect on salt-free LB, phenotypes that could be suppressed by deleting sugar uptake systems and by supplementing cell wall precursors in the growth medium. Our data suggest an important connection between central metabolism and cell envelope integrity and highlight a potential new target for developing novel antimicrobial agents. IMPORTANCE Antibiotic tolerance (the ability to survive exposure to antibiotics) is a stepping stone toward antibiotic resistance (the ability to grow in the presence of antibiotics), an increasingly common cause of antibiotic treatment failure. The mechanisms promoting tolerance are poorly understood. Here, we identified central carbon metabolism as a key contributor to antibiotic tolerance and resistance. A strain with a mutation in a sugar utilization pathway accumulates metabolites that likely shut down the synthesis of cell wall precursors, which weakens the cell wall and thus increases susceptibility to cell wall-active drugs. Our results illuminate the connection between central carbon metabolism and cell wall homeostasis in V. cholerae and suggest that interfering with metabolism may be a fruitful future strategy for the development of antibiotic adjuvants.
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Affiliation(s)
- Megan Keller
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
| | - Xiang Han
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
- Department of Microbiology, Cornell University, Ithaca, New York, USA
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, USA
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10
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Downregulation of Nrf2 in the Hippocampus Contributes to Postoperative Cognitive Dysfunction in Aged Rats by Sensitizing Oxidative Stress and Neuroinflammation. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2023; 2023:7272456. [PMID: 36819786 PMCID: PMC9935806 DOI: 10.1155/2023/7272456] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 01/15/2023] [Accepted: 01/24/2023] [Indexed: 02/11/2023]
Abstract
Postoperative cognitive dysfunction (POCD) is a recognized clinical complication defined by a new cognitive impairment arising after a surgical procedure. Elderly patients are especially vulnerable to cognitive impairment after surgical operations, but the underlying mechanisms remain elusive. Oxidative stress and neuroinflammation in the hippocampus, a brain region involved in memory formation, are considered as major contributors to the development of POCD. Activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of endogenous inducible defense system, plays a crucial role in protecting cells against oxidative stress and inflammation by enhancing transcription of antioxidant and anti-inflammatory target genes. Here, we examined whether aging downregulates Nrf2 in the hippocampus and, if so, whether downregulation of hippocampal Nrf2 contributes to POCD in aging. Young and aged rats underwent abdominal surgery or sham operation. One week later, cognitive function was assessed, and brains were collected for molecular studies. Compared with young sham rats, aged sham rats exhibited a significant reduction in expression of Nrf2 in the hippocampus. Interestingly, the expression of Nrf2 downstream target genes and levels of reactive oxygen species (ROS) and proinflammatory cytokines in the hippocampus as well as cognitive function were comparable between aged sham and young sham rats. After abdominal surgery, young rats showed significant upregulation of Nrf2 and its target genes in the hippocampus. However, aged rats did not show changes in expression of Nrf2 and its target genes but had increased levels of ROS and proinflammatory cytokines in the hippocampus, along with cognitive impairment as indicated by reduced contextual freezing time. Moreover, upregulation of hippocampal Nrf2 in aged rats with intracerebroventricular infusion of a Nrf2 activator reduced levels of ROS and proinflammatory cytokines in the hippocampus, ameliorating cognitive dysfunction after surgery. The results suggest that aging-induced downregulation of Nrf2 in the hippocampus causes the failure to activate Nrf2-regulated antioxidant defense system in response to surgical insult, which contributes to POCD by sensitizing oxidative stress and neuroinflammation. Nrf2 activation in the brain may be a novel strategy to prevent the cognitive decline in elderly patients after surgery.
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11
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Lou J, Cai J, Hu X, Liang Y, Sun Y, Zhu Y, Meng Q, Zhu T, Gao H, Yu Z, Yin J. The stringent starvation protein SspA modulates peptidoglycan synthesis by regulating the expression of peptidoglycan synthases. Mol Microbiol 2022; 118:716-730. [PMID: 36308522 DOI: 10.1111/mmi.14996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/19/2022] [Accepted: 10/22/2022] [Indexed: 01/18/2023]
Abstract
The peptidoglycan (PG) layer of bacterial cells is essential for maintaining the cell shape and survival of cells; therefore, the synthesis of PG needs to be spatiotemporally controlled. While it is well established that PG synthesis is mediated posttranslationally through interactions between PG synthases and their cognate partners, much less is known about the transcriptional regulation of genes encoding these synthases. Based on a previous finding that the Gram-negative bacterium Shewanella oneidensis lacking the prominent PG synthase exhibits impaired cell wall integrity, we performed genetic selections to isolate the suppressors. We discovered that disrupting the sspA gene encoding stringent starvation protein A (SspA) is sufficient to suppress compromised PG. SspA serves as a transcriptional repressor that regulates the expression of the two types of PG synthases, class A penicillin-binding proteins and SEDS/bPBP protein complexes. SspA is an RNA polymerase-associated protein, and its regulation involves interactions with the σ70 -RNAP complex and an antagonistic effect of H-NS, a global nucleoid-associated protein. We also present evidence that the regulation of PG synthases by SspA is conserved in Escherichia coli, adding a new dimension to the current understanding of PG synthesis and its regulation.
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Affiliation(s)
- Jie Lou
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Jingxiao Cai
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Xiao Hu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yanqun Liang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yijuan Sun
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yiling Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Qiu Meng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Tingheng Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Haichun Gao
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Zhiliang Yu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Jianhua Yin
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
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12
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Lazenby JJ, Li ES, Whitchurch CB. Cell wall deficiency - an alternate bacterial lifestyle? MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35925044 DOI: 10.1099/mic.0.001218] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Historically, many species of bacteria have been reported to produce viable, cell wall deficient (CWD) variants. A variety of terms have been used to refer to CWD bacteria and a plethora of methods described in which to induce, cultivate and propagate them. In this review, we will examine the long history of scientific research on CWD bacteria examining the methods by which CWD bacteria are generated; the requirements for survival in a CWD state; the replicative processes within a CWD state; and the reversion of CWD bacteria into a walled state, or lack thereof. In doing so, we will present evidence that not all CWD variants are alike and that, at least in some cases, CWD variants arise through an adaptive lifestyle switch that enables them to live and thrive without a cell wall, often to avoid antimicrobial activity. Finally, the implications of CWD bacteria in recurring infections, tolerance to antibiotic therapy and antimicrobial resistance will be examined to illustrate the importance of greater understanding of the CWD bacteria in human health and disease.
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Affiliation(s)
- James J Lazenby
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
| | - Erica S Li
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
| | - Cynthia B Whitchurch
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TK, UK
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13
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Peptidoglycan Recycling Promotes Outer Membrane Integrity and Carbapenem Tolerance in Acinetobacter baumannii. mBio 2022; 13:e0100122. [PMID: 35638738 PMCID: PMC9239154 DOI: 10.1128/mbio.01001-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
β-Lactam antibiotics exploit the essentiality of the bacterial cell envelope by perturbing the peptidoglycan layer, typically resulting in rapid lysis and death. Many Gram-negative bacteria do not lyse but instead exhibit "tolerance," the ability to sustain viability in the presence of bactericidal antibiotics for extended periods. Antibiotic tolerance has been implicated in treatment failure and is a stepping-stone in the acquisition of true resistance, and the molecular factors that promote intrinsic tolerance are not well understood. Acinetobacter baumannii is a critical-threat nosocomial pathogen notorious for its ability to rapidly develop multidrug resistance. Carbapenem β-lactam antibiotics (i.e., meropenem) are first-line prescriptions to treat A. baumannii infections, but treatment failure is increasingly prevalent. Meropenem tolerance in Gram-negative pathogens is characterized by morphologically distinct populations of spheroplasts, but the impact of spheroplast formation is not fully understood. Here, we show that susceptible A. baumannii clinical isolates demonstrate tolerance to high-level meropenem treatment, form spheroplasts upon exposure to the antibiotic, and revert to normal growth after antibiotic removal. Using transcriptomics and genetic screens, we show that several genes associated with outer membrane integrity maintenance and efflux promote tolerance, likely by limiting entry into the periplasm. Genes associated with peptidoglycan homeostasis in the periplasm and cytoplasm also answered our screen, and their disruption compromised cell envelope barrier function. Finally, we defined the enzymatic activity of the tolerance determinants penicillin-binding protein 7 (PBP7) and ElsL (a cytoplasmic ld-carboxypeptidase). These data show that outer membrane integrity and peptidoglycan recycling are tightly linked in their contribution to A. baumannii meropenem tolerance. IMPORTANCE Carbapenem treatment failure associated with "superbug" infections has rapidly increased in prevalence, highlighting the urgent need to develop new therapeutic strategies. Antibiotic tolerance can directly lead to treatment failure but has also been shown to promote the acquisition of true resistance within a population. While some studies have addressed mechanisms that promote tolerance, factors that underlie Gram-negative bacterial survival during carbapenem treatment are not well understood. Here, we characterized the role of peptidoglycan recycling in outer membrane integrity maintenance and meropenem tolerance in A. baumannii. These studies suggest that the pathogen limits antibiotic concentrations in the periplasm and highlight physiological processes that could be targeted to improve antimicrobial treatment.
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14
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Kanungo S, Azman AS, Ramamurthy T, Deen J, Dutta S. Cholera. Lancet 2022; 399:1429-1440. [PMID: 35397865 DOI: 10.1016/s0140-6736(22)00330-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 12/14/2021] [Accepted: 02/07/2022] [Indexed: 12/11/2022]
Abstract
Cholera was first described in the areas around the Bay of Bengal and spread globally, resulting in seven pandemics during the past two centuries. It is caused by toxigenic Vibrio cholerae O1 or O139 bacteria. Cholera is characterised by mild to potentially fatal acute watery diarrhoeal disease. Prompt rehydration therapy is the cornerstone of management. We present an overview of cholera and its pathogenesis, natural history, bacteriology, and epidemiology, while highlighting advances over the past 10 years in molecular epidemiology, immunology, and vaccine development and deployment. Since 2014, the Global Task Force on Cholera Control, a WHO coordinated network of partners, has been working with several countries to develop national cholera control strategies. The global roadmap for cholera control focuses on stopping transmission in cholera hotspots through vaccination and improved water, sanitation, and hygiene, with the aim to reduce cholera deaths by 90% and eliminate local transmission in at least 20 countries by 2030.
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Affiliation(s)
- Suman Kanungo
- National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Andrew S Azman
- Department of Epidemiology, Johns Hopkins University, Baltimore, MD, USA; Institute of Global Health, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | | | - Jaqueline Deen
- Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines-Manila, Manila, Philippines
| | - Shanta Dutta
- National Institute of Cholera and Enteric Diseases, Kolkata, India.
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15
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Kumar S, Mollo A, Kahne D, Ruiz N. The Bacterial Cell Wall: From Lipid II Flipping to Polymerization. Chem Rev 2022; 122:8884-8910. [PMID: 35274942 PMCID: PMC9098691 DOI: 10.1021/acs.chemrev.1c00773] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The peptidoglycan (PG) cell wall is an extra-cytoplasmic glycopeptide polymeric structure that protects bacteria from osmotic lysis and determines cellular shape. Since the cell wall surrounds the cytoplasmic membrane, bacteria must add new material to the PG matrix during cell elongation and division. The lipid-linked precursor for PG biogenesis, Lipid II, is synthesized in the inner leaflet of the cytoplasmic membrane and is subsequently translocated across the bilayer so that the PG building block can be polymerized and cross-linked by complex multiprotein machines. This review focuses on major discoveries that have significantly changed our understanding of PG biogenesis in the past decade. In particular, we highlight progress made toward understanding the translocation of Lipid II across the cytoplasmic membrane by the MurJ flippase, as well as the recent discovery of a novel class of PG polymerases, the SEDS (shape, elongation, division, and sporulation) glycosyltransferases RodA and FtsW. Since PG biogenesis is an effective target of antibiotics, these recent developments may lead to the discovery of much-needed new classes of antibiotics to fight bacterial resistance.
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Affiliation(s)
- Sujeet Kumar
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Aurelio Mollo
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, United States.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Natividad Ruiz
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
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16
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Murtha AN, Kazi MI, Schargel RD, Cross T, Fihn C, Cattoir V, Carlson EE, Boll JM, Dörr T. High-level carbapenem tolerance requires antibiotic-induced outer membrane modifications. PLoS Pathog 2022; 18:e1010307. [PMID: 35130322 PMCID: PMC8853513 DOI: 10.1371/journal.ppat.1010307] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/17/2022] [Accepted: 01/26/2022] [Indexed: 12/22/2022] Open
Abstract
Antibiotic tolerance is an understudied potential contributor to antibiotic treatment failure and the emergence of multidrug-resistant bacteria. The molecular mechanisms governing tolerance remain poorly understood. A prominent type of β-lactam tolerance relies on the formation of cell wall-deficient spheroplasts, which maintain structural integrity via their outer membrane (OM), an asymmetric lipid bilayer consisting of phospholipids on the inner leaflet and a lipid-linked polysaccharide (lipopolysaccharide, LPS) enriched in the outer monolayer on the cell surface. How a membrane structure like LPS, with its reliance on mere electrostatic interactions to maintain stability, is capable of countering internal turgor pressure is unknown. Here, we have uncovered a novel role for the PhoPQ two-component system in tolerance to the β-lactam antibiotic meropenem in Enterobacterales. We found that PhoPQ is induced by meropenem treatment and promotes an increase in 4-amino-4-deoxy-L-aminoarabinose [L-Ara4N] modification of lipid A, the membrane anchor of LPS. L-Ara4N modifications likely enhance structural integrity, and consequently tolerance to meropenem, in several Enterobacterales species. Importantly, mutational inactivation of the negative PhoPQ regulator mgrB (commonly selected for during clinical therapy with the last-resort antibiotic colistin, an antimicrobial peptide [AMP]) results in dramatically enhanced tolerance, suggesting that AMPs can collaterally select for meropenem tolerance via stable overactivation of PhoPQ. Lastly, we identify histidine kinase inhibitors (including an FDA-approved drug) that inhibit PhoPQ-dependent LPS modifications and consequently potentiate meropenem to enhance lysis of tolerant cells. In summary, our results suggest that PhoPQ-mediated LPS modifications play a significant role in stabilizing the OM, promoting survival when the primary integrity maintenance structure, the cell wall, is removed. Treating an infection with an antibiotic often fails, resulting in a tremendous public health burden. One understudied likely reason for treatment failure is the development of “antibiotic tolerance”, the ability of bacteria to survive normally lethal exposure to an antibiotic. Here, we describe a molecular mechanism promoting tolerance. A bacterial stress sensor (PhoPQ) is activated in response to antibiotic (meropenem) treatment and consequently strengthens a bacterial protective “shell” to enhance survival. We also identify inhibitors of this mechanism, opening the door to developing compounds that help antibiotics work better against tolerant bacteria.
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Affiliation(s)
- Andrew N. Murtha
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
| | - Misha I. Kazi
- Department of Biology, University of Texas Arlington, Arlington, Texas, United States of America
| | - Richard D. Schargel
- Department of Biology, University of Texas Arlington, Arlington, Texas, United States of America
| | - Trevor Cross
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
| | - Conrad Fihn
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Vincent Cattoir
- Department of Clinical Microbiology and National Reference Center for Antimicrobial Resistance (Lab Enterococci), Rennes University Hospital, Rennes, France; Inserm Unit U1230, University of Rennes 1, Rennes, France
| | - Erin E. Carlson
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Molecular Pharmacology and Therapeutics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Joseph M. Boll
- Department of Biology, University of Texas Arlington, Arlington, Texas, United States of America
- * E-mail: (JMB); (TD)
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, United States of America
- * E-mail: (JMB); (TD)
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17
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Lazar JT, Tabor JJ. Bacterial two-component systems as sensors for synthetic biology applications. CURRENT OPINION IN SYSTEMS BIOLOGY 2021; 28:100398. [PMID: 34917859 PMCID: PMC8670732 DOI: 10.1016/j.coisb.2021.100398] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Two-component systems (TCSs) are a ubiquitous family of signal transduction pathways that enable bacteria to sense and respond to diverse physical, chemical, and biological stimuli outside and inside the cell. Synthetic biologists have begun to repurpose TCSs for applications in optogenetics, materials science, gut microbiome engineering, and soil nutrient biosensing, among others. New engineering methods including genetic refactoring, DNA-binding domain swapping, detection threshold tuning, and phosphorylation cross-talk insulation are being used to increase the reliability of TCS sensor performance and tailor TCS signaling properties to the requirements of specific applications. There is now potential to combine these methods with large-scale gene synthesis and laboratory screening to discover the inputs sensed by many uncharacterized TCSs and develop a large new family of genetically-encoded sensors that respond to an unrivaled breadth of stimuli.
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Affiliation(s)
- John T Lazar
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX, USA
| | - Jeffrey J Tabor
- Department of Bioengineering, Rice University, Houston, TX, USA
- PhD Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, USA
- Department of Biosciences, Rice University, Houston, TX, USA
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18
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Ortiz-Severín J, Stuardo CJ, Jiménez NE, Palma R, Cortés MP, Maldonado J, Maass A, Cambiazo V. Nutrient Scarcity in a New Defined Medium Reveals Metabolic Resistance to Antibiotics in the Fish Pathogen Piscirickettsia salmonis. Front Microbiol 2021; 12:734239. [PMID: 34707589 PMCID: PMC8542936 DOI: 10.3389/fmicb.2021.734239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/14/2021] [Indexed: 11/16/2022] Open
Abstract
Extensive use of antibiotics has been the primary treatment for the Salmonid Rickettsial Septicemia, a salmonid disease caused by the bacterium Piscirickettsia salmonis. Occurrence of antibiotic resistance has been explored in various P. salmonis isolates using different assays; however, P. salmonis is a nutritionally demanding intracellular facultative pathogen; thus, assessing its antibiotic susceptibility with standardized and validated protocols is essential. In this work, we studied the pathogen response to antibiotics using a genomic, a transcriptomic, and a phenotypic approach. A new defined medium (CMMAB) was developed based on a metabolic model of P. salmonis. CMMAB was formulated to increase bacterial growth in nutrient-limited conditions and to be suitable for performing antibiotic susceptibility tests. Antibiotic resistance was evaluated based on a comprehensive search of antibiotic resistance genes (ARGs) from P. salmonis genomes. Minimum inhibitory concentration assays were conducted to test the pathogen susceptibility to antibiotics from drug categories with predicted ARGs. In all tested P. salmonis strains, resistance to erythromycin, ampicillin, penicillin G, streptomycin, spectinomycin, polymyxin B, ceftazidime, and trimethoprim was medium-dependent, showing resistance to higher antibiotic concentrations in the CMMAB medium. The mechanism for antibiotic resistance to ampicillin in the defined medium was further explored and was proven to be associated to a decrease in the bacterial central metabolism, including the TCA cycle, the pentose-phosphate pathway, energy production, and nucleotide metabolism, and it was not associated with decreased growth rate of the bacterium or with the expression of any predicted ARG. Our results suggest that nutrient scarcity plays a role in the bacterial antibiotic resistance, protecting against the detrimental effects of antibiotics, and thus, we propose that P. salmonis exhibits a metabolic resistance to ampicillin when growing in a nutrient-limited medium.
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Affiliation(s)
- Javiera Ortiz-Severín
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile
| | - Camila J Stuardo
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile
| | - Natalia E Jiménez
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - Ricardo Palma
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - María P Cortés
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - Jonathan Maldonado
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile
| | - Alejandro Maass
- Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile.,Centro de Modelamiento Matemático (AFB170001), Departamento de Ingeniería Matemática, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile and UMI-CNRS 2807, Santiago, Chile
| | - Verónica Cambiazo
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Fondap Center for Genome Regulation (Fondap 15200002), Universidad de Chile, Santiago, Chile
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19
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Dörr T. Understanding tolerance to cell wall-active antibiotics. Ann N Y Acad Sci 2021; 1496:35-58. [PMID: 33274447 PMCID: PMC8359209 DOI: 10.1111/nyas.14541] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 12/19/2022]
Abstract
Antibiotic tolerance-the ability of bacteria to survive for an extended time in the presence of bactericidal antibiotics-is an understudied contributor to antibiotic treatment failure. Herein, I review the manifestations, mechanisms, and clinical relevance of tolerance to cell wall-active (CWA) antibiotics, one of the most important groups of antibiotics at the forefront of clinical use. I discuss definitions of tolerance and assays for tolerance detection, comprehensively discuss the mechanism of action of β-lactams and other CWA antibiotics, and then provide an overview of how cells mitigate the potentially lethal effects of CWA antibiotic-induced cell damage to become tolerant. Lastly, I discuss evidence for a role of CWA antibiotic tolerance in clinical antibiotic treatment failure.
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Affiliation(s)
- Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Department of Microbiology, and Cornell Institute of Host–Pathogen Interactions and DiseaseCornell UniversityIthacaNew York
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20
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Sensor Domain of Histidine Kinase VxrA of Vibrio cholerae- A Hairpin-swapped Dimer and its Conformational Change. J Bacteriol 2021; 203:JB.00643-20. [PMID: 33753465 PMCID: PMC8117521 DOI: 10.1128/jb.00643-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
VxrA and VxrB are cognate histidine kinase (HK) - response regulator (RR) pairs of a two-component signaling system (TCS) found in Vibrio cholerae, a bacterial pathogen that causes cholera. The VxrAB TCS positively regulates virulence, the Type VI Secretion System, biofilm formation, and cell wall homeostasis in V. cholerae, providing protection from environmental stresses and contributing to the transmission and virulence of the pathogen. The VxrA HK has a unique periplasmic sensor domain (SD) and, remarkably, lacks a cytoplasmic linker domain between the second transmembrane helix and the dimerization and histidine phosphotransfer (DHp) domain, indicating that this system may utilize a potentially unique signal sensing and transmission TCS mechanism. In this study, we have determined several crystal structures of VxrA-SD and its mutants. These structures reveal a novel structural fold forming an unusual β hairpin-swapped dimer. A conformational change caused by relative rotation of the two monomers in a VxrA-SD dimer could potentially change the association of transmembrane helices and, subsequently, the pairing of cytoplasmic DHp domains. Based on the structural observation, we propose a putative scissor-like closing regulation mechanism for the VxrA HK.IMPORTANCE V. cholerae has a dynamic life cycle, which requires rapid adaptation to changing external conditions. Two-component signal transduction (TCS) systems allow V. cholerae to sense and respond to these environmental changes. The VxrAB TCS positively regulates a number of important V. cholerae phenotypes, including virulence, the Type Six Secretion System, biofilm formation, and cell wall homeostasis. Here, we provide the crystal structure of the VxrA sensor histidine kinase sensing domain and propose a mechanism for signal transduction. The cognate signal for VxrAB remains unknown, however, in this work we couple our structural analysis with functional assessments of key residues to further our understanding of this important TCS.
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Shin J, Choe D, Ransegnola B, Hong H, Onyekwere I, Cross T, Shi Q, Cho B, Westblade LF, Brito IL, Dörr T. A multifaceted cellular damage repair and prevention pathway promotes high-level tolerance to β-lactam antibiotics. EMBO Rep 2021; 22:e51790. [PMID: 33463026 PMCID: PMC7857431 DOI: 10.15252/embr.202051790] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/17/2020] [Accepted: 12/02/2020] [Indexed: 12/27/2022] Open
Abstract
Bactericidal antibiotics are powerful agents due to their ability to convert essential bacterial functions into lethal processes. However, many important bacterial pathogens are remarkably tolerant against bactericidal antibiotics due to inducible damage repair responses. The cell wall damage response two-component system VxrAB of the gastrointestinal pathogen Vibrio cholerae promotes high-level β-lactam tolerance and controls a gene network encoding highly diverse functions, including negative control over multiple iron uptake systems. How this system contributes to tolerance is poorly understood. Here, we show that β-lactam antibiotics cause an increase in intracellular free iron levels and collateral oxidative damage, which is exacerbated in the ∆vxrAB mutant. Mutating major iron uptake systems dramatically increases ∆vxrAB tolerance to β-lactams. We propose that VxrAB reduces antibiotic-induced toxic iron and concomitant metabolic perturbations by downregulating iron uptake transporters and show that iron sequestration enhances tolerance against β-lactam therapy in a mouse model of cholera infection. Our results suggest that a microorganism's ability to counteract diverse antibiotic-induced stresses promotes high-level antibiotic tolerance and highlights the complex secondary responses elicited by antibiotics.
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Affiliation(s)
- Jung‐Ho Shin
- Weill Institute for Cell and Molecular BiologyCornell, UniversityIthacaNYUSA
- Department of MicrobiologyCornell UniversityIthacaNYUSA
| | - Donghui Choe
- Department of Biological SciencesKorea Advanced Institute of Science and TechnologyDaejeonKorea
- KI for the BioCenturyKorea Advanced Institute of Science and TechnologyDaejeonKorea
| | - Brett Ransegnola
- Weill Institute for Cell and Molecular BiologyCornell, UniversityIthacaNYUSA
- Department of MicrobiologyCornell UniversityIthacaNYUSA
| | - Hye‐Rim Hong
- Weill Institute for Cell and Molecular BiologyCornell, UniversityIthacaNYUSA
- Department of MicrobiologyCornell UniversityIthacaNYUSA
| | - Ikenna Onyekwere
- Weill Institute for Cell and Molecular BiologyCornell, UniversityIthacaNYUSA
- Department of MicrobiologyCornell UniversityIthacaNYUSA
| | - Trevor Cross
- Weill Institute for Cell and Molecular BiologyCornell, UniversityIthacaNYUSA
- Department of MicrobiologyCornell UniversityIthacaNYUSA
| | - Qiaojuan Shi
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNYUSA
| | - Byung‐Kwan Cho
- Department of Biological SciencesKorea Advanced Institute of Science and TechnologyDaejeonKorea
- KI for the BioCenturyKorea Advanced Institute of Science and TechnologyDaejeonKorea
- Intelligent Synthetic Biology CenterDaejeonKorea
| | - Lars F Westblade
- Department of Pathology and Laboratory MedicineWeill Cornell MedicineNew YorkNYUSA
- Division of Infectious DiseasesDepartment of MedicineWeill Cornell MedicineNew YorkNYUSA
| | - Ilana L Brito
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNYUSA
| | - Tobias Dörr
- Weill Institute for Cell and Molecular BiologyCornell, UniversityIthacaNYUSA
- Department of MicrobiologyCornell UniversityIthacaNYUSA
- Cornell Institute of Host‐Microbe Interactions and DiseaseCornell UniversityIthacaNYUSA
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