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Mondry Cohen N, Krishna Kumar C, Iitoyo H, Rookyard AW, Cain JA, Man L, White MY, Dale AL, Cordwell SJ. Exploring the Targets of Reactive Oxygen Species and Defense against Oxidative Stress in Campylobacter jejuni Using a Multiomics Approach. J Proteome Res 2025. [PMID: 40426317 DOI: 10.1021/acs.jproteome.5c00182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2025]
Abstract
Campylobacter jejuni is a major cause of human gastroenteritis. Pathogenesis depends on survival in reactive oxygen species (ROS) that are produced endogenously and by host phagocytes and microbiota. Label-based proteomics by LC-MS/MS quantified 1347 proteins (83.0% of the predicted proteome) in response to hydrogen peroxide (10 μM/0.5 mM) and superoxide-inducing paraquat (PQ; 2 μM/10 μM). Antioxidants including catalase (KatA) and alkylhydroperoxide reductase (AhpC), were induced, consistent with the oxidative stress response. Changes to nutrient transporters (SdaC/PutP/LctP) correlated with the intracellular abundance of substrates (serine/proline/lactate). ROS significantly elevated the abundance of the outer membrane protein Cj1170c, and Δcj1170c bacteria were compromised for survival in H2O2 and under osmotic stress. PQ induced intracellular accumulation of threonine and homoserine, while Δcj1170c bacteria were depleted of these metabolites. ROS targets cysteine thiols that can be irreversibly modified to sulfinic and sulfonic (SO2H/SO3H) acids. We identified 1334 Cys-SO2H/SO3H-modified peptides (867 sites in 495 proteins) using SCX negative and HILIC positive selection coupled to LC-MS/MS. Many sites were modified without exogenous H2O2, suggesting that C. jejuni maintains an oxidative intracellular environment potentially related to microaerophilicity. Fe-S clusters were the primary targets of ROS. ROS trigger molecular remodeling associated with in-host growth, while overoxidizable Cys sites provide targets for redox-based antimicrobials.
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Affiliation(s)
- Nova Mondry Cohen
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
| | - Chiranth Krishna Kumar
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
| | - Haruta Iitoyo
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
| | - Alexander W Rookyard
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
- Sydney Mass Spectrometry, The University of Sydney , Sydney2006, Australia
| | - Joel A Cain
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
| | - Lok Man
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
| | - Melanie Y White
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
- School of Medical Sciences, The University of Sydney , Sydney2006, Australia
| | - Ashleigh L Dale
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
- Sydney Mass Spectrometry, The University of Sydney , Sydney2006, Australia
| | - Stuart J Cordwell
- School of Life and Environmental Sciences, The University of Sydney , Sydney2006, Australia
- Charles Perkins Centre, The University of Sydney , Sydney2006, Australia
- Sydney Mass Spectrometry, The University of Sydney , Sydney2006, Australia
- School of Medical Sciences, The University of Sydney , Sydney2006, Australia
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Sawers RG. How FocA facilitates fermentation and respiration of formate by Escherichia coli. J Bacteriol 2025; 207:e0050224. [PMID: 39868885 PMCID: PMC11841067 DOI: 10.1128/jb.00502-24] [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: 01/28/2025] Open
Abstract
Formic acid is an important source of reductant and energy for many microorganisms. Formate is also produced as a fermentation product, e.g., by enterobacteria like Escherichia coli. As such, formic acid shares many features in common with dihydrogen, explaining perhaps why their metabolism and physiology show considerable overlap. At physiological pH, formic acid is mainly present as the dissociated formate anion and therefore cannot diffuse freely across the cytoplasmic membrane. Specific and bidirectional translocation of formate across the cytoplasmic membrane is, however, achieved in E. coli by the homopentameric membrane protein, FocA. Formic acid translocation from the cytoplasm into the periplasm (efflux) serves to maintain a near-neutral cytosolic pH and to deliver formate to the periplasmically-oriented respiratory formate dehydrogenases, Fdh-N and Fdh-O. These enzymes oxidize formate, with the electrons being used to reduce nitrate, oxygen, or other acceptors. In the absence of exogenous electron acceptors, formate is re-imported into the cytoplasm by FocA, where it is sensed by the transcriptional regulator FhlA, resulting in induction of the formate regulon. The genes and operons of the formate regulon encode enzymes necessary to assemble the formate hydrogenlyase complex, which disproportionates formic acid into H2 and CO2. Combined, these mechanisms of dealing with formate help to maintain cellular pH homeostasis and are suggested to maintain the proton gradient during growth and in stationary phase cells. This review highlights our current understanding of how formate metabolism helps balance cellular pH, how it responds to the redox status, and how it helps conserve energy.
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Affiliation(s)
- R. Gary Sawers
- Institute for Microbiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Saxony-Anhalt, Germany
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Delaporte E, Karki AB, Fakhr MK. Aerotolerancy of Campylobacter spp.: A Comprehensive Review. Pathogens 2024; 13:842. [PMID: 39452714 PMCID: PMC11510350 DOI: 10.3390/pathogens13100842] [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: 08/14/2024] [Revised: 09/13/2024] [Accepted: 09/23/2024] [Indexed: 10/26/2024] Open
Abstract
Campylobacter spp. constitute a group of microaerophilic bacteria that includes strains that are aerotolerant and capable of surviving in aerobic conditions. Recent studies have shown that aerotolerant strains are highly prevalent in meats, animals, and clinical settings. Changes in growth media and other environmental conditions can affect the aerotolerance of Campylobacter strains and must be considered when studying their aerotolerance in vitro. Polymicrobial interactions and biofilms also play a significant role in the ability of Campylobacter to survive oxygen exposure. Continuous subculturing may foster aerotolerance, and studies have demonstrated a positive correlation between aerotolerance and virulence and between aerotolerance and the ability to survive stressful environmental conditions. Various mechanisms and genetic origins for aerotolerance have been proposed; however, most of the potential genes involved in aerotolerance require further investigation, and many candidate genes remain unidentified. Research is also needed to investigate if there are any clinical implications for Campylobacter aerotolerance. Understanding the aerotolerance of Campylobacter remains an important target for further research, and it will be an important step towards identifying potential targets for intervention against this clinically important food-borne pathogen.
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Affiliation(s)
- Elise Delaporte
- Department of Biological Science, The University of Tulsa, Tulsa, OK 74104, USA;
| | - Anand B. Karki
- Department of Biological Sciences, Sam Houston State University, Huntsville, TX 77341, USA
| | - Mohamed K. Fakhr
- Department of Biological Science, The University of Tulsa, Tulsa, OK 74104, USA;
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Man L, Soh PXY, McEnearney TE, Cain JA, Dale AL, Cordwell SJ. Multi-Omics of Campylobacter jejuni Growth in Chicken Exudate Reveals Molecular Remodelling Associated with Altered Virulence and Survival Phenotypes. Microorganisms 2024; 12:860. [PMID: 38792690 PMCID: PMC11123243 DOI: 10.3390/microorganisms12050860] [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: 03/21/2024] [Revised: 04/15/2024] [Accepted: 04/22/2024] [Indexed: 05/26/2024] Open
Abstract
Campylobacter jejuni is the leading cause of foodborne human gastroenteritis in the developed world. Infections are largely acquired from poultry produced for human consumption and poor food handling is thus a major risk factor. Chicken exudate (CE) is a liquid produced from defrosted commercial chicken products that facilitates C. jejuni growth. We examined the response of C. jejuni to growth in CE using a multi-omics approach. Changes in the C. jejuni proteome were assessed by label-based liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). We quantified 1328 and 1304 proteins, respectively, in experiments comparing 5% CE in Mueller-Hinton (MH) medium and 100% CE with MH-only controls. These proteins represent 81.8% and 80.3% of the predicted C. jejuni NCTC11168 proteome. Growth in CE induced profound remodelling of the proteome. These changes were typically conserved between 5% and 100% CE, with a greater magnitude of change observed in 100% CE. We confirmed that CE induced C. jejuni biofilm formation, as well as increasing motility and resistance against oxidative stress, consistent with changes to proteins representing those functions. Assessment of the C. jejuni metabolome showed CE also led to increased intracellular abundances of serine, proline, and lactate that were correlated with the elevated abundances of their respective transporters. Analysis of carbon source uptake showed prolonged culture supernatant retention of proline and succinate in CE-supplemented medium. Metabolomics data provided preliminary evidence for the uptake of chicken-meat-associated dipeptides. C. jejuni exposed to CE showed increased resistance to several antibiotics, including polymyxin B, consistent with changes to tripartite efflux system proteins and those involved in the synthesis of lipid A. The C. jejuni CE proteome was also characterised by very large increases in proteins associated with iron acquisition, while a decrease in proteins containing iron-sulphur clusters was also observed. Our data suggest CE is both oxygen- and iron-limiting and provide evidence of factors required for phenotypic remodelling to enable C. jejuni survival on poultry products.
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Affiliation(s)
- Lok Man
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
| | - Pamela X. Y. Soh
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Tess E. McEnearney
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
| | - Joel A. Cain
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
| | - Ashleigh L. Dale
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
| | - Stuart J. Cordwell
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
- Sydney Mass Spectrometry, The University of Sydney, Sydney, NSW 2006, Australia
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Deblais L, Drozd M, Kumar A, Antwi J, Fuchs J, Khupse R, Helmy YA, Rajashekara G. Identification of novel small molecule inhibitors of twin arginine translocation (Tat) pathway and their effect on the control of Campylobacter jejuni in chickens. Front Microbiol 2024; 15:1342573. [PMID: 38694802 PMCID: PMC11061419 DOI: 10.3389/fmicb.2024.1342573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 03/08/2024] [Indexed: 05/04/2024] Open
Abstract
Introduction Control of Campylobacter from farm to fork is challenging due to the frequent emergence of antimicrobial-resistant isolates. Furthermore, poultry production systems are known reservoirs of Campylobacter. The twin-arginine translocation (Tat) pathway is a crucial bacterial secretion system that allows Campylobacter to colonize the host intestinal tract by using formate as the main source of energy. However, Tat pathway is also a major contributing factor for resistance to copper sulfate (CuSO4). Methods Since mammals and chickens do not have proteins or receptors that are homologous to bacterial Tat proteins, identification of small molecule (SM) inhibitors targeting the Tat system would allow the development of safe and effective control methods to mitigate Campylobacter in infected or colonized hosts in both pre-harvest and post-harvest. In this study, we screened 11 commercial libraries (n = 50,917 SM) for increased susceptibility to CuSO4 (1 mM) in C. jejuni 81-176, a human isolate which is widely studied. Results Furthermore, we evaluated 177 SM hits (2.5 μg/mL and above) that increased the susceptibility to CuSO4 for the inhibition of formate dehydrogenase (Fdh) activity, a Tat-dependent substrate. Eight Tat-dependent inhibitors (T1-T8) were selected for further studies. These selected eight Tat inhibitors cleared all tested Campylobacter strains (n = 12) at >10 ng/mL in the presence of 0.5 mM CuSO4in vitro. These selected SMs were non-toxic to colon epithelial (Caco-2) cells when treated with 50 μg/mL for 24 h and completely cleared intracellular C. jejuni cells when treated with 0.63 μg/mL of SM for 24 h in the presence of 0.5 mM of CuSO4. Furthermore, 3 and 5-week-old chicks treated with SM candidates for 5 days had significantly decreased cecal colonization (up to 1.2 log; p < 0.01) with minimal disruption of microbiota. In silico analyses predicted that T7 has better drug-like properties than T2 inhibitor and might target a key amino acid residue (glutamine 165), which is located in the hydrophobic core of TatC protein. Discussion Thus, we have identified novel SM inhibitors of the Tat pathway, which represent a potential strategy to control C. jejuni spread on farms.
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Affiliation(s)
- Loïc Deblais
- Department of Animal Sciences, The Ohio State University, OARDC, Wooster, OH, United States
| | - Mary Drozd
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Anand Kumar
- Los Alamos National Laboratory, Bioscience Division, Group B-10: Biosecurity and Public Health, Los Alamos, NM, United States
| | - Janet Antwi
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, United States
| | - James Fuchs
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, United States
| | - Rahul Khupse
- College of Pharmacy, University of Findlay, OH, United States
| | - Yosra A. Helmy
- Department of Animal Sciences, The Ohio State University, OARDC, Wooster, OH, United States
| | - Gireesh Rajashekara
- Department of Animal Sciences, The Ohio State University, OARDC, Wooster, OH, United States
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Duan J, Zhao Q, Wang Y, Chi Z, Li W, Wang X, Liu S, Bi S. The dCache Domain of the Chemoreceptor Tlp1 in Campylobacter jejuni Binds and Triggers Chemotaxis toward Formate. mBio 2023:e0356422. [PMID: 37052512 DOI: 10.1128/mbio.03564-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Chemotaxis is an important virulence factor in some enteric pathogens, and it is involved in the pathogenesis and colonization of the host. However, there is limited knowledge regarding the environmental signals that promote chemotactic behavior and the sensing of these signals by chemoreceptors. To date, there is no information on the ligand molecule that directly binds to and is sensed by Campylobacter jejuni Tlp1, which is a chemoreceptor with a dCache-type ligand-binding domain (LBD). dCache (double Calcium channels and chemotaxis receptor) is the largest group of sensory domains in bacteria, but the dCache-type chemoreceptor that directly binds to formate has not yet been discovered. In this study, formate was identified as a direct-binding ligand of C. jejuni Tlp1 with high sensing specificity. We used the strategy of constructing a functional hybrid receptor of C. jejuni Tlp1 and the Escherichia coli chemoreceptor Tar to screen for the potential ligand of Tlp1, with the binding of formate to Tlp1-LBD being verified using isothermal titration calorimetry. Molecular docking and experimental analyses indicated that formate binds to the membrane-proximal pocket of the dCache subdomain. Chemotaxis assays demonstrated that formate elicits robust attractant responses of the C. jejuni strain NCTC 11168, specifically via Tlp1. The chemoattraction effect of formate via Tlp1 promoted the growth of C. jejuni, especially when competing with Tlp1- or CheY-knockout strains. Our study reveals the molecular mechanisms by which C. jejuni mediates chemotaxis toward formate, and, to our knowledge, is the first report on the high-specificity binding of the dCache-type chemoreceptor to formate as well as the physiological role of chemotaxis toward formate. IMPORTANCE Chemotaxis is important for Campylobacter jejuni to colonize favorable niches in the gastrointestinal tract of its host. However, there is still a lack of knowledge about the ligand molecules for C. jejuni chemoreceptors. The dCache-type chemoreceptor, namely, Tlp1, is the most conserved chemoreceptor in C. jejuni strains; however, the direct-binding ligand(s) triggering chemotaxis has not yet been discovered. In the present study, we found that the ligand that binds directly to Tlp1-LBD with high specificity is formate. C. jejuni exhibits robust chemoattraction toward formate, primarily via Tlp1. Tlp1 is the first reported dCache-type chemoreceptor that specifically binds formate and triggers strong chemotaxis. We further demonstrated that the formate-mediated promotion of C. jejuni growth is correlated with Tlp1-mediated chemotaxis toward formate. Our work provides important insights into the mechanism and physiological function of chemotaxis toward formate and will facilitate further investigations into the involvement of microbial chemotaxis in pathogen-host interactions.
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Affiliation(s)
- Jingjing Duan
- State Key Laboratory of Microbial Biotechnology, Shandong University, Qingdao, China
| | - Qi Zhao
- State Key Laboratory of Microbial Biotechnology, Shandong University, Qingdao, China
| | - Yuxin Wang
- State Key Laboratory of Microbial Biotechnology, Shandong University, Qingdao, China
| | - Zhe Chi
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Wei Li
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, China
| | - Xue Wang
- State Key Laboratory of Microbial Biotechnology, Shandong University, Qingdao, China
| | - Shuangjiang Liu
- State Key Laboratory of Microbial Biotechnology, Shandong University, Qingdao, China
- State Key Laboratory of Microbial Resources, and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Shuangyu Bi
- State Key Laboratory of Microbial Biotechnology, Shandong University, Qingdao, China
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Deblais L, Ranjit S, Vrisman C, Antony L, Scaria J, Miller SA, Rajashekara G. Role of Stress-Induced Proteins RpoS and YicC in the Persistence of Salmonella enterica subsp. enterica Serotype Typhimurium in Tomato Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2023; 36:109-118. [PMID: 36394339 DOI: 10.1094/mpmi-07-22-0152-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Understanding the functional role of bacterial genes in the persistence of Salmonella in plant organs can facilitate the development of agricultural practices to mitigate food safety risks associated with the consumption of fresh produce contaminated with Salmonella spp. Our study showed that Salmonella enterica subsp. enterica serotype Typhimurium (strain MDD14) persisted less in inoculated tomato plants than other Salmonella Typhimurium strains tested (JSG210, JSG626, JSG634, JSG637, JSG3444, and EV030415; P < 0.01). In-vitro assays performed in limited-nutrient conditions (growth rate, biofilm production, and motility) were inconclusive in explaining the in-planta phenotype observed with MDD14. Whole-genome sequencing combined with non-synonymous single nucleotide variations analysis was performed to identify genomic differences between MDD14 and the other Salmonella Typhimurium strains. The genome of MDD14 contained a truncated version (123 bp N-terminal) of yicC and a mutated version of rpoS (two non-synonymous substitutions, i.e., G66E and R82C), which are two stress-induced proteins involved in iron acquisition, environmental sensing, and cell envelope integrity. The rpoS and yicC genes were deleted in Salmonella Typhimurium JSG210 with the Lambda Red recombining system. Both mutants had limited persistence in tomato plant organs, similar to that of MDD14. In conclusion, we demonstrated that YicC and RpoS are involved in the persistence of Salmonella in tomato plants in greenhouse conditions and, thus, could represent potential targets to mitigate persistence of Salmonella spp. in planta. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Loïc Deblais
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
| | - Sochina Ranjit
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
| | - Claudio Vrisman
- Department of Plant Pathology, The Ohio State University, Wooster, OH, U.S.A
| | - Linto Antony
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, U.S.A
| | - Joy Scaria
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, U.S.A
| | - Sally A Miller
- Department of Plant Pathology, The Ohio State University, Wooster, OH, U.S.A
| | - Gireesh Rajashekara
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
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Stoakes E, Savva GM, Coates R, Tejera N, Poolman MG, Grant AJ, Wain J, Singh D. Substrate Utilisation and Energy Metabolism in Non-Growing Campylobacter jejuni M1cam. Microorganisms 2022; 10:1355. [PMID: 35889074 PMCID: PMC9318392 DOI: 10.3390/microorganisms10071355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/23/2022] [Accepted: 06/30/2022] [Indexed: 02/04/2023] Open
Abstract
Campylobacter jejuni, the major cause of bacterial foodborne illness, is also a fastidious organism that requires strict growth requirements in the laboratory. Our aim was to study substrate utilisation and energy metabolism in non-growing C. jejuni to investigate the ability of these bacteria to survive so effectively in the food chain. We integrated phenotypic microarrays and genome-scale metabolic modelling (GSM) to investigate the survival of C. jejuni on 95 substrates. We further investigated the underlying metabolic re-adjustment associated with varying energy demands on each substrate. We identified amino acids, organic acids and H2, as single substrates supporting survival without growth. We identified several different mechanisms, which were used alone or in combination, for ATP production: substrate-level phosphorylation via acetate kinase, the TCA cycle, and oxidative phosphorylation via the electron transport chain that utilised alternative electron donors and acceptors. The benefit of ATP production through each of these mechanisms was associated with the cost of enzyme investment, nutrient availability and/or O2 utilisation. C. jejuni can utilise a wide range of substrates as energy sources, including organic acids commonly used for marination or preservation of ingredients, which might contribute to the success of their survival in changing environments.
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Affiliation(s)
- Emily Stoakes
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK; (E.S.); (R.C.); (A.J.G.)
| | - George M. Savva
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (G.M.S.); (N.T.)
| | - Ruby Coates
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK; (E.S.); (R.C.); (A.J.G.)
| | - Noemi Tejera
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (G.M.S.); (N.T.)
| | - Mark G. Poolman
- Cell System Modelling Group, Oxford Brookes University, Oxford OX3 0BP, UK;
| | - Andrew J. Grant
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK; (E.S.); (R.C.); (A.J.G.)
| | - John Wain
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (G.M.S.); (N.T.)
| | - Dipali Singh
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (G.M.S.); (N.T.)
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9
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Lanzl MI, van Mastrigt O, Zwietering MH, Abee T, den Besten HMW. Role of substrate availability in the growth of Campylobacter co-cultured with extended spectrum beta-lactamase-producing Escherichia coli in Bolton broth. Int J Food Microbiol 2021; 363:109518. [PMID: 34996645 DOI: 10.1016/j.ijfoodmicro.2021.109518] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 12/17/2021] [Accepted: 12/24/2021] [Indexed: 01/03/2023]
Abstract
It is well-established that Extended-spectrum beta-lactamase-producing (ESBL-) Escherichia coli challenge reliable detection of campylobacters during enrichment in Bolton broth (BB) following ISO 10272-1:2017. The overgrowth of Campylobacter by ESBL-E. coli in the enrichment medium BB can lead to false-negative detection outcomes, but the cause for the growth suppression is yet unknown. A plausible reason could be the competition-induced lack of certain growth substrates. Therefore, this study aimed to investigate whether campylobacters and ESBL-E. coli compete for the same medium components and whether this is the cause for the observed growth repression. The availability of possible growth substrates in BB was determined and changes in their extracellular concentration were measured over time during mono-culture enrichment of C. jejuni, C. coli or ESBL-E. coli as well as in co-culture enrichments of campylobacters and ESBL-E. coli. Comparative analysis showed lactate and fumarate utilization by C. jejuni and C. coli exclusively, whereas ESBL-E. coli rapidly consumed asparagine, glutamine/arginine, lysine, threonine, tryptophan, pyruvate, glycerol, cellobiose, and glucose. Both campylobacters and ESBL-E. coli utilized aspartate, serine, formate, a-ketoglutarate and malate. Trends in compound utilization were similar for C. jejuni and C. coli and trends in compound utilization were rather comparable during enrichment of reference and freeze-stressed campylobacters. Since final cell densities of C. jejuni and C. coli in co-cultures were not enhanced by the addition of surplus l-serine and final cell densities were similar in fresh and spent medium, growth suppression seems not to be caused by a lack of substrates or production of inhibitory compounds. We hypothesized that oxygen availability was limiting growth in co-cultures. Higher oxygen availability increased the competitive fitness of C. jejuni 81-176 in co-culture with ESBL-E. coli in duplicate experiments, as cell concentrations in stationary phase were similar to those without competition. This could indicate the critical role of oxygen availability during the growth of Campylobacter and offers potential for further improvement of Campylobacter spp. enrichment efficacy.
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Affiliation(s)
- M I Lanzl
- Food Microbiology, Wageningen University & Research, Netherlands
| | - O van Mastrigt
- Food Microbiology, Wageningen University & Research, Netherlands
| | - M H Zwietering
- Food Microbiology, Wageningen University & Research, Netherlands
| | - T Abee
- Food Microbiology, Wageningen University & Research, Netherlands
| | - H M W den Besten
- Food Microbiology, Wageningen University & Research, Netherlands.
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10
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Interplay between DsbA1, DsbA2 and C8J_1298 Periplasmic Oxidoreductases of Campylobacter jejuni and Their Impact on Bacterial Physiology and Pathogenesis. Int J Mol Sci 2021; 22:ijms222413451. [PMID: 34948248 PMCID: PMC8708908 DOI: 10.3390/ijms222413451] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 01/13/2023] Open
Abstract
The bacterial proteins of the Dsb family catalyze the formation of disulfide bridges between cysteine residues that stabilize protein structures and ensure their proper functioning. Here, we report the detailed analysis of the Dsb pathway of Campylobacter jejuni. The oxidizing Dsb system of this pathogen is unique because it consists of two monomeric DsbAs (DsbA1 and DsbA2) and one dimeric bifunctional protein (C8J_1298). Previously, we showed that DsbA1 and C8J_1298 are redundant. Here, we unraveled the interaction between the two monomeric DsbAs by in vitro and in vivo experiments and by solving their structures and found that both monomeric DsbAs are dispensable proteins. Their structures confirmed that they are homologs of EcDsbL. The slight differences seen in the surface charge of the proteins do not affect the interaction with their redox partner. Comparative proteomics showed that several respiratory proteins, as well as periplasmic transport proteins, are targets of the Dsb system. Some of these, both donors and electron acceptors, are essential elements of the C. jejuni respiratory process under oxygen-limiting conditions in the host intestine. The data presented provide detailed information on the function of the C. jejuni Dsb system, identifying it as a potential target for novel antibacterial molecules.
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11
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Garg N, Taylor AJ, Pastorelli F, Flannery SE, Jackson PJ, Johnson MP, Kelly DJ. Genes Linking Copper Trafficking and Homeostasis to the Biogenesis and Activity of the cbb 3-Type Cytochrome c Oxidase in the Enteric Pathogen Campylobacter jejuni. Front Microbiol 2021; 12:683260. [PMID: 34248902 PMCID: PMC8267372 DOI: 10.3389/fmicb.2021.683260] [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: 03/20/2021] [Accepted: 05/26/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial C-type haem-copper oxidases in the cbb 3 family are widespread in microaerophiles, which exploit their high oxygen-binding affinity for growth in microoxic niches. In microaerophilic pathogens, C-type oxidases can be essential for infection, yet little is known about their biogenesis compared to model bacteria. Here, we have identified genes involved in cbb 3-oxidase (Cco) assembly and activity in the Gram-negative pathogen Campylobacter jejuni, the commonest cause of human food-borne bacterial gastroenteritis. Several genes of unknown function downstream of the oxidase structural genes ccoNOQP were shown to be essential (cj1483c and cj1486c) or important (cj1484c and cj1485c) for Cco activity; Cj1483 is a CcoH homologue, but Cj1484 (designated CcoZ) has structural similarity to MSMEG_4692, involved in Qcr-oxidase supercomplex formation in Mycobacterium smegmatis. Blue-native polyacrylamide gel electrophoresis of detergent solubilised membranes revealed three major bands, one of which contained CcoZ along with Qcr and oxidase subunits. Deletion of putative copper trafficking genes ccoI (cj1155c) and ccoS (cj1154c) abolished Cco activity, which was partially restored by addition of copper during growth, while inactivation of cj0369c encoding a CcoG homologue led to a partial reduction in Cco activity. Deletion of an operon encoding PCu A C (Cj0909) and Sco (Cj0911) periplasmic copper chaperone homologues reduced Cco activity, which was partially restored in the cj0911 mutant by exogenous copper. Phenotypic analyses of gene deletions in the cj1161c-1166c cluster, encoding several genes involved in intracellular metal homeostasis, showed that inactivation of copA (cj1161c), or copZ (cj1162c) led to both elevated intracellular Cu and reduced Cco activity, effects exacerbated at high external Cu. Our work has therefore identified (i) additional Cco subunits, (ii) a previously uncharacterized set of genes linking copper trafficking and Cco activity, and (iii) connections with Cu homeostasis in this important pathogen.
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Affiliation(s)
- Nitanshu Garg
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
| | - Aidan J Taylor
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
| | - Federica Pastorelli
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
| | - Sarah E Flannery
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
| | - Phillip J Jackson
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
| | - Matthew P Johnson
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
| | - David J Kelly
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
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12
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Molecular Mechanisms of Campylobacter Biofilm Formation and Quorum Sensing. Curr Top Microbiol Immunol 2021. [PMID: 33620656 DOI: 10.1007/978-3-030-65481-8_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Even though Campylobacter spp. are known to be fastidious organisms, they can survive within the natural environment. One mechanism to withstand unfavourable conditions is the formation of biofilms, a multicellular structure composed of different bacterial and other microbial species which are embedded in an extracellular matrix. High oxygen levels, low substrate concentrations and the presence of external DNA stimulate the biofilm formation by C. jejuni. These external factors trigger internal adaptation processes, e.g. via regulating the expression of genes encoding proteins required for surface structure formation, as well as motility, stress response and antimicrobial resistance. Known genes impacting biofilm formation will be summarized in this review. The formation of biofilms as well as the expression of virulence genes is often regulated in a cell density depending manner by quorum sensing, which is mediated via small signalling molecules termed autoinducers. Even though quorum sensing mechanisms of other bacteria are well understood, knowledge on the role of these mechanisms in C. jejuni biofilm formation is still scarce. The LuxS enzyme involved in generation of autoinducer-2 is present in C. jejuni, but autoinducer receptors have not been identified so far. Phenotypes of C. jejuni strains lacking a functional luxS like reduced growth, motility, oxygen stress tolerance, biofilm formation, adhesion, invasion and colonization are also summarized within this chapter. However, these phenotypes are highly variable in distinct C. jejuni strains and depend on the culture conditions applied.
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13
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Ricke SC, Dittoe DK, Richardson KE. Formic Acid as an Antimicrobial for Poultry Production: A Review. Front Vet Sci 2020; 7:563. [PMID: 33088825 PMCID: PMC7494846 DOI: 10.3389/fvets.2020.00563] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 07/15/2020] [Indexed: 02/06/2023] Open
Abstract
Organic acids continue to receive considerable attention as feed additives for animal production. Most of the emphasis to date has focused on food safety aspects, particularly on lowering the incidence of foodborne pathogens in poultry and other livestock. Several organic acids are currently either being examined or are already being implemented in commercial settings. Among the several organic acids that have been studied extensively, is formic acid. Formic acid has been added to poultry diets as a means to limit Salmonella spp. and other foodborne pathogens both in the feed and potentially in the gastrointestinal tract once consumed. As more becomes known about the efficacy and impact formic acid has on both the host and foodborne pathogens, it is clear that the presence of formic acid can trigger certain pathways in Salmonella spp. This response may become more complex when formic acid enters the gastrointestinal tract and interacts not only with Salmonella spp. that has colonized the gastrointestinal tract but the indigenous microbial community as well. This review will cover current findings and prospects for further research on the poultry microbiome and feeds treated with formic acid.
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Affiliation(s)
- Steven C. Ricke
- Department of Food Science, Center of Food Safety, University of Arkansas, Fayetteville, AR, United States
| | - Dana K. Dittoe
- Department of Food Science, Center of Food Safety, University of Arkansas, Fayetteville, AR, United States
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14
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Beier RC, Byrd JA, Caldwell D, Andrews K, Crippen TL, Anderson RC, Nisbet DJ. Inhibition and Interactions of Campylobacter jejuni from Broiler Chicken Houses with Organic Acids. Microorganisms 2019; 7:E223. [PMID: 31366094 PMCID: PMC6722939 DOI: 10.3390/microorganisms7080223] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/19/2019] [Accepted: 07/27/2019] [Indexed: 12/11/2022] Open
Abstract
Campylobacter jejuni is a bacterium that causes major diarrheal disease worldwide and is also one of the top five foodborne pathogens encountered in the United States. Poultry is a major source of C. jejuni, and a high-risk factor for contracting campylobacteriosis. Organic acids are used in the United States during food animal processing for removal of bacterial contamination from animal carcasses. Six organic acids were evaluated in inhibition studies of 96 C. jejuni strains obtained from shoe covers used in broiler chicken houses at different poultry farms in several states by determining the susceptibilities of the C. jejuni strains, along with the pH values at the molar minimum inhibitory concentrations (MICMs). The undissociated and dissociated organic acid concentrations were calculated at the MICMs with the Henderson-Hasselbalch equation. The results for the 96 C. jejuni strains were treated similarly for each different organic acid. Campylobacter jejuni inhibition did correlate with the dissociated organic acids, but did not correlate with pH or with the undissociated organic acids. When the concentrations of dissociated organic acids decreased, the C. jejuni strains were not disinfected. A carcass wash using organic acids should have the concentration of dissociated acid species carefully controlled. It is suggested to maintain a dissociated acid concentration for propionic, l-lactic, formic, citric, butyric, and acetic acids at 24, 40, 36, 21, 23, and 25 mM, respectively, and at these dissociated organic acid levels an acid wash would be expected to remove or inhibit 97% or more of the C. jejuni bacteria studied here. However, studies must be undertaken to confirm that the suggested concentrations of dissociated organic acids are adequate to remove C. jejuni bacteria in the field vs. the laboratory. Due to propionate, l-lactate, formate, butyrate, and acetate being utilized by C. jejuni, these organic acids may not be appropriate for use as a carcass wash to remove C. jejuni surface contamination. Of all tested organic acids, dissociated citric acid was the most efficient at inhibiting C. jejuni.
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Affiliation(s)
- Ross C Beier
- United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845-4988, USA.
| | - J Allen Byrd
- United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845-4988, USA
| | - Denise Caldwell
- United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845-4988, USA
| | - Kathleen Andrews
- United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845-4988, USA
| | - Tawni L Crippen
- United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845-4988, USA
| | - Robin C Anderson
- United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845-4988, USA
| | - David J Nisbet
- United States Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, Food and Feed Safety Research Unit, College Station, TX 77845-4988, USA
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15
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Taylor AJ, Kelly DJ. The function, biogenesis and regulation of the electron transport chains in Campylobacter jejuni: New insights into the bioenergetics of a major food-borne pathogen. Adv Microb Physiol 2019; 74:239-329. [PMID: 31126532 DOI: 10.1016/bs.ampbs.2019.02.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Campylobacter jejuni is a zoonotic Epsilonproteobacterium that grows in the gastrointestinal tract of birds and mammals, and is the most frequent cause of food-borne bacterial gastroenteritis worldwide. As an oxygen-sensitive microaerophile, C. jejuni has to survive high environmental oxygen tensions, adapt to oxygen limitation in the host intestine and resist host oxidative attack. Despite its small genome size, C. jejuni is a versatile and metabolically active pathogen, with a complex and highly branched set of respiratory chains allowing the use of a wide range of electron donors and alternative electron acceptors in addition to oxygen, including fumarate, nitrate, nitrite, tetrathionate and N- or S-oxides. Several novel enzymes participate in these electron transport chains, including a tungsten containing formate dehydrogenase, a Complex I that uses flavodoxin and not NADH, a periplasmic facing fumarate reductase and a cytochrome c tetrathionate reductase. This review presents an updated description of the composition and bioenergetics of these various respiratory chains as they are currently understood, including recent work that gives new insights into energy conservation during electron transport to various alternative electron acceptors. The regulation of synthesis and assembly of the electron transport chains is also discussed. A deeper appreciation of the unique features of the respiratory systems of C. jejuni may be helpful in informing strategies to control this important pathogen.
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Affiliation(s)
- Aidan J Taylor
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - David J Kelly
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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16
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Chandrashekhar K, Kassem II, Rajashekara G. Campylobacter jejuni transducer like proteins: Chemotaxis and beyond. Gut Microbes 2017; 8:323-334. [PMID: 28080213 PMCID: PMC5570417 DOI: 10.1080/19490976.2017.1279380] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 12/12/2016] [Accepted: 12/29/2016] [Indexed: 02/03/2023] Open
Abstract
Chemotaxis, a process that mediates directional motility toward or away from chemical stimuli (chemoeffectors/ligands that can be attractants or repellents) in the environment, plays an important role in the adaptation of Campylobacter jejuni to disparate niches. The chemotaxis system consists of core signal transduction proteins and methyl-accepting-domain-containing Transducer like proteins (Tlps). Ligands binding to Tlps relay a signal to chemotaxis proteins in the cytoplasm which initiate a signal transduction cascade, culminating into a directional flagellar movement. Tlps facilitate substrate-specific chemotaxis in C. jejuni, which plays an important role in the pathogen's adaptation, pathobiology and colonization of the chicken gastrointestinal tract. However, the role of Tlps in C. jejuni's host tissue specific colonization, physiology and virulence remains not completely understood. Based on recent studies, it can be predicted that Tlps might be important targets for developing strategies to control C. jejuni via vaccines and antimicrobials.
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Affiliation(s)
- Kshipra Chandrashekhar
- Department of Food Animal Health and Preventive Medicine, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, Ohio, USA
| | - Issmat I. Kassem
- Department of Food Animal Health and Preventive Medicine, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, Ohio, USA
| | - Gireesh Rajashekara
- Department of Food Animal Health and Preventive Medicine, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, Ohio, USA
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17
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van der Stel AX, Boogerd FC, Huynh S, Parker CT, van Dijk L, van Putten JPM, Wösten MMSM. Generation of the membrane potential and its impact on the motility, ATP production and growth in Campylobacter jejuni. Mol Microbiol 2017; 105:637-651. [PMID: 28586527 DOI: 10.1111/mmi.13723] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/29/2017] [Accepted: 06/04/2017] [Indexed: 02/06/2023]
Abstract
The generation of a membrane potential (Δψ), the major constituent of the proton motive force (pmf), is crucial for ATP synthesis, transport of nutrients and flagellar rotation. Campylobacter jejuni harbors a branched electron transport chain, enabling respiration with different electron donors and acceptors. Here, we demonstrate that a relatively high Δψ is only generated in the presence of either formate as electron donor or oxygen as electron acceptor, in combination with an acceptor/donor respectively. We show the necessity of the pmf for motility and growth of C. jejuni. ATP generation is not only accomplished by oxidative phosphorylation via the pmf, but also by substrate-level phosphorylation via the enzyme AckA. In response to a low oxygen tension, C. jejuni increases the transcription and activity of the donor complexes formate dehydrogenase (FdhABC) and hydrogenase (HydABCD) as well as the transcription of the alternative respiratory acceptor complexes. Our findings suggest that in the gut of warm-blooded animals, C. jejuni depends on at least formate or hydrogen as donor (in the anaerobic lumen) or oxygen as acceptor (near the epithelial cells) to generate a pmf that sustains efficient motility and growth for colonization and pathogenesis.
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Affiliation(s)
| | - Fred C Boogerd
- Department of Molecular Cell Biology, VU University Amsterdam, Amsterdam, The Netherlands
| | - Steven Huynh
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA, USA
| | - Craig T Parker
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA, USA
| | - Linda van Dijk
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
| | - Jos P M van Putten
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
| | - Marc M S M Wösten
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
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Microbiota-Derived Short-Chain Fatty Acids Modulate Expression of Campylobacter jejuni Determinants Required for Commensalism and Virulence. mBio 2017; 8:mBio.00407-17. [PMID: 28487428 PMCID: PMC5424204 DOI: 10.1128/mbio.00407-17] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Campylobacter jejuni promotes commensalism in the intestinal tracts of avian hosts and diarrheal disease in humans, yet components of intestinal environments recognized as spatial cues specific for different intestinal regions by the bacterium to initiate interactions in either host are mostly unknown. By analyzing a C. jejuni acetogenesis mutant defective in converting acetyl coenzyme A (Ac-CoA) to acetate and commensal colonization of young chicks, we discovered evidence for in vivo microbiota-derived short-chain fatty acids (SCFAs) and organic acids as cues recognized by C. jejuni that modulate expression of determinants required for commensalism. We identified a set of C. jejuni genes encoding catabolic enzymes and transport systems for amino acids required for in vivo growth whose expression was modulated by SCFAs. Transcription of these genes was reduced in the acetogenesis mutant but was restored upon supplementation with physiological concentrations of the SCFAs acetate and butyrate present in the lower intestinal tracts of avian and human hosts. Conversely, the organic acid lactate, which is abundant in the upper intestinal tract where C. jejuni colonizes less efficiently, reduced expression of these genes. We propose that microbiota-generated SCFAs and lactate are cues for C. jejuni to discriminate between different intestinal regions. Spatial gradients of these metabolites likely allow C. jejuni to locate preferred niches in the lower intestinal tract and induce expression of factors required for intestinal growth and commensal colonization. Our findings provide insights into the types of cues C. jejuni monitors in the avian host for commensalism and likely in humans to promote diarrheal disease. Campylobacter jejuni is a commensal of the intestinal tracts of avian species and other animals and a leading cause of diarrheal disease in humans. The types of cues sensed by C. jejuni to influence responses to promote commensalism or infection are largely lacking. By analyzing a C. jejuni acetogenesis mutant, we discovered a set of genes whose expression is modulated by lactate and short-chain fatty acids produced by the microbiota in the intestinal tract. These genes include those encoding catabolic enzymes and transport systems for amino acids that are required by C. jejuni for in vivo growth and intestinal colonization. We propose that gradients of these microbiota-generated metabolites are cues for spatial discrimination between areas of the intestines so that the bacterium can locate niches in the lower intestinal tract for optimal growth for commensalism in avian species and possibly infection of human hosts leading to diarrheal disease.
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