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Alejandro-Navarreto X, Freitag NE. Revisiting old friends: updates on the role of two-component signaling systems in Listeria monocytogenes survival and pathogenesis. Infect Immun 2024; 92:e0034523. [PMID: 38591895 PMCID: PMC11003226 DOI: 10.1128/iai.00345-23] [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: 04/10/2024] Open
Abstract
Listeria monocytogenes is well recognized for both its broad resistance to stress conditions and its ability to transition from a soil bacterium to an intracellular pathogen of mammalian hosts. The bacterium's impressive ability to adapt to changing environments and conditions requires the rapid sensing of environmental cues and the coordinated response of gene products that enable bacterial growth and survival. Two-component signaling systems (TCSs) have been long recognized for their ability to detect environmental stimuli and transmit those signals into transcriptional responses; however, often the precise nature of the stimulus triggering TCS responses can be challenging to define. L. monocytogenes has up to 16 TCSs that have been recognized based on homology and included in this list are several whose functions remain poorly described. This review highlights the current understanding of the breadth and scope of L. monocytogenes TCS as relates to stress resistance and pathogenesis. Precise signals still often remain elusive, but the gene networks associated with TCSs are providing clues into possible functions.
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Affiliation(s)
| | - Nancy E. Freitag
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois, USA
- Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
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2
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Bombelli A, Araya-Cloutier C, Boeren S, Vincken JP, Abee T, den Besten HMW. Effects of the antimicrobial glabridin on membrane integrity and stress response activation in Listeria monocytogenes. Food Res Int 2024; 175:113687. [PMID: 38128979 DOI: 10.1016/j.foodres.2023.113687] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/02/2023] [Accepted: 11/06/2023] [Indexed: 12/23/2023]
Abstract
Glabridin is a prenylated isoflavan which can be extracted from liquorice roots and has shown antimicrobial activity against foodborne pathogens and spoilage microorganisms. However, its application may be hindered due to limited information about its mode of action. In this study, we aimed to investigate the mode of action of glabridin using a combined phenotypic and proteomic approach on Listeria monocytogenes. Fluorescence and transmission electron microscopy of cells exposed to glabridin showed membrane permeabilization upon treatment with lethal concentrations of glabridin. Comparative proteomics analysis of control cells and cells exposed to sub-lethal concentrations of glabridin showed upregulation of proteins related to the two-component systems LiaSR and VirRS, confirming cell envelope damage during glabridin treatment. Additional upregulation of SigmaB regulon members signified activation of the general stress response in L. monocytogenes during this treatment. In line with the observed upregulation of cell envelope and general stress response proteins, sub-lethal treatment of glabridin induced (cross)protection against lethal heat and low pH stress and against antimicrobials such as nisin and glabridin itself. Overall, this study sheds light on the mode of action of glabridin and activation of the main stress responses to this antimicrobial isoflavan and highlights possible implications of its use as a naturally derived antimicrobial compound.
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Affiliation(s)
- Alberto Bombelli
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands; Food Chemistry, Wageningen University & Research, Wageningen, the Netherlands
| | | | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University & Research, Wageningen, the Netherlands
| | - Jean-Paul Vincken
- Food Chemistry, Wageningen University & Research, Wageningen, the Netherlands
| | - Tjakko Abee
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands.
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3
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Bannenberg JW, Boeren S, Zwietering MH, Abee T, den Besten HMW. Insight in lag phase of Listeria monocytogenes during enrichment through proteomic and transcriptomic responses. Food Res Int 2024; 175:113609. [PMID: 38128973 DOI: 10.1016/j.foodres.2023.113609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 10/16/2023] [Accepted: 10/18/2023] [Indexed: 12/23/2023]
Abstract
The dynamics of the enrichment-based detection procedure of the foodborne pathogen Listeria monocytogenes from food still remains poorly understood. This enrichment is crucial in the reliable detection of this pathogen and more insight into the recovery mechanism during this step is important to advance our understanding of lag phase behaviour during enrichment. In this study we combined transcriptomic and proteomic analyses to better understand the physiological processes within the lag phase of L. monocytogenes during enrichment. Upon transfer of BHI-cultured stationary phase L. monocytogenes cells to half-Fraser enrichment broth (HFB), motility-associated genes and proteins were downregulated, while expression of metal uptake transporters, resuscitation-promoting factors that stimulate growth from dormancy, antibiotic efflux pumps and oxidative stress proteins were upregulated. Next to this, when cells with a heat stress history were cultured in enrichment broth, proteins necessary for recovery were upregulated with functions in DNA-damage repair, protein refolding, cell-wall repair, and zinc transport. Proteomic results pointed to possible factors that support shortening the lag duration, including the addition of 10 µM zinc and the addition of spent HFB containing presumed concentrations of resuscitation-promoting factors. However, these interventions did not lead to biologically relevant reduction of lag phase. Also, when cells were enriched in spent HFB, final cell concentrations were similar to enrichments in fresh HFB, indicating that the enrichment broth seems not to lack critical substrates. Concludingly, this study gives insight into the proteomic changes in the lag phase during enrichment and shows that supplementation of HFB is not the best strategy to optimize the current enrichment method.
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Affiliation(s)
- Jasper W Bannenberg
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University and Research, Wageningen, The Netherlands
| | - Marcel H Zwietering
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Tjakko Abee
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Heidy M W den Besten
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands.
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The Roles of the Two-Component System, MtrAB, in Response to Diverse Cell Envelope Stresses in Dietzia sp. DQ12-45-1b. Appl Environ Microbiol 2022; 88:e0133722. [PMID: 36190258 PMCID: PMC9599347 DOI: 10.1128/aem.01337-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Two-component systems (TCSs) act as common regulatory systems allowing bacteria to detect and respond to multiple environmental stimuli, including cell envelope stress. The MtrAB TCS of Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance, and thus is found to be highly conserved across this phylum. However, how precisely the MtrAB TCS regulates cellular homeostasis in response to environmental stress remains unclear. Here, we show that the MtrAB TCS plays an important role in the tolerance to different types of cell envelope stresses, including environmental stresses (i.e., oxidative stress, lysozyme, SDS, osmotic pressure, and alkaline pH stresses) and envelope-targeting antibiotics (i.e., isoniazid, ethambutol, glycopeptide, and β-lactam antibiotics) in Dietzia sp. DQ12-45-1b. An mtrAB mutant strain exhibited slower growth compared to the wild-type strain and was characterized by abnormal cell shapes when exposed to various environmental stresses. Moreover, deletion of mtrAB resulted in decreased resistance to isoniazid, ethambutol, and β-lactam antibiotics. Further, Cleavage under targets and tagmentation sequencing (CUT&Tag-seq) and electrophoretic mobility shift assays (EMSAs) revealed that MtrA binds the promoters of genes involved in peptidoglycan biosynthesis (ldtB, ldtA, murJ), hydrolysis (GJR88_03483, GJR88_4713), and cell division (ftsE). Together, our findings demonstrated that the MtrAB TCS is essential for the survival of Dietzia sp. DQ12-45-1b under various cell envelope stresses, primarily by controlling multiple downstream cellular pathways. Our work suggests that TCSs act as global sensors and regulators in maintaining cellular homeostasis, such as during episodes of various environmental stresses. The present study should shed light on the understanding of mechanisms for bacterial adaptivity to extreme environments. IMPORTANCE The multilayered cell envelope is the first line of bacterial defense against various extreme environments. Bacteria utilize a large number of sensing and regulatory systems to maintain cell envelope homeostasis under multiple stress conditions. The two-component system (TCS) is the main sensing and responding apparatus for environmental adaptation. The MtrAB TCS highly conserved in Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance. However, how MtrAB works with regard to signals impacting changes to the cell envelope is not fully understood. Here, we found that in the Actinobacterium Dietzia sp. DQ12-45-1b, a TCS named MtrAB is pivotal for ensuring normal cell growth as well as maintaining proper cell morphology in response to various cell envelope stresses, namely, by regulating the expression of cell envelope-related genes. Our findings should greatly advance our understanding of the adaptive mechanisms responsible for maintaining cell integrity in times of sustained environmental shocks.
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Cahoon LA, Alejandro‐Navarreto X, Gururaja AN, Light SH, Alonzo F, Anderson WF, Freitag NE. Listeria monocytogenes two component system PieRS regulates secretion chaperones PrsA1 and PrsA2 and enhances bacterial translocation across the intestine. Mol Microbiol 2022; 118:278-293. [PMID: 35943959 PMCID: PMC9545042 DOI: 10.1111/mmi.14967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 11/30/2022]
Abstract
Listeria monocytogenes (Lm) is a widespread environmental Gram-positive bacterium that can transition into a pathogen following ingestion by a susceptible host. To cross host barriers and establish infection, Lm is dependent upon the regulated secretion and activity of many proteins including PrsA2, a peptidyl-prolyl cis-trans isomerase with foldase activity. PrsA2 contributes to the stability and activity of a number of secreted virulence factors that are required for Lm invasion, replication, and cell-to-cell spread within the infected host. In contrast, a second related secretion chaperone, PrsA1, has thus far no identified contributions to Lm pathogenesis. Here we describe the characterization of a two-component signal transduction system PieRS that regulates the expression of a regulon that includes the secretion chaperones PrsA1 and PrsA2. PieRS regulated gene products are required for bacterial resistance to ethanol exposure and are important for bacterial survival during transit through the gastrointestinal tract. PrsA1 was also found to make a unique contribution to Lm survival in the GI tract, revealing for the first time a non-overlapping requirement for both secretion chaperones PrsA1 and PrsA2 during the process of intra-gastric infection.
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Affiliation(s)
- Laty A. Cahoon
- Department of Microbiology and ImmunologyUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | | | - Avinash N. Gururaja
- Department of Microbiology and ImmunologyUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Sam H. Light
- Department of MicrobiologyUniversity of ChicagoChicagoIllinoisUSA
| | - Francis Alonzo
- Department of Microbiology and ImmunologyLoyola UniversityChicagoIllinoisUSA
| | - Wayne F. Anderson
- Center for Genomics and Infectious Diseases, Feinberg School of MedicineNorthwestern UniversityChicagoIllinoisUSA
| | - Nancy E. Freitag
- Department of Microbiology and ImmunologyUniversity of Illinois at ChicagoChicagoIllinoisUSA
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Pang X, Wu Y, Liu X, Wu Y, Shu Q, Niu J, Chen Q, Zhang X. The Lipoteichoic Acid-Related Proteins YqgS and LafA Contribute to the Resistance of Listeria monocytogenes to Nisin. Microbiol Spectr 2022; 10:e0209521. [PMID: 35196823 PMCID: PMC8865564 DOI: 10.1128/spectrum.02095-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/24/2022] [Indexed: 11/20/2022] Open
Abstract
Listeria monocytogenes is a major pathogen contributing to foodborne outbreaks with high mortality. Nisin, a natural antimicrobial, has been widely used as a food preservative. However, the mechanisms of L. monocytogenes involved in nisin resistance have not yet to be fully defined. A mariner transposon library was constructed in L. monocytogenes, leading to the identification of 99 genes associated with the innate resistance to nisin via Transposon sequencing (Tn-seq) analysis. To validate the accuracy of the Tn-seq results, we constructed five mutants (ΔyqgS, ΔlafA, ΔvirR, ΔgtcA, and Δlmo1464) in L. monocytogenes. The results revealed that yqgS and lafA, the lipoteichoic acid-related genes, were essential for resistance to nisin, while the gtcA and lmo1464 mutants showed substantially enhanced nisin resistance. Densely wrinkled, collapsed surface and membrane breakdown were shown on ΔyqgS and ΔlafA mutants under nisin treatment. Deletion of yqgS and lafA altered the surface charge, and decreased the resistance to general stress conditions and cell envelope-acting antimicrobials. Furthermore, YqgS and LafA are required for biofilm formation and cell invasion of L. monocytogenes. Collectively, these results reveal novel mechanisms of nisin resistance in L. monocytogenes and may provide unique targets for the development of food-grade inhibitors for nisin-resistant foodborne pathogens. IMPORTANCE Listeria monocytogenes is an opportunistic Gram-positive pathogen responsible for listeriosis, and is widely present in a variety of foods including ready-to-eat foods, meat, and dairy products. Nisin is the only licensed lantibiotic by the FDA for use as a food-grade inhibitor in over 50 countries. A prior study suggests that L. monocytogenes are more resistant than other Gram-positive pathogens in nisin-mediated bactericidal effects. However, the mechanisms of L. monocytogenes involved in nisin resistance have not yet to be fully defined. Here, we used a mariner transposon library to identify nisin-resistance-related genes on a genome-wide scale via transposon sequencing. We found, for the first time, that YqgS and LafA (Lipoteichoic acid-related proteins) are required for resistance to nisin. Subsequently, we investigated the roles of YqgS and LafA in L. monocytogenes stress resistance, antimicrobial resistance, biofilm formation, and virulence in mammalian cells.
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Affiliation(s)
- Xinxin Pang
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yansha Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xiayu Liu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yajing Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Qin Shu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Jianrui Niu
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Qihe Chen
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xinglin Zhang
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
- College of Agriculture and Forestry, Linyi University, Linyi, China
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7
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Muchaamba F, Wambui J, Stephan R, Tasara T. Cold Shock Proteins Promote Nisin Tolerance in Listeria monocytogenes Through Modulation of Cell Envelope Modification Responses. Front Microbiol 2022; 12:811939. [PMID: 35003042 PMCID: PMC8740179 DOI: 10.3389/fmicb.2021.811939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 11/24/2021] [Indexed: 12/03/2022] Open
Abstract
Listeria monocytogenes continues to be a food safety challenge owing to its stress tolerance and virulence traits. Several listeriosis outbreaks have been linked to the consumption of contaminated ready-to-eat food products. Numerous interventions, including nisin application, are presently employed to mitigate against L. monocytogenes risk in food products. In response, L. monocytogenes deploys several defense mechanisms, reducing nisin efficacy, that are not yet fully understood. Cold shock proteins (Csps) are small, highly conserved nucleic acid-binding proteins involved in several gene regulatory processes to mediate various stress responses in bacteria. L. monocytogenes possesses three csp gene paralogs; cspA, cspB, and cspD. Using a panel of single, double, and triple csp gene deletion mutants, the role of Csps in L. monocytogenes nisin tolerance was examined, demonstrating their importance in nisin stress responses of this bacterium. Without csp genes, a L. monocytogenes ΔcspABD mutant displayed severely compromised growth under nisin stress. Characterizing single (ΔcspA, ΔcspB, and ΔcspD) and double (ΔcspBD, ΔcspAD, and ΔcspAB) csp gene deletion mutants revealed a hierarchy (cspD > cspB > cspA) of importance in csp gene contributions toward the L. monocytogenes nisin tolerance phenotype. Individual eliminations of either cspA or cspB improved the nisin stress tolerance phenotype, suggesting that their expression has a curbing effect on the expression of nisin resistance functions through CspD. Gene expression analysis revealed that Csp deficiency altered the expression of DltA, MprF, and penicillin-binding protein-encoding genes. Furthermore, the ΔcspABD mutation induced an overall more electronegative cell surface, enhancing sensitivity to nisin and other cationic antimicrobials as well as the quaternary ammonium compound disinfectant benzalkonium chloride. These observations demonstrate that the molecular functions of Csps regulate systems important for enabling the constitution and maintenance of an optimal composed cell envelope that protects against cell-envelope-targeting stressors, including nisin. Overall, our data show an important contribution of Csps for L. monocytogenes stress protection in food environments where antimicrobial peptides are used. Such knowledge can be harnessed in the development of better L. monocytogenes control strategies. Furthermore, the potential that Csps have in inducing cross-protection must be considered when combining hurdle techniques or using them in a series.
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Affiliation(s)
- Francis Muchaamba
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
| | - Joseph Wambui
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
| | - Taurai Tasara
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
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Quereda JJ, Morón-García A, Palacios-Gorba C, Dessaux C, García-del Portillo F, Pucciarelli MG, Ortega AD. Pathogenicity and virulence of Listeria monocytogenes: A trip from environmental to medical microbiology. Virulence 2021; 12:2509-2545. [PMID: 34612177 PMCID: PMC8496543 DOI: 10.1080/21505594.2021.1975526] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 08/23/2021] [Accepted: 08/25/2021] [Indexed: 01/02/2023] Open
Abstract
Listeria monocytogenes is a saprophytic gram-positive bacterium, and an opportunistic foodborne pathogen that can produce listeriosis in humans and animals. It has evolved an exceptional ability to adapt to stress conditions encountered in different environments, resulting in a ubiquitous distribution. Because some food preservation methods and disinfection protocols in food-processing environments cannot efficiently prevent contaminations, L. monocytogenes constitutes a threat to human health and a challenge to food safety. In the host, Listeria colonizes the gastrointestinal tract, crosses the intestinal barrier, and disseminates through the blood to target organs. In immunocompromised individuals, the elderly, and pregnant women, the pathogen can cross the blood-brain and placental barriers, leading to neurolisteriosis and materno-fetal listeriosis. Molecular and cell biology studies of infection have proven L. monocytogenes to be a versatile pathogen that deploys unique strategies to invade different cell types, survive and move inside the eukaryotic host cell, and spread from cell to cell. Here, we present the multifaceted Listeria life cycle from a comprehensive perspective. We discuss genetic features of pathogenic Listeria species, analyze factors involved in food contamination, and review bacterial strategies to tolerate stresses encountered both during food processing and along the host's gastrointestinal tract. Then we dissect host-pathogen interactions underlying listerial pathogenesis in mammals from a cell biology and systemic point of view. Finally, we summarize the epidemiology, pathophysiology, and clinical features of listeriosis in humans and animals. This work aims to gather information from different fields crucial for a comprehensive understanding of the pathogenesis of L. monocytogenes.
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Affiliation(s)
- Juan J. Quereda
- Departamento de Producción y Sanidad Animal, Salud Pública Veterinaria y Ciencia y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities. Valencia, Spain
| | - Alvaro Morón-García
- Departamento de Biología Celular. Facultad de Ciencias Biológicas, Universidad Complutense de Madrid. Madrid, Spain
| | - Carla Palacios-Gorba
- Departamento de Producción y Sanidad Animal, Salud Pública Veterinaria y Ciencia y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities. Valencia, Spain
| | - Charlotte Dessaux
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB)- Consejo Superior De Investigaciones Científicas (CSIC), Madrid, Spain
| | - Francisco García-del Portillo
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB)- Consejo Superior De Investigaciones Científicas (CSIC), Madrid, Spain
| | - M. Graciela Pucciarelli
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB)- Consejo Superior De Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Biología Molecular ‘Severo Ochoa’. Departamento de Biología Molecular, Facultad de Ciencias, Universidad Autónoma de Madrid. Madrid, Spain
| | - Alvaro D. Ortega
- Departamento de Biología Celular. Facultad de Ciencias Biológicas, Universidad Complutense de Madrid. Madrid, Spain
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB)- Consejo Superior De Investigaciones Científicas (CSIC), Madrid, Spain
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Nowak J, Visnovsky SB, Pitman AR, Cruz CD, Palmer J, Fletcher GC, Flint S. Biofilm Formation by Listeria monocytogenes 15G01, a Persistent Isolate from a Seafood-Processing Plant, Is Influenced by Inactivation of Multiple Genes Belonging to Different Functional Groups. Appl Environ Microbiol 2021; 87:e02349-20. [PMID: 33741610 PMCID: PMC8117777 DOI: 10.1128/aem.02349-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 02/25/2021] [Indexed: 01/13/2023] Open
Abstract
Listeria monocytogenes is a ubiquitous foodborne pathogen that results in a high rate of mortality in sensitive and immunocompromised people. Contamination of food with L. monocytogenes is thought to occur during food processing, most often as a result of the pathogen producing a biofilm that persists in the environment and acting as the source for subsequent dispersal of cells onto food. A survey of seafood-processing plants in New Zealand identified the persistent strain 15G01, which has a high capacity to form biofilms. In this study, a transposon library of L. monocytogenes 15G01 was screened for mutants with altered biofilm formation, assessed by a crystal violet assay, to identify genes involved in biofilm formation. This screen identified 36 transposants that showed a significant change in biofilm formation compared to the wild type. The insertion sites were in 27 genes, 20 of which led to decreased biofilm formation and seven to an increase. Two insertions were in intergenic regions. Annotation of the genes suggested that they are involved in diverse cellular processes, including stress response, autolysis, transporter systems, and cell wall/membrane synthesis. Analysis of the biofilms produced by the transposants using scanning electron microscopy and fluorescence microscopy showed notable differences in the structure of the biofilms compared to the wild type. In particular, inactivation of uvrB and mltD produced coccoid-shaped cells and elongated cells in long chains, respectively, and the mgtB mutant produced a unique biofilm with a sandwich structure which was reversed to the wild-type level upon magnesium addition. The mltD transposant was successfully complemented with the wild-type gene, whereas the phenotypes were not or only partially restored for the remaining mutants.IMPORTANCE The major source of contamination of food with Listeria monocytogenes is thought to be due to biofilm formation and/or persistence in food-processing plants. By establishing as a biofilm, L. monocytogenes cells become harder to eradicate due to their increased resistance to environmental threats. Understanding the genes involved in biofilm formation and their influence on biofilm structure will help identify new ways to eliminate harmful biofilms in food processing environments. To date, multiple genes have been identified as being involved in biofilm formation by L. monocytogenes; however, the exact mechanism remains unclear. This study identified four genes associated with biofilm formation by a persistent strain. Extensive microscopic analysis illustrated the effect of the disruption of mgtB, clsA, uvrB, and mltD and the influence of magnesium on the biofilm structure. The results strongly suggest an involvement in biofilm formation for the four genes and provide a basis for further studies to analyze gene regulation to assess the specific role of these biofilm-associated genes.
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Affiliation(s)
- Jessika Nowak
- The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Sandra B Visnovsky
- The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand
| | - Andrew R Pitman
- The Foundation for Arable Research, Christchurch, New Zealand
| | - Cristina D Cruz
- The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Jon Palmer
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Graham C Fletcher
- The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand
| | - Steve Flint
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
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Nikparvar B, Andreevskaya M, Duru IC, Bucur FI, Grigore-Gurgu L, Borda D, Nicolau AI, Riedel CU, Auvinen P, Bar N. Analysis of temporal gene regulation of Listeria monocytogenes revealed distinct regulatory response modes after exposure to high pressure processing. BMC Genomics 2021; 22:266. [PMID: 33853520 PMCID: PMC8045354 DOI: 10.1186/s12864-021-07461-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 02/10/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND The pathogen Listeria (L.) monocytogenes is known to survive heat, cold, high pressure, and other extreme conditions. Although the response of this pathogen to pH, osmotic, temperature, and oxidative stress has been studied extensively, its reaction to the stress produced by high pressure processing HPP (which is a preservation method in the food industry), and the activated gene regulatory network (GRN) in response to this stress is still largely unknown. RESULTS We used RNA sequencing transcriptome data of L. monocytogenes (ScottA) treated at 400 MPa and 8∘C, for 8 min and combined it with current information in the literature to create a transcriptional regulation database, depicting the relationship between transcription factors (TFs) and their target genes (TGs) in L. monocytogenes. We then applied network component analysis (NCA), a matrix decomposition method, to reconstruct the activities of the TFs over time. According to our findings, L. monocytogenes responded to the stress applied during HPP by three statistically different gene regulation modes: survival mode during the first 10 min post-treatment, repair mode during 1 h post-treatment, and re-growth mode beyond 6 h after HPP. We identified the TFs and their TGs that were responsible for each of the modes. We developed a plausible model that could explain the regulatory mechanism that L. monocytogenes activated through the well-studied CIRCE operon via the regulator HrcA during the survival mode. CONCLUSIONS Our findings suggest that the timely activation of TFs associated with an immediate stress response, followed by the expression of genes for repair purposes, and then re-growth and metabolism, could be a strategy of L. monocytogenes to survive and recover extreme HPP conditions. We believe that our results give a better understanding of L. monocytogenes behavior after exposure to high pressure that may lead to the design of a specific knock-out process to target the genes or mechanisms. The results can help the food industry select appropriate HPP conditions to prevent L. monocytogenes recovery during food storage.
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Affiliation(s)
- Bahareh Nikparvar
- Department of Chemical Engineering, Norwegian University of Science and Technology, Trondheim, Norway
| | | | - Ilhan C Duru
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Florentina I Bucur
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Galati, Romania
| | - Leontina Grigore-Gurgu
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Galati, Romania
| | - Daniela Borda
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Galati, Romania
| | - Anca I Nicolau
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Galati, Romania
| | - Christian U Riedel
- Institute of Microbiology and Biotechnology, Ulm University, Ulm, Germany
| | - Petri Auvinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Nadav Bar
- Department of Chemical Engineering, Norwegian University of Science and Technology, Trondheim, Norway.
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11
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Transcriptome Analysis of Listeria monocytogenes Exposed to Beef Fat Reveals Antimicrobial and Pathogenicity Attenuation Mechanisms. Appl Environ Microbiol 2021; 87:AEM.03027-20. [PMID: 33608290 DOI: 10.1128/aem.03027-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/09/2021] [Indexed: 12/13/2022] Open
Abstract
Listeria monocytogenes is a deadly intracellular pathogen mostly associated with consumption of ready-to-eat foods. This study investigated the effectiveness of total beef fat (BF-T) from flaxseed-fed cattle and its fractions enriched with monounsaturated fatty acids (BF-MUFA) and polyunsaturated fatty acids (BF-PUFA), along with commercially available long-chain fatty acids (LC-FA), as natural antimicrobials against L. monocytogenes BF-T was ineffective at concentrations up to 6 mg/ml, while L. monocytogenes was susceptible to BF-MUFA and BF-PUFA, with MICs at pH 7 of 0.33 ± 0.21 mg/ml and 0.06 ± 0.03 mg/ml, respectively. The MIC of C14:0 was significantly lower than those of C16:0 and C18:0 (P < 0.05). Fatty acids c9-C16:1, C18:2n-6, and C18:3n-3 showed stronger inhibitory activity than c9-C18:1 and conjugated C18:2, with MICs of <1 mg/ml. Furthermore, global transcriptional analysis by transcriptome sequencing (RNA-seq) was performed to characterize the response of L. monocytogenes to selected fatty acids. Functional analysis indicated that antimicrobial LC-UFA repressed the expression of genes associated with nutrient transmembrane transport, energy generation, and oxidative stress resistance. On the other hand, upregulation of ribosome assembly and translation process is possibly associated with adaptive and repair mechanisms activated in response to LC-UFA. Virulence genes and genes involved in bile, acid, and osmotic stresses were largely downregulated, and more so for c9-C16:1, C18:2n-6, and C18:3n-3, likely through interaction with the master virulence regulator PrfA and the alternative sigma factor σB IMPORTANCE Listeria monocytogenes is a bacterial pathogen known for its ability to survive and thrive under adverse environments and, as such, its control poses a significant challenge, especially with the trend of minimally processed and ready-to-eat foods. This work investigated the effectiveness of fatty acids from various sources as natural antimicrobials against L. monocytogenes and evaluated their potential role in L. monocytogenes pathogenicity modulation, using the strain ATCC 19111. The findings show that long-chain unsaturated fatty acids (LC-UFA), including unsaturated beef fat fractions from flaxseed-fed cattle, could have the potential to be used as effective antimicrobials for L. monocytogenes through controlling growth as well as virulence attenuation. This not only advances our understanding of the mode of action of LC-UFA against L. monocytogenes but also suggests the potential for use of beef fat or its fractions as natural antimicrobials for controlling foodborne pathogens.
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12
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Pinilla CMB, Stincone P, Brandelli A. Proteomic analysis reveals differential responses of Listeria monocytogenes to free and nanoencapsulated nisin. Int J Food Microbiol 2021; 346:109170. [PMID: 33770680 DOI: 10.1016/j.ijfoodmicro.2021.109170] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 12/18/2022]
Abstract
The ability of Listeria monocytogenes grow on ready-to-eat food is a major concern in food safety. Natural antimicrobials, such as nisin, can be used to control this pathogen, but the increasing reports of nisin tolerance and resistance make necessary novel approaches to increase its effectiveness, such as encapsulation. The goal of this study was to investigate how L. monocytogenes ATCC7644 regulates and shapes its proteome in response to sublethal doses of nisin and nisin-loaded phosphatidylcholine liposomes (lipo-nisin), compared to untreated cells growing under optimal conditions. Total proteins were extracted from L. monocytogenes cells treated for 1 h with free and lipo-nisin. As result, of 803 proteins that were initially identified, 64 and 53 proteins were differentially upregulated and downregulated respectively, in the treatments with nisin and lipo-nisin. Changes of Listeria proteome in response to treatments containing nisin were mainly related to ATP-binding cassette (ABC) transporter systems, transmembrane proteins, RNA-binding proteins and diverse stress response proteins. Some of the proteins uniquely detected in samples treated with free nisin were the membrane proteins SecD, Lmo1539 and the YfhO enzyme, which are related to translocation of L. monocytogenes virulence factors, activation of the LiaR-mediated stress defense and glycosylation of wall teichoic acid, respectively. The L. monocytogenes treated with liposome encapsulated nisin showed no expression of some stress response factors as compared with the free nisin, suggesting a reduction of stress mediated response and production of nisin-resistance factors by exposure to encapsulated nisin.
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Affiliation(s)
| | - Paolo Stincone
- Laboratório de Bioquímica e Microbiologia Aplicada, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Adriano Brandelli
- Laboratório de Bioquímica e Microbiologia Aplicada, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
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13
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Aslan H, Petersen ME, De Berardinis A, Zacho Brunhede M, Khan N, Vergara A, Kallipolitis B, Meyer RL. Activation of the Two-Component System LisRK Promotes Cell Adhesion and High Ampicillin Tolerance in Listeria monocytogenes. Front Microbiol 2021; 12:618174. [PMID: 33584621 PMCID: PMC7873292 DOI: 10.3389/fmicb.2021.618174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/06/2021] [Indexed: 11/13/2022] Open
Abstract
Listeria monocytogenes is a foodborne pathogen which can survive in harsh environmental conditions. It responds to external stimuli through an array of two-component systems (TCS) that sense external cues. Several TCS, including LisRK, have been linked to Listeria’s ability to grow at slightly elevated antibiotic levels. The aim of this study was to determine if the TCS LisRK is also involved in acquiring the high antibiotic tolerance that is characteristic of persister cells. LisRK activates a response that leads to remodeling of the cell envelope, and we therefore hypothesized that activation of LisRK could also increase in the cells’ adhesiveness and initiate the first step in biofilm formation. We used a ΔlisR mutant to study antibiotic tolerance in the presence and absence of LisRK, and a GFP reporter strain to visualize the activation of LisRK in L. monocytogenes LO28 at a single-cell level. LisRK was activated in most cells in stationary phase cultures. Antimicrobial susceptibility tests showed that LisRK was required for the generation of ampicillin tolerance under these conditions. The wildtype strain tolerated exposure to ampicillin at 1,000 × inhibitory levels for 24 h, and the fraction of surviving cells was 20,000-fold higher in the wildtype strain compared to the ΔlisR mutant. The same protection was not offered to other antibiotics (vancomycin, gentamicin, tetracycline), and the mechanism for antibiotic tolerance is thus highly specific. Furthermore, quantification of bacterial attachment rates and attachment force also revealed that the absence of a functional LisRK rendered the cells less adhesive. Hence, LisRK TCS promotes multiple protective mechanisms simultaneously.
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Affiliation(s)
- Hüsnü Aslan
- Faculty of Natural Sciences, Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | | | | | - Maja Zacho Brunhede
- Faculty of Natural Sciences, Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Nasar Khan
- Faculty of Natural Sciences, Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Alberto Vergara
- Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy
| | - Birgitte Kallipolitis
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Rikke Louise Meyer
- Faculty of Natural Sciences, Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark.,Department of Biology, Faculty of Natural Sciences, Aarhus University, Aarhus, Denmark
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14
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Brunhede MZ, Santos PTD, Gal L, Garmyn D, Kallipolitis BH, Piveteau P. LisRK is required for optimal fitness of Listeria monocytogenes in soil. FEMS Microbiol Lett 2020; 367:5986613. [PMID: 33202028 DOI: 10.1093/femsle/fnaa188] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/13/2020] [Indexed: 01/10/2023] Open
Abstract
Listeria monocytogenes is a food-borne pathogen responsible for the disease listeriosis. It is ubiquitously found in the environment and soil is one of its natural habitats. Listeria monocytogenes is highly capable of coping with various stressful conditions. We hypothesized that stress-responsive two-component systems such as LisRK might contribute to the adaptation of L. monocytogenes to the soil environment. Indeed, investigations of the population dynamics of wild-type and mutant strains suggest an important role of LisRK for optimal fitness of L. monocytogenes in sterile soil. Results from non-sterile soil showed that the parental strain was capable of surviving longer than mutant strains lacking lisRK or genes encoding the LisRK-regulated LhrC small RNAs (sRNAs), suggesting that LisRK as well as the LhrC sRNAs were important for survival. Transcription of five LisRK-regulated genes was assessed after 1 h incubation in sterile soil. We observed that LisRK and the LhrC sRNAs contribute to the upregulation of lmo2522 in the soil environment. Notably, lmo2522 encodes an equivalent of the resuscitation promoting factors, Rpfs, in actinobacteria. Collectively, our study demonstrates that LisRK is important for growth and survival in sterile and non-sterile soil and suggests a role for LisRK-regulation of Lmo2522 in resuscitation from dormancy in the soil environment.
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Affiliation(s)
- Maja Z Brunhede
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne Franche-Comté, Dijon, France
| | - Patrícia T Dos Santos
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Laurent Gal
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne Franche-Comté, Dijon, France
| | - Dominique Garmyn
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne Franche-Comté, Dijon, France
| | - Birgitte H Kallipolitis
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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15
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Regulation of virulence and antibiotic resistance in Gram-positive microbes in response to cell wall-active antibiotics. Curr Opin Infect Dis 2020; 32:217-222. [PMID: 31021953 DOI: 10.1097/qco.0000000000000542] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Antibiotic stress can evoke considerable genotypic and phenotypic changes in Gram-positive bacteria. Here, we review recent studies describing altered virulence expression in response to cell wall-acting antibiotics and discuss mechanisms that coordinate regulation of the antibiotic response. RECENT FINDINGS Pleiotropic effects induced by antibiotic exposure include alterations to bacterial metabolism, cell wall structure and antibiotic resistance. In addition, subinhibitory concentrations of cell wall-active (CWA) antibiotics have increasingly been shown to induce the production of exotoxins and biofilm formation that may influence virulence. Remarkably, phenotypes associated with comparable antibiotic stresses can vary considerably, emphasizing the need to better understand the response to CWA antibiotics. Recent studies support both direct antibiotic recognition and recognition of antibiotic-induced stress to the bacterial cell wall. Specifically, bacterial two-component systems, penicillin-binding protein and serine/threonine kinase-associated kinases and conserved oxidative-stress sensors each contribute to modulating the antibiotic stress response. SUMMARY Bacterial sensory systems and global regulators coordinate signaling in response to CWA antibiotics. Regulation of the antibiotic response is complex and involves integration of signals from multiple response pathways. A better definition of the antibiotic stress response among Gram-positive pathogens may yield novel therapeutic targets to counter antibiotic resistance and virulence factor expression.
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16
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Henderson LO, Erazo Flores BJ, Skeens J, Kent D, Murphy SI, Wiedmann M, Guariglia-Oropeza V. Nevertheless, She Resisted - Role of the Environment on Listeria monocytogenes Sensitivity to Nisin Treatment in a Laboratory Cheese Model. Front Microbiol 2020; 11:635. [PMID: 32328054 PMCID: PMC7160321 DOI: 10.3389/fmicb.2020.00635] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 03/20/2020] [Indexed: 01/24/2023] Open
Abstract
The growth of Listeria monocytogenes on refrigerated, ready-to-eat food products is a major health and economic concern. The natural antimicrobial nisin targets the bacterial cell wall and can be used to inhibit L. monocytogenes growth on cheese. Cell wall composition and structure, and therefore the efficacy of cell wall acting control strategies, can be severely affected by environmental and stress conditions. The goal of this study was to determine the effect of a range of pH and temperatures on the efficacy of nisin against several strains of L. monocytogenes in a lab-scale, cheese model. Cheese was made with or without the addition of nisin at different pH and then inoculated with L. monocytogenes; L. monocytogenes numbers were quantified after 1, 7, and 14 days of incubation at 6, 14, or 22°C. While our data show that nisin treatment is able to reduce L. monocytogenes numbers, at least initially, growth of this pathogen can occur even in the presence of nisin, especially when cheese is stored at higher temperatures. Several environmental factors were found to affect nisin efficacy against L. monocytogenes. For example, nisin is more effective when cheese is stored at lower temperatures. Nisin is also more effective when cheese is made at higher pH (6 and 6.5), compared to cheese made at pH 5.5, and this effect is at least partially due to the activity of cell envelope modification genes dltA and mprF. Serotype was also found to affect nisin efficacy against L. monocytogenes; serotype 4b strains showed lower susceptibility to nisin treatment compared to serotype 1/2 strains. Overall, our results highlight the importance of considering environmental conditions specific to a food matrix when developing and applying nisin-based intervention strategies against L. monocytogenes.
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Affiliation(s)
- L. O. Henderson
- Department of Food Science, Cornell University, Ithaca, NY, United States
| | - B. J. Erazo Flores
- Department of Food Science, Cornell University, Ithaca, NY, United States
- Universidad de Puerto Rico, Mayagüez, Puerto Rico
| | - J. Skeens
- Department of Food Science, Cornell University, Ithaca, NY, United States
| | - D. Kent
- Department of Food Science, Cornell University, Ithaca, NY, United States
| | - S. I. Murphy
- Department of Food Science, Cornell University, Ithaca, NY, United States
| | - M. Wiedmann
- Department of Food Science, Cornell University, Ithaca, NY, United States
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17
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Rismondo J, Halbedel S, Gründling A. Cell Shape and Antibiotic Resistance Are Maintained by the Activity of Multiple FtsW and RodA Enzymes in Listeria monocytogenes. mBio 2019; 10:e01448-19. [PMID: 31387909 PMCID: PMC6686043 DOI: 10.1128/mbio.01448-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 07/08/2019] [Indexed: 12/17/2022] Open
Abstract
Rod-shaped bacteria have two modes of peptidoglycan synthesis: lateral synthesis and synthesis at the cell division site. These two processes are controlled by two macromolecular protein complexes, the elongasome and divisome. Recently, it has been shown that the Bacillus subtilis RodA protein, which forms part of the elongasome, has peptidoglycan glycosyltransferase activity. The cell division-specific RodA homolog FtsW fulfils a similar role at the divisome. The human pathogen Listeria monocytogenes carries genes that encode up to six FtsW/RodA homologs; however, their functions have not yet been investigated. Analysis of deletion and depletion strains led to the identification of the essential cell division-specific FtsW protein, FtsW1. Interestingly, L. monocytogenes carries a gene that encodes a second FtsW protein, FtsW2, which can compensate for the lack of FtsW1, when expressed from an inducible promoter. L. monocytogenes also possesses three RodA homologs, RodA1, RodA2, and RodA3, and their combined absence is lethal. Cells of a rodA1 rodA3 double mutant are shorter and have increased antibiotic and lysozyme sensitivity, probably due to a weakened cell wall. Results from promoter activity assays revealed that expression of rodA3 and ftsW2 is induced in the presence of antibiotics targeting penicillin binding proteins. Consistent with this, a rodA3 mutant was more susceptible to the β-lactam antibiotic cefuroxime. Interestingly, overexpression of RodA3 also led to increased cefuroxime sensitivity. Our study highlights that L. monocytogenes genes encode a multitude of functional FtsW and RodA enzymes to produce its rigid cell wall and that their expression needs to be tightly regulated to maintain growth, cell division, and antibiotic resistance.IMPORTANCE The human pathogen Listeria monocytogenes is usually treated with high doses of β-lactam antibiotics, often combined with gentamicin. However, these antibiotics only act bacteriostatically on L. monocytogenes, and the immune system is needed to clear the infection. Therefore, individuals with a compromised immune system are at risk to develop a severe form of Listeria infection, which can be fatal in up to 30% of cases. The development of new strategies to treat Listeria infections is necessary. Here we show that the expression of some of the FtsW and RodA enzymes of L. monocytogenes is induced by the presence of β-lactam antibiotics, and the combined absence of these enzymes makes bacteria more susceptible to this class of antibiotics. The development of antimicrobial agents that inhibit the activity or production of FtsW and RodA enzymes might therefore help to improve the treatment of Listeria infections and thereby lead to a reduction in mortality.
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Affiliation(s)
- Jeanine Rismondo
- Section of Microbiology, Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Sven Halbedel
- FG11 Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | - Angelika Gründling
- Section of Microbiology, Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
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18
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Tierney AR, Rather PN. Roles of two-component regulatory systems in antibiotic resistance. Future Microbiol 2019; 14:533-552. [PMID: 31066586 DOI: 10.2217/fmb-2019-0002] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Two-component regulatory systems (TCSs) are a major mechanism by which bacteria sense and respond to changes in their environment. TCSs typically consist of two proteins that bring about major regulation of the cell genome through coordinated action mediated by phosphorylation. Environmental conditions that activate TCSs are numerous and diverse and include exposure to antibiotics as well as conditions inside a host. The resulting regulatory action often involves activation of antibiotic defenses and changes to cell physiology that increase antibiotic resistance. Examples of resistance mechanisms enacted by TCSs contained in this review span those found in both Gram-negative and Gram-positive species and include cell surface modifications, changes in cell permeability, increased biofilm formation, and upregulation of antibiotic-degrading enzymes.
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Affiliation(s)
- Aimee Rp Tierney
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA, 30322 USA
| | - Philip N Rather
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA, 30322 USA.,Research Service, Department of Veterans' Affairs, Atlanta VA Health Care System, Decatur, GA, 30033 USA
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19
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Dos Santos PT, Larsen PT, Menendez-Gil P, Lillebæk EMS, Kallipolitis BH. Listeria monocytogenes Relies on the Heme-Regulated Transporter hrtAB to Resist Heme Toxicity and Uses Heme as a Signal to Induce Transcription of lmo1634, Encoding Listeria Adhesion Protein. Front Microbiol 2018; 9:3090. [PMID: 30619169 PMCID: PMC6305404 DOI: 10.3389/fmicb.2018.03090] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/29/2018] [Indexed: 01/29/2023] Open
Abstract
For pathogenic bacteria, host-derived heme represents an important metabolic cofactor and a source for iron. However, high levels of heme are toxic to bacteria. We have previously shown that excess heme has a growth-inhibitory effect on the Gram-positive foodborne pathogen Listeria monocytogenes, and we have learned that the LhrC1-5 family of small RNAs, together with the two-component system (TCS) LisRK, play a role in the adaptation of L. monocytogenes to heme stress conditions. However, a broader knowledge on how this pathogen responds to heme toxicity is still lacking. Here, we analyzed the global transcriptomic response of L. monocytogenes to heme stress. We found that the response of L. monocytogenes to excess heme is multifaceted, involving various strategies acting to minimize the toxic effects of heme. For example, heme exposure triggers the SOS response that deals with DNA damage. In parallel, L. monocytogenes shuts down the transcription of genes involved in heme/iron uptake and utilization. Furthermore, heme stress resulted in a massive increase in the transcription of a putative heme detoxification system, hrtAB, which is highly conserved in Gram-positive bacteria. As expected, we found that the TCS HssRS is required for heme-mediated induction of hrtAB and that a functional heme efflux system is essential for L. monocytogenes to resist heme toxicity. Curiously, the most highly up-regulated gene upon heme stress was lmo1634, encoding the Listeria adhesion protein, LAP, which acts to promote the translocation of L. monocytogenes across the intestinal barrier. Additionally, LAP is predicted to act as a bifunctional acetaldehyde-CoA/alcohol dehydrogenase. Surprisingly, a mutant lacking lmo1634 grows well under heme stress conditions, showing that LAP is not required for L. monocytogenes to resist heme toxicity. Likewise, a functional ResDE TCS, which contributes to heme-mediated expression of lmo1634, is not required for the adaptation of L. monocytogenes to heme stress conditions. Collectively, this study provides novel insights into the strategies employed by L. monocytogenes to resist heme toxicity. Our findings indicate that L. monocytogenes is using heme as a host-derived signaling molecule to control the expression of its virulence genes, as exemplified by lmo1634.
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Affiliation(s)
| | - Pernille Tholund Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Pilar Menendez-Gil
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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20
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Crystal Structures of Penicillin-Binding Protein D2 from Listeria monocytogenes and Structural Basis for Antibiotic Specificity. Antimicrob Agents Chemother 2018; 62:AAC.00796-18. [PMID: 30082290 DOI: 10.1128/aac.00796-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 07/06/2018] [Indexed: 02/05/2023] Open
Abstract
β-Lactam antibiotics that inhibit penicillin-binding proteins (PBPs) have been widely used in the treatment of bacterial infections. However, the molecular basis underlying the different inhibitory potencies of β-lactams against specific PBPs is not fully understood. Here, we present the crystal structures of penicillin-binding protein D2 (PBPD2) from Listeria monocytogenes, a Gram-positive foodborne bacterial pathogen that causes listeriosis in humans. The acylated structures in complex with four antibiotics (penicillin G, ampicillin, cefotaxime, and cefuroxime) revealed that the β-lactam core structures were recognized by a common set of residues; however, the R1 side chains of each antibiotic participate in different interactions with PBPD2. In addition, the structural complementarities between the side chains of β-lactams and the enzyme were found to be highly correlated with the relative reactivities of penam or cephem antibiotics against PBPD2. Our study provides the structural basis for the inhibition of PBPD2 by clinically important β-lactam antibiotics that are commonly used in listeriosis treatment. Our findings imply that the modification of β-lactam side chains based on structural complementarity could be useful for the development of potent inhibitors against β-lactam-resistant PBPs.
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21
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Wu S, Yu PL, Wheeler D, Flint S. Transcriptomic study on persistence and survival of Listeria monocytogenes following lethal treatment with nisin. J Glob Antimicrob Resist 2018; 15:25-31. [PMID: 29933119 DOI: 10.1016/j.jgar.2018.06.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 06/01/2018] [Accepted: 06/11/2018] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES The aim of this study was to determine gene expression associated with the persistence of a Listeria monocytogenes stationary-phase population when facing lethal nisin treatment. METHODS RNA-Seq analysis was used for gene expression profiling of persister cells in nutrient-rich medium (persister TN) compared with untreated cells (non-persister). The results were confirmed using reverse transcription quantitative PCR (RT-qPCR). RESULTS Functional genes associated with the persister population were identified in multiple systems, such as heat-shock-related stress response, cell wall synthesis, ATP-binding cassette (ABC) transport system, phosphotransferase system (PTS) and SOS/DNA repair. CONCLUSIONS This study pointed to genetic regulation of persister cells exposed to lethal nisin concentrations and provides some insight into possible mechanisms of impeding bacterial persistence.
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Affiliation(s)
- Shuyan Wu
- Massey Institute of Food Science and Technology, Massey University, Riddet Road, 4442 Palmerston North, New Zealand
| | - Pak-Lam Yu
- School of Engineering & Advanced Technology, Massey University, Riddet Road, 4442 Palmerston North, New Zealand
| | - Dave Wheeler
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Steve Flint
- Massey Institute of Food Science and Technology, Massey University, Riddet Road, 4442 Palmerston North, New Zealand.
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22
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Kleine B, Chattopadhyay A, Polen T, Pinto D, Mascher T, Bott M, Brocker M, Freudl R. The three-component system EsrISR regulates a cell envelope stress response in Corynebacterium glutamicum. Mol Microbiol 2017; 106:719-741. [PMID: 28922502 DOI: 10.1111/mmi.13839] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2017] [Indexed: 02/03/2023]
Abstract
When the cell envelope integrity is compromised, bacteria trigger signaling cascades resulting in the production of proteins that counteract these extracytoplasmic stresses. Here, we show that the two-component system EsrSR regulates a cell envelope stress response in the Actinobacterium Corynebacterium glutamicum. The sensor kinase EsrS possesses an amino-terminal phage shock protein C (PspC) domain, a property that sets EsrSR apart from all other two-component systems characterized so far. An integral membrane protein, EsrI, whose gene is divergently transcribed to the esrSR gene locus and which interestingly also possesses a PspC domain, acts as an inhibitor of EsrSR under non-stress conditions. The resulting EsrISR three-component system is activated among others by antibiotics inhibiting the lipid II cycle, such as bacitracin and vancomycin, and it orchestrates a broad regulon including the esrI-esrSR gene locus itself, genes encoding heat shock proteins, ABC transporters, and several putative membrane-associated or secreted proteins of unknown function. Among those, the ABC transporter encoded by cg3322-3320 was shown to be directly involved in bacitracin resistance of C. glutamicum. Since similar esrI-esrSR loci are present in a large number of actinobacterial genomes, EsrISR represents a novel type of stress-responsive system whose components are highly conserved in the phylum Actinobacteria.
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Affiliation(s)
- Britta Kleine
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Ava Chattopadhyay
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Tino Polen
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Daniela Pinto
- Institut für Mikrobiologie, Technische Universität Dresden, Zellescher Weg 20b, Dresden D-01217, Germany
| | - Thorsten Mascher
- Institut für Mikrobiologie, Technische Universität Dresden, Zellescher Weg 20b, Dresden D-01217, Germany
| | - Michael Bott
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Melanie Brocker
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Roland Freudl
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
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Jensen PA, Zhu Z, van Opijnen T. Antibiotics Disrupt Coordination between Transcriptional and Phenotypic Stress Responses in Pathogenic Bacteria. Cell Rep 2017; 20:1705-1716. [PMID: 28813680 PMCID: PMC5584877 DOI: 10.1016/j.celrep.2017.07.062] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/28/2017] [Accepted: 07/23/2017] [Indexed: 01/19/2023] Open
Abstract
Bacterial genes that change in expression upon environmental disturbance have commonly been seen as those that must also phenotypically matter. However, several studies suggest that differentially expressed genes are rarely phenotypically important. We demonstrate, for Gram-positive and Gram-negative bacteria, that these seemingly uncoordinated gene sets are involved in responses that can be linked through topological network analysis. However, the level of coordination is stress dependent. While a well-coordinated response is triggered in response to nutrient stress, antibiotics trigger an uncoordinated response in which transcriptionally and phenotypically important genes are neither linked spatially nor in their magnitude. Moreover, a gene expression meta-analysis reveals that genes with large fitness changes during stress have low transcriptional variation across hundreds of other conditions, and vice versa. Our work suggests that cellular responses can be understood through network models that incorporate regulatory and genetic relationships, which could aid drug target predictions and genetic network engineering.
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Affiliation(s)
- Paul A Jensen
- Biology Department, Boston College, Chestnut Hill, MA, USA.
| | - Zeyu Zhu
- Biology Department, Boston College, Chestnut Hill, MA, USA.
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24
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Metabolic determinants in Listeria monocytogenes anaerobic listeriolysin O production. Arch Microbiol 2017; 199:827-837. [PMID: 28289786 PMCID: PMC5504256 DOI: 10.1007/s00203-017-1355-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 02/21/2017] [Indexed: 11/21/2022]
Abstract
Listeria monocytogenes is a human pathogen and a facultative anaerobe. To better understand how anaerobic growth affects L. monocytogenes pathogenesis, we first showed that anaerobic growth led to decreased growth and changes in surface morphology. Moreover, compared to aerobically grown bacteria, anaerobically grown L. monocytogenes established higher level of invasion but decreased intracellular growth and actin polymerization in cultured cells. The production of listeriolysin O (LLO) was significantly lower in anaerobic cultures—a phenotype observed in wild type and isogenic mutants lacking transcriptional regulators SigB or CodY or harboring a constitutively active PrfA. To explore potential regulatory mechanisms, we established that the addition of central carbon metabolism intermediates, such as acetate, citrate, fumarate, pyruvate, lactate, and succinate, led to an increase in LLO activity in the anaerobic culture supernatant. These results highlight the regulatory role of central carbon metabolism in L. monocytogenes pathogenesis under anaerobic conditions.
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25
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Sievers S, Lund A, Menendez-Gil P, Nielsen A, Storm Mollerup M, Lambert Nielsen S, Buch Larsson P, Borch-Jensen J, Johansson J, Kallipolitis BH. The multicopy sRNA LhrC controls expression of the oligopeptide-binding protein OppA in Listeria monocytogenes. RNA Biol 2016; 12:985-97. [PMID: 26176322 DOI: 10.1080/15476286.2015.1071011] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Listeria monocytogenes is the causative agent of the foodborne disease listeriosis. During infection, L. monocytogenes produces an array of non-coding RNAs, including the multicopy sRNA LhrC. These five, nearly identical sRNAs are highly induced in response to cell envelope stress and target the virulence adhesin lapB at the post-transcriptional level. Here, we demonstrate that LhrC controls expression of additional genes encoding cell envelope-associated proteins with virulence function. Using transcriptomics and proteomics, we identified a set of genes affected by LhrC in response to cell envelope stress. Three targets were significantly down-regulated by LhrC at both the RNA and protein level: lmo2349, tcsA and oppA. All three genes encode membrane-associated proteins: A putative substrate binding protein of an amino acid ABC transporter (Lmo2349); the CD4+ T cell-stimulating antigen TcsA, and the oligopeptide binding protein OppA, of which the latter 2 are required for full virulence of L. monocytogenes. For OppA, we show that LhrC acts by direct base paring to the ribosome binding site of the oppA mRNA, leading to an impediment of its translation and a decreased mRNA level. The sRNA-mRNA interaction depends on 2 of 3 CU-rich regions in LhrC allowing binding of 2 oppA mRNAs to a single LhrC molecule. Finally, we found that LhrC contributes to infection in macrophage-like cells. These findings demonstrate a central role for LhrC in controlling the level of OppA and other virulence-associated cell envelope proteins in response to cell envelope stress.
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Affiliation(s)
- Susanne Sievers
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark.,b Institute for Microbiology; Ernst-Moritz-Arndt-University Greifswald ; Greifswald , Germany.,d These authors equally contributed to this work
| | - Anja Lund
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark.,d These authors equally contributed to this work
| | - Pilar Menendez-Gil
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark
| | - Aaraby Nielsen
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark
| | - Maria Storm Mollerup
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark
| | - Stine Lambert Nielsen
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark
| | - Pernille Buch Larsson
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark
| | - Jonas Borch-Jensen
- a Department of Biochemistry and Molecular Biology ; University of Southern Denmark ; Odense , Denmark
| | - Jörgen Johansson
- c Department of Molecular Biology ; Umeå University ; Umeå , Sweden
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26
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Knudsen GM, Fromberg A, Ng Y, Gram L. Sublethal Concentrations of Antibiotics Cause Shift to Anaerobic Metabolism in Listeria monocytogenes and Induce Phenotypes Linked to Antibiotic Tolerance. Front Microbiol 2016; 7:1091. [PMID: 27462313 PMCID: PMC4940397 DOI: 10.3389/fmicb.2016.01091] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 06/30/2016] [Indexed: 02/05/2023] Open
Abstract
The human pathogenic bacterium Listeria monocytogenes is exposed to antibiotics both during clinical treatment and in its saprophytic lifestyle. As one of the keys to successful treatment is continued antibiotic sensitivity, the purpose of this study was to determine if exposure to sublethal antibiotic concentrations would affect the bacterial physiology and induce antibiotic tolerance. Transcriptomic analyses demonstrated that each of the four antibiotics tested caused an antibiotic-specific gene expression pattern related to mode-of-action of the particular antibiotic. All four antibiotics caused the same changes in expression of several metabolic genes indicating a shift from aerobic to anaerobic metabolism and higher ethanol production. A mutant in the bifunctional acetaldehyde-CoA/alcohol dehydrogenase encoded by lmo1634 did not have altered antibiotic tolerance. However, a mutant in lmo1179 (eutE) encoding an aldehyde oxidoreductase where rerouting caused increased ethanol production was tolerant to three of four antibiotics tested. This shift in metabolism could be a survival strategy in response to antibiotics to avoid generation of ROS production from respiration by oxidation of NADH through ethanol production. The monocin locus encoding a cryptic prophage was induced by co-trimoxazole and repressed by ampicillin and gentamicin, and this correlated with an observed antibiotic-dependent biofilm formation. A monocin mutant (ΔlmaDCBA) had increased biofilm formation when exposed to increasing concentration of co-trimoxazole similar to the wild type, but was more tolerant to killing by co-trimoxazole and ampicillin. Thus, sublethal concentrations of antibiotics caused metabolic and physiological changes indicating that the organism is preparing to withstand lethal antibiotic concentrations.
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Affiliation(s)
- Gitte M Knudsen
- Department of Bioengineering, Technical University of Denmark Kongens Lyngby, Denmark
| | - Arvid Fromberg
- National Food Institute, Technical University of Denmark Søborg, Denmark
| | - Yin Ng
- Department of Bioengineering, Technical University of Denmark Kongens Lyngby, Denmark
| | - Lone Gram
- Department of Bioengineering, Technical University of Denmark Kongens Lyngby, Denmark
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27
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Listeria monocytogenes – An examination of food chain factors potentially contributing to antimicrobial resistance. Food Microbiol 2016. [DOI: 10.1016/j.fm.2014.08.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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28
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Krawczyk-Balska A, Markiewicz Z. The intrinsic cephalosporin resistome of Listeria monocytogenes in the context of stress response, gene regulation, pathogenesis and therapeutics. J Appl Microbiol 2015; 120:251-65. [PMID: 26509460 DOI: 10.1111/jam.12989] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/18/2015] [Accepted: 08/28/2015] [Indexed: 12/22/2022]
Abstract
Intrinsic resistance to antibiotics is a serious therapeutic problem in the case of many bacterial species. The Gram-positive human pathogen Listeria monocytogenes is intrinsically resistant to broad spectrum cephalosporin antibiotics, which are commonly used in therapy of bacterial infections. Besides three penicillin-binding proteins the intrinsic cephalosporin resistome of L. monocytogenes includes multidrug resistance transporter transporters, proteins involved in peptidoglycan biosynthesis and modification, cell envelope proteins with structural or general detoxification function, cytoplasmic proteins with unknown function and regulatory proteins. Analysis of the regulation of the expression of genes involved in the intrinsic resistance of L. monocytogenes to cephalosporins highlights the high complexity of control of the intrinsic resistance phenotype. The regulation of the transcription of the intrinsic resistome determinants involves the activity of eight regulators, namely LisR, CesR, LiaR, VirR, σ(B) , σ(H) , σ(L) and PrfA, of which the most prominent role play LisR, CesR and σ(B) . Furthermore, the vast majority of the intrinsic resistome determinants contribute to the tolerance of different stress conditions and virulence. A study indicates that O-acetyltransferase OatA is the most promising candidate for co-drug development since an agent targeting OatA should sensitize L. monocytogenes to certain antibiotics, therefore improving the efficacy of listeriosis treatment as well as food preservation measures.
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Affiliation(s)
- A Krawczyk-Balska
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Z Markiewicz
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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29
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Kang J, Wiedmann M, Boor KJ, Bergholz TM. VirR-Mediated Resistance of Listeria monocytogenes against Food Antimicrobials and Cross-Protection Induced by Exposure to Organic Acid Salts. Appl Environ Microbiol 2015; 81:4553-62. [PMID: 25911485 PMCID: PMC4475887 DOI: 10.1128/aem.00648-15] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/21/2015] [Indexed: 12/17/2022] Open
Abstract
Formulations of ready-to-eat (RTE) foods with antimicrobial compounds constitute an important safety measure against foodborne pathogens such as Listeria monocytogenes. While the efficacy of many commercially available antimicrobial compounds has been demonstrated in a variety of foods, the current understanding of the resistance mechanisms employed by L. monocytogenes to counteract these stresses is limited. In this study, we screened in-frame deletion mutants of two-component system response regulators associated with the cell envelope stress response for increased sensitivity to commercially available antimicrobial compounds (nisin, lauric arginate, ε-polylysine, and chitosan). A virR deletion mutant showed increased sensitivity to all antimicrobials and significantly greater loss of membrane integrity when exposed to nisin, lauric arginate, or ε-polylysine (P < 0.05). The VirR-regulated operon, dltABCD, was shown to be the key contributor to resistance against these antimicrobial compounds, whereas another VirR-regulated gene, mprF, displayed an antimicrobial-specific contribution to resistance. An experiment with a β-glucuronidase (GUS) reporter fusion with the dlt promoter indicated that nisin does not specifically induce VirR-dependent upregulation of dltABCD. Lastly, prior exposure of L. monocytogenes parent strain H7858 and the ΔvirR mutant to 2% potassium lactate enhanced subsequent resistance against nisin and ε-polylysine (P < 0.05). These data demonstrate that VirRS-mediated regulation of dltABCD is the major resistance mechanism used by L. monocytogenes against cell envelope-damaging food antimicrobials. Further, the potential for cross-protection induced by other food-related stresses (e.g., organic acids) needs to be considered when applying these novel food antimicrobials as a hurdle strategy for RTE foods.
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Affiliation(s)
- Jihun Kang
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Kathryn J Boor
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Teresa M Bergholz
- Department of Food Science, Cornell University, Ithaca, New York, USA Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, North Dakota, USA
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30
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Pöntinen A, Markkula A, Lindström M, Korkeala H. Two-Component-System Histidine Kinases Involved in Growth of Listeria monocytogenes EGD-e at Low Temperatures. Appl Environ Microbiol 2015; 81:3994-4004. [PMID: 25841007 PMCID: PMC4524140 DOI: 10.1128/aem.00626-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/28/2015] [Indexed: 01/23/2023] Open
Abstract
Two-component systems (TCSs) aid bacteria in adapting to a wide variety of stress conditions. While the role of TCS response regulators in the cold tolerance of the psychrotrophic foodborne pathogen Listeria monocytogenes has been demonstrated previously, no comprehensive studies showing the role of TCS histidine kinases of L. monocytogenes at low temperature have been performed. We compared the expression levels of each histidine kinase-encoding gene of L. monocytogenes EGD-e in logarithmic growth phase at 3°C and 37°C, as well as the expression levels 30 min, 3 h, and 7 h after cold shock at 5°C and preceding cold shock (at 37°C). We constructed a deletion mutation in each TCS histidine kinase gene, monitored the growth of the EGD-e wild-type and mutant strains at 3°C and 37°C, and measured the minimum growth temperature of each strain. Two genes, yycG and lisK, proved significant in regard to induced relative expression levels under cold conditions and cold-sensitive mutant phenotypes. Moreover, the ΔresE mutant showed a lower growth rate than that of wild-type EGD-e at 3°C. Eleven other genes showed upregulated gene expression but revealed no cold-sensitive phenotypes. The results show that the histidine kinases encoded by yycG and lisK are important for the growth and adaptation of L. monocytogenes EGD-e at low temperature.
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Affiliation(s)
- Anna Pöntinen
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Annukka Markkula
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Miia Lindström
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Hannu Korkeala
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
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31
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Cyclic di-GMP modulates gene expression in Lyme disease spirochetes at the tick-mammal interface to promote spirochete survival during the blood meal and tick-to-mammal transmission. Infect Immun 2015; 83:3043-60. [PMID: 25987708 DOI: 10.1128/iai.00315-15] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 05/11/2015] [Indexed: 01/02/2023] Open
Abstract
Borrelia burgdorferi, the Lyme disease spirochete, couples environmental sensing and gene regulation primarily via the Hk1/Rrp1 two-component system (TCS) and Rrp2/RpoN/RpoS pathways. Beginning with acquisition, we reevaluated the contribution of these pathways to spirochete survival and gene regulation throughout the enzootic cycle. Live imaging of B. burgdorferi caught in the act of being acquired revealed that the absence of RpoS and the consequent derepression of tick-phase genes impart a Stay signal required for midgut colonization. In addition to the behavioral changes brought on by the RpoS-off state, acquisition requires activation of cyclic di-GMP (c-di-GMP) synthesis by the Hk1/Rrp1 TCS; B. burgdorferi lacking either component is destroyed during the blood meal. Prior studies attributed this dramatic phenotype to a metabolic lesion stemming from reduced glycerol uptake and utilization. In a head-to-head comparison, however, the B. burgdorferi Δglp mutant had a markedly greater capacity to survive tick feeding than B. burgdorferi Δhk1 or Δrrp1 mutants, establishing unequivocally that glycerol metabolism is only one component of the protection afforded by c-di-GMP. Data presented herein suggest that the protective response mediated by c-di-GMP is multifactorial, involving chemotactic responses, utilization of alternate substrates for energy generation and intermediary metabolism, and remodeling of the cell envelope as a means of defending spirochetes against threats engendered during the blood meal. Expression profiling of c-di-GMP-regulated genes through the enzootic cycle supports our contention that the Hk1/Rrp1 TCS functions primarily, if not exclusively, in ticks. These data also raise the possibility that c-di-GMP enhances the expression of a subset of RpoS-dependent genes during nymphal transmission.
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32
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Nguyen UT, Harvey H, Hogan AJ, Afonso ACF, Wright GD, Burrows LL. Role of PBPD1 in stimulation of Listeria monocytogenes biofilm formation by subminimal inhibitory β-lactam concentrations. Antimicrob Agents Chemother 2014; 58:6508-17. [PMID: 25136010 PMCID: PMC4249420 DOI: 10.1128/aac.03671-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 08/10/2014] [Indexed: 12/19/2022] Open
Abstract
Disinfectant-tolerant Listeria monocytogenes biofilms can colonize surfaces that come into contact with food, leading to contamination and, potentially, food-borne illnesses. To better understand the process of L. monocytogenes biofilm formation and dispersal, we screened 1,120 off-patent FDA-approved drugs and identified several that modulate Listeria biofilm development. Among the hits were more than 30 β-lactam antibiotics, with effects ranging from inhibiting (≤50%) to stimulating (≥200%) biofilm formation compared to control. Most β-lactams also dispersed a substantial proportion of established biofilms. This phenotype did not necessarily involve killing, as >50% dispersal could be achieved with concentrations as low as 1/20 of the MIC of some cephalosporins. Penicillin-binding protein (PBP) profiling using a fluorescent penicillin analogue showed similar inhibition patterns for most β-lactams, except that biofilm-stimulatory drugs did not bind PBPD1, a low-molecular-weight d,d-carboxypeptidase. Compared to the wild type, a pbpD1 mutant had an attenuated biofilm response to stimulatory β-lactams. The cephalosporin-responsive CesRK two-component regulatory system, whose regulon includes PBPs, was not required for the response. The requirement for PBPD1 activity for β-lactam stimulation of L. monocytogenes biofilms shows that the specific set of PBPs that are inactivated by a particular drug dictates whether a protective biofilm response is provoked.
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Affiliation(s)
- Uyen T Nguyen
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Hanjeong Harvey
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Andrew J Hogan
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Alexandria C F Afonso
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Gerard D Wright
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
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33
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Milecka D, Samluk A, Wasiak K, Krawczyk-Balska A. An essential role of a ferritin-like protein in acid stress tolerance of Listeria monocytogenes. Arch Microbiol 2014; 197:347-51. [PMID: 25352185 PMCID: PMC4326649 DOI: 10.1007/s00203-014-1053-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 09/01/2014] [Accepted: 10/22/2014] [Indexed: 12/15/2022]
Abstract
The expression of ten genes of Listeria monocytogenes previously identified as penicillin G-inducible was transcriptionally analyzed in the presence of 0.5 M KCl, pH 5.0 and 42 °C. This study revealed that all the genes are upregulated by osmotic stress, seven by acid stress and four by temperature stress conditions. The contribution of a gene encoding a ferritin-like protein (fri), a two-component phosphate-response regulator (phoP) and an AraC/XylS family transcription regulator (axyR) to temperature, acid and osmotic stress tolerance was further examined by analysis of nonpolar deletion mutants. This revealed that a lack of PhoP or AxyR does not affect the ability to grow under the tested stress conditions. However, the Δ fri strain showed slightly delayed growth under osmotic and clearly impaired growth under acid stress conditions, indicating an important role of the ferritin-like protein in acid stress tolerance.
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Affiliation(s)
- Dorota Milecka
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland
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34
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Cabrita P, Trigo MJ, Ferreira RB, Brito L. Is the exoproteome important for bacterial pathogenesis? Lessons learned from interstrain exoprotein diversity in Listeria monocytogenes grown at different temperatures. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2014; 18:553-69. [PMID: 25127015 DOI: 10.1089/omi.2013.0151] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacterial exoproteomes vary in composition and quantity among species and within each species, depending on the environmental conditions to which the cells are exposed. This article critically reviews the literature available on exoproteins synthesized by the foodborne pathogenic bacterium Listeria monocytogenes grown at different temperatures. The main challenges posed for exoproteome analyses and the strategies that are being used to overcome these constraints are discussed. Over thirty exoproteins from L. monocytogenes are considered, and the multifunctionality of some of them is discussed. Thus, at the host temperature of 37°C, good examples are provided by Lmo0443, a potential marker for low virulence, and by the virulence factors internalin C (InlC) and listeriolysin O (LLO). Based on the reported LLO-induced mucin exocytosis, a model is proposed for the involvement of extracellular LLO in optimizing the conditions for InlC intervention in the invasion of intestinal epithelial cells. At lower growth temperatures, exoproteins such as flagellin (FlaA) and oligopeptide permease (OppA) may explain the persistence of particular strains in the food industry environment, eventually allowing the development of new tools to eradicate L. monocytogenes, a major concern for public health.
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Affiliation(s)
- Paula Cabrita
- 1 CBAA/DRAT-Departamento dos Recursos Naturais, Ambiente e Território, Instituto Superior de Agronomia, University of Lisbon , Lisbon, Portugal
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35
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Krawczyk-Balska A, Korsak D, Popowska M. The surface protein Lmo1941 with LysM domain influences cell wall structure and susceptibility of Listeria monocytogenes to cephalosporins. FEMS Microbiol Lett 2014; 357:175-83. [PMID: 24974853 DOI: 10.1111/1574-6968.12518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 06/04/2014] [Accepted: 06/20/2014] [Indexed: 11/30/2022] Open
Abstract
Listeria monocytogenes is a Gram-positive bacterium causing rare but dangerous cases of disease in humans and animals. The β-lactams penicillin G and ampicillin are the antibiotics of choice in the treatment of listeriosis. Recently, lmo1941, encoding a surface protein of L. monocytogenes with unknown function, was identified as a gene transcriptionally upregulated under penicillin G pressure. In this study, the effect of lmo1941 knockout on the susceptibility of L. monocytogenes to β-lactams was examined. Deletion mutant in lmo1941 was constructed and subjected to studies, which revealed that the deletion of lmo1941 had no effect on susceptibility and tolerance to penicillin G and ampicillin but resulted, however, in increased susceptibility of L. monocytogenes to several cephalosporins. Subsequently, the potential effect of lmo1941 mutation on the cell wall of L. monocytogenes was investigated. The analysis revealed quantitative changes in the muropeptide profile of peptidoglycan and a decrease in density of the high-density zone of cell wall of the mutant strain. Both these changes were observed in cells taken from the stationary phase. These results indicate that the surface protein Lmo1941 affects peptidoglycan composition and cell wall structure of L. monocytogenes in the stationary phase of growth.
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Affiliation(s)
- Agata Krawczyk-Balska
- Faculty of Biology, Department of Applied Microbiology, Institute of Microbiology, University of Warsaw, Warsaw, Poland
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36
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Sievers S, Sternkopf Lillebæk EM, Jacobsen K, Lund A, Mollerup MS, Nielsen PK, Kallipolitis BH. A multicopy sRNA of Listeria monocytogenes regulates expression of the virulence adhesin LapB. Nucleic Acids Res 2014; 42:9383-98. [PMID: 25034691 PMCID: PMC4132741 DOI: 10.1093/nar/gku630] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The multicopy sRNA LhrC of the intracellular pathogen Listeria monocytogenes has been shown to be induced under infection-relevant conditions, but its physiological role and mechanism of action is not understood. In an attempt to pinpoint the exact terms of LhrC expression, cell envelope stress could be defined as a specific inducer of LhrC. In this process, the two-component system LisRK was shown to be indispensable for expression of all five copies of LhrC. lapB mRNA, encoding a cell wall associated protein that was recently identified as an important virulence factor, was disclosed to be directly bound by LhrC leading to an impediment of its translation. Although LhrC binds to Hfq, it does not require the RNA chaperone for stability or lapB mRNA interaction. The mechanism of LhrC-lapB mRNA binding was shown to involve three redundant CU-rich sites and a structural rearrangement in the sRNA. This study represents an extensive depiction of a so far uncharacterized multicopy sRNA and reveals interesting new aspects concerning its regulation, virulence association and mechanism of target binding.
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Affiliation(s)
- Susanne Sievers
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | | | - Kirstine Jacobsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Anja Lund
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Maria Storm Mollerup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Pia Kiil Nielsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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Laursen MF, Bahl MI, Licht TR, Gram L, Knudsen GM. A single exposure to a sublethal pediocin concentration initiates a resistance-associated temporal cell envelope and general stress response inListeria monocytogenes. Environ Microbiol 2014; 17:1134-51. [DOI: 10.1111/1462-2920.12534] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 06/08/2014] [Indexed: 01/08/2023]
Affiliation(s)
- Martin F. Laursen
- Department of Systems Biology; Technical University of Denmark; DK-2800 Kongens Lyngby Denmark
- National Food Institute; Technical University of Denmark; DK-2860 Søborg Denmark
| | - Martin I. Bahl
- National Food Institute; Technical University of Denmark; DK-2860 Søborg Denmark
| | - Tine R. Licht
- National Food Institute; Technical University of Denmark; DK-2860 Søborg Denmark
| | - Lone Gram
- Department of Systems Biology; Technical University of Denmark; DK-2800 Kongens Lyngby Denmark
| | - Gitte M. Knudsen
- Department of Systems Biology; Technical University of Denmark; DK-2800 Kongens Lyngby Denmark
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Stress response and adaptation of Listeria monocytogenes 08-5923 exposed to a sublethal dose of carnocyclin A. Appl Environ Microbiol 2014; 80:3835-41. [PMID: 24747893 DOI: 10.1128/aem.00350-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Carnocyclin A (CCLA) is an antimicrobial peptide produced by Carnobacterium maltaromaticum ATCC PTA-5313, which can be used to control the growth of Listeria monocytogenes in ready-to-eat meat products. The aim of this research was to elucidate the cellular responses of L. monocytogenes 08-5923 exposed to a sublethal dose of CCLA. Microarray, quantitative reverse transcription-PCR, tandem mass spectrometry, and electron microscopy were used to investigate the alteration in gene expression, protein production, and morphological changes in cells of Listeria following treatment with CCLA. The genes involved in metabolism (baiE, trn, and pykA), cell wall synthesis (murZ and dacB2), and cell division (clpE and divIVA) were upregulated following a 15-min exposure to CCLA as a result of stress responses. Genes involved in cell division, cell wall synthesis, flagellar synthesis, and metabolism were downregulated after 4 h as a result of adaptation. Analysis of total soluble proteins confirmed the downregulation of pykA and gnd after 4 h of exposure to CCLA. The absence of flagella was observed in L. monocytogenes following 30 h of exposure to CCLA. A sublethal dose of CCLA induced adaptation in L. monocytogenes 08-5923 by inhibition of expression of genes and proteins critical for synthesis of cell wall structures and maintaining metabolic functions. Both the mannose- and cellobiose-specific phosphotransferase systems could be targets for CCLA.
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Durack J, Ross T, Bowman JP. Characterisation of the transcriptomes of genetically diverse Listeria monocytogenes exposed to hyperosmotic and low temperature conditions reveal global stress-adaptation mechanisms. PLoS One 2013; 8:e73603. [PMID: 24023890 PMCID: PMC3762727 DOI: 10.1371/journal.pone.0073603] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 07/29/2013] [Indexed: 12/29/2022] Open
Abstract
The ability of Listeria monocytogenes to adapt to various food and food- processing environments has been attributed to its robustness, persistence and prevalence in the food supply chain. To improve the present understanding of molecular mechanisms involved in hyperosmotic and low-temperature stress adaptation of L. monocytogenes, we undertook transcriptomics analysis on three strains adapted to sub-lethal levels of these stress stimuli and assessed functional gene response. Adaptation to hyperosmotic and cold-temperature stress has revealed many parallels in terms of gene expression profiles in strains possessing different levels of stress tolerance. Gene sets associated with ribosomes and translation, transcription, cell division as well as fatty acid biosynthesis and peptide transport showed activation in cells adapted to either cold or hyperosmotic stress. Repression of genes associated with carbohydrate metabolism and transport as well as flagella was evident in stressed cells, likely linked to activation of CodY regulon and consequential cellular energy conservation.
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Affiliation(s)
- Juliana Durack
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
| | - Tom Ross
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
| | - John P. Bowman
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
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Krawczyk-Balska A, Marchlewicz J, Dudek D, Wasiak K, Samluk A. Identification of a ferritin-like protein of Listeria monocytogenes as a mediator of β-lactam tolerance and innate resistance to cephalosporins. BMC Microbiol 2012; 12:278. [PMID: 23176286 PMCID: PMC3534079 DOI: 10.1186/1471-2180-12-278] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 11/20/2012] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The food-borne pathogen Listeria monocytogenes is the causative agent of listeriosis. The β-lactam antibiotics penicillin G and ampicillin are the current drugs of choice for the treatment of listerial infections. While isolates of L. monocytogenes are susceptible to these antibiotics, their action is only bacteriostatic and consequently, this bacterium is regarded as tolerant to β-lactams. In addition, L. monocytogenes has a high level of innate resistance to the cephalosporin family of β-lactams frequently used to treat sepsis of unknown etiology. Given the high mortality rate of listeriosis despite rational antibiotic therapy, it is important to identify genes that play a role in the susceptibility and tolerance of L. monocytogenes to β-lactams. RESULTS The hly-based promoter trap system was applied to identify penicillin G-inducible genes of L. monocytogenes. The results of reporter system studies, verified by transcriptional analysis, identified ten penicillin G-inducible genes. The contribution of three of these genes, encoding a ferritin-like protein (fri), a two-component phosphate-response regulator (phoP) and an AraC/XylS family transcriptional regulator (axyR), to the susceptibility and tolerance of L. monocytogenes to β-lactams was examined by analysis of nonpolar deletion mutants. The absence of PhoP or AxyR resulted in more rapid growth of the strains in the presence of sublethal concentration of β-lactams, but had no effect on the MIC values or the ability to survive a lethal dose of these antibiotics. However, the Δfri strain showed impaired growth in the presence of sublethal concentrations of penicillin G and ampicillin and a significantly reduced ability to survive lethal concentrations of these β-lactams. A lack of Fri also caused a 2-fold increase in the sensitivity of L. monocytogenes to cefalotin and cephradine. CONCLUSIONS The present study has identified Fri as an important mediator of β-lactam tolerance and innate resistance to cephalosporins in L. monocytogenes. PhoP and AxyR are probably involved in transmitting signals to adjust the rate of growth of L. monocytogenes under β-lactam pressure, but these regulators do not play a significant role in susceptibility and tolerance to this class of antibiotics.
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Affiliation(s)
- Agata Krawczyk-Balska
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
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Knudsen G, Holch A, Gram L. Subinhibitory concentrations of antibiotics affect stress and virulence gene expression inListeria monocytogenesand cause enhanced stress sensitivity but do not affect Caco-2 cell invasion. J Appl Microbiol 2012; 113:1273-86. [DOI: 10.1111/j.1365-2672.2012.05435.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/14/2012] [Accepted: 08/15/2012] [Indexed: 11/29/2022]
Affiliation(s)
- G.M. Knudsen
- National Food Institute; Technical University of Denmark; Kongens Lyngby; Denmark
| | - A. Holch
- National Food Institute; Technical University of Denmark; Kongens Lyngby; Denmark
| | - L. Gram
- National Food Institute; Technical University of Denmark; Kongens Lyngby; Denmark
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Tessema GT, Møretrø T, Snipen L, Heir E, Holck A, Naterstad K, Axelsson L. Microarray-based transcriptome ofListeria monocytogenesadapted to sublethal concentrations of acetic acid, lactic acid, and hydrochloric acid. Can J Microbiol 2012; 58:1112-23. [DOI: 10.1139/w2012-091] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Listeria monocytogenes , an important foodborne pathogen, commonly encounters organic acids in food-related environments. The transcriptome of L. monocytogenes L502 was analyzed after adaptation to pH 5 in the presence of acetic acid, lactic acid, or hydrochloric acid (HCl) at 25 °C, representing a condition encountered in mildly acidic ready-to-eat food kept at room temperature. The acid-treated cells were compared with a reference culture with a pH of 6.7 at the time of RNA harvesting. The number of genes and magnitude of transcriptional responses were higher for the organic acids than for HCl. Protein coding genes described for low pH stress, energy transport and metabolism, virulence determinates, and acid tolerance response were commonly regulated in the 3 acid-stressed cultures. Interestingly, the transcriptional levels of histidine and cell wall biosynthetic operons were upregulated, indicating possible universal response against low pH stress in L. monocytogenes. The opuCABCD operon, coding proteins for compatible solutes transport, and the transcriptional regulator sigL were significantly induced in the organic acids, strongly suggesting key roles during organic acid stress. The present study revealed the complex transcriptional responses of L. monocytogenes towards food-related acidulants and opens the roadmap for more specific and in-depth future studies.
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Affiliation(s)
- Girum Tadesse Tessema
- Nofima - Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway
- Norwegian Veterinary Institute, P.O. Box 750 Sentrum, N-0106 Oslo, Norway
| | - Trond Møretrø
- Nofima - Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway
| | - Lars Snipen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway
| | - Even Heir
- Nofima - Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway
| | - Askild Holck
- Nofima - Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway
| | - Kristine Naterstad
- Nofima - Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway
| | - Lars Axelsson
- Nofima - Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway
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Poole K. Bacterial stress responses as determinants of antimicrobial resistance. J Antimicrob Chemother 2012; 67:2069-89. [PMID: 22618862 DOI: 10.1093/jac/dks196] [Citation(s) in RCA: 305] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria encounter a myriad of stresses in their natural environments, including, for pathogens, their hosts. These stresses elicit a variety of specific and highly regulated adaptive responses that not only protect bacteria from the offending stress, but also manifest changes in the cell that impact innate antimicrobial susceptibility. Thus exposure to nutrient starvation/limitation (nutrient stress), reactive oxygen and nitrogen species (oxidative/nitrosative stress), membrane damage (envelope stress), elevated temperature (heat stress) and ribosome disruption (ribosomal stress) all impact bacterial susceptibility to a variety of antimicrobials through their initiation of stress responses that positively impact recruitment of resistance determinants or promote physiological changes that compromise antimicrobial activity. As de facto determinants of antimicrobial, even multidrug, resistance, stress responses may be worthy of consideration as therapeutic targets.
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Affiliation(s)
- Keith Poole
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada K7L 3N6.
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