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Sass AM, Coenye T. The Small RNA NcS25 Regulates Biological Amine-Transporting Outer Membrane Porin BCAL3473 in Burkholderia cenocepacia. mSphere 2023; 8:e0008323. [PMID: 36971554 PMCID: PMC10117139 DOI: 10.1128/msphere.00083-23] [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] [Received: 02/15/2023] [Accepted: 03/03/2023] [Indexed: 03/29/2023] Open
Abstract
Regulation of porin expression in bacteria is complex and often involves small-RNA regulators. Several small-RNA regulators have been described for Burkholderia cenocepacia, and this study aimed to characterize the biological role of the conserved small RNA NcS25 and its cognate target, outer membrane protein BCAL3473. The B. cenocepacia genome carries a large number of genes encoding porins with yet-uncharacterized functions. Expression of the porin BCAL3473 is strongly repressed by NcS25 and activated by other factors, such as a LysR-type regulator and nitrogen-depleted growth conditions. The porin is involved in transport of arginine, tyrosine, tyramine, and putrescine across the outer membrane. Porin BCAL3473, with NcS25 as a major regulator, plays an important role in the nitrogen metabolism of B. cenocepacia. IMPORTANCE Burkholderia cenocepacia is a Gram-negative bacterium which causes infections in immunocompromised individuals and in people with cystic fibrosis. A low outer membrane permeability is one of the factors giving it a high level of innate resistance to antibiotics. Porins provide selective permeability for nutrients, and antibiotics can also traverse the outer membrane by this means. Knowing the properties and specificities of porin channels is therefore important for understanding resistance mechanisms and for developing new antibiotics and could help in overcoming permeability issues in antibiotic treatment.
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Affiliation(s)
- Andrea M. Sass
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
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2
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Modi SK, Gaur S, Sengupta M, Singh MS. Mechanistic insights into nanoparticle surface-bacterial membrane interactions in overcoming antibiotic resistance. Front Microbiol 2023; 14:1135579. [PMID: 37152753 PMCID: PMC10160668 DOI: 10.3389/fmicb.2023.1135579] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 03/30/2023] [Indexed: 05/09/2023] Open
Abstract
Antimicrobial Resistance (AMR) raises a serious concern as it contributes to the global mortality by 5 million deaths per year. The overall impact pertaining to significant membrane changes, through broad spectrum drugs have rendered the bacteria resistant over the years. The economic expenditure due to increasing drug resistance poses a global burden on healthcare community and must be dealt with immediate effect. Nanoparticles (NP) have demonstrated inherent therapeutic potential or can serve as nanocarriers of antibiotics against multidrug resistant (MDR) pathogens. These carriers can mask the antibiotics and help evade the resistance mechanism of the bacteria. The targeted delivery can be fine-tuned through surface functionalization of Nanocarriers using aptamers, antibodies etc. This review covers various molecular mechanisms acquired by resistant bacteria towards membrane modification. Mechanistic insight on 'NP surface-bacterial membrane' interactions are crucial in deciding the role of NP as therapeutic. Finally, we highlight the potential accessible membrane targets for designing smart surface-functionalized nanocarriers which can act as bacteria-targeted robots over the existing clinically available antibiotics. As the bacterial strains around us continue to evolve into resistant versions, nanomedicine can offer promising and alternative tools in overcoming AMR.
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Affiliation(s)
- Suraj Kumar Modi
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
| | - Smriti Gaur
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
| | - Mrittika Sengupta
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
- Mrittika Sengupta, ;
| | - Manu Smriti Singh
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
- *Correspondence: Manu Smriti Singh, ;
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3
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Briones AC, Lorca D, Cofre A, Cabezas CE, Krüger GI, Pardo-Esté C, Baquedano MS, Salinas CR, Espinoza M, Castro-Severyn J, Remonsellez F, Hidalgo AA, Morales EH, Saavedra CP. Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress. Biol Res 2022; 55:8. [PMID: 35193678 PMCID: PMC8862304 DOI: 10.1186/s40659-022-00377-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/30/2022] [Indexed: 11/11/2022] Open
Abstract
Background Salmonella Typhimurium is a Gram-negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella-containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin-encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post-transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. Results In this work we sought to evaluate the transcriptional and post-transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S. Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild-type strain, suggesting that ompX mRNA is also regulated at a post-transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2-induced stress in Salmonella during the exponential growth phase in Lennox broth. Conclusions Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium. Supplementary Information The online version contains supplementary material available at 10.1186/s40659-022-00377-3.
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Affiliation(s)
- A C Briones
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - D Lorca
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - A Cofre
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C E Cabezas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - G I Krüger
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - M S Baquedano
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C R Salinas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - M Espinoza
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - J Castro-Severyn
- Laboratorio de Microbiología Aplicada Y Extremófilos, Facultad de Ingeniería Y Ciencias Geológicas, Universidad Católica 83 del Norte, Antofagasta, Chile
| | - F Remonsellez
- Laboratorio de Microbiología Aplicada Y Extremófilos, Facultad de Ingeniería Y Ciencias Geológicas, Universidad Católica 83 del Norte, Antofagasta, Chile.,Centro de Investigación Tecnológica del Agua en El Desierto (CEITSAZA), Universidad Católica del Norte, Antofagasta, Chile
| | - A A Hidalgo
- Laboratory of Molecular Pathogenesis and Antimicrobials, Escuela de Química Y Farmacia, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - E H Morales
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - C P Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias de La Vida, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.
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4
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Rosas NC, Lithgow T. Targeting bacterial outer-membrane remodelling to impact antimicrobial drug resistance. Trends Microbiol 2021; 30:544-552. [PMID: 34872824 DOI: 10.1016/j.tim.2021.11.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 12/14/2022]
Abstract
The cell envelope is essential for survival and adaptation of bacteria. Bacterial membrane proteins include the major porins that mediate the influx of nutrients and several classes of antimicrobial drugs. Consequently, membrane remodelling is closely linked to antimicrobial resistance (AMR). Knowledge of bacterial membrane protein biogenesis and turnover underpins our understanding of bacterial membrane remodelling and the consequences that this process have in the evolution of AMR phenotypes. At the population level, the evolution of phenotypes is a reversible process, and we can use these insights to deploy evolutionary principles to resensitize bacteria to existing antimicrobial drugs. In our opinion, fundamental knowledge is opening a new way of thinking towards sustainable solutions to the mounting crisis in AMR. Here we discuss what is known about outer-membrane remodelling in bacteria and how the process could be targeted as a means to restore sensitivity to antimicrobial drugs. Bacteriophages are highlighted as a powerful means to exert this control over membrane remodelling but they require careful selection so as to reverse, and not exacerbate, AMR phenotypes.
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Affiliation(s)
- Natalia C Rosas
- Centre to Impact AMR, Monash University, Melbourne, Australia; Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Australia
| | - Trevor Lithgow
- Centre to Impact AMR, Monash University, Melbourne, Australia; Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Australia.
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5
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Lucchini V, Sivignon A, Pieren M, Gitzinger M, Lociuro S, Barnich N, Kemmer C, Trebosc V. The Role of OmpR in Bile Tolerance and Pathogenesis of Adherent-Invasive Escherichia coli. Front Microbiol 2021; 12:684473. [PMID: 34262546 PMCID: PMC8273539 DOI: 10.3389/fmicb.2021.684473] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/31/2021] [Indexed: 12/11/2022] Open
Abstract
Gut microbiota dysbiosis toward adherent-invasive Escherichia coli (AIEC) plays an important role in Crohn's disease (CD). The OmpR transcriptional regulator is required for the AIEC LF82 prototype strain to adhere and invade intestinal epithelial cells. In this study, we explored the role of OmpR in AIEC pathogenesis using a panel of eight Escherichia coli strains isolated from CD patients and identified as AIEC. The deletion of ompR together with the implementation of two cell-based assays revealed that the role of OmpR in adhesion in vitro was not conserved in AIEC clinical strains. Nevertheless, we showed that OmpR was required for robust gut colonization of transgenic mice expressing human CEACAM receptors, suggesting that OmpR is involved in alternative virulence mechanisms in AIEC strains. We found that deletion of ompR compromised the ability of AIEC strains to cope with the stress induced by bile salts, which may be key for AIEC pathogenesis. More specifically, we demonstrated that OmpR was involved in a tolerance mechanism toward sodium deoxycholate (DOC), one of bile salts main component. We showed that the misregulation of OmpF or the loss of outer membrane integrity are not the drivers of OmpR-mediated DOC tolerance, suggesting that OmpR regulates a specific mechanism enhancing AIEC survival in the presence of DOC. In conclusion, the newly discovered role of OmpR in AIEC bile tolerance suggests that OmpR inhibition would interfere with different aspects of AIEC virulence arsenal and could be an alternative strategy for CD-treatment.
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Affiliation(s)
- Valentina Lucchini
- BioVersys AG, Basel, Switzerland
- Biozentrum, University of Basel, Basel, Switzerland
| | - Adeline Sivignon
- Université Clermont Auvergne, Inserm U1071, USC-INRAE 2018, Microbes, Intestin, Inflammation et Susceptibilité de l’Hôte (M2iSH), Clermont-Ferrand, France
| | | | | | | | - Nicolas Barnich
- Université Clermont Auvergne, Inserm U1071, USC-INRAE 2018, Microbes, Intestin, Inflammation et Susceptibilité de l’Hôte (M2iSH), Clermont-Ferrand, France
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6
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Medina-Aparicio L, Rodriguez-Gutierrez S, Rebollar-Flores JE, Martínez-Batallar ÁG, Mendoza-Mejía BD, Aguirre-Partida ED, Vázquez A, Encarnación S, Calva E, Hernández-Lucas I. The CRISPR-Cas System Is Involved in OmpR Genetic Regulation for Outer Membrane Protein Synthesis in Salmonella Typhi. Front Microbiol 2021; 12:657404. [PMID: 33854491 PMCID: PMC8039139 DOI: 10.3389/fmicb.2021.657404] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/10/2021] [Indexed: 12/11/2022] Open
Abstract
The CRISPR-Cas cluster is found in many prokaryotic genomes including those of the Enterobacteriaceae family. Salmonella enterica serovar Typhi (S. Typhi) harbors a Type I-E CRISPR-Cas locus composed of cas3, cse1, cse2, cas7, cas5, cas6e, cas1, cas2, and a CRISPR1 array. In this work, it was determined that, in the absence of cas5 or cas2, the amount of the OmpC porin decreased substantially, whereas in individual cse2, cas6e, cas1, or cas3 null mutants, the OmpF porin was not observed in an electrophoretic profile of outer membrane proteins. Furthermore, the LysR-type transcriptional regulator LeuO was unable to positively regulate the expression of the quiescent OmpS2 porin, in individual S. Typhi cse2, cas5, cas6e, cas1, cas2, and cas3 mutants. Remarkably, the expression of the master porin regulator OmpR was dependent on the Cse2, Cas5, Cas6e, Cas1, Cas2, and Cas3 proteins. Therefore, the data suggest that the CRISPR-Cas system acts hierarchically on OmpR to control the synthesis of outer membrane proteins in S. Typhi.
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Affiliation(s)
- Liliana Medina-Aparicio
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Sarahí Rodriguez-Gutierrez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Javier E Rebollar-Flores
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | | | - Blanca D Mendoza-Mejía
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Eira D Aguirre-Partida
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Alejandra Vázquez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Sergio Encarnación
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Edmundo Calva
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Ismael Hernández-Lucas
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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7
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Mutation of kvrA Causes OmpK35 and OmpK36 Porin Downregulation and Reduced Meropenem-Vaborbactam Susceptibility in KPC-Producing Klebsiella pneumoniae. Antimicrob Agents Chemother 2020; 64:AAC.02208-19. [PMID: 32312773 DOI: 10.1128/aac.02208-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 04/09/2020] [Indexed: 01/05/2023] Open
Abstract
Meropenem-vaborbactam resistance in Klebsiella pneumoniae isolates is associated with loss-of-function mutations in the OmpK35 and OmpK36 porins. We identify two previously unknown loss-of-function mutations that confer cefuroxime resistance in K. pneumoniae isolates. The proteins lost were NlpD and KvrA; the latter is a transcriptional repressor that controls capsule production. We demonstrate that KvrA loss reduces OmpK35 and OmpK36 porin production, which confers reduced susceptibility to meropenem-vaborbactam in a KPC-3-producing K. pneumoniae isolate.
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8
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The role of bacterial cell envelope structures in acid stress resistance in E. coli. Appl Microbiol Biotechnol 2020; 104:2911-2921. [PMID: 32067056 DOI: 10.1007/s00253-020-10453-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/29/2020] [Accepted: 02/07/2020] [Indexed: 12/14/2022]
Abstract
Acid resistance (AR) is an indispensable mechanism for the survival of neutralophilic bacteria, such as Escherichia coli (E. coli) strains that survive in the gastrointestinal tract. E. coli acid tolerance has been extensively studied during past decades, with most studies focused on gene regulation and mechanisms. However, the role of cell membrane structure in the context of acid stress resistance has not been discussed in depth. Here, we provide a comprehensive review of the roles and mechanisms of the E. coli cell envelope from different membrane components, such as membrane proteins, fatty acids, chaperones, and proton-consuming systems, and particularly focus on the innovative effects revealed by recent studies. We hope that the information guides us to understand the bacterial survival strategies under acid stress and to further explore the AR regulatory mechanisms to prevent or treat E. coli and other related Gram-negative bacteria infection, or to enhance the AR of engineering E. coli.
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Davin-Regli A, Lavigne JP, Pagès JM. Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance. Clin Microbiol Rev 2019; 32:e00002-19. [PMID: 31315895 PMCID: PMC6750132 DOI: 10.1128/cmr.00002-19] [Citation(s) in RCA: 249] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The genus Enterobacter is a member of the ESKAPE group, which contains the major resistant bacterial pathogens. First described in 1960, this group member has proven to be more complex as a result of the exponential evolution of phenotypic and genotypic methods. Today, 22 species belong to the Enterobacter genus. These species are described in the environment and have been reported as opportunistic pathogens in plants, animals, and humans. The pathogenicity/virulence of this bacterium remains rather unclear due to the limited amount of work performed to date in this field. In contrast, its resistance against antibacterial agents has been extensively studied. In the face of antibiotic treatment, it is able to manage different mechanisms of resistance via various local and global regulator genes and the modulation of the expression of different proteins, including enzymes (β-lactamases, etc.) or membrane transporters, such as porins and efflux pumps. During various hospital outbreaks, the Enterobacter aerogenes and E. cloacae complex exhibited a multidrug-resistant phenotype, which has stimulated questions about the role of cascade regulation in the emergence of these well-adapted clones.
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Affiliation(s)
- Anne Davin-Regli
- INSERM, SSA, IRBA, MCT, Aix Marseille University, Marseille, France
| | - Jean-Philippe Lavigne
- Department of Microbiology, U1047, INSERM, University Montpellier and University Hospital Nîmes, Nîmes, France
| | - Jean-Marie Pagès
- INSERM, SSA, IRBA, MCT, Aix Marseille University, Marseille, France
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10
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Reciprocal Regulation of OmpR and Hfq and Their Regulatory Actions on the Vi Polysaccharide Capsular Antigen in Salmonella enterica Serovar Typhi. Curr Microbiol 2018; 75:773-778. [DOI: 10.1007/s00284-018-1447-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 01/31/2018] [Indexed: 11/30/2022]
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11
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Cruz-Rabadán JS, Miranda-Ríos J, Espín-Ocampo G, Méndez-Tovar LJ, Maya-Pineda HR, Hernández-Hernández F. Non-Coding RNAs are Differentially Expressed by Nocardia brasiliensis in Vitro and in Experimental Actinomycetoma. Open Microbiol J 2017; 11:112-125. [PMID: 28839491 PMCID: PMC5543724 DOI: 10.2174/1874285801711010112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 05/04/2017] [Accepted: 05/05/2017] [Indexed: 01/01/2023] Open
Abstract
Introduction: Nocardia spp. are common soil-inhabiting bacteria that frequently infect humans through traumatic injuries or inhalation routes and cause infections, such as actinomycetoma and nocardiosis, respectively. Nocardia brasiliensis is the main aetiological agent of actinomycetoma in various countries. Many bacterial non-coding RNAs are regulators of genes associated with virulence factors. Objective: The aim of this work was to identify non-coding RNAs (ncRNAs) expressed during infection conditions and in free-living form (in vitro) in Nocardia brasiliensis. Methods and Result: The N. brasiliensis transcriptome (predominately < 200 nucleotides) was determined by RNA next-generation sequencing in both conditions. A total of seventy ncRNAs were identified in both conditions. Among these ncRNAs, 18 were differentially expressed, 12 were located within intergenic regions, and 2 were encoded as antisense of 2 different genes. Finally, 10 of these ncRNAs were studied by rapid amplification of cDNA ends and/or quantitative reverse transcription polymerase chain reaction. Interestingly, 3 transcripts corresponded to tRNA-derived fragments (tRNAsCys, Met, Thr), and one transcript was overlapped between an intergenic region and the 5´end of the 23S rRNA. Expression of these last four transcripts was increased during N. brasiliensis infection compared with the in vitro conditions. Conclusion: The results of this work suggest a possible role for these transcripts in the regulation of virulence genes in actinomycetoma pathogenesis.
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Affiliation(s)
- Josué S Cruz-Rabadán
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, México
| | - Juan Miranda-Ríos
- Unidad de Genética de la Nutrición, Instituto Nacional de Pediatría and Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, UNAM, Ciudad de México, México
| | - Guadalupe Espín-Ocampo
- Departamento de Microbiología Molecular, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos, México
| | - Luis J Méndez-Tovar
- Hospital de Especialidades, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - Héctor Rubén Maya-Pineda
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, México
| | - Francisca Hernández-Hernández
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, México
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12
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Bearson BL, Bearson SMD, Brunelle BW, Bayles DO, Lee IS, Kich JD. Salmonella DIVA vaccine reduces disease, colonization and shedding due to virulent S. Typhimurium infection in swine. J Med Microbiol 2017; 66:651-661. [PMID: 28516860 PMCID: PMC5817229 DOI: 10.1099/jmm.0.000482] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE Non-host-adapted Salmonella serovars, including the common human food-borne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), are opportunistic pathogens that can colonize food-producing animals without causing overt disease. Interventions against Salmonella are needed to enhance food safety, protect animal health and allow the differentiation of infected from vaccinated animals (DIVA). METHODOLOGY An attenuated S. Typhimurium DIVA vaccine (BBS 866) was characterized for the protection of pigs following challenge with virulent S. Typhimurium. The porcine transcriptional response to BBS 866 vaccination was evaluated. RNA-Seq analysis was used to compare gene expression between BBS 866 and its parent; phenotypic assays were performed to confirm transcriptional differences observed between the strains. RESULTS Vaccination significantly reduced fever and interferon-gamma (IFNγ) levels in swine challenged with virulent S. Typhimurium compared to mock-vaccinated pigs. Salmonella faecal shedding and gastrointestinal tissue colonization were significantly lower in vaccinated swine. RNA-Seq analysis comparing BBS 866 to its parental S. Typhimurium strain demonstrated reduced expression of the genes involved in cellular invasion and bacterial motility; decreased invasion of porcine-derived IPEC-J2 cells and swimming motility for the vaccine strain was consistent with the RNA-Seq analysis. Numerous membrane proteins were differentially expressed, which was an anticipated gene expression pattern due to the targeted deletion of several regulatory genes in the vaccine strain. RNA-Seq analysis indicated that genes involved in the porcine immune and inflammatory response were differentially regulated at 2 days post-vaccination compared to pre-vaccination. CONCLUSION Evaluation of the S. Typhimurium DIVA vaccine indicates that vaccination will provide both swine health and food safety benefits.
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Affiliation(s)
- Bradley L Bearson
- USDA/ARS/National Laboratory for Agriculture and the Environment, Ames, IA, 50011, USA
| | | | | | | | - In Soo Lee
- Hannam University, Daejeon, Republic of Korea
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13
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Baron F, Bonnassie S, Alabdeh M, Cochet MF, Nau F, Guérin-Dubiard C, Gautier M, Andrews SC, Jan S. Global Gene-expression Analysis of the Response of Salmonella Enteritidis to Egg White Exposure Reveals Multiple Egg White-imposed Stress Responses. Front Microbiol 2017; 8:829. [PMID: 28553268 PMCID: PMC5428311 DOI: 10.3389/fmicb.2017.00829] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 04/24/2017] [Indexed: 12/20/2022] Open
Abstract
Chicken egg white protects the embryo from bacterial invaders by presenting an assortment of antagonistic activities that combine together to both kill and inhibit growth. The key features of the egg white anti-bacterial system are iron restriction, high pH, antibacterial peptides and proteins, and viscosity. Salmonella enterica serovar Enteritidis is the major pathogen responsible for egg-borne infection in humans, which is partly explained by its exceptional capacity for survival under the harsh conditions encountered within egg white. However, at temperatures up to 42°C, egg white exerts a much stronger bactericidal effect on S. Enteritidis than at lower temperatures, although the mechanism of egg white-induced killing is only partly understood. Here, for the first time, the impact of exposure of S. Enteritidis to egg white under bactericidal conditions (45°C) is explored by global-expression analysis. A large-scale (18.7% of genome) shift in transcription is revealed suggesting major changes in specific aspects of S. Enteritidis physiology: induction of egg white related stress-responses (envelope damage, exposure to heat and alkalinity, and translation shutdown); shift in energy metabolism from respiration to fermentation; and enhanced micronutrient provision (due to iron and biotin restriction). Little evidence of DNA damage or redox stress was obtained. Instead, data are consistent with envelope damage resulting in cell death by lysis. A surprise was the high degree of induction of hexonate/hexuronate utilization genes, despite no evidence indicating the presence of these substrates in egg white.
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Affiliation(s)
- Florence Baron
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Sylvie Bonnassie
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- Science de la Vie et de la Terre, Université de Rennes IRennes, France
| | - Mariah Alabdeh
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Marie-Françoise Cochet
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Françoise Nau
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Catherine Guérin-Dubiard
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Michel Gautier
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | | | - Sophie Jan
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
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14
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Pérez-Toledo M, Valero-Pacheco N, Pastelin-Palacios R, Gil-Cruz C, Perez-Shibayama C, Moreno-Eutimio MA, Becker I, Pérez-Tapia SM, Arriaga-Pizano L, Cunningham AF, Isibasi A, Bonifaz LC, López-Macías C. Salmonella Typhi Porins OmpC and OmpF Are Potent Adjuvants for T-Dependent and T-Independent Antigens. Front Immunol 2017; 8:230. [PMID: 28337196 PMCID: PMC5344031 DOI: 10.3389/fimmu.2017.00230] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/17/2017] [Indexed: 02/05/2023] Open
Abstract
Several microbial components, such as bacterial DNA and flagellin, have been used as experimental vaccine adjuvants because of their inherent capacity to efficiently activate innate immune responses. Likewise, our previous work has shown that the major Salmonella Typhi (S. Typhi) outer membrane proteins OmpC and OmpF (porins) are highly immunogenic protective antigens that efficiently stimulate innate and adaptive immune responses in the absence of exogenous adjuvants. Moreover, S. Typhi porins induce the expression of costimulatory molecules on antigen-presenting cells through toll-like receptor canonical signaling pathways. However, the potential of major S. Typhi porins to be used as vaccine adjuvants remains unknown. Here, we evaluated the adjuvant properties of S. Typhi porins against a range of experimental and clinically relevant antigens. Co-immunization of S. Typhi porins with ovalbumin (OVA), an otherwise poorly immunogenic antigen, enhanced anti-OVA IgG titers, antibody class switching, and affinity maturation. This adjuvant effect was dependent on CD4+ T-cell cooperation and was associated with an increase in IFN-γ, IL-17A, and IL-2 production by OVA-specific CD4+ T cells. Furthermore, co-immunization of S. Typhi porins with an inactivated H1N1 2009 pandemic influenza virus experimental vaccine elicited higher hemagglutinating anti-influenza IgG titers, antibody class switching, and affinity maturation. Unexpectedly, co-administration of S. Typhi porins with purified, unconjugated Vi capsular polysaccharide vaccine (Vi CPS)—a T-independent antigen—induced higher IgG antibody titers and class switching. Together, our results suggest that S. Typhi porins OmpC and OmpF are versatile vaccine adjuvants, which could be used to enhance T-cell immune responses toward a Th1/Th17 profile, while improving antibody responses to otherwise poorly immunogenic T-dependent and T-independent antigens.
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Affiliation(s)
- Marisol Pérez-Toledo
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI", Mexican Social Security Institute, Mexico City, Mexico; Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Nuriban Valero-Pacheco
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI", Mexican Social Security Institute, Mexico City, Mexico; Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | | | - Cristina Gil-Cruz
- Institute of Immunobiology, Kantonsspital St. Gallen , St. Gallen , Switzerland
| | | | - Mario A Moreno-Eutimio
- Immunity and Inflammation Research Unit, Hospital Juárez de México, Ministry of Health , Mexico City , Mexico
| | - Ingeborg Becker
- Facultad de Medicina, Departamento de Medicina Experimental, Universidad Nacional Autónoma de México , Mexico City , Mexico
| | - Sonia Mayra Pérez-Tapia
- Unit of R&D in Bioprocesses (UDIBI), Department of Immunology, National School of Biological Sciences, National Polytechnic Institute , Mexico City , Mexico
| | - Lourdes Arriaga-Pizano
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI", Mexican Social Security Institute , Mexico City , Mexico
| | - Adam F Cunningham
- MRC Centre for Immune Regulation, College of Medical and Dental Sciences, Institute of Immunology and Immunotherapy, University of Birmingham , Birmingham , UK
| | - Armando Isibasi
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI", Mexican Social Security Institute , Mexico City , Mexico
| | - Laura C Bonifaz
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI", Mexican Social Security Institute , Mexico City , Mexico
| | - Constantino López-Macías
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI", Mexican Social Security Institute, Mexico City, Mexico; Nuffield Department of Medicine, University of Oxford, Oxford, UK
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15
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Phan K, Ferenci T. The fitness costs and trade-off shapes associated with the exclusion of nine antibiotics by OmpF porin channels. ISME JOURNAL 2017; 11:1472-1482. [PMID: 28072422 DOI: 10.1038/ismej.2016.202] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 11/20/2016] [Accepted: 12/01/2016] [Indexed: 02/01/2023]
Abstract
The trade-off relationship between antibiotic exclusion and nutrient access across the Gram-negative outer membrane is determined by structural constraints in porin channels. The precise nutritional cost of exclusion is unknown for different antibiotics, as are the shapes of the nutrition-susceptibility trade-off. Using a library of 10 engineered isogenic Escherichia coli strains with structural modifications of OmpF porin expressed at a constant level, susceptibilities were measured for nine antibiotics and the nutritional fitness costs estimated by competitions in chemostats. Different antibiotics exhibited a remarkably varied range of geometries in the nutrition-susceptibility trade-off, including convex, concave and sigmoidal trade-off shapes. The trade-off patterns predict the possibility of adaptations in contributing to antibiotic resistance; exclusion of amoxicillin or trimethoprim in ompF mutants can occur with little loss of fitness whereas kanamycin and streptomycin exclusion has a high cost. Some individual OmpF changes even allow positive correlations (trade-ups), resulting in increased fitness and decreased susceptibility specifically to cephalexin or ciprofloxacin. The surprising plasticity of the nutrition-exclusion relationship means that there are no generalisable rules that apply to decreasing susceptibility for all antibiotics. The protein changes are exquisitely specific in determining nutritional fitness and adaptive outcomes in a structural constraint trade-off.
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Affiliation(s)
- Katherine Phan
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Thomas Ferenci
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
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16
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Li S, Li H, Qi T, Yan X, Wang B, Guan J, Li Y. Comparative transcriptomics analyses of the different growth states of multidrug-resistant Acinetobacter baumannii. Biomed Pharmacother 2016; 85:564-574. [PMID: 27916419 DOI: 10.1016/j.biopha.2016.11.065] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 11/03/2016] [Accepted: 11/14/2016] [Indexed: 11/30/2022] Open
Abstract
Multidrug-resistant (MDR) Acinetobacter baumannii is an important bacterial pathogen commonly associated with hospital acquired infections. A. baumannii can remain viable and hence virulent in the environment for a long period of time due primarily to its ability to form biofilms. A total of 459 cases of MDR A. baumannii our hospital collected from March 2014 to March 2015 were examined in this study, and a representative isolate selected for high-throughput mRNA sequencing and comparison of gene expression profiles under the biofilm and exponential growth conditions. Our study found that the same bacteria indeed exhibited differential mRNA expression under different conditions. Compared to the rapidly growing bacteria, biofilm bacteria had 106 genes upregulated and 92 genes downregulated. Bioinformatics analyses suggested that many of these genes are involved in the formation and maintenance of biofilms, whose expression also depends on the environment and specific signaling pathways and transcription factors that are absent in the log phase bacteria. These differentially expressed mRNAs might contribute to A. baumannii's unique pathogenicity and ability to inflict chronic and recurrent infections.
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Affiliation(s)
- Shuai Li
- Department of Respiratory Medicine, The Second Hospital of Hebei Medical University, No. 215 Heping West Road, Xinhua, Shijiazhuang, Hebei Province 050000, China
| | - Haitao Li
- Department of Respiratory Medicine, The Second Hospital of Hebei Medical University, No. 215 Heping West Road, Xinhua, Shijiazhuang, Hebei Province 050000, China
| | - Tianjie Qi
- Department of Respiratory Medicine, The Second Hospital of Hebei Medical University, No. 215 Heping West Road, Xinhua, Shijiazhuang, Hebei Province 050000, China
| | - Xixin Yan
- Department of Respiratory Medicine, The Second Hospital of Hebei Medical University, No. 215 Heping West Road, Xinhua, Shijiazhuang, Hebei Province 050000, China.
| | - Boli Wang
- Department of Respiratory Medicine, The Second Hospital of Hebei Medical University, No. 215 Heping West Road, Xinhua, Shijiazhuang, Hebei Province 050000, China
| | - Jitao Guan
- Department of Respiratory Medicine, The Second Hospital of Hebei Medical University, No. 215 Heping West Road, Xinhua, Shijiazhuang, Hebei Province 050000, China
| | - Yu Li
- Hebei Medical University, No. 48 Donggang Road, Yuhua, Shijiazhuang, Hebei 050000, China
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17
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Zhao Y, Fan J, Li J, Li J, Zhou X, Li C. Visualized and precise design of artificial small RNAs for regulating T7 RNA polymerase and enhancing recombinant protein folding in Escherichia coli. Synth Syst Biotechnol 2016; 1:265-270. [PMID: 29062952 PMCID: PMC5625733 DOI: 10.1016/j.synbio.2016.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/30/2016] [Accepted: 08/30/2016] [Indexed: 11/18/2022] Open
Abstract
Small non-coding RNAs (sRNAs) have received much attention in recent years due to their unique biological properties, which can efficiently and specifically tune target gene expressions in bacteria. Inspired by natural sRNAs, recent works have proposed the use of artificial sRNAs (asRNAs) as genetic tools to regulate desired gene that has been applied in several fields, such as metabolic engineering and bacterial physiology studies. However, the rational design of asRNAs is still a challenge. In this study, we proposed structure and length as two criteria to implement rational visualized and precise design of asRNAs. T7 expression system was one of the most useful recombinant protein expression systems. However, it was deeply limited by the formation of inclusion body. To settle this problem, we designed a series of asRNAs to inhibit the T7 RNA polymerase (Gene1) expression to balance the rate between transcription and folding of recombinant protein. Based on the heterologous expression of Aspergillus oryzae Li-3 glucuronidase in E. coli, the asRNA-antigene1-17bp can effectively decrease the inclusion body and increase the enzyme activity by 169.9%.
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18
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Xiao M, Lai Y, Sun J, Chen G, Yan A. Transcriptional Regulation of the Outer Membrane Porin Gene ompW Reveals its Physiological Role during the Transition from the Aerobic to the Anaerobic Lifestyle of Escherichia coli. Front Microbiol 2016; 7:799. [PMID: 27303386 PMCID: PMC4886647 DOI: 10.3389/fmicb.2016.00799] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 05/11/2016] [Indexed: 11/13/2022] Open
Abstract
Understanding bacterial physiology relies on elucidating the regulatory mechanisms and cellular functions of those differentially expressed genes in response to environmental changes. A widespread Gram-negative bacterial outer membrane protein OmpW has been implicated in the adaptation to stresses in various species. It is recently found to be present in the regulon of the global anaerobic transcription factor FNR and ArcA in Escherichia coli. However, little is known about the physiological implications of this regulatory disposition. In this study, we demonstrate that transcription of ompW is indeed mediated by a series of global regulators involved in the anaerobiosis of E. coli. We show that FNR can both activate and repress the expression of ompW through its direct binding to two distinctive sites, -81.5 and -126.5 bp respectively, on ompW promoter. ArcA also participates in repression of ompW under anaerobic condition, but in an FNR dependent manner. Additionally, ompW is also subject to the regulation by CRP and NarL which senses the availability and types of carbon sources and respiration electron acceptors in the environment respectively, implying a role of OmpW in the carbon and energy metabolism of E. coli during its anaerobic adaptation. Molecular docking reveals that OmpW can bind fumarate, an alternative electron acceptor in anaerobic respiration, with sufficient affinity. Moreover, supplement of fumarate or succinate which belongs to the C4-dicarboxylates family of metabolite, to E. coli culture rescues OmpW-mediated colicin S4 killing. Taken together, we propose that OmpW is involved in anaerobic carbon and energy metabolism to mediate the transition from aerobic to anaerobic lifestyle in E. coli.
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Affiliation(s)
- Minfeng Xiao
- School of Biological Sciences, The University of Hong Kong Hong Kong, China
| | - Yong Lai
- School of Biological Sciences, The University of Hong Kong Hong Kong, China
| | - Jian Sun
- Department of Chemistry, The University of Hong Kong Hong Kong, China
| | - Guanhua Chen
- Department of Chemistry, The University of Hong Kong Hong Kong, China
| | - Aixin Yan
- School of Biological Sciences, The University of Hong Kong Hong Kong, China
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19
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Saw HTH, Webber MA, Mushtaq S, Woodford N, Piddock LJV. Inactivation or inhibition of AcrAB-TolC increases resistance of carbapenemase-producing Enterobacteriaceae to carbapenems. J Antimicrob Chemother 2016; 71:1510-9. [PMID: 26945714 DOI: 10.1093/jac/dkw028] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/27/2016] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVES The objective of this study was to study the contribution of the multidrug resistance AcrAB-TolC efflux system to carbapenem resistance in carbapenemase-producing Enterobacteriaceae and the impact of the efflux inhibitor PABN on this resistance. METHODS Klebsiella pneumoniae, Escherichia coli, Salmonella enterica serovar Typhimurium and their corresponding AcrAB-TolC mutants, each carrying carbapenemase-carrying plasmids (pKpQIL-UK with blaKPC and pNDM-HK with blaNDM), were tested for their susceptibility to six β-lactam antibiotics according to the BSAC agar dilution method. MICs were also determined in the presence of efflux inhibitors. The susceptibility of ertapenem in the presence of 25 and 100 mg/L PABN was also determined for 86 non-replicate clinical isolates of carbapenemase-producing Enterobacteriaceae with OXA-48-like (n = 18), IMP (n = 12), VIM (n = 16), NDM (n = 20) or KPC (n = 20) enzymes. Outer membrane protein profiles were determined with SDS-PAGE. RESULTS The carbapenemase-producing AcrAB mutants of K. pneumoniae and E. coli and the TolC mutant of Salmonella Typhimurium had elevated resistance to carbapenem antibiotics. In Salmonella Typhimurium, the increase in carbapenem MIC correlated with the loss of OmpF. Sixty-two (72%) of the clinical isolates tested were also more resistant to ertapenem in the presence of PABN. SDS-PAGE showed that the presence of PABN affected outer membrane porin production, which was associated with the increased MIC values of ertapenem. CONCLUSIONS The decreased susceptibility to carbapenems of carbapenemase-producing Enterobacteriaceae in the absence of AcrAB or TolC and/or in the presence of an efflux inhibitor (e.g. PABN) is likely due to the changes in porin expression (e.g. OmpF). Efflux inhibitors may not potentiate carbapenem activity, but rather could increase levels of resistance in carbapenemase-producing organisms.
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Affiliation(s)
- Howard T H Saw
- Antimicrobials Research Group, Institute of Microbiology & Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Mark A Webber
- Antimicrobials Research Group, Institute of Microbiology & Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Shazad Mushtaq
- Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, Public Health England, London NW9 5EQ, UK
| | - Neil Woodford
- Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, Public Health England, London NW9 5EQ, UK
| | - Laura J V Piddock
- Antimicrobials Research Group, Institute of Microbiology & Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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20
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Predictability of Phenotype in Relation to Common β-Lactam Resistance Mechanisms in Escherichia coli and Klebsiella pneumoniae. J Clin Microbiol 2016; 54:1243-50. [PMID: 26912748 DOI: 10.1128/jcm.02153-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 02/01/2016] [Indexed: 12/26/2022] Open
Abstract
The minimal concentration of antibiotic required to inhibit the growth of different isolates of a given species with no acquired resistance mechanisms has a normal distribution. We have previously shown that the presence or absence of transmissible antibiotic resistance genes has excellent predictive power for phenotype. In this study, we analyzed the distribution of six β-lactam antibiotic susceptibility phenotypes associated with commonly acquired resistance genes in Enterobacteriaceae in Sydney, Australia. Escherichia coli (n = 200) and Klebsiella pneumoniae (n = 178) clinical isolates, with relevant transmissible resistance genes (blaTEM, n = 33; plasmid AmpC, n = 69; extended-spectrum β-lactamase [ESBL], n = 116; and carbapenemase, n = 100), were characterized. A group of 60 isolates with no phenotypic resistance to any antibiotics tested and carrying none of the important β-lactamase genes served as comparators. The MICs for all drug-bacterium combinations had a normal distribution, varying only in the presence of additional genes relevant to the phenotype or, for ertapenem resistance in K. pneumoniae, with a loss or change in the outer membrane porin protein OmpK36. We demonstrated mutations in ompK36 or absence of OmpK36 in all isolates in which reduced susceptibility to ertapenem (MIC, >1 mg/liter) was evident. Ertapenem nonsusceptibility in K. pneumoniae was most common in the context of an OmpK36 variant with an ESBL or AmpC gene. Surveillance strategies to define appropriate antimicrobial therapies should include genotype-phenotype relationships for all major transmissible resistance genes and the characterization of mutations in relevant porins in organisms, like K. pneumoniae.
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21
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Nguyen MP, Yoon JM, Cho MH, Lee SW. Prokaryotic 2-component systems and the OmpR/PhoB superfamily. Can J Microbiol 2015; 61:799-810. [DOI: 10.1139/cjm-2015-0345] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In bacteria, 2-component regulatory systems (TCSs) are the critical information-processing pathways that link stimuli to specific adaptive responses. Signals perceived by membrane sensors, which are generally histidine kinases, are transmitted by response regulators (RRs) to allow cells to cope rapidly and effectively with environmental challenges. Over the past few decades, genes encoding components of TCSs and their responsive proteins have been identified, crystal structures have been described, and signaling mechanisms have been elucidated. Here, we review recent findings and interesting breakthroughs in bacterial TCS research. Furthermore, we discuss structural features, mechanisms of activation and regulation, and cross-regulation of RRs, with a focus on the largest RR family, OmpR/PhoB, to provide a comprehensive overview of these critically important signaling molecules.
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Affiliation(s)
| | - Joo-Mi Yoon
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
| | - Man-Ho Cho
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
| | - Sang-Won Lee
- Crop Biotech Institute, Kyung Hee University, Yongin 446-701, Korea
- Department of Genetic Engineering and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea
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22
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How Porin Heterogeneity and Trade-Offs Affect the Antibiotic Susceptibility of Gram-Negative Bacteria. Genes (Basel) 2015; 6:1113-24. [PMID: 26506392 PMCID: PMC4690030 DOI: 10.3390/genes6041113] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/04/2015] [Accepted: 10/08/2015] [Indexed: 11/17/2022] Open
Abstract
Variations in porin proteins are common in Gram-negative pathogens. Altered or absent porins reduce access of polar antibiotics across the outer membrane and can thus contribute to antibiotic resistance. Reduced permeability has a cost however, in lowering access to nutrients. This trade-off between permeability and nutritional competence is the source of considerable natural variation in porin gate-keeping. Mutational changes in this trade-off are frequently selected, so susceptibility to detergents and antibiotics is polymorphic in environmental isolates as well as pathogens. Understanding the mechanism, costs and heterogeneity of antibiotic exclusion by porins will be crucial in combating Gram negative infections.
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23
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Gao T, Ju L, Yin J, Gao H. Positive regulation of the Shewanella oneidensis OmpS38, a major porin facilitating anaerobic respiration, by Crp and Fur. Sci Rep 2015; 5:14263. [PMID: 26381456 PMCID: PMC4585640 DOI: 10.1038/srep14263] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/21/2015] [Indexed: 12/20/2022] Open
Abstract
Major porins are among the most abundant proteins embedded in the outer membrane (OM) of Gram-negative bacteria, playing crucial roles in maintenance of membrane structural integrity and OM permeability. Although many OM proteins (especially c-type cytochromes) in Shewanella oneidensis, a research model for respiratory versatility, have been extensively studied, physiological significance of major porins remains largely unexplored. In this study, we show that OmpS38 and OmpA are two major porins, neither of which is responsive to changes in osmolarity or contributes to the intrinsic resistance to β-lactam antibiotics. However, OmpS38 but not OmpA is largely involved in respiration of non-oxygen electron acceptors. We then provide evidence that expression of ompS38 is transcribed from two promoters, the major of which is favored under anaerobic conditions while the other appears constitutive. The major promoter is under the direct control of Crp, the master regulator dictating respiration. As a result, the increase in the level of OmpS38 correlates with an elevated activity in Crp under anaerobic conditions. In addition, we show that the activity of the major promoter is also affected by Fur, presumably indirectly, the transcription factor for iron-dependent gene expression.
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Affiliation(s)
- Tong Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Lili Ju
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Jianhua Yin
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
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24
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Shimada T, Takada H, Yamamoto K, Ishihama A. Expanded roles of two-component response regulator OmpR in Escherichia coli: genomic SELEX search for novel regulation targets. Genes Cells 2015; 20:915-31. [PMID: 26332955 DOI: 10.1111/gtc.12282] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/26/2015] [Indexed: 12/22/2022]
Abstract
The two-component system (TCS) is a sophisticated bacterial signal transduction system for regulation of genome transcription in response to environmental conditions. The EnvZ-OmpR system is one of the well-characterized TCS of Escherichia coli, responding to changes in environmental osmolality. Regulation has largely focused on the differential expression of two porins, OmpF and OmpC, which transport small molecules across the outer membrane. Recently, it has become apparent that OmpR serves a more global regulatory role and regulates additional targets. To identify the entire set of regulatory targets of OmpR, we performed the genomic SELEX screening of OmpR-binding sites along the E. coli genome. As a result, more than 30 novel genes have been identified to be under the direct control of OmpR. One abundant group includes the genes encoding a variety of membrane-associated transporters that mediate uptake or efflux of small molecules, while another group encodes a set of transcription regulators, raising a concept that OmpR is poised to control a diverse set of responses by altering downstream transcriptional regulators.
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Affiliation(s)
- Tomohiro Shimada
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan.,Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuda, Yokohama, 226-8503, Japan
| | - Hiraku Takada
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan
| | - Kaneyoshi Yamamoto
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan.,Department of Frontier Bioscience, Hosei University, Koganai, Tokyo, 184-8584, Japan
| | - Akira Ishihama
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan.,Department of Frontier Bioscience, Hosei University, Koganai, Tokyo, 184-8584, Japan
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Pinet E, Franceschi C, Davin-Regli A, Zambardi G, Pagès JM. Role of the culture medium in porin expression and piperacillin-tazobactam susceptibility in Escherichia coli. J Med Microbiol 2015; 64:1305-1314. [PMID: 26242994 DOI: 10.1099/jmm.0.000152] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The continuing emergence of the multidrug resistance phenotype in Gram-negative bacteria makes the development of rapid susceptibility tests mandatory. To achieve this goal, proprietary specific media for bacterial growth can be used but may have some adverse effects. In this study, we dissected the role of media on porin, efflux pump and β-lactamase expression. Depending on the medium used, we observed a change in piperacillin-tazobactam susceptibility for some isolates, such as increases in MIC values. No significant alteration in efflux activity or in β-lactamase production was detected after changing the incubation medium. The ratio of piperacillinase:nitrocefinase showed no specific alteration, indicating that the various media did not affect significantly the relative enzymic affinity for the substrates. In contrast, osmotic variation was able to modulate both porin expression and OmpC : OmpF balance, thus modulating the antibiotic uptake. This study suggests that porin expression may be impacted by a susceptibility testing medium, which may modify the antibiotic diffusion into the bacteria, thus affecting MIC results.
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Affiliation(s)
- Elizabeth Pinet
- UMR-MD-1, Aix-Marseille Université, IRBA, Transporteurs Membranaires, Chimiorésistance et Drug Design, Marseille, France
| | | | - Anne Davin-Regli
- UMR-MD-1, Aix-Marseille Université, IRBA, Transporteurs Membranaires, Chimiorésistance et Drug Design, Marseille, France
| | - Gilles Zambardi
- R&D Microbiology Innovation, bioMérieux, La Balme les Grottes, France
| | - Jean-Marie Pagès
- UMR-MD-1, Aix-Marseille Université, IRBA, Transporteurs Membranaires, Chimiorésistance et Drug Design, Marseille, France
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Costa Ramos JM, Stein C, Pfeifer Y, Brandt C, Pletz MW, Makarewicz O. Mutagenesis of the CTX-M-type ESBL-is MIC-guided treatment according to the new EUCAST recommendations a safe approach? J Antimicrob Chemother 2015; 70:2528-35. [PMID: 26071519 DOI: 10.1093/jac/dkv153] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 05/15/2015] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVES Spurred by the latest EUCAST and CLSI recommendation to adjust antibiotic therapy on the basis of MICs instead of resistance mechanisms, we aimed to investigate the ability of CTX-M-1 and CTX-M-14 to achieve ceftazidime resistance under selective conditions. METHODS We exposed Escherichia coli transconjugants bearing natural plasmids that express CTX-M-1, CTX-M-14 or CTX-M-15 to various selective culture conditions and tracked their growth and mutational frequencies. For selected mutants we analysed the sequences of the bla CTX-M genes, determined the altered MICs of cefotaxime, cefepime, ceftazidime and meropenem, and measured the efflux properties and the changes in transcriptional levels of bla CTX-M genes. RESULTS The CTX-M-1- and CTX-M-14-bearing clones switched from ceftazidime-susceptible to ceftazidime-resistant phenotypes under selective conditions within 24 h. However, no mutations within the bla CTX-M genes were found, and the efflux was unlikely to be involved in the increased ceftazidime MICs. In CTX-M-1-bearing clones bla CTX-M-1 expression was 19-fold increased under ceftazidime-selective conditions but there was a high variance within the clones. Reasons for increased ceftazidime MICs of CTX-M-bearing clones remain unclear but might be the increased enzymatic activity or other intrachromosomal mutations. CONCLUSIONS It can be speculated that different strategies to survive under selective conditions can be adopted by E. coli, thereby establishing an optimal mechanism with the lowest energy demand for each transconjugant. Based on our in vitro findings, we cannot fully recommend the use of ceftazidime, particularly in critically ill patients with infections due to ESBL producers, regardless of susceptibility to ceftazidime.
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Affiliation(s)
- João M Costa Ramos
- Center for Infectious Diseases and Infection Control, Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
| | - Claudia Stein
- Center for Infectious Diseases and Infection Control, Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
| | - Yvonne Pfeifer
- Nosocomial Pathogens and Antibiotic Resistance, Robert Koch Institute, Burgstrasse 37, D-8855 Wernigerode, Germany
| | - Christian Brandt
- Center for Infectious Diseases and Infection Control, Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
| | - Mathias W Pletz
- Center for Infectious Diseases and Infection Control, Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
| | - Oliwia Makarewicz
- Center for Infectious Diseases and Infection Control, Jena University Hospital, Erlanger Allee 101, D-07747 Jena, Germany
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Hydrogen peroxide and hypochlorous acid influx through the major S. Typhimurium porin OmpD is affected by substitution of key residues of the channel. Arch Biochem Biophys 2015; 568:38-45. [DOI: 10.1016/j.abb.2015.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/07/2015] [Accepted: 01/08/2015] [Indexed: 11/23/2022]
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Carraro L, Fasolato L, Montemurro F, Martino ME, Balzan S, Servili M, Novelli E, Cardazzo B. Polyphenols from olive mill waste affect biofilm formation and motility in Escherichia coli K-12. Microb Biotechnol 2014; 7:265-75. [PMID: 24628798 PMCID: PMC3992022 DOI: 10.1111/1751-7915.12119] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 01/16/2014] [Accepted: 01/26/2014] [Indexed: 11/28/2022] Open
Abstract
Olive mill wastes are sources of phenolic compounds with a wide array of biological activities, including antimicrobial effects. A potential option for bioremediation to overcome ecological problems is the reutilization of these natural compounds in food production. The aim of this work was to gain a better understanding of the antimicrobial mode of action of a phenols extract from olive vegetation water (PEOVW) at molecular level by studying Escherichia coli as a model microorganism. Genome-wide transcriptional analysis was performed on E. coli K-12 exposed to PEOVW. The repression of genes for flagellar synthesis and the involvement of genes linked to biofilm formation and stress response were observed. Sub-inhibitory concentrations of PEOVW significantly decreased biofilm formation, swarming and swimming motility, thus confirming the gene expression data. This study provides interesting insights on the molecular action of PEOVW on E. coli K-12. Given these anti-biofilm properties and considering that biofilm formation is a serious problem for the food industry and human health, PEOVW has proved to be a high-value natural product.
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Affiliation(s)
- Lisa Carraro
- Department of Comparative Biomedicine and Food Science, University of PadovaLegnaro, 35020, Italy
| | - Luca Fasolato
- Department of Comparative Biomedicine and Food Science, University of PadovaLegnaro, 35020, Italy
| | - Filomena Montemurro
- Department of Comparative Biomedicine and Food Science, University of PadovaLegnaro, 35020, Italy
| | - Maria Elena Martino
- Department of Comparative Biomedicine and Food Science, University of PadovaLegnaro, 35020, Italy
| | - Stefania Balzan
- Department of Comparative Biomedicine and Food Science, University of PadovaLegnaro, 35020, Italy
| | - Maurizio Servili
- Department of Economical and Food Science, University of PerugiaPerugia, 06123, Italy
| | - Enrico Novelli
- Department of Comparative Biomedicine and Food Science, University of PadovaLegnaro, 35020, Italy
| | - Barbara Cardazzo
- Department of Comparative Biomedicine and Food Science, University of PadovaLegnaro, 35020, Italy
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Flores-Valdez MA, Fernández-Mora M, Ares MÁ, Girón JA, Calva E, De la Cruz MÁ. OmpR phosphorylation regulates ompS1 expression by differentially controlling the use of promoters. Microbiology (Reading) 2014; 160:733-741. [DOI: 10.1099/mic.0.071381-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Salmonella enterica ompS1 gene encodes a quiescent porin that belongs to the OmpC/OmpF family. In the present work we analysed the regulatory effects of OmpR phosphorylation on ompS1 expression. We found that in vivo, OmpR in its phosphorylated form (OmpR-P) was important in the regulation of the two ompS1 promoters: OmpR-P activated the P1 promoter and repressed the P2 promoter in an EnvZ-dependent manner; expression occurs from the P2 promoter in an ompR mutant. In vitro, OmpR-P had a higher DNA-binding-affinity to the ompS1 promoter region than OmpR and OmpRD55A, showing an affinity even higher than that of equivalent DNA regions in the 5′-upstream regulatory sequence of the major porin-encoding genes ompC and ompF. By analysing different environmental conditions, we found that glucose and glycerol enhanced ompS1 expression in the wild-type strain. Interestingly the stimulation by glycerol was OmpR-dependent while the effect of glucose was still observed in the absence of OmpR. Acetyl phosphate produced by the AckA-Pta pathway did not influence ompS1 regulation. These data indicate the important role of the phosphorylation in the activity of OmpR on the differential regulation of both ompS1 promoters and its impact on the pathogenesis.
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Affiliation(s)
- Mario Alberto Flores-Valdez
- Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco A. C., Normalistas 800, Colinas de la Normal, Guadalajara 44270, Jalisco, Mexico
| | - Marcos Fernández-Mora
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, Mexico
| | - Miguel Ángel Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico
| | - Jorge A. Girón
- Department of Molecular Genetics and Microbiology, Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Edmundo Calva
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, Mexico
| | - Miguel Ángel De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, Mexico
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Brambilla L, Morán-Barrio J, Viale AM. Expression of the Escherichia coli ompW colicin S4 receptor gene is regulated by temperature and modulated by the H-NS and StpA nucleoid-associated proteins. FEMS Microbiol Lett 2014; 352:238-44. [PMID: 24444297 DOI: 10.1111/1574-6968.12385] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/09/2014] [Accepted: 01/13/2014] [Indexed: 12/15/2022] Open
Abstract
The OmpW family consists of a ubiquitous group of small outer membrane (OM) β-barrel proteins of Gram-negative bacteria with proposed roles in environmental adaptation but poorly understood mechanisms of expression. We report here that Escherichia coli K-12 OmpW contents are drastically modified by temperature changes compatible with the leap from the environment to warm-blooded hosts and/or vice versa. Thus, while OmpW is present in the OM of bacteria grown at 37 °C, it sharply disappears at 23 °C with the concomitant acquisition of colicin S4 resistance by the cells. ompW::lacZY fusions indicated that temperature regulation operates at the level of transcription, being ompW expression almost abolished at 23 °C as compared to 37 °C. Moreover, E. coli Δhns mutants lacking H-NS showed reductions in ompW transcription and OmpW contents at 37 °C, indicating positive modulatory roles for this nucleoid-structuring protein in ompW expression. Also, ΔhnsΔstpA double mutants simultaneously lacking H-NS and its paralog StpA showed more severe reductions in ompW expression at 37 °C, resulting in the complete loss of OmpW. The overall results indicate that OmpW contents in E. coli are regulated by both temperature and H-NS and reinforce OmpW functions in bacterial adaptation to warm-blooded hosts.
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Affiliation(s)
- Luciano Brambilla
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET) and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, Argentina
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Valade E, Davin-Regli A, Bolla JM, Pagès JM. Bacterial Membrane, a Key for Controlling Drug Influx and Efflux. Antibiotics (Basel) 2013. [DOI: 10.1002/9783527659685.ch9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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32
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Rumbo-Feal S, Gómez MJ, Gayoso C, Álvarez-Fraga L, Cabral MP, Aransay AM, Rodríguez-Ezpeleta N, Fullaondo A, Valle J, Tomás M, Bou G, Poza M. Whole transcriptome analysis of Acinetobacter baumannii assessed by RNA-sequencing reveals different mRNA expression profiles in biofilm compared to planktonic cells. PLoS One 2013; 8:e72968. [PMID: 24023660 PMCID: PMC3758355 DOI: 10.1371/journal.pone.0072968] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/15/2013] [Indexed: 11/18/2022] Open
Abstract
Acinetobacterbaumannii has emerged as a dangerous opportunistic pathogen, with many strains able to form biofilms and thus cause persistent infections. The aim of the present study was to use high-throughput sequencing techniques to establish complete transcriptome profiles of planktonic (free-living) and sessile (biofilm) forms of A. baumannii ATCC 17978 and thereby identify differences in their gene expression patterns. Collections of mRNA from planktonic (both exponential and stationary phase cultures) and sessile (biofilm) cells were sequenced. Six mRNA libraries were prepared following the mRNA-Seq protocols from Illumina. Reads were obtained in a HiScanSQ platform and mapped against the complete genome to describe the complete mRNA transcriptomes of planktonic and sessile cells. The results showed that the gene expression pattern of A. baumannii biofilm cells was distinct from that of planktonic cells, including 1621 genes over-expressed in biofilms relative to stationary phase cells and 55 genes expressed only in biofilms. These differences suggested important changes in amino acid and fatty acid metabolism, motility, active transport, DNA-methylation, iron acquisition, transcriptional regulation, and quorum sensing, among other processes. Disruption or deletion of five of these genes caused a significant decrease in biofilm formation ability in the corresponding mutant strains. Among the genes over-expressed in biofilm cells were those in an operon involved in quorum sensing. One of them, encoding an acyl carrier protein, was shown to be involved in biofilm formation as demonstrated by the significant decrease in biofilm formation by the corresponding knockout strain. The present work serves as a basis for future studies examining the complex network systems that regulate bacterial biofilm formation and maintenance.
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Affiliation(s)
- Soraya Rumbo-Feal
- Department of Microbiology, Biomedical Research Institute, University Hospital, A Coruña, Spain
| | - Manuel J. Gómez
- Department of Molecular Evolution, Center for Astrobiology, INTA-CSIC, Madrid, Spain
| | - Carmen Gayoso
- Department of Microbiology, Biomedical Research Institute, University Hospital, A Coruña, Spain
| | - Laura Álvarez-Fraga
- Department of Microbiology, Biomedical Research Institute, University Hospital, A Coruña, Spain
| | - María P. Cabral
- Department of Microbiology, Biomedical Research Institute, University Hospital, A Coruña, Spain
| | - Ana M. Aransay
- Genome Analysis Platform, CIC bioGUNE & CIBERehd, Derio, Spain
| | - Naiara Rodríguez-Ezpeleta
- Genome Analysis Platform, CIC bioGUNE & CIBERehd, Derio, Spain
- Marine Research Division, AZTI, Tecnalia, Sukarrieta, Spain
| | - Ane Fullaondo
- Genome Analysis Platform, CIC bioGUNE & CIBERehd, Derio, Spain
| | - Jaione Valle
- Department of Microbial biofilms, Agrobiotechnology Institute, Navarra, Spain
| | - María Tomás
- Department of Microbiology, Biomedical Research Institute, University Hospital, A Coruña, Spain
| | - Germán Bou
- Department of Microbiology, Biomedical Research Institute, University Hospital, A Coruña, Spain
- * E-mail: (MP); (GB)
| | - Margarita Poza
- Department of Microbiology, Biomedical Research Institute, University Hospital, A Coruña, Spain
- * E-mail: (MP); (GB)
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Moreno-Eutimio MA, Tenorio-Calvo A, Pastelin-Palacios R, Perez-Shibayama C, Gil-Cruz C, López-Santiago R, Baeza I, Fernández-Mora M, Bonifaz L, Isibasi A, Calva E, López-Macías C. Salmonella Typhi OmpS1 and OmpS2 porins are potent protective immunogens with adjuvant properties. Immunology 2013; 139:459-71. [PMID: 23432484 PMCID: PMC3719063 DOI: 10.1111/imm.12093] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 02/13/2013] [Accepted: 02/15/2013] [Indexed: 12/25/2022] Open
Abstract
Salmonella enterica serovar Typhi (S. Typhi) is the causal agent of typhoid fever, a disease that primarily affects developing countries. Various antigens from this bacterium have been reported to be targets of the immune response. Recently, the S. Typhi genome has been shown to encode two porins--OmpS1 and OmpS2--which are expressed at low levels under in vitro culture conditions. In this study, we demonstrate that immunizing mice with either OmpS1 or OmpS2 induced production of specific, long-term antibody titres and conferred protection against S. Typhi challenge; in particular, OmpS1 was more immunogenic and conferred greater protective effects than OmpS2. We also found that OmpS1 is a Toll-like receptor 4 (TLR4) agonist, whereas OmpS2 is a TLR2 and TLR4 agonist. Both porins induced the production of tumour necrosis factor and interleukin-6, and OmpS2 was also able to induce interleukin-10 production. Furthermore, OmpS1 induced the over-expression of MHC II molecules in dendritic cells and OmpS2 induced the over-expression of CD40 molecules in macrophages and dendritic cells. Co-immunization of OmpS1 or OmpS2 with ovalbumin (OVA) increased anti-OVA antibody titres, the duration and isotype diversity of the OVA-specific antibody response, and the proliferation of T lymphocytes. These porins also had adjuvant effects on the antibody response when co-immunized with either the Vi capsular antigen from S. Typhi or inactivated 2009 pandemic influenza A(H1N1) virus [A(H1N1)pdm09]. Taken together, the data indicate that OmpS1 and OmpS2, despite being expressed at low levels under in vitro culture conditions, are potent protective immunogens with intrinsic adjuvant properties.
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Affiliation(s)
- Mario A Moreno-Eutimio
- Medical Research Unit on Immunochemistry, National Medical Centre Siglo XXI, Mexican Social Security Institute (IMSS), Specialties Hospital, Mexico City, Mexico
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Adaptive and mutational resistance: role of porins and efflux pumps in drug resistance. Clin Microbiol Rev 2013; 25:661-81. [PMID: 23034325 DOI: 10.1128/cmr.00043-12] [Citation(s) in RCA: 530] [Impact Index Per Article: 48.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The substantial use of antibiotics in the clinic, combined with a dearth of new antibiotic classes, has led to a gradual increase in the resistance of bacterial pathogens to these compounds. Among the various mechanisms by which bacteria endure the action of antibiotics, those affecting influx and efflux are of particular importance, as they limit the interaction of the drug with its intracellular targets and, consequently, its deleterious effects on the cell. This review evaluates the impact of porins and efflux pumps on two major types of resistance, namely, mutational and adaptive types of resistance, both of which are regarded as key phenomena in the global rise of antibiotic resistance among pathogenic microorganisms. In particular, we explain how adaptive and mutational events can dramatically influence the outcome of antibiotic therapy by altering the mechanisms of influx and efflux of antibiotics. The identification of porins and pumps as major resistance markers has opened new possibilities for the development of novel therapeutic strategies directed specifically against these mechanisms.
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Duval V, Lister IM. MarA, SoxS and Rob of Escherichia coli - Global regulators of multidrug resistance, virulence and stress response. ACTA ACUST UNITED AC 2013; 2:101-124. [PMID: 24860636 DOI: 10.6000/1927-3037.2013.02.03.2] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Bacteria have a great capacity for adjusting their metabolism in response to environmental changes by linking extracellular stimuli to the regulation of genes by transcription factors. By working in a co-operative manner, transcription factors provide a rapid response to external threats, allowing the bacteria to survive. This review will focus on transcription factors MarA, SoxS and Rob in Escherichia coli, three members of the AraC family of proteins. These homologous proteins exemplify the ability to respond to multiple threats such as oxidative stress, drugs and toxic compounds, acidic pH, and host antimicrobial peptides. MarA, SoxS and Rob recognize similar DNA sequences in the promoter region of more than 40 regulatory target genes. As their regulons overlap, a finely tuned adaptive response allows E. coli to survive in the presence of different assaults in a co-ordinated manner. These regulators are well conserved amongst Enterobacteriaceae and due to their broad involvement in bacterial adaptation in the host, have recently been explored as targets to develop new anti-virulence agents. The regulators are also being examined for their roles in novel technologies such as biofuel production.
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Affiliation(s)
- Valérie Duval
- Center for Adaptation Genetics and Drug Resistance, Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111
| | - Ida M Lister
- Arietis Corporation, 650 Albany Street, Room 130, Boston, MA 02118
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36
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Seregina TA, Shakulov RS, Mironov AS. Butanol as a regulatory factor of ompC gene expression in E. coli cells. RUSS J GENET+ 2012. [DOI: 10.1134/s1022795412110099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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37
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Sarathy JP, Dartois V, Lee EJD. The role of transport mechanisms in mycobacterium tuberculosis drug resistance and tolerance. Pharmaceuticals (Basel) 2012; 5:1210-35. [PMID: 24281307 PMCID: PMC3816664 DOI: 10.3390/ph5111210] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 10/25/2012] [Accepted: 11/02/2012] [Indexed: 02/02/2023] Open
Abstract
In the fight against tuberculosis, cell wall permeation of chemotherapeutic agents remains a critical but largely unsolved question. Here we review the major mechanisms of small molecule penetration into and efflux from Mycobacterium tuberculosis and other mycobacteria, and outline how these mechanisms may contribute to the development of phenotypic drug tolerance and induction of drug resistance. M. tuberculosis is intrinsically recalcitrant to small molecule permeation thanks to its thick lipid-rich cell wall. Passive diffusion appears to account for only a fraction of total drug permeation. As in other bacterial species, influx of hydrophilic compounds is facilitated by water-filled open channels, or porins, spanning the cell wall. However, the diversity and density of M. tuberculosis porins appears lower than in enterobacteria. Besides, physiological adaptations brought about by unfavorable conditions are thought to reduce the efficacy of porins. While intracellular accumulation of selected drug classes supports the existence of hypothesized active drug influx transporters, efflux pumps contribute to the drug resistant phenotype through their natural abundance and diversity, as well as their highly inducible expression. Modulation of efflux transporter expression has been observed in phagocytosed, non-replicating persistent and multi-drug resistant bacilli. Altogether, M. tuberculosis has evolved both intrinsic properties and acquired mechanisms to increase its level of tolerance towards xenobiotic substances, by preventing or minimizing their entry. Understanding these adaptation mechanisms is critical to counteract the natural mechanisms of defense against toxic compounds and develop new classes of chemotherapeutic agents that positively exploit the influx and efflux pathways of mycobacteria.
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Affiliation(s)
- Jansy Passiflora Sarathy
- Novartis Institute for Tropical Diseases Pte Ltd, 10 Biopolis Road #05-01, Chromos, 138670, Singapore.
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Jindal G, Tewari R, Gautam A, Pandey SK, Rishi P. Immunological characterization of recombinant Salmonella enterica serovar Typhi FliC protein expressed in Escherichia coli. AMB Express 2012; 2:55. [PMID: 23067582 PMCID: PMC3502275 DOI: 10.1186/2191-0855-2-55] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 09/29/2012] [Indexed: 11/17/2022] Open
Abstract
Like any other enteric pathogen, Salmonella also encounters acidic stress in the stomach as well as within the host macrophage milieu. However, the pathogen is reported to combat this stress through acid tolerance response (ATR), expressing a number of genes and eventually the proteins. Recently, an acid induced outer membrane phenotype encoded by fliC gene in Salmonella enterica serovar Typhi has been identified. In the present study, fliC gene was cloned to study its biological implications. The recombinant FliC (rFliC) protein was observed to stimulate the production of antibodies. These antibodies could also recognize the FliC protein (antigen) in the clinical samples i.e. blood samples from typhoid patents as well as healthy blood samples spiked with serovar Typhi. Moreover, the rFliC also reacted with the sera from patients suffering with typhoid fever indicating its in-vivo immunogenicity. Ex-vivo study revealed that rFliC has the potential to stimulate the macrophages to generate higher levels of inflammatory mediators such as malondialdehyde (MDA) and nitrite. The inflammatory potential of FliC was also confirmed in-vivo, by the paw oedema test as well as by flicking response of the inflamed paw indicating hyperalgesia occurring during inflammatory response. The findings of the present study indicate that acid induced FliC might be one of the factors enhancing the virulence of serovar Typhi under the host acidic conditions and may prove to be helpful in designing the prophylactic measures.
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Adler M, Anjum M, Andersson DI, Sandegren L. Influence of acquired β-lactamases on the evolution of spontaneous carbapenem resistance in Escherichia coli. J Antimicrob Chemother 2012; 68:51-9. [PMID: 22977158 DOI: 10.1093/jac/dks368] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To investigate the influence of plasmid-borne β-lactamases on the evolution of spontaneous carbapenem resistance in Escherichia coli and the fitness costs associated with resistance. METHODS Stepwise selection of carbapenem-resistant mutants with or without the extended-spectrum β-lactamase (ESBL)-encoding plasmid pUUH239.2 was performed. Mutation rates and mutational pathways to resistance were determined. In vitro-selected and constructed mutants were characterized regarding the MICs of the carbapenems, porin expression profiles, growth rates and the presence of mutations in the porins ompC/ompF and their regulatory genes. The influence of the plasmid-encoded β-lactamases TEM-1, OXA-1 and CTX-M-15 on resistance development was determined. RESULTS Results show that E. coli readily developed reduced carbapenem susceptibility and clinical resistance levels by a combination of porin loss and increased β-lactamase expression, especially towards ertapenem. All tested β-lactamases (CTX-M-15, TEM-1 and OXA-1) contributed to reduced carbapenem susceptibility in the absence of porin expression. However, complete loss of porin expression conferred a 20% fitness cost on the bacterial growth rate. Increased β-lactamase expression through spontaneous gene amplification on the plasmid was a major resistance factor. CONCLUSIONS Plasmid-encoded β-lactamases, including non-ESBL enzymes, have a strong influence on the frequency and resistance level of spontaneous carbapenem-resistant mutants. The fitness cost associated with the loss of OmpC/OmpF in E. coli most likely reduces the survivability of porin mutants and could explain why they have not emerged as a clinical problem in this species.
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Affiliation(s)
- Marlen Adler
- Department of Medical Biochemistry and Microbiology, Uppsala University, SE-751 23 Uppsala, Sweden
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A distinct regulatory sequence is essential for the expression of a subset of nle genes in attaching and effacing Escherichia coli. J Bacteriol 2012; 194:5589-603. [PMID: 22904277 DOI: 10.1128/jb.00190-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic Escherichia coli uses a type III secretion system (T3SS), encoded in the locus of enterocyte effacement (LEE) pathogenicity island, to translocate a wide repertoire of effector proteins into the host cell in order to subvert cell signaling cascades and promote bacterial colonization and survival. Genes encoding type III-secreted effectors are located in the LEE and scattered throughout the chromosome. While LEE gene regulation is better understood, the conditions and factors involved in the expression of effectors encoded outside the LEE are just starting to be elucidated. Here, we identified a highly conserved sequence containing a 13-bp inverted repeat (IR), located upstream of a subset of genes coding for different non-LEE-encoded effectors in A/E pathogens. Site-directed mutagenesis and deletion analysis of the nleH1 and nleB2 regulatory regions revealed that this IR is essential for the transcriptional activation of both genes. Growth conditions that favor the expression of LEE genes also facilitate the activation of nleH1 and nleB2; however, their expression is independent of the LEE-encoded positive regulators Ler and GrlA but is repressed by GrlR and the global regulator H-NS. In contrast, GrlA and Ler are required for nleA expression, while H-NS silences it. Consistent with their role in the regulation of nleA, purified Ler and H-NS bound to the regulatory region of nleA upstream of its promoter. This work shows that at least two modes of regulation control the expression of effector genes in attaching and effacing (A/E) pathogens, suggesting that a subset of effector functions may be coordinately expressed in a particular niche or time during infection.
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Martínez-Gómez K, Flores N, Castañeda HM, Martínez-Batallar G, Hernández-Chávez G, Ramírez OT, Gosset G, Encarnación S, Bolivar F. New insights into Escherichia coli metabolism: carbon scavenging, acetate metabolism and carbon recycling responses during growth on glycerol. Microb Cell Fact 2012; 11:46. [PMID: 22513097 PMCID: PMC3390287 DOI: 10.1186/1475-2859-11-46] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 04/18/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Glycerol has enhanced its biotechnological importance since it is a byproduct of biodiesel synthesis. A study of Escherichia coli physiology during growth on glycerol was performed combining transcriptional-proteomic analysis as well as kinetic and stoichiometric evaluations in the strain JM101 and certain derivatives with important inactivated genes. RESULTS Transcriptional and proteomic analysis of metabolic central genes of strain JM101 growing on glycerol, revealed important changes not only in the synthesis of MglB, LamB and MalE proteins, but also in the overexpression of carbon scavenging genes: lamB, malE, mglB, mglC, galP and glk and some members of the RpoS regulon (pfkA, pfkB, fbaA, fbaB, pgi, poxB, acs, actP and acnA). Inactivation of rpoS had an important effect on stoichiometric parameters and growth adaptation on glycerol. The observed overexpression of poxB, pta, acs genes, glyoxylate shunt genes (aceA, aceB, glcB and glcC) and actP, suggested a possible carbon flux deviation into the PoxB, Acs and glyoxylate shunt. In this scenario acetate synthesized from pyruvate with PoxB was apparently reutilized via Acs and the glyoxylate shunt enzymes. In agreement, no acetate was detected when growing on glycerol, this strain was also capable of glycerol and acetate coutilization when growing in mineral media and derivatives carrying inactivated poxB or pckA genes, accumulated acetate. Tryptophanase A (TnaA) was synthesized at high levels and indole was produced by this enzyme, in strain JM101 growing on glycerol. Additionally, in the isogenic derivative with the inactivated tnaA gene, no indole was detected and acetate and lactate were accumulated. A high efficiency aromatic compounds production capability was detected in JM101 carrying pJLBaroG(fbr)tktA, when growing on glycerol, as compared to glucose. CONCLUSIONS The overexpression of several carbon scavenging, acetate metabolism genes and the absence of acetate accumulation occurred in JM101 cultures growing on glycerol. To explain these results it is proposed that in addition to the glycolytic metabolism, a gluconeogenic carbon recycling process that involves acetate is occurring simultaneously in this strain when growing on glycerol. Carbon flux from glycerol can be efficiently redirected in JM101 strain into the aromatic pathway using appropriate tools.
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Affiliation(s)
- Karla Martínez-Gómez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 510-3, Cuernavaca, Morelos, CP 62250, Mexico
| | - Noemí Flores
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 510-3, Cuernavaca, Morelos, CP 62250, Mexico
| | - Héctor M Castañeda
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 510-3, Cuernavaca, Morelos, CP 62250, Mexico
| | - Gabriel Martínez-Batallar
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 565-A, Cuernavaca, Morelos, CP 62210, Mexico
| | - Georgina Hernández-Chávez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 510-3, Cuernavaca, Morelos, CP 62250, Mexico
| | - Octavio T Ramírez
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 510-3, Cuernavaca, Morelos, CP 62250, Mexico
| | - Guillermo Gosset
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 510-3, Cuernavaca, Morelos, CP 62250, Mexico
| | - Sergio Encarnación
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 565-A, Cuernavaca, Morelos, CP 62210, Mexico
| | - Francisco Bolivar
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 510-3, Cuernavaca, Morelos, CP 62250, Mexico
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The TonB3 system in the human pathogen Vibrio vulnificus is under the control of the global regulators Lrp and cyclic AMP receptor protein. J Bacteriol 2012; 194:1897-911. [PMID: 22307757 DOI: 10.1128/jb.06614-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
TonB systems transduce the proton motive force of the cytoplasmic membrane to energize substrate transport through a specific TonB-dependent transporter across the outer membrane. Vibrio vulnificus, an opportunistic marine pathogen that can cause a fatal septicemic disease in humans and eels, possesses three TonB systems. While the TonB1 and TonB2 systems are iron regulated, the TonB3 system is induced when the bacterium grows in human serum. In this work we have determined the essential roles of the leucine-responsive protein (Lrp) and cyclic AMP (cAMP) receptor protein (CRP) in the transcriptional activation of this system. Whereas Lrp shows at least four very distinctive DNA binding regions spread out from position -59 to -509, cAMP-CRP binds exclusively in a region centered at position -122.5 from the start point of the transcription. Our results suggest that both proteins bind simultaneously to the region closer to the RNA polymerase binding site. Importantly, we report that the TonB3 system is induced not only by serum but also during growth in minimal medium with glycerol as the sole carbon source and low concentrations of Casamino Acids. In addition to catabolite repression by glucose, l-leucine acts by inhibiting the binding of Lrp to the promoter region, hence preventing transcription of the TonB3 operon. Thus, this TonB system is under the direct control of two global regulators that can integrate different environmental signals (i.e., glucose starvation and the transition between "feast" and "famine"). These results shed light on new mechanisms of regulation for a TonB system that could be widespread in other organisms.
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McQuillan JS, Groenaga Infante H, Stokes E, Shaw AM. Silver nanoparticle enhanced silver ion stress response inEscherichia coliK12. Nanotoxicology 2011; 6:857-66. [DOI: 10.3109/17435390.2011.626532] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Expression of OmpATb is dependent on small membrane proteins in Mycobacterium bovis BCG. Tuberculosis (Edinb) 2011; 91:544-8. [PMID: 21802366 DOI: 10.1016/j.tube.2011.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/26/2011] [Accepted: 06/22/2011] [Indexed: 11/21/2022]
Abstract
Small membrane proteins emerge as a novel class of regulatory molecules in bacteria. Experiments carried out in Mycobacterium bovis BCG indicate that the ompATb gene (Rv0899), encoding a major outer membrane protein, is organized in operon with Rv0900 and Rv0901, encoding two small proteins with a predicted transmembrane domain. Fractioning experiment confirmed the association of Rv0901 with the membrane fraction. To investigate the role of Rv0900 and Rv0901 in M. bovis BCG, we have constructed a strain deleted for the whole operon as well as complemented strains carrying a deletion of Rv0900 or a frameshift mutation in either Rv0900 or Rv0901. Importantly, mutations in Rv0900 and/or Rv0901 strongly altered OmpATb expression, demonstrating that Rv0900 and Rv0901 play a regulatory role, which appears to occur at a post-transcriptional level.
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Chubiz LM, Rao CV. Role of the mar-sox-rob regulon in regulating outer membrane porin expression. J Bacteriol 2011; 193:2252-60. [PMID: 21398557 PMCID: PMC3133058 DOI: 10.1128/jb.01382-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 02/27/2011] [Indexed: 11/20/2022] Open
Abstract
Multiple factors control the expression of the outer membrane porins OmpF and OmpC in Escherichia coli. In this work, we investigated the role of the mar-sox-rob regulon in regulating outer membrane porin expression in response to salicylate. We provide both genetic and physiological evidence that MarA and Rob can independently activate micF transcription in response to salicylate, leading to reduced OmpF expression. MarA was also found to repress OmpF expression through a MicF-independent pathway. In the case of OmpC, we found that its transcription was moderately increased in response to salicylate. However, this increase was independent of MarA and Rob. Finally, we found that the reduction in OmpF expression in a tolC mutant is due primarily to Rob. Collectively, this work further clarifies the coordinated role of MarA and Rob in regulating the expression of the outer membrane porins.
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Affiliation(s)
| | - Christopher V. Rao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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Calderón IL, Morales E, Caro NJ, Chahúan CA, Collao B, Gil F, Villarreal JM, Ipinza F, Mora GC, Saavedra CP. Response regulator ArcA of Salmonella enterica serovar Typhimurium downregulates expression of OmpD, a porin facilitating uptake of hydrogen peroxide. Res Microbiol 2011; 162:214-22. [DOI: 10.1016/j.resmic.2010.11.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 10/01/2010] [Indexed: 11/30/2022]
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