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Willett JLE, Barnes AMT, Brunson DN, Lecomte A, Robertson EB, Dunny GM. Optimized Replication of Arrayed Bacterial Mutant Libraries Increases Access to Biological Resources. Microbiol Spectr 2023; 11:e0169323. [PMID: 37432110 PMCID: PMC10434011 DOI: 10.1128/spectrum.01693-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 06/19/2023] [Indexed: 07/12/2023] Open
Abstract
Biological collections, including arrayed libraries of single transposon (Tn) or deletion mutants, greatly accelerate the pace of bacterial genetic research. Despite the importance of these resources, few protocols exist for the replication and distribution of these materials. Here, we describe a protocol for creating multiple replicates of an arrayed bacterial Tn library consisting of approximately 6,800 mutants in 96-well plates (73 plates). Our protocol provides multiple checkpoints to guard against contamination and minimize genetic drift caused by freeze/thaw cycles. This approach can also be scaled for arrayed culture collections of various sizes. Overall, this protocol is a valuable resource for other researchers considering the construction and distribution of arrayed culture collection resources for the benefit of the greater scientific community. IMPORTANCE Arrayed mutant collections drive robust genetic screens, but few protocols exist for replication of these resources and subsequent quality control. Increasing the distribution of arrayed biological collections will increase the accessibility and use of these resources. Developing standardized techniques for replication of these resources is essential for ensuring their quality and usefulness to the scientific community.
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Affiliation(s)
- Julia L. E. Willett
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Aaron M. T. Barnes
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Debra N. Brunson
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Alexandre Lecomte
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Ethan B. Robertson
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Gary M. Dunny
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
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Willett JLE, Barnes AMT, Brunson DN, Lecomte A, Robertson EB, Dunny GM. Optimized replication of arrayed bacterial mutant libraries increase access to biological resources. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.25.537918. [PMID: 37162974 PMCID: PMC10168237 DOI: 10.1101/2023.04.25.537918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Biological collections, including arrayed libraries of single transposon or deletion mutants, greatly accelerate the pace of bacterial genetics research. Despite the importance of these resources, few protocols exist for the replication and distribution of these materials. Here, we describe a protocol for creating multiple replicates of an arrayed bacterial Tn library consisting of approximately 6,800 mutants in 73 × 96-well plates. Our protocol provides multiple checkpoints to guard against contamination and minimize genetic drift caused by freeze/thaw cycles. This approach can also be scaled for arrayed culture collections of various sizes. Overall, this protocol is a valuable resource for other researchers considering the construction and distribution of arrayed culture collection resources for the benefit of the greater scientific community. Importance Arrayed mutant collections drive robust genetic screens, yet few protocols exist for replication of these resources and subsequent quality control. Increasing distribution of arrayed biological collections will increase accessibility to and use of these resources. Developing standardized techniques for replication of these resources is essential for ensuring their quality and usefulness to the scientific community.
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Affiliation(s)
- Julia L. E. Willett
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN USA
| | - Aaron M. T. Barnes
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN USA
- Present address: Minnesota Department of Health, MN, USA
| | - Debra N. Brunson
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL USA
| | - Alexandre Lecomte
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Ethan B. Robertson
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN USA
| | - Gary M. Dunny
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN USA
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3
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Construction and Activity Testing of a Modular Fusion Peptide against Enterococcus faecalis. Antibiotics (Basel) 2023; 12:antibiotics12020388. [PMID: 36830298 PMCID: PMC9951850 DOI: 10.3390/antibiotics12020388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/08/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
The emergence of antibiotic resistance in enterococci is a great concern encountered worldwide. Almost all enterococci exhibit significant levels of resistance to penicillin, ampicillin, semi-synthetic penicillin and most cephalosporins, primarily due to the expression of low-affinity penicillin-binding proteins. The development of new and novel antibacterial agents against enterococci is a significant need of the hour. In this research, we have constructed a modular peptide against Enterococcus faecalis. The enzymatic domain of the constructed peptide BP404 is from the bacteriocin BacL1 and the cell wall binding domain from endolysin PlyV12 of phage ϕ1. The protein BP404 was found to be active against two tested strains of Enterococcus faecalis, with a reduction in cell density amounting to 85% and 65%. The cell wall binding assay confirms the binding of the protein to Enterococcus faecalis, which was not seen towards the control strain Escherichia coli, invariably pointing to the specificity of BP404. To the best of our knowledge, this is one of the first instances of the development of a chimeric peptide against Enterococcus faecalis. This study points out that novel proteins can be genetically engineered against clinically relevant enterococci.
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Schaffer SD, Hutchison CA, Rouchon CN, Mdluli NV, Weinstein AJ, McDaniel D, Frank KL. Diverse Enterococcus faecalis strains show heterogeneity in biofilm properties. Res Microbiol 2023; 174:103986. [PMID: 35995340 PMCID: PMC9825631 DOI: 10.1016/j.resmic.2022.103986] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/02/2022] [Accepted: 08/03/2022] [Indexed: 01/11/2023]
Abstract
Biofilm formation is important for Enterococcus faecalis to cause healthcare-associated infections. It is unclear how E. faecalis biofilms vary in parameters such as development and composition. To test the hypothesis that differences in biofilms exist among E. faecalis strains, we evaluated in vitro biofilm formation and matrix characteristics of five genetically diverse E. faecalis lab-adapted strains and clinical isolates (OG1RF, V583, DS16, MMH594, and VA1128). Biofilm formation of all strains was repressed in TSB+10% FBS. However, DMEM+10% FBS enhanced biofilm formation of clinical isolate VA1128. Crystal violet staining and fluorescence microscopy of biofilms grown on Aclar membranes demonstrated differences between OG1RF and VA1128 in biofilm development over a 48-h time course. None of the biofilms were dispersed by single treatments of sodium (meta)periodate, DNase, or Proteinase K alone, but the biofilm biomass of both OG1RF and DS16 was partially removed by a sequential treatment of sodium (meta)periodate and DNase. Reversing the treatment order was not effective, suggesting that the extracellular DNA targeted by DNase was obscured by carbohydrates that are susceptible to sodium (meta)periodate degradation. Fluorescent staining of biofilm matrix components further demonstrated that more carbohydrates bound by wheat germ agglutinin comprise OG1RF biofilms compared to VA1128 biofilms. This study highlights the existence of heterogeneity in biofilm properties among diverse E. faecalis strains, which may have implications for the design of novel anti-biofilm treatment strategies.
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Affiliation(s)
- Scott D Schaffer
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, MD, USA
| | - Carissa A Hutchison
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, MD, USA
| | - Candace N Rouchon
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, MD, USA
| | - Nontokozo V Mdluli
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, MD, USA
| | - Arielle J Weinstein
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, MD, USA
| | - Dennis McDaniel
- Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Kristi L Frank
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
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A previously uncharacterized gene, PA2146, contributes to biofilm formation and drug tolerance across the ɣ-Proteobacteria. NPJ Biofilms Microbiomes 2022; 8:54. [PMID: 35798749 PMCID: PMC9262955 DOI: 10.1038/s41522-022-00314-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 06/14/2022] [Indexed: 01/11/2023] Open
Abstract
Transcriptomic studies have revealed a large number of uncharacterized genes that are differentially expressed in biofilms, which may be important in regulating biofilm phenotypes such as resistance to antimicrobial agents. To identify biofilm genes of unknown function in P. aeruginosa, we made use of RNA-seq and selected 27 uncharacterized genes that were induced upon biofilm growth. Biofilms by respective mutants were subsequently analyzed for two biofilm characteristics, the biofilm architecture and drug susceptibility. The screen revealed 12 out of 27 genes to contribute to biofilm formation and 13 drug susceptibility, with 8 genes affecting both biofilm phenotypes. Amongst the genes affecting both biofilm phenotypes was PA2146, encoding a small hypothetical protein that exhibited some of the most substantial increases in transcript abundance during biofilm growth by P. aeruginosa PAO1 and clinical isolates. PA2146 is highly conserved in ɣ-proteobacteria. Inactivation of PA2146 affected both biofilm phenotypes in P. aeruginosa PAO1, with inactivation of homologs in Klebsiella pneumoniae and Escherichia coli having similar effects. Heterologous expression of PA2146 homologs complemented the P. aeruginosa ∆PA2146, suggesting that PA2146 homologs substitute for and play a similar role as PA2146 in P. aeruginosa.
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Li Y, Sun W, Wang Q, Yu Y, Wan Y, Zhou K, Guo R, Han X, Chen Z, Fang W, Jiang W. The GntR-like transcriptional regulator HutC involved in motility, biofilm-forming ability, and virulence in Vibrio parahaemolyticus. Microb Pathog 2022; 167:105546. [DOI: 10.1016/j.micpath.2022.105546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 06/12/2021] [Accepted: 04/15/2022] [Indexed: 12/19/2022]
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Barnes AMT, Frank KL, Dunny GM. Enterococcal Endocarditis: Hiding in Plain Sight. Front Cell Infect Microbiol 2021; 11:722482. [PMID: 34527603 PMCID: PMC8435889 DOI: 10.3389/fcimb.2021.722482] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/09/2021] [Indexed: 12/12/2022] Open
Abstract
Enterococcus faecalis is a major opportunistic bacterial pathogen of increasing clinical relevance. A substantial body of experimental evidence suggests that early biofilm formation plays a critical role in these infections, as well as in colonization and persistence in the GI tract as a commensal member of the microbiome in most terrestrial animals. Animal models of experimental endocarditis generally involve inducing mechanical valve damage by cardiac catheterization prior to infection, and it has long been presumed that endocarditis vegetation formation resulting from bacterial attachment to the endocardial endothelium requires some pre-existing tissue damage. Here we review both historical and contemporary animal model studies demonstrating the robust ability of E. faecalis to directly attach and form stable microcolony biofilms encased within a bacterially-derived extracellular matrix on the undamaged endovascular endothelial surface. We also discuss the morphological similarities when these biofilms form on other host tissues, including when E. faecalis colonizes the GI epithelium as a commensal member of the normal vertebrate microbiome - hiding in plain sight where it can serve as a source for systemic infection via translocation. We propose that these phenotypes may allow the organism to persist as an undetected infection in asymptomatic individuals and thus provide an infectious reservoir for later clinical endocarditis.
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Affiliation(s)
- Aaron M. T. Barnes
- Department of Microbiology and Immunology, University of Minnesota School of Medicine, Minneapolis, MN, United States
- Department of Laboratory Medicine and Pathology, University of Minnesota School of Medicine, Minneapolis, MN, United States
| | - Kristi L. Frank
- Department of Microbiology and Immunology, University of Minnesota School of Medicine, Minneapolis, MN, United States
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Gary M. Dunny
- Department of Microbiology and Immunology, University of Minnesota School of Medicine, Minneapolis, MN, United States
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Agius JE, Phalen DN, Rose K, Eden JS. Genomic Insights Into the Pathogenicity of a Novel Biofilm-Forming Enterococcus sp. Bacteria ( Enterococcus lacertideformus) Identified in Reptiles. Front Microbiol 2021; 12:635208. [PMID: 33737921 PMCID: PMC7960928 DOI: 10.3389/fmicb.2021.635208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/09/2021] [Indexed: 11/23/2022] Open
Abstract
Whole genome analysis of a novel species of enterococci, Enterococcus lacertideformus, causing multi-systemic and invariably fatal disease in critically endangered Christmas Island reptiles was undertaken to determine the genetic elements and potential mechanisms conferring its pathogenic nature, biofilm-forming capabilities, immune recognition avoidance, and inability to grow in vitro. Comparative genomic analyses with related and clinically significant enterococci were further undertaken to infer the evolutionary history of the bacterium and identify genes both novel and absent. The genome had a G + C content of 35.1%, consisted of a circular chromosome, no plasmids, and was 2,419,934 bp in length (2,321 genes, 47 tRNAs, and 13 rRNAs). Multi-locus sequence typing (MLST), and single nucleotide polymorphism (SNP) analysis of multiple E. lacertideformus samples revealed they were effectively indistinguishable from one another and highly clonal. E. lacertideformus was found to be located within the Enterococcus faecium species clade and was closely related to Enterococcus villorum F1129D based on 16S rDNA and MLST house-keeping gene analysis. Antimicrobial resistance (DfreE, EfrB, tetM, bcrRABD, and sat4) and virulence genes (Fss3 and ClpP), and genes conferring tolerance to metals and biocides (n = 9) were identified. The detection of relatively few genes encoding antimicrobial resistance and virulence indicates that this bacterium may have had no exposure to recently developed and clinically significant antibiotics. Genes potentially imparting beneficial functional properties were identified, including prophages, insertion elements, integrative conjugative elements, and genomic islands. Functional CRISPR-Cas arrays, and a defective prophage region were identified in the genome. The study also revealed many genomic loci unique to E. lacertideformus which contained genes enriched in cell wall/membrane/envelop biogenesis, and carbohydrate metabolism and transport functionality. This finding and the detection of putative enterococcal biofilm determinants (EfaAfs, srtC, and scm) may underpin the novel biofilm phenotype observed for this bacterium. Comparative analysis of E. lacertideformus with phylogenetically related and clinically significant enterococci (E. villorum F1129D, Enterococcus hirae R17, E. faecium AUS0085, and Enterococcus faecalis OG1RF) revealed an absence of genes (n = 54) in E. lacertideformus, that encode metabolic functionality, which potentially hinders nutrient acquisition and/or utilization by the bacterium and precludes growth in vitro. These data provide genetic insights into the previously determined phenotype and pathogenic nature of the bacterium.
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Affiliation(s)
- Jessica Esther Agius
- Faculty of Science, Sydney School of Veterinary Science, University of Sydney, Camden, NSW, Australia
| | - David Norton Phalen
- Faculty of Science, Sydney School of Veterinary Science, University of Sydney, Camden, NSW, Australia.,Schubot Exotic Bird Health Center, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Karrie Rose
- Australian Registry of Wildlife Health, Taronga Conservation Society Australia, Mosman, NSW, Australia
| | - John-Sebastian Eden
- Centre for Virus Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia.,Marie Bashir Institute for Infectious Diseases and Biosecurity, Faculty of Medicine and Health, Sydney School of Medicine, University of Sydney, Camperdown, NSW, Australia
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Exploiting biofilm phenotypes for functional characterization of hypothetical genes in Enterococcus faecalis. NPJ Biofilms Microbiomes 2019; 5:23. [PMID: 31552139 PMCID: PMC6753144 DOI: 10.1038/s41522-019-0099-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 08/21/2019] [Indexed: 12/12/2022] Open
Abstract
Enterococcus faecalis is a commensal organism as well as an important nosocomial pathogen, and its infections are typically linked to biofilm formation. Nearly 25% of the E. faecalis OG1RF genome encodes hypothetical genes or genes of unknown function. Elucidating their function and how these gene products influence biofilm formation is critical for understanding E. faecalis biology. To identify uncharacterized early biofilm determinants, we performed a genetic screen using an arrayed transposon (Tn) library containing ~2000 mutants in hypothetical genes/intergenic regions and identified eight uncharacterized predicted protein-coding genes required for biofilm formation. We demonstrate that OG1RF_10435 encodes a phosphatase that modulates global protein expression and arginine catabolism and propose renaming this gene bph (biofilm phosphatase). We present a workflow for combining phenotype-driven experimental and computational evaluation of hypothetical gene products in E. faecalis, which can be used to study hypothetical genes required for biofilm formation and other phenotypes of diverse bacteria.
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Banla LI, Salzman NH, Kristich CJ. Colonization of the mammalian intestinal tract by enterococci. Curr Opin Microbiol 2018; 47:26-31. [PMID: 30439685 DOI: 10.1016/j.mib.2018.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/08/2018] [Accepted: 10/16/2018] [Indexed: 02/08/2023]
Abstract
Enterococci are colonizers of the mammalian gastrointestinal tract (GIT) and normally live in healthy association with their human host. However, enterococci are also major causes of healthcare-acquired infections, prompting the US Centers for Disease Control and Prevention to declare vancomycin-resistant enterococci (VRE) a serious threat to public health. Because of both intrinsic and acquired antibiotic resistance, enterococci proliferate in the GIT during antibiotic therapy, leading to dissemination and disease. The recognition that colonization of the GIT is a pre-requisite for enterococcal infections has prompted research to study mechanisms used by enterococci to colonize this niche. This review discusses major findings of recent research to understand GIT colonization by enterococci using diverse experimental models, each of which exhibits unique strengths. This work has revealed enterococcal transcriptional reprogramming in the GIT, contributions of specific enterococcal genes encoded by the core genome to GIT colonization, the impact of genome plasticity, and roles for intra-species and inter-species interactions in modulation of GIT colonization.
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Affiliation(s)
- Leou Ismael Banla
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Nita H Salzman
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States.
| | - Christopher J Kristich
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.
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Comprehensive Functional Analysis of the Enterococcus faecalis Core Genome Using an Ordered, Sequence-Defined Collection of Insertional Mutations in Strain OG1RF. mSystems 2018; 3:mSystems00062-18. [PMID: 30225373 PMCID: PMC6134198 DOI: 10.1128/msystems.00062-18] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/03/2018] [Indexed: 12/14/2022] Open
Abstract
The robust ability of Enterococcus faecalis to survive outside the host and to spread via oral-fecal transmission and its high degree of intrinsic and acquired antimicrobial resistance all complicate the treatment of hospital-acquired enterococcal infections. The conserved E. faecalis core genome serves as an important genetic scaffold for evolution of this bacterium in the modern health care setting and also provides interesting vaccine and drug targets. We used an innovative pooling/sequencing strategy to map a large collection of arrayed transposon insertions in E. faecalis OG1RF and generated an arrayed library of defined mutants covering approximately 70% of the OG1RF genome. Then, we performed high-throughput transposon sequencing experiments using this library to determine core genomic determinants of bile resistance in OG1RF. This collection is a valuable resource for comprehensive, functional enterococcal genomics using both traditional and high-throughput approaches and enables immediate recovery of mutants of interest. Enterococcus faecalis is a common commensal bacterium in animal gastrointestinal (GI) tracts and a leading cause of opportunistic infections of humans in the modern health care setting. E. faecalis OG1RF is a plasmid-free strain that contains few mobile elements yet retains the robust survival characteristics, intrinsic antibiotic resistance, and virulence traits characteristic of most E. faecalis genotypes. To facilitate interrogation of the core enterococcal genetic determinants for competitive fitness in the GI tract, biofilm formation, intrinsic antimicrobial resistance, and survival in the environment, we generated an arrayed, sequence-defined set of chromosomal transposon insertions in OG1RF. We used an orthogonal pooling strategy in conjunction with Illumina sequencing to identify a set of mutants with unique, single Himar-based transposon insertions. The mutants contained insertions in 1,926 of 2,651 (72.6%) annotated open reading frames and in the majority of hypothetical protein-encoding genes and intergenic regions greater than 100 bp in length, which could encode small RNAs. As proof of principle of the usefulness of this arrayed transposon library, we created a minimal input pool containing 6,829 mutants chosen for maximal genomic coverage and used an approach that we term SMarT (sequence-defined marinertechnology) transposon sequencing (TnSeq) to identify numerous genetic determinants of bile resistance in E. faecalis OG1RF. These included several genes previously associated with bile acid resistance as well as new loci. Our arrayed library allows functional screening of a large percentage of the genome with a relatively small number of mutants, reducing potential effects of bottlenecking, and enables immediate recovery of mutants following competitions. IMPORTANCE The robust ability of Enterococcus faecalis to survive outside the host and to spread via oral-fecal transmission and its high degree of intrinsic and acquired antimicrobial resistance all complicate the treatment of hospital-acquired enterococcal infections. The conserved E. faecalis core genome serves as an important genetic scaffold for evolution of this bacterium in the modern health care setting and also provides interesting vaccine and drug targets. We used an innovative pooling/sequencing strategy to map a large collection of arrayed transposon insertions in E. faecalis OG1RF and generated an arrayed library of defined mutants covering approximately 70% of the OG1RF genome. Then, we performed high-throughput transposon sequencing experiments using this library to determine core genomic determinants of bile resistance in OG1RF. This collection is a valuable resource for comprehensive, functional enterococcal genomics using both traditional and high-throughput approaches and enables immediate recovery of mutants of interest.
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Hua R, Xia Y, Wu W, Yan J, Yang M. Whole transcriptome analysis reveals potential novel mechanisms of low-level linezolid resistance in Enterococcus faecalis. Gene 2018; 647:143-149. [DOI: 10.1016/j.gene.2018.01.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 01/01/2018] [Accepted: 01/02/2018] [Indexed: 11/26/2022]
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13
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Favre L, Ortalo-Magné A, Pichereaux C, Gargaros A, Burlet-Schiltz O, Cotelle V, Culioli G. Metabolome and proteome changes between biofilm and planktonic phenotypes of the marine bacterium Pseudoalteromonas lipolytica TC8. BIOFOULING 2018; 34:132-148. [PMID: 29319346 DOI: 10.1080/08927014.2017.1413551] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 11/29/2017] [Indexed: 06/07/2023]
Abstract
A number of bacteria adopt various lifestyles such as planktonic free-living or sessile biofilm stages. This enables their survival and development in a wide range of contrasting environments. With the aim of highlighting specific metabolic shifts between these phenotypes and to improve the overall understanding of marine bacterial adhesion, a dual metabolomics/proteomics approach was applied to planktonic and biofilm cultures of the marine bacterium Pseudoalteromonas lipolytica TC8. The liquid chromatography mass spectrometry (LC-MS) based metabolomics study indicated that membrane lipid composition was highly affected by the culture mode: phosphatidylethanolamine (PEs) derivatives were over-produced in sessile cultures while ornithine lipids (OLs) were more specifically synthesized in planktonic samples. In parallel, differences between proteomes revealed that peptidases, oxidases, transcription factors, membrane proteins and the enzymes involved in histidine biosynthesis were over-expressed in biofilms while proteins involved in heme production, nutrient assimilation, cell division and arginine/ornithine biosynthesis were specifically up-regulated in free-living cells.
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Affiliation(s)
- Laurie Favre
- a MAPIEM EA 4323 , Université de Toulon , Toulon , France
| | | | - Carole Pichereaux
- b Fédération de Recherche FR3450 , CNRS , Toulouse , France
- c Institut de Pharmacologie et de Biologie Structurale, IPBS , Université de Toulouse, CNRS, UPS , Toulouse , France
| | - Audrey Gargaros
- c Institut de Pharmacologie et de Biologie Structurale, IPBS , Université de Toulouse, CNRS, UPS , Toulouse , France
| | - Odile Burlet-Schiltz
- c Institut de Pharmacologie et de Biologie Structurale, IPBS , Université de Toulouse, CNRS, UPS , Toulouse , France
| | - Valérie Cotelle
- d Laboratoire de Recherche en Sciences Végétales , Université de Toulouse, CNRS, UPS , Castanet-Tolosan , France
| | - Gérald Culioli
- a MAPIEM EA 4323 , Université de Toulon , Toulon , France
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14
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Saavedra JT, Schwartzman JA, Gilmore MS. Mapping Transposon Insertions in Bacterial Genomes by Arbitrarily Primed PCR. CURRENT PROTOCOLS IN MOLECULAR BIOLOGY 2017; 118:15.15.1-15.15.15. [PMID: 28369678 PMCID: PMC5679462 DOI: 10.1002/cpmb.38] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Transposons can be used to easily generate and label the location of mutations throughout bacterial and other genomes. Transposon insertion mutants may be screened for a phenotype as individual isolates, or by selection applied to a pool of thousands of mutants. Identifying the location of a transposon insertion is critical for connecting phenotype to the genetic lesion. In this unit, we present an easy and detailed approach for mapping transposon insertion sites using arbitrarily-primed PCR (AP-PCR). Two rounds of PCR are used to (1) amplify DNA spanning the transposon insertion junction, and (2) increase the specific yield of transposon insertion junction fragments for sequence analysis. The resulting sequence is mapped to a bacterial genome to identify the site of transposon insertion. In this protocol, AP-PCR as it is routinely used to map sites of transposon insertion within Staphylococcus aureus, is used to illustrate the principle. Guidelines are provided for adapting this protocol for mapping insertions in other bacterial genomes. Mapping transposon insertions using this method is typically achieved in 2 to 3 days if starting from a culture of the transposon insertion mutant. © 2017 by John Wiley & Sons, Inc.
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Affiliation(s)
- José T Saavedra
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
| | - Julia A Schwartzman
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
- Department of Ophthalmology, and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts
- The Broad Institute, Cambridge, Massachusetts
| | - Michael S Gilmore
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
- Department of Ophthalmology, and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts
- The Broad Institute, Cambridge, Massachusetts
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15
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Saffari F, Dalfardi MS, Mansouri S, Ahmadrajabi R. Survey for Correlation between Biofilm Formation and Virulence Determinants in a Collection of Pathogenic and Fecal Enterococcus faecalis Isolates. Infect Chemother 2017; 49:176-183. [PMID: 29027384 PMCID: PMC5620384 DOI: 10.3947/ic.2017.49.3.176] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 06/15/2017] [Indexed: 11/24/2022] Open
Abstract
Background Enterococcus faecalis is an opportunistic pathogen that causes most of the enterococcal infections. Among the different factors implicated in the pathogenesis of these organisms, biofilm formation and antibiotic resistance are the most important. The ability for biofilm formation has been attributed to the presence of some virulence genes. However, no definite correlation has been found. This study aimed to detect biofilm formation and antibiotic resistance patterns in E. faecalis isolates collected from clinical and fecal samples, and to investigate possible correlation between some virulence genes (esp, cyl, gelE) and biofilm formation. Materials and Methods A collection of 123 E. faecalis isolates were investigated for antibiotic resistance and production of hemolysin, gelatinase, and biofilm using phenotypic methods. The esp, gelE and cyl genes were detected using polymerase chain reaction. Results Thirty-eight pathogenic isolates (37%) were positive for biofilm formation. Additionally, the gelE, esp, and cyl genes were detected in 74 (71.8%), 79 (76.7%) and 42 (40.8%) isolates, respectively. In the fecal samples, 18 (90%) isolates were biofilm producers and 11 (55%), 17 (85%) and 8 (40%) isolates were positive for gelE, esp, and cyl, respectively. There were significant differences in biofilm production between pathogenic and fecal isolates (P <0.001). Multidrug resistance (MDR) was found among 32% (n = 33) and 15% (n = 3) of the clinical and fecal isolates, respectively. However, no significant difference was seen between MDR and biofilm formation. Five pathogenic and two fecal isolates were negative for all investigated genes while they were they were biofilm producers. In contrast, 22 pathogenic isolates and 1 fecal isolate were positive for the tested genes, but did not form any biofilm. No significant differences were observed between biofilm formation and the presence of the esp, gelE and cyl genes in the pathogenic and fecal isolates (P ˃0.05). Conclusion The presence of the esp, gelE and cyl genes might not be determining factors for biofilm formation in enterococci and other mechanisms might be involved in this process.
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Affiliation(s)
- Fereshteh Saffari
- Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, Iran
| | | | - Shahla Mansouri
- Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, Iran
| | - Roya Ahmadrajabi
- Faculty of Medicine, Microbiology Section, Bam University of Medical Sciences, Bam, Iran. ,
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16
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Phenotypic and Genotypic Characterization of Bacteriocinogenic Enterococci Against Clostridium botulinum. Probiotics Antimicrob Proteins 2016; 9:182-188. [DOI: 10.1007/s12602-016-9240-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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17
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Cathro P, McCarthy P, Hoffmann P, Zilm P. Isolation and identification of Enterococcus faecalis membrane proteins using membrane shaving, 1D SDS/PAGE, and mass spectrometry. FEBS Open Bio 2016; 6:586-93. [PMID: 27419061 PMCID: PMC4887974 DOI: 10.1002/2211-5463.12075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 03/22/2016] [Accepted: 04/11/2016] [Indexed: 11/24/2022] Open
Abstract
Enterococcus faecalis is a significant nosocomial pathogen, which is able to survive in diverse environments and resist killing with antimicrobial therapies. The expression of cell membrane proteins play an important role in how bacteria respond to environmental stress. As such, the capacity to identify and study membrane protein expression is critical to our understanding of how specific proteins influence bacterial survival. Here, we describe a combined approach to identify membrane proteins of E. faecalis ATCC V583 using membranes fractionated by either 1D SDS/PAGE or membrane shaving, coupled with LC‐ESI mass spectrometry. We identified 222 membrane‐associated proteins, which represent approximately 24% of the predicted membrane‐associated proteome: 170 were isolated using 1D SDS/PAGE and 68 with membrane shaving, with 36 proteins being common to both the techniques. Of the proteins identified by membrane shaving, 97% were membrane‐associated with the majority being integral membrane proteins (89%). Most of the proteins identified with known physiology are involved with transportation across the membrane. The combined 1D SDS/PAGE and membrane shaving approach has produced the greatest number of membrane proteins identified from E. faecalis to date. These protocols will aid future researchers investigating changes in the membrane proteome of E. faecalis by improving our understanding of how E. faecalis adapts and responds to its environment.
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Affiliation(s)
- Peter Cathro
- Oral Microbiology Laboratory School of Dentistry The University of Adelaide South Australia Australia
| | - Peter McCarthy
- Neurovascular Research Laboratory Centre for Cancer Biology University of South Australia Adelaide South Australia Australia
| | - Peter Hoffmann
- Adelaide Proteomics Centre The University of Adelaide South Australia Australia
| | - Peter Zilm
- Oral Microbiology Laboratory School of Dentistry The University of Adelaide South Australia Australia
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18
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Su HZ, Wu L, Qi YH, Liu GF, Lu GT, Tang JL. Characterization of the GntR family regulator HpaR1 of the crucifer black rot pathogen Xanthomonas campestris pathovar campestris. Sci Rep 2016; 6:19862. [PMID: 26818230 PMCID: PMC4730234 DOI: 10.1038/srep19862] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 12/17/2015] [Indexed: 01/05/2023] Open
Abstract
The GntR family transcription regulator HpaR1 identified from Xanthomonas campestris pv. campestris has been previously shown to positively regulate the genes responsible for hypersensitive reaction and pathogenicity and to autorepress its own expression. Here, we demonstrated that HpaR1 is a global regulator that positively regulates diverse biological processes, including xanthan polysaccharide production, extracellular enzyme activity, cell motility and tolerance to various stresses. To investigate the regulatory mechanisms of HpaR1, we began with xanthan polysaccharide production, which is governed by a cluster of gum genes. These are directed by the gumB promoter. Disruption of HpaR1 significantly reduced gumB transcription and an electrophoretic mobility shift assay demonstrated that HpaR1 interacts directly with gumB promoter. DNase I footprint analysis revealed that HpaR1 and RNA polymerase were bound to the sequences extending from −21 to +10 and −41 to +29 relative to the transcription initiation site of gumB, respectively. Furthermore, in vitro transcription assays showed that HpaR1 facilitated the binding of RNA polymerase to gumB promoter, leading to an enhancement of its transcription. These results suggest that HpaR1 regulates gumB transcription via a mechanism similar but different to what was found, until now, to only be used by some MerR family transcription activators.
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Affiliation(s)
- Hui-Zhao Su
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Liu Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Yan-Hua Qi
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Guo-Fang Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Guang-Tao Lu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
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19
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Ruiz-Cruz S, Espinosa M, Goldmann O, Bravo A. Global Regulation of Gene Expression by the MafR Protein of Enterococcus faecalis. Front Microbiol 2016; 6:1521. [PMID: 26793169 PMCID: PMC4707282 DOI: 10.3389/fmicb.2015.01521] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/17/2015] [Indexed: 12/27/2022] Open
Abstract
Enterococcus faecalis is a natural inhabitant of the human gastrointestinal tract. However, as an opportunistic pathogen, it is able to colonize other host niches and cause life-threatening infections. Its adaptation to new environments involves global changes in gene expression. The EF3013 gene (here named mafR) of E. faecalis strain V583 encodes a protein (MafR, 482 residues) that has sequence similarity to global response regulators of the Mga/AtxA family. The enterococcal OG1RF genome also encodes the MafR protein (gene OG1RF_12293). In this work, we have identified the promoter of the mafR gene using several in vivo approaches. Moreover, we show that MafR influences positively the transcription of many genes on a genome-wide scale. The most significant target genes encode components of PTS-type membrane transporters, components of ABC-type membrane transporters, and proteins involved in the metabolism of carbon sources. Some of these genes were previously reported to be up-regulated during the growth of E. faecalis in blood and/or in human urine. Furthermore, we show that a mafR deletion mutant strain induces a significant lower degree of inflammation in the peritoneal cavity of mice, suggesting that enterococcal cells deficient in MafR are less virulent. Our work indicates that MafR is a global transcriptional regulator. It might facilitate the adaptation of E. faecalis to particular host niches and, therefore, contribute to its potential virulence.
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Affiliation(s)
- Sofía Ruiz-Cruz
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Oliver Goldmann
- Infection Immunology Research Group, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Alicia Bravo
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
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20
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Taw MN, Lee HI, Lee SH, Chang WS. Characterization of MocR, a GntR-like transcriptional regulator, in Bradyrhizobium japonicum: its impact on motility, biofilm formation, and soybean nodulation. J Microbiol 2015; 53:518-25. [PMID: 26224454 DOI: 10.1007/s12275-015-5313-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 07/15/2015] [Accepted: 07/20/2015] [Indexed: 10/23/2022]
Abstract
Bradyrhizobium japonicum is a Gram-negative soil bacterium that can fix nitrogen into ammonia by developing a symbiotic relationship with the soybean plant. MocR proteins make up a subfamily of GntR superfamily, one of the most widely distributed and prolific groups of the helix-turn-helix transcription factors. In this study, we constructed a mutant strain for mocR (blr6977) to investigate its role in cellular processes and symbiosis in B. japonicum. Although growth rate and morphology of the mutant were indistinguishable from those of the wild type, the mutant showed significant differences in motility and attachment (i.e., biofilm formation) from the wild type. The mutant displayed a decrease in biofilm formation, but was more motile than the wild type. The inactivation of mocR did not affect the number of nodules on soybean roots, but caused delayed nodulation. Delayed nodulation intrigued us to study competitiveness of the mutant infecting soybeans. The mutant was less competitive than the wild type, indicating that delayed nodulation might be due to competitiveness. Gene expressions of other MocR subfamily members were also compared between the wild type and mutant strains. None of the mocR-like genes examined in this study were differentially expressed between both strains.
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Affiliation(s)
- May Nyan Taw
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019, USA
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21
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Frank KL, Vergidis P, Brinkman CL, Greenwood Quaintance KE, Barnes AMT, Mandrekar JN, Schlievert PM, Dunny GM, Patel R. Evaluation of the Enterococcus faecalis Biofilm-Associated Virulence Factors AhrC and Eep in Rat Foreign Body Osteomyelitis and In Vitro Biofilm-Associated Antimicrobial Resistance. PLoS One 2015; 10:e0130187. [PMID: 26076451 PMCID: PMC4467866 DOI: 10.1371/journal.pone.0130187] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/18/2015] [Indexed: 02/01/2023] Open
Abstract
Enterococcus faecalis can cause healthcare-associated biofilm infections, including those of orthopedic devices. Treatment of enterococcal prosthetic joint infection is difficult, in part, due to biofilm-associated antimicrobial resistance. We previously showed that the E. faecalis OG1RF genes ahrC and eep are in vitro biofilm determinants and virulence factors in animal models of endocarditis and catheter-associated urinary tract infection. In this study, we evaluated the role of these genes in a rat acute foreign body osteomyelitis model and in in vitro biofilm-associated antimicrobial resistance. Osteomyelitis was established for one week following the implantation of stainless steel orthopedic wires inoculated with E. faecalis strains OG1RF, ΩahrC, and ∆eep into the proximal tibiae of rats. The median bacterial loads recovered from bones and wires did not differ significantly between the strains at multiple inoculum concentrations. We hypothesize that factors present at the infection site that affect biofilm formation, such as the presence or absence of shear force, may account for the differences in attenuation in the various animal models we have used to study the ΩahrC and ∆eep strains. No differences among the three strains were observed in the planktonic and biofilm antimicrobial susceptibilities to ampicillin, vancomycin, daptomycin, linezolid, and tetracycline. These findings suggest that neither ahrC nor eep directly contribute to E. faecalis biofilm-associated antimicrobial resistance. Notably, the experimental evidence that the biofilm attachment mutant ΩahrC displays biofilm-associated antimicrobial resistance suggests that surface colonization alone is sufficient for E. faecalis cells to acquire the biofilm antimicrobial resistance phenotype.
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Affiliation(s)
- Kristi L. Frank
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Paschalis Vergidis
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Cassandra L. Brinkman
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Kerryl E. Greenwood Quaintance
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Aaron M. T. Barnes
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Jayawant N. Mandrekar
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Patrick M. Schlievert
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Gary M. Dunny
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Robin Patel
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail:
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22
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Zischka M, Künne CT, Blom J, Wobser D, Sakιnç T, Schmidt-Hohagen K, Dabrowski PW, Nitsche A, Hübner J, Hain T, Chakraborty T, Linke B, Goesmann A, Voget S, Daniel R, Schomburg D, Hauck R, Hafez HM, Tielen P, Jahn D, Solheim M, Sadowy E, Larsen J, Jensen LB, Ruiz-Garbajosa P, Quiñones Pérez D, Mikalsen T, Bender J, Steglich M, Nübel U, Witte W, Werner G. Comprehensive molecular, genomic and phenotypic analysis of a major clone of Enterococcus faecalis MLST ST40. BMC Genomics 2015; 16:175. [PMID: 25887115 PMCID: PMC4374294 DOI: 10.1186/s12864-015-1367-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 02/20/2015] [Indexed: 11/28/2022] Open
Abstract
Background Enterococcus faecalis is a multifaceted microorganism known to act as a beneficial intestinal commensal bacterium. It is also a dreaded nosocomial pathogen causing life-threatening infections in hospitalised patients. Isolates of a distinct MLST type ST40 represent the most frequent strain type of this species, distributed worldwide and originating from various sources (animal, human, environmental) and different conditions (colonisation/infection). Since enterococci are known to be highly recombinogenic we determined to analyse the microevolution and niche adaptation of this highly distributed clonal type. Results We compared a set of 42 ST40 isolates by assessing key molecular determinants, performing whole genome sequencing (WGS) and a number of phenotypic assays including resistance profiling, formation of biofilm and utilisation of carbon sources. We generated the first circular closed reference genome of an E. faecalis isolate D32 of animal origin and compared it with the genomes of other reference strains. D32 was used as a template for detailed WGS comparisons of high-quality draft genomes of 14 ST40 isolates. Genomic and phylogenetic analyses suggest a high level of similarity regarding the core genome, also demonstrated by similar carbon utilisation patterns. Distribution of known and putative virulence-associated genes did not differentiate between ST40 strains from a commensal and clinical background or an animal or human source. Further analyses of mobile genetic elements (MGE) revealed genomic diversity owed to: (1) a modularly structured pathogenicity island; (2) a site-specifically integrated and previously unknown genomic island of 138 kb in two strains putatively involved in exopolysaccharide synthesis; and (3) isolate-specific plasmid and phage patterns. Moreover, we used different cell-biological and animal experiments to compare the isolate D32 with a closely related ST40 endocarditis isolate whose draft genome sequence was also generated. D32 generally showed a greater capacity of adherence to human cell lines and an increased pathogenic potential in various animal models in combination with an even faster growth in vivo (not in vitro). Conclusion Molecular, genomic and phenotypic analysis of representative isolates of a major clone of E. faecalis MLST ST40 revealed new insights into the microbiology of a commensal bacterium which can turn into a conditional pathogen. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1367-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Melanie Zischka
- Division of Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, D-38855, Wernigerode, Germany. .,Present address: Institute for Pathology, Hannover Medical School (MHH), Hannover, Germany.
| | - Carsten T Künne
- Functional Genomics of Bacterial Pathogens, Institute for Medical Microbiology, Justus Liebig University Giessen and German Center for Infection Research (DZIF), Partner site Giessen-Marburg-Langen, Campus Giessen, Giessen, Germany. .,Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.
| | - Jochen Blom
- Center for Biotechnology (CeBiTec)/University of Bielefeld, Bielefeld, Germany. .,Institute for Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany.
| | - Dominique Wobser
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany.
| | - Türkân Sakιnç
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany.
| | - Kerstin Schmidt-Hohagen
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany.
| | - P Wojtek Dabrowski
- Robert Koch Institute, ZBS 1 Highly Pathogenic Viruses, Centre for Biological Threats and Special Pathogens, Berlin, Germany.
| | - Andreas Nitsche
- Robert Koch Institute, ZBS 1 Highly Pathogenic Viruses, Centre for Biological Threats and Special Pathogens, Berlin, Germany.
| | - Johannes Hübner
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany. .,Division of Pediatric Infectious Diseases, Hauner Children's Hospital, Ludwig-Maximilians University Munich, Munich, Germany.
| | - Torsten Hain
- Functional Genomics of Bacterial Pathogens, Institute for Medical Microbiology, Justus Liebig University Giessen and German Center for Infection Research (DZIF), Partner site Giessen-Marburg-Langen, Campus Giessen, Giessen, Germany.
| | - Trinad Chakraborty
- Functional Genomics of Bacterial Pathogens, Institute for Medical Microbiology, Justus Liebig University Giessen and German Center for Infection Research (DZIF), Partner site Giessen-Marburg-Langen, Campus Giessen, Giessen, Germany.
| | - Burkhard Linke
- Center for Biotechnology (CeBiTec)/University of Bielefeld, Bielefeld, Germany. .,Institute for Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany.
| | - Alexander Goesmann
- Center for Biotechnology (CeBiTec)/University of Bielefeld, Bielefeld, Germany. .,Institute for Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany.
| | - Sonja Voget
- Goettingen Genomics Laboratory, Georg August University, Goettingen, Germany.
| | - Rolf Daniel
- Goettingen Genomics Laboratory, Georg August University, Goettingen, Germany.
| | - Dietmar Schomburg
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany.
| | - Rüdiger Hauck
- Department of Veterinary Medicine, Institute for Poultry Diseases, Free University Berlin, Berlin, Germany.
| | - Hafez M Hafez
- Department of Veterinary Medicine, Institute for Poultry Diseases, Free University Berlin, Berlin, Germany.
| | - Petra Tielen
- Institute for Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.
| | - Dieter Jahn
- Institute for Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.
| | - Margrete Solheim
- Laboratory of Microbial Gene Technology and Food Microbiology, The Norwegian University of Life Sciences, Ås, Norway.
| | - Ewa Sadowy
- National Medicines Institute, Warsaw, Poland.
| | | | - Lars B Jensen
- Division of Microbiology, National Food Institute, Danish Technical University, Copenhagen, Denmark.
| | | | - Dianelys Quiñones Pérez
- Instituto de Medicina Tropical Pedro Kourí, Servicio de Bacteriología-Micología, La Habana, Cuba.
| | - Theresa Mikalsen
- Department of Medical Biology, Faculty of Health Sciences, Research Group for Host Microbe Interactions, University of Tromsø, Tromsø, Norway.
| | - Jennifer Bender
- Division of Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, D-38855, Wernigerode, Germany.
| | - Matthias Steglich
- Division of Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, D-38855, Wernigerode, Germany.
| | - Ulrich Nübel
- Division of Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, D-38855, Wernigerode, Germany. .,Leibniz-Institut DSMZ - Deutsche Sammlung von Mikrorganismen und Zellkulturen GmbH, Braunschweig, Germany.
| | - Wolfgang Witte
- Division of Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, D-38855, Wernigerode, Germany.
| | - Guido Werner
- Division of Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, D-38855, Wernigerode, Germany.
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Enterococcus faecalis 6-phosphogluconolactonase is required for both commensal and pathogenic interactions with Manduca sexta. Infect Immun 2014; 83:396-404. [PMID: 25385794 DOI: 10.1128/iai.02442-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Enterococcus faecalis is a commensal and pathogen of humans and insects. In Manduca sexta, E. faecalis is an infrequent member of the commensal gut community, but its translocation to the hemocoel results in a commensal-to-pathogen switch. To investigate E. faecalis factors required for commensalism, we identified E. faecalis genes that are upregulated in the gut of M. sexta using recombinase-based in vivo expression technology (RIVET). The RIVET screen produced 113 clones, from which we identified 50 genes that are more highly expressed in the insect gut than in culture. The most frequently recovered gene was locus OG1RF_11582, which encodes a 6-phosphogluconolactonase that we designated pglA. A pglA deletion mutant was impaired in both pathogenesis and gut persistence in M. sexta and produced enhanced biofilms compared with the wild type in an in vitro polystyrene plate assay. Mutation of four other genes identified by RIVET did not affect persistence in caterpillar guts but led to impaired pathogenesis. This is the first identification of genetic determinants for E. faecalis commensal and pathogenic interactions with M. sexta. Bacterial factors identified in this model system may provide insight into colonization or persistence in other host-associated microbial communities and represent potential targets for interventions to prevent E. faecalis infections.
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Kucera J, Sojka M, Pavlik V, Szuszkiewicz K, Velebny V, Klein P. Multispecies biofilm in an artificial wound bed—A novel model for in vitro assessment of solid antimicrobial dressings. J Microbiol Methods 2014; 103:18-24. [DOI: 10.1016/j.mimet.2014.05.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/04/2014] [Accepted: 05/05/2014] [Indexed: 01/30/2023]
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25
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Malamud F, Homem RA, Conforte VP, Yaryura PM, Castagnaro AP, Marano MR, do Amaral AM, Vojnov AA. Identification and characterization of biofilm formation-defective mutants of Xanthomonas citri subsp. citri. Microbiology (Reading) 2013; 159:1911-1919. [DOI: 10.1099/mic.0.064709-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Florencia Malamud
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Rafael Augusto Homem
- Embrapa Recursos Genéticos e Biotecnología and Centro APTA Citros Sylvio Moreira, Instituto Agronômico de Campinas, Cordeiropolis, Sao Pablo, Brazil
| | - Valeria Paola Conforte
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Pablo Marcelo Yaryura
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Atilio Pedro Castagnaro
- Estación Experimental Agroindustrial Obispo Colombres, Av. William Cross 3150, Las Talitas, Tucumán, Argentina
| | - María Rosa Marano
- IBR-Depto Microbiología, Facultad de Ciencias, Bioquímicas y Farmacéuticas, U.N.R. Suipacha 531, S2002LRK Rosario, Argentina
| | - Alexandre Morais do Amaral
- Embrapa Recursos Genéticos e Biotecnología and Centro APTA Citros Sylvio Moreira, Instituto Agronômico de Campinas, Cordeiropolis, Sao Pablo, Brazil
| | - Adrián Alberto Vojnov
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
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Lozano MJ, Salas ME, Giusti MDLA, Martini MC, López JL, Salto I, Del Papa MF, Pistorio M, Lagares A. Novel tnpR-based transposable promoter traps suitable for RIVET studies in different gram-negative bacteria. J Microbiol Methods 2013; 93:9-11. [PMID: 23384825 DOI: 10.1016/j.mimet.2013.01.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 01/14/2013] [Accepted: 01/14/2013] [Indexed: 11/26/2022]
Abstract
The preparation of plasmid-borne RIVET libraries can be troublesome when high genomic coverages are needed. We present here the construction and functional validation of a new set of miniTn5 promoter traps to generate tnpR-based RIVET libraries. The ability to generate tnpR transcriptional fusions by transposition will significantly facilitate the setup of RIVET studies in those bacteria where Tn5 transposition is operative.
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Affiliation(s)
- Mauricio J Lozano
- IBBM-Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata,Calles 47 y 115 (1900), La Plata, Argentina
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Comerlato CB, de Resende MCC, Caierão J, d'Azevedo PA. Presence of virulence factors in Enterococcus faecalis and Enterococcus faecium susceptible and resistant to vancomycin. Mem Inst Oswaldo Cruz 2013; 108. [PMID: 23903974 PMCID: PMC3970601 DOI: 10.1590/0074-0276108052013009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Despite the increasing importance of Enterococcus as opportunistic pathogens, their virulence factors are still poorly understood. This study determines the frequency of virulence factors in clinical and commensal Enterococcus isolates from inpatients in Porto Alegre, Brazil. Fifty Enterococcus isolates were analysed and the presence of the gelE, asa1 and esp genes was determined. Gelatinase activity and biofilm formation were also tested. The clonal relationships among the isolates were evaluated using pulsed-field gel electrophoresis. The asa1, gelE and esp genes were identified in 38%, 60% and 76% of all isolates, respectively. The first two genes were more prevalent in Enterococcus faecalis than in Enterococcus faecium, as was biofilm formation, which was associated with gelE and asa1 genes, but not with the esp gene. The presence of gelE and the activity of gelatinase were not fully concordant. No relationship was observed among any virulence factors and specific subclones of E. faecalis or E. faecium resistant to vancomycin. In conclusion, E. faecalis and E. faecium isolates showed significantly different patterns of virulence determinants. Neither the source of isolation nor the clonal relationship or vancomycin resistance influenced their distribution.
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Affiliation(s)
| | | | - Juliana Caierão
- Universidade Federal de Ciências da Saúde de Porto Alegre, Porto
Alegre, RS, Brasil , Corresponding author:
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Comerlato CB, Resende MCCD, Caierão J, d'Azevedo PA. Presence of virulence factors in Enterococcus faecalis and Enterococcus faecium susceptible and resistant to vancomycin. Mem Inst Oswaldo Cruz 2013; 108:590-5. [DOI: 10.1590/s0074-02762013000500009] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 05/03/2013] [Indexed: 12/25/2022] Open
Affiliation(s)
| | | | - Juliana Caierão
- Universidade Federal de Ciências da Saúde de Porto Alegre, Brasil
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Wassinger A, Zhang L, Tracy E, Munson RS, Kathariou S, Wang HH. Role of a GntR-family response regulator LbrA in Listeria monocytogenes biofilm formation. PLoS One 2013; 8:e70448. [PMID: 23894658 PMCID: PMC3720924 DOI: 10.1371/journal.pone.0070448] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 06/21/2013] [Indexed: 01/08/2023] Open
Abstract
The formation of Listeria monocytogenes biofilms contributes to persistent contamination in food processing facilities. A microarray comparison of L. monocytogenes between the transcriptome of the strong biofilm forming strain (Bfms) Scott A and the weak biofilm forming (Bfmw) strain F2365 was conducted to identify genes potentially involved in biofilm formation. Among 951 genes with significant difference in expression between the two strains, a GntR-family response regulator encoding gene (LMOf2365_0414), designated lbrA, was found to be highly expressed in Scott A relative to F2365. A Scott A lbrA-deletion mutant, designated AW3, formed biofilm to a much lesser extent as compared to the parent strain by a rapid attachment assay and scanning electron microscopy. Complementation with lbrA from Scott A restored the Bfms phenotype in the AW3 derivative. A second microarray assessment using the lbrA deletion mutant AW3 and the wild type Scott A revealed a total of 304 genes with expression significantly different between the two strains, indicating the potential regulatory role of LbrA in L. monocytogenes. A cloned copy of Scott A lbrA was unable to confer enhanced biofilm forming potential in F2365, suggesting that additional factors contributed to weak biofilm formation by F2365.
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Affiliation(s)
- Andrew Wassinger
- Department of Food Science and Technology, The Ohio State University, Columbus, Ohio, United States of America
| | - Lu Zhang
- Department of Food Science and Technology, The Ohio State University, Columbus, Ohio, United States of America
| | - Erin Tracy
- The Research Institute at Nationwide Children’s Hospital, and the Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Robert S. Munson
- The Research Institute at Nationwide Children’s Hospital, and the Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
- Department of Microbiology, The Ohio State University, Columbus, Ohio, United States of America
| | - Sophia Kathariou
- Department of Food Sciences, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Hua H. Wang
- Department of Food Science and Technology, The Ohio State University, Columbus, Ohio, United States of America
- Department of Microbiology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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AhrC and Eep are biofilm infection-associated virulence factors in Enterococcus faecalis. Infect Immun 2013; 81:1696-708. [PMID: 23460519 DOI: 10.1128/iai.01210-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Enterococcus faecalis is part of the human intestinal microbiome and is a prominent cause of health care-associated infections. The pathogenesis of many E. faecalis infections, including endocarditis and catheter-associated urinary tract infection (CAUTI), is related to the ability of clinical isolates to form biofilms. To identify chromosomal genetic determinants responsible for E. faecalis biofilm-mediated infection, we used a rabbit model of endocarditis to test strains with transposon insertions or in-frame deletions in biofilm-associated loci: ahrC, argR, atlA, opuBC, pyrC, recN, and sepF. Only the ahrC mutant was significantly attenuated in endocarditis. We demonstrate that the transcriptional regulator AhrC and the protease Eep, which we showed previously to be an endocarditis virulence factor, are also required for full virulence in murine CAUTI. Therefore, AhrC and Eep can be classified as enterococcal biofilm-associated virulence factors. Loss of ahrC caused defects in early attachment and accumulation of biofilm biomass. Characterization of ahrC transcription revealed that the temporal expression of this locus observed in wild-type cells promotes initiation of early biofilm formation and the establishment of endocarditis. This is the first report of AhrC serving as a virulence factor in any bacterial species.
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Effects of biofilm growth on plasmid copy number and expression of antibiotic resistance genes in Enterococcus faecalis. Antimicrob Agents Chemother 2013; 57:1850-6. [PMID: 23380728 DOI: 10.1128/aac.02010-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biofilm growth causes increased average plasmid copy number as well as increased copy number heterogeneity in Enterococcus faecalis cells carrying plasmid pCF10. In this study, we examined whether biofilm growth affected the copy number and expression of antibiotic resistance determinants for several plasmids with diverse replication systems. Four different E. faecalis plasmids, unrelated to pCF10, demonstrated increased copy number in biofilm cells. In biofilm cells, we also observed increased transcription of antibiotic resistance genes present on these plasmids. The increase in plasmid copy number correlated with increased plating efficiency on high concentrations of antibiotics. Single-cell analysis of strains carrying two different plasmids suggested that the increase in plasmid copy number associated with biofilm growth was restricted to a subpopulation of biofilm cells. Regrowth of harvested biofilm cells in liquid culture resulted in a rapid reduction of plasmid copy number to that observed in the planktonic state. These results suggest a possible mechanism by which biofilm growth could reduce susceptibility to antibiotics in clinical settings.
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Frank KL, Barnes AMT, Grindle SM, Manias DA, Schlievert PM, Dunny GM. Use of recombinase-based in vivo expression technology to characterize Enterococcus faecalis gene expression during infection identifies in vivo-expressed antisense RNAs and implicates the protease Eep in pathogenesis. Infect Immun 2012; 80:539-49. [PMID: 22144481 PMCID: PMC3264308 DOI: 10.1128/iai.05964-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 11/19/2011] [Indexed: 12/28/2022] Open
Abstract
Enterococcus faecalis is a member of the mammalian gastrointestinal microflora that has become a leading cause of nosocomial infections over the past several decades. E. faecalis must be able to adapt its physiology based on its surroundings in order to thrive in a mammalian host as both a commensal and a pathogen. We employed recombinase-based in vivo expression technology (RIVET) to identify promoters on the E. faecalis OG1RF chromosome that were specifically activated during the course of infection in a rabbit subdermal abscess model. The RIVET screen identified 249 putative in vivo-activated loci, over one-third of which are predicted to generate antisense transcripts. Three predicted antisense transcripts were detected in in vitro- and in vivo-grown cells, providing the first evidence of in vivo-expressed antisense RNAs in E. faecalis. Deletions in the in vivo-activated genes that encode glutamate 5-kinase (proB [EF0038]), the transcriptional regulator EbrA (ebrA [EF1809]), and the membrane metalloprotease Eep (eep [EF2380]) did not hinder biofilm formation in in vitro assays. In a rabbit model of endocarditis, the ΔebrA strain was fully virulent, the ΔproB strain was slightly attenuated, and the Δeep strain was severely attenuated. The Δeep virulence defect could be complemented by the expression of the wild-type gene in trans. Microscopic analysis of early Δeep biofilms revealed an abundance of small cellular aggregates that were not observed in wild-type biofilms. This work illustrates the use of a RIVET screen to provide information about the temporal activation of genes during infection, resulting in the identification and confirmation of a new virulence determinant in an important pathogen.
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Affiliation(s)
- Kristi L Frank
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
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Link between culture zeta potential homogeneity and Ebp in Enterococcus faecalis. Appl Environ Microbiol 2012; 78:2282-8. [PMID: 22267669 DOI: 10.1128/aem.07618-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterococcus faecalis, a commensal of the gastrointestinal tract and an opportunistic pathogen, has the ability to adhere to surfaces and form biofilms. It has been shown earlier that only 10 to 20% of an E. faecalis OG1RF culture expresses endocarditis- and biofilm-associated pili (Ebp), which are involved in biofilm formation. Another study revealed that E. faecalis clinical isolates, as well as OG1RF, are heterogeneous with respect to their apparent zeta potential, which was also correlated with increased ability to form biofilm. The aim of this study was to demonstrate that the heterogeneity in the presence of Ebp is correlated to that in apparent zeta potential. Heterogeneous cultures of OG1RF showed two distinct subpopulations with the most (-38 mV) and least (-26 mV) negative zeta potential. Deletion of EbpR, the activator of the ebp operon, or the structural genes ebpABC resulted in homogeneous culture with the most negative zeta potential. Conversely, overexpression of EbpR or the structural genes ebpABC resulted in homogeneous culture with the least negative zeta potential. The results show that ebp operon expression in E. faecalis, as measured by using P(ebp)-gfp promoter fusion, is the cause of heterogeneity in zeta potential and that pilus production causes the cells to behave as the least negative particle in an electric field.
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Large-scale screening of a targeted Enterococcus faecalis mutant library identifies envelope fitness factors. PLoS One 2011; 6:e29023. [PMID: 22194979 PMCID: PMC3240637 DOI: 10.1371/journal.pone.0029023] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 11/18/2011] [Indexed: 11/25/2022] Open
Abstract
Spread of antibiotic resistance among bacteria responsible for nosocomial and community-acquired infections urges for novel therapeutic or prophylactic targets and for innovative pathogen-specific antibacterial compounds. Major challenges are posed by opportunistic pathogens belonging to the low GC% Gram-positive bacteria. Among those, Enterococcus faecalis is a leading cause of hospital-acquired infections associated with life-threatening issues and increased hospital costs. To better understand the molecular properties of enterococci that may be required for virulence, and that may explain the emergence of these bacteria in nosocomial infections, we performed the first large-scale functional analysis of E. faecalis V583, the first vancomycin-resistant isolate from a human bloodstream infection. E. faecalis V583 is within the high-risk clonal complex 2 group, which comprises mostly isolates derived from hospital infections worldwide. We conducted broad-range screenings of candidate genes likely involved in host adaptation (e.g., colonization and/or virulence). For this purpose, a library was constructed of targeted insertion mutations in 177 genes encoding putative surface or stress-response factors. Individual mutants were subsequently tested for their i) resistance to oxidative stress, ii) antibiotic resistance, iii) resistance to opsonophagocytosis, iv) adherence to the human colon carcinoma Caco-2 epithelial cells and v) virulence in a surrogate insect model. Our results identified a number of factors that are involved in the interaction between enterococci and their host environments. Their predicted functions highlight the importance of cell envelope glycopolymers in E. faecalis host adaptation. This study provides a valuable genetic database for understanding the steps leading E. faecalis to opportunistic virulence.
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Paganelli FL, Willems RJ, Leavis HL. Optimizing future treatment of enterococcal infections: attacking the biofilm? Trends Microbiol 2011; 20:40-9. [PMID: 22169461 DOI: 10.1016/j.tim.2011.11.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/19/2011] [Accepted: 11/02/2011] [Indexed: 11/16/2022]
Abstract
Enterococcus faecalis and Enterococcus faecium are among the leading causative agents of nosocomial infections and are infamous for their resistance to many antibiotics. They cause difficult-to-treat infections, often originating from biofilm-mediated infections associated with implanted medical devices or endocarditis. Biofilms protect bacteria against antibiotics and phagocytosis, and physical removal of devices or infected tissue is often needed but is frequently not possible. Currently there are no clinically available compounds that disassemble biofilms. In this review we discuss all known structural and regulatory genes involved in enterococcal biofilm formation, the compounds directed against biofilm formation that have been studied, and potentially useful targets for future drugs to treat enterococcal biofilm-associated infections.
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Affiliation(s)
- Fernanda L Paganelli
- Department of Medical Microbiology, University Medical Center Utrecht, The Netherlands
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36
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Novel genes associated with biofilm formation of Actinobacillus pleuropneumoniae. Vet Microbiol 2011; 153:134-43. [DOI: 10.1016/j.vetmic.2011.03.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 03/14/2011] [Accepted: 03/23/2011] [Indexed: 12/15/2022]
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Abstract
UNLABELLED In bacteria, RNAs regulate gene expression and function via several mechanisms. An RNA may pair with complementary sequences in a target RNA to impact transcription, translation, or degradation of the target. Control of conjugation of pCF10, a pheromone response plasmid of Enterococcus faecalis, is a well-characterized system that serves as a model for the regulation of gene expression in bacteria by intercellular signaling. The prgQ operon, whose products mediate conjugation, is negatively regulated by two products of the prgX operon, Anti-Q, a small RNA, and PrgX, the transcriptional repressor of the prgQ promoter. Here we show that Qs, an RNA from the 5' end of the prgQ operon, represses expression of PrgX by targeting prgX mRNA for cleavage by RNase III. Our results demonstrate that the prgQ and prgX operons each use RNAs to negatively regulate gene expression from the opposing operon by different mechanisms. Such reciprocal regulation between two operons using RNAs has not been previously demonstrated. Furthermore, these results show that Qs is an unusually versatile RNA, serving three separate functions in the regulation of conjugation. Understanding the potential versatility of RNAs and their various roles in gene regulatory networks will allow us to better understand how cells regulate complex behavior. IMPORTANCE Bacteria use RNA to regulate gene expression by a variety of mechanisms. The prgQ and prgX operons of pCF10, a conjugative plasmid of Enterococcus faecalis, have been shown to negatively regulate one another by a variety of mechanisms. One of these mechanisms involves Anti-Q, a small RNA from the prgX operon that prevents gene expression from the prgQ operon. In this work, we find that Qs, an RNA from the prgQ operon, negatively regulates gene expression from the prgX operon. These findings have a number of implications. (i) The Anti-Q and Qs RNAs act by different mechanisms, highlighting the variety of ways in which bacteria can regulate gene expression using RNAs. (ii) Reciprocal regulation between operons mediated by small RNAs has not been previously described, deepening our understanding of how bacteria regulate complex behavior. (iii) Additional roles for Qs have been described, demonstrating the versatility of this RNA.
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38
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Development of new positive-selection RIVET tools: Detection of induced promoters by the excision-based transcriptional activation of an aacCI (GmR)–gfp fusion. J Biotechnol 2011; 155:147-55. [DOI: 10.1016/j.jbiotec.2011.06.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 05/05/2011] [Accepted: 06/17/2011] [Indexed: 11/30/2022]
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39
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Zhu X, Liu W, Lametsch R, Aarestrup F, Shi C, She Q, Shi X, Knøchel S. Phenotypic, Proteomic, and Genomic Characterization of a Putative ABC-Transporter Permease Involved in Listeria monocytogenes Biofilm Formation. Foodborne Pathog Dis 2011; 8:495-501. [DOI: 10.1089/fpd.2010.0697] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Xinna Zhu
- Joint Sino-U.S. Food Safety Research Center and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P.R. China
- Food Microbiology, Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark
- Archaeal Genetics Laboratory, Functional Genomics Section, Department of Biology, University of Copenhagen, Biocenter, Copenhagen N, Denmark
| | - Weibing Liu
- Joint Sino-U.S. Food Safety Research Center and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P.R. China
| | - René Lametsch
- Meat Science, Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Frank Aarestrup
- WHO Collaborating Centre for Antimicrobial Resistance in Foodborne Pathogens, National Food Institute, Technical University of Denmark, Copenhagen V, Denmark
| | - Chunlei Shi
- Joint Sino-U.S. Food Safety Research Center and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P.R. China
| | - Qunxin She
- Archaeal Genetics Laboratory, Functional Genomics Section, Department of Biology, University of Copenhagen, Biocenter, Copenhagen N, Denmark
| | - Xianming Shi
- Joint Sino-U.S. Food Safety Research Center and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P.R. China
| | - Susanne Knøchel
- Food Microbiology, Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark
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40
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Gene expression analysis of monospecies Salmonella Typhimurium biofilms using Differential Fluorescence Induction. J Microbiol Methods 2011; 84:467-78. [DOI: 10.1016/j.mimet.2011.01.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 01/10/2011] [Accepted: 01/14/2011] [Indexed: 12/22/2022]
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41
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Dunny GM, Johnson CM. Regulatory circuits controlling enterococcal conjugation: lessons for functional genomics. Curr Opin Microbiol 2011; 14:174-80. [PMID: 21353627 DOI: 10.1016/j.mib.2011.01.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2010] [Accepted: 01/28/2011] [Indexed: 11/30/2022]
Abstract
The regulatory system controlling pheromone-induced plasmid transfer in Enterococcus faecalis is the most thoroughly studied genetic system of this species. Transcription initiation from the target promoter is controlled by a pheromone receptor/repressor protein whose activity is determined by its interaction with two peptide signaling molecules that compete for the same binding site, but have opposing effects on the activity of the receptor protein. For the system to function as a sensitive and robust biological switch, several additional levels of post-transcriptional regulation are also required. Expression of important functions encoded within the enterococcal core genome may also be controlled by multilayered regulatory circuitry. The pheromone system may serve as a useful paradigm to guide comprehensive functional genomic analysis of E. faecalis.
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Affiliation(s)
- Gary M Dunny
- Department of Microbiology, University of Minnesota, 420 Delaware St. SE, Minneapolis, MN 55455, USA.
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Fouquier d'Hérouel A, Wessner F, Halpern D, Ly-Vu J, Kennedy SP, Serror P, Aurell E, Repoila F. A simple and efficient method to search for selected primary transcripts: non-coding and antisense RNAs in the human pathogen Enterococcus faecalis. Nucleic Acids Res 2011; 39:e46. [PMID: 21266481 PMCID: PMC3074167 DOI: 10.1093/nar/gkr012] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Enterococcus faecalis is a commensal bacterium and a major opportunistic human pathogen. In this study, we combined in silico predictions with a novel 5′RACE-derivative method coined ‘5′tagRACE’, to perform the first search for non-coding RNAs (ncRNAs) encoded on the E. faecalis chromosome. We used the 5′tagRACE to simultaneously probe and characterize primary transcripts, and demonstrate here the simplicity, the reliability and the sensitivity of the method. The 5′tagRACE is complementary to tiling arrays or RNA-sequencing methods, and is also directly applicable to deep RNA sequencing and should significantly improve functional studies of bacterial RNA landscapes. From 45 selected loci of the E. faecalis chromosome, we discovered and mapped 29 novel ncRNAs, 10 putative novel mRNAs and 16 antisense transcriptional organizations. We describe in more detail the oxygen-dependent expression of one ncRNA located in an E. faecalis pathogenicity island, the existence of an ncRNA that is antisense to the ncRNA modulator of the RNA polymerase, SsrS and provide evidences for the functional interplay between two distinct toxin–antitoxin modules.
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A selenium-dependent xanthine dehydrogenase triggers biofilm proliferation in Enterococcus faecalis through oxidant production. J Bacteriol 2011; 193:1643-52. [PMID: 21257770 DOI: 10.1128/jb.01063-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Selenium has been shown to be present as a labile cofactor in a small class of molybdenum hydroxylase enzymes in several species of clostridia that specialize in the fermentation of purines and pyrimidines. This labile cofactor is poorly understood, yet recent bioinformatic studies have suggested that Enterococcus faecalis could serve as a model system to better understand the way in which this enzyme cofactor is built and the role of these metalloenzymes in the physiology of the organism. An mRNA that encodes a predicted selenium-dependent molybdenum hydroxylase (SDMH) has also been shown to be specifically increased during the transition from planktonic growth to biofilm growth. Based on these studies, we examined whether this organism produces an SDMH and probed whether selenoproteins may play a role in biofilm physiology. We observed a substantial increase in biofilm density upon the addition of uric acid to cells grown in a defined culture medium, but only when molybdate (Mo) and selenite (Se) were also added. We also observed a significant increase in biofilm density in cells cultured in tryptic soy broth with 1% glucose (TSBG) when selenite was added. In-frame deletion of selD, which encodes selenophosphate synthetase, also blocked biofilm formation that occurred upon addition of selenium. Moreover, mutation in the gene encoding the molybdoenzyme (xdh) prevented the induction of biofilm proliferation upon supplementation with selenium. Tungstate or auranofin addition also blocked this enhanced biofilm density, likely through inhibition of molybdenum or selenium cofactor synthesis. A large protein complex labeled with (75)Se is present in higher concentrations in biofilms than in planktonic cells, and the same complex is formed in TSBG. Xanthine dehydrogenase activity correlates with the presence of this labile selenoprotein complex and is absent in a selD or an xdh mutant. Enhanced biofilm density correlates strongly with higher levels of extracellular peroxide, which is produced upon the addition of selenite to TSBG. Peroxide levels are not increased in either the selD or the xdh mutant upon addition of selenite. Extracellular superoxide production, a phenomenon well established to be linked to clinical isolates, is abolished in both mutant strains. Taken together, these data provide evidence that an SDMH is involved in biofilm formation in Enterococcus faecalis, contributing to oxidant production either directly or alternatively through its involvement in redox-dependent processes linked to oxidant production.
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44
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Chuang-Smith ON, Wells CL, Henry-Stanley MJ, Dunny GM. Acceleration of Enterococcus faecalis biofilm formation by aggregation substance expression in an ex vivo model of cardiac valve colonization. PLoS One 2010; 5:e15798. [PMID: 21209892 PMCID: PMC3012704 DOI: 10.1371/journal.pone.0015798] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 11/23/2010] [Indexed: 11/18/2022] Open
Abstract
Infectious endocarditis involves formation of a microbial biofilm in vivo. Enterococcus faecalis Aggregation Substance (Asc10) protein enhances the severity of experimental endocarditis, where it has been implicated in formation of large vegetations and in microbial persistence during infection. In the current study, we developed an ex vivo porcine heart valve adherence model to study the initial interactions between Asc10(+) and Asc10(-)E. faecalis and valve tissue, and to examine formation of E. faecalis biofilms on a relevant tissue surface. Scanning electron microscopy of the infected valve tissue provided evidence for biofilm formation, including growing masses of bacterial cells and the increasing presence of exopolymeric matrix over time; accumulation of adherent biofilm populations on the cardiac valve surfaces during the first 2-4 h of incubation was over 10-fold higher than was observed on abiotic membranes incubated in the same culture medium. Asc10 expression accelerated biofilm formation via aggregation between E. faecalis cells; the results also suggested that in vivo adherence to host tissue and biofilm development by E. faecalis can proceed by Asc10-dependent or Asc10-independent pathways. Mutations in either of two Asc10 subdomains previously implicated in endocarditis virulence reduced levels of adherent bacterial populations in the ex vivo system. Interference with the molecular interactions involved in adherence and initiation of biofilm development in vivo with specific inhibitory compounds could lead to more effective treatment of infectious endocarditis.
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Affiliation(s)
- Olivia N. Chuang-Smith
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Carol L. Wells
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Michelle J. Henry-Stanley
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Gary M. Dunny
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
- * E-mail:
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Abstract
Bacterial biofilms are structured communities of bacterial cells enclosed in a self-produced polymer matrix that is attached to a surface. Biofilms protect and allow bacteria to survive and thrive in hostile environments. Bacteria within biofilms can withstand host immune responses, and are much less susceptible to antibiotics and disinfectants when compared with their planktonic counterparts. The ability to form biofilms is now considered a universal attribute of micro-organisms. Diseases associated with biofilms require novel methods for their prevention, diagnosis and treatment; this is largely due to the properties of biofilms. Surprisingly, biofilm formation by bacterial pathogens of veterinary importance has received relatively little attention. Here, we review the current knowledge of bacterial biofilms as well as studies performed on animal pathogens.
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Hanin A, Sava I, Bao Y, Huebner J, Hartke A, Auffray Y, Sauvageot N. Screening of in vivo activated genes in Enterococcus faecalis during insect and mouse infections and growth in urine. PLoS One 2010; 5:e11879. [PMID: 20686694 PMCID: PMC2912369 DOI: 10.1371/journal.pone.0011879] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Accepted: 07/05/2010] [Indexed: 12/15/2022] Open
Abstract
Enterococcus faecalis is part of the commensal microbiota of humans and its main habitat is the gastrointestinal tract. Although harmless in healthy individuals, E. faecalis has emerged as a major cause of nosocomial infections. In order to better understand the transformation of a harmless commensal into a life-threatening pathogen, we developed a Recombination-based In VivoExpression Technology for E. faecalis. Two R-IVET systems with different levels of sensitivity have been constructed in a E. faecalis V583 derivative strain and tested in the insect model Galleria mellonella, during growth in urine, in a mouse bacteremia and in a mouse peritonitis model. Our combined results led to the identification of 81 in vivo activated genes. Among them, the ef_3196/7 operon was shown to be strongly induced in the insect host model. Deletion of this operonic structure demonstrated that this two-component system was essential to the E. faecalis pathogenic potential in Galleria. Gene ef_0377, induced in insect and mammalian models, has also been further analyzed and it has been demonstrated that this ankyrin-encoding gene was also involved in E. faecalis virulence. Thus these R-IVET screenings led to the identification of new E. faecalis factors implied in in vivo persistence and pathogenic potential of this opportunistic pathogen.
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Affiliation(s)
- Aurelie Hanin
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
| | - Irina Sava
- Division of Infection Diseases, Department of Medicine, University Medical Center, Freiburg, Germany
| | - YinYin Bao
- Division of Infection Diseases, Department of Medicine, University Medical Center, Freiburg, Germany
| | - Johannes Huebner
- Division of Infection Diseases, Department of Medicine, University Medical Center, Freiburg, Germany
| | - Axel Hartke
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
| | - Yanick Auffray
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
| | - Nicolas Sauvageot
- Laboratoire de Microbiologie de l'Environnement, EA956 USC INRA2017, Université de Caen, Caen, France
- * E-mail:
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Rocha-Estrada J, Aceves-Diez AE, Guarneros G, de la Torre M. The RNPP family of quorum-sensing proteins in Gram-positive bacteria. Appl Microbiol Biotechnol 2010; 87:913-23. [PMID: 20502894 DOI: 10.1007/s00253-010-2651-y] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 03/29/2010] [Accepted: 04/20/2010] [Indexed: 11/29/2022]
Abstract
Quorum sensing is one of several mechanisms that bacterial cells use to interact with each other and coordinate certain physiological processes in response to cell density. This mechanism is mediated by extracellular signaling molecules; once a critical threshold concentration has been reached, a target sensor kinase or response regulator is activated (or repressed), facilitating the expression of quorum sensing-dependent genes. Gram-positive bacteria mostly use oligo-peptides as signaling molecules. These cells have a special kind of quorum-sensing systems in which the receptor protein interacts directly with its cognate signaling peptide. The receptors are either Rap phosphatases or transcriptional regulators and integrate the protein family RNPP, from Rap, Npr, PlcR, and PrgX. These quorum-sensing systems control several microbial processes, like sporulation, virulence, biofilm formation, conjugation, and production of extracellular enzymes. Insights of the mechanism of protein-signaling peptide binding as well as the molecular interaction among receptor protein, signaling peptide, and target DNA have changed some earlier perceptions. In spite of the increased knowledge and the potential biotechnological applications of these quorum-sensing systems, few examples on engineering for biotechnological applications have been published. Real applications will arise only when researchers working in applied microbiology and biotechnology are aware of the importance of quorum-sensing systems for health and bioprocess applications.
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Affiliation(s)
- Jorge Rocha-Estrada
- Centro de Investigación en Alimentación y Desarrollo, A. C., Carretera a la Victoria Km. 0.6, 83304, Hermosillo, Sonora, México
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Direct evidence for control of the pheromone-inducible prgQ operon of Enterococcus faecalis plasmid pCF10 by a countertranscript-driven attenuation mechanism. J Bacteriol 2010; 192:1634-42. [PMID: 20097859 DOI: 10.1128/jb.01525-09] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mating response of Enterococcus faecalis cells carrying the conjugative plasmid pCF10 is controlled by multiple regulatory circuits. Initiation of transcription of the prgQ conjugation operon is controlled by the peptide receptor protein PrgX; binding of the pheromone peptide cCF10 to PrgX abolishes PrgX repression, while binding of the inhibitor peptide iCF10 enhances repression. The results of molecular analysis of prgQ transcripts and genetic studies suggested that the elongation of prgQ transcripts past a putative terminator (IRS1) may be controlled by the interaction of nascent prgQ mRNAs with a small antisense RNA (Anti-Q) encoded within prgQ. Direct evidence for interaction of these RNAs, as well as the resulting effects on readthrough of prgQ transcription, has been limited. Here we report the results of experiments that (i) determine the inherent termination properties of prgQ transcripts in the absence of Anti-Q; (ii) determine the direct effects of the interaction of Anti-Q with nascent prgQ transcripts in the absence of complicating effects of the PrgX protein; and (iii) begin to dissect the structural components involved in these interactions. The results confirm the existence of alternative terminating and antiterminating forms of nascent prgQ transcripts in vivo and demonstrate that the interaction of Anti-Q with these transcripts leads to termination via inhibition of antiterminator formation. In vitro transcription assays support the major results of the in vivo studies. The data support a model for Anti-Q function suggested from recent studies of these RNAs and their interactions in vitro (S. Shokeen, C. M. Johnson, T. J. Greenfield, D. A. Manias, G. M. Dunny, and K. E. Weaver, submitted for publication).
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Creti R, Fabretti F, Koch S, Huebner J, Garsin DA, Baldassarri L, Montanaro L, Arciola CR. Surface protein EF3314 contributes to virulence properties of Enterococcus faecalis. Int J Artif Organs 2010; 32:611-20. [PMID: 19856273 DOI: 10.1177/039139880903200910] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE Identification of putative new virulence factors as additional targets for therapeutic approaches alternative to antibiotic treatment of multi-resistant enterococcal infections. METHODS The EF3314 gene, coding for a putative surface-exposed antigen, was identified by the analysis of the Enterococcus faecalis V583 genome for LPXTG-motif cell wall anchor surface protein genes. A non-polar EF3314 gene deletion mutant in the E. faecalis 12030 human clinical isolate was obtained. The wild type and the isogenic mutant strain were investigated for biofilm formation, adherence to Hela cells, survival in human macrophages and a Caenorhabditis elegans infection model. The aminoterminal portion of the EF3314 protein was overexpressed in E. coli to obtain mouse polyclonal antibodies for use in Western blotting and immunolocalization experiments. RESULTS The EF3314 gene has an unusually high GC content (46.88% vs. an average of 37.5% in the E. faecalis chromosome) and encodes a protein of 1744 amino acids that presents a series of 14 imperfect repeats of 90 amino acids covering almost the entire length of the protein. Its global organization is similar to the alpha-like protein family of group B streptococci, enterococcal surface protein Esp and biofilm associated protein Bap from S. aureus. The EF3314 gene was always present and specific for E. faecalis strains of human, food and animal origin. Differences in size depended on variable numbers of repeats in the repetitive region. CONCLUSIONS EF3314 is a newly described, surface exposed protein that contributes to the virulence properties of E. faecalis.
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Affiliation(s)
- Roberta Creti
- Respiratory and Systemic Disease Unit, Department of Infectious, Parasitic, and Immune-mediated Diseases, National Health Institute (ISS), Rome, Italy.
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