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Costan SA, Ryan PM, Kim H, Wolgemuth CW, Riedel-Kruse IH. Biophysical characterization of synthetic adhesins for predicting and tuning engineered living material properties. MATTER 2024; 7:2125-2143. [PMID: 39165662 PMCID: PMC11335339 DOI: 10.1016/j.matt.2024.03.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
Bacterial synthetic multicellular systems are promising platforms for engineered living materials (ELMs) for medical, biosynthesis, environmental, and smart materials applications. Recent advancements in genetically encoded adhesion toolkits have enabled precise manipulation of cell-cell adhesion and the design and patterning of self-assembled multicellular materials. However, in contrast to gene regulation in synthetic biology, the characterization and control of synthetic adhesins remains limited. Here, we demonstrate the quantitative characterization of a bacterial synthetic adhesion toolbox through various biophysical methods. We determine key parameters, including number of adhesins per cell, in-membrane diffusion constant, production and decay rates, and bond-breaking force between adhesins. With these parameters, we demonstrate the bottom-up prediction and quantitative tuning of macroscopic ELM properties (tensile strength) and, furthermore, that cells inside ELMs are connected only by a small fraction of available adhesins. These results enable the rational engineering, characterization, and modeling of other synthetic and natural adhesins and multicellular consortia.
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Affiliation(s)
- Stefana A. Costan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85721, USA
| | - Paul M. Ryan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
| | - Honesty Kim
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Charles W. Wolgemuth
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
- Department of Applied Mathematics, University of Arizona, Tucson, AZ 85721, USA
| | - Ingmar H. Riedel-Kruse
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85721, USA
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
- Department of Applied Mathematics, University of Arizona, Tucson, AZ 85721, USA
- Lead contact
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Differential Localization and Functional Specialization of parS Centromere-Like Sites in repABC Replicons of Alphaproteobacteria. Appl Environ Microbiol 2022; 88:e0020722. [PMID: 35389251 PMCID: PMC9040568 DOI: 10.1128/aem.00207-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Partitioning systems ensure the stable inheritance of bacterial low-copy-number replicons, such as chromosomes, chromids, and megaplasmids. These loci consist of two genes encoding partition proteins A and B, and at least one parS centromere-like sequence. In chromids and megaplasmids, partitioning systems are often located in the vicinity of replication systems. An extreme example of this co-localization are alphaproteobacterial repABC replicons, where the partition (repAB) and replication (repC) genes form a single operon, with parS sequences usually positioned in close proximity to these genes. In this study, we characterized a more complex repABC system found in Paracoccus aminophilus (Rhodobacterales) megaplasmid pAMI4 (438 kb). Besides the repABC operon with a single parS site, this replicon has a 2-kb non-coding locus positioned 11.5 kb downstream of repC, which contains three additional parS repeats (3parS). We demonstrated that 3parS is bound by partition protein B in vitro and is essential for proper pAMI4 partitioning in vivo. In search of similar loci, we conducted a comparative analysis of parS distribution in other repABC replicons. This revealed different patterns of parS localization in Rhodobacterales and Rhizobiales. However, in both these taxonomic orders, parS sites are almost always located inside or close to the repABC operon. No other 3parS-like loci were found in the closest relatives of pAMI4. Another evolutionarily-independent example of such a locus was identified as a conserved feature in chromosome 2 of Allorhizobium vitis and related replicons. IMPORTANCE The repABC replication/partitioning loci are widespread in extrachromosomal replicons of Alphaproteobacteria. They are evolutionarily diverse, subject to multi-layer self-regulation, and are responsible for the maintenance of different types of replicons, such as plasmids (e.g., Agrobacterium pTi and pRi tumorigenic and rhizogenic plasmids), megaplasmids (e.g., Sinorhizobium pSymA and pSymB) and essential chromids (e.g., secondary chromosomes of Agrobacterium, Brucella and Rhodobacter). In this study, we functionally analyzed an atypical partition-related component of repABC systems, the 3parS locus, found in the P. aminophilus megaplasmid pAMI4. We also identified parS centromere-like site distribution patterns in different groups of repABC replicons and found other unrelated 3parS-like loci, which had been overlooked. Our findings raise questions concerning the biological reasons for differential parS distribution, which may reflect variations in repABC operon regulation as well as different replication and partition modes of replicons belonging to the repABC family.
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Zhang P, Mao D, Gao H, Zheng L, Chen Z, Gao Y, Duan Y, Guo J, Luo Y, Ren H. Colonization of gut microbiota by plasmid-carrying bacteria is facilitated by evolutionary adaptation to antibiotic treatment. THE ISME JOURNAL 2021; 16:1284-1293. [PMID: 34903849 PMCID: PMC9038720 DOI: 10.1038/s41396-021-01171-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 11/25/2021] [Accepted: 12/02/2021] [Indexed: 12/27/2022]
Abstract
Multidrug-resistant plasmid-carrying bacteria are of particular clinical concern as they could transfer antibiotic resistance genes to other bacterial species. However, little is known whether evolutionary adaptation of plasmid-carrying bacteria after long-term antibiotic exposure could affect their subsequent colonization of the human gut. Herein, we combined a long-term evolutionary model based on Escherichia coli K-12 MG1655 and the multidrug-resistant plasmid RP4 with in vivo colonization experiments in mice. We found that the evolutionary adaptation of plasmid-carrying bacteria to antibiotic exposure facilitated colonization of the murine gut and subsequent plasmid transfer to gut bacteria. The evolved plasmid-carrying bacteria exhibited phenotypic alterations, including multidrug resistance, enhanced bacterial growth and biofilm formation capability and decreased plasmid fitness cost, which might be jointly caused by chromosomal mutations (SNPs in rpoC, proQ, and hcaT) and transcriptional modifications. The upregulated transcriptional genes, e.g., type 1 fimbrial-protein pilus (fimA and fimH) and the surface adhesin gene (flu) were likely responsible for the enhanced biofilm-forming capacity. The gene tnaA that encodes a tryptophanase-catalyzing indole formation was transcriptionally upregulated, and increased indole products participated in facilitating the maximum population density of the evolved strains. Furthermore, several chromosomal genes encoding efflux pumps (acriflavine resistance proteins A and B (acrA, acrB), outer-membrane protein (tolC), multidrug-resistance protein (mdtM), and macrolide export proteins A and B (macA, macB)) were transcriptionally upregulated, while most plasmid-harboring genes (conjugal transfer protein (traF) and (trbB), replication protein gene (trfA), beta-lactamase TEM precursor (blaTEM), aminoglycoside 3'-phosphotransferase (aphA) and tetracycline resistance protein A (tetA)) were downregulated. Collectively, these findings demonstrated that evolutionary adaptation of plasmid-carrying bacteria in an antibiotic-influenced environment facilitated colonization of the murine gut by the bacteria and plasmids.
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Affiliation(s)
- Peng Zhang
- College of Environmental Sciences and Engineering, Nankai University, Tianjin, 300350, China.,State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210046, China
| | - Daqing Mao
- School of Medicine, Nankai University, Tianjin, 300071, China.
| | - Huihui Gao
- School of Medicine, Nankai University, Tianjin, 300071, China
| | - Liyang Zheng
- School of Medicine, Nankai University, Tianjin, 300071, China
| | - Zeyou Chen
- College of Environmental Sciences and Engineering, Nankai University, Tianjin, 300350, China
| | - Yuting Gao
- College of Environmental Sciences and Engineering, Nankai University, Tianjin, 300350, China
| | - Yitao Duan
- College of Environmental Sciences and Engineering, Nankai University, Tianjin, 300350, China
| | - Jianhua Guo
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, St. Lucia, Brisbane, QLD, 4072, Australia.
| | - Yi Luo
- College of Environmental Sciences and Engineering, Nankai University, Tianjin, 300350, China. .,State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210046, China.
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210046, China
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Bacterial Biofilm Formation Using PCL/Curcumin Electrospun Fibers and Its Potential Use for Biotechnological Applications. MATERIALS 2020; 13:ma13235556. [PMID: 33291216 PMCID: PMC7729789 DOI: 10.3390/ma13235556] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/20/2020] [Accepted: 10/27/2020] [Indexed: 01/19/2023]
Abstract
Electrospun nanofibers are used for many applications due to their large surface area, mechanical properties, and bioactivity. Bacterial biofilms are the cause of numerous problems in biomedical devices and in the food industry. On the other hand, these bacterial biofilms can produce interesting metabolites. Hence, the objective of this study is to evaluate the efficiency of poly (Ɛ- caprolactone)/Curcumin (PCL/CUR) nanofibers to promote bacterial biofilm formation. These scaffolds were characterized by scanning electron microscopy (SEM), which showed homogeneous fibers with diameters between 441-557 nm; thermogravimetric analysis and differential scanning calorimetry (TGA and DSC) demonstrated high temperature resilience with degradation temperatures over >350 °C; FTIR and 1H-NMR serve as evidence of CUR incorporation in the PCL fibers. PCL/CUR scaffolds successfully promoted the formation of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa biofilms. These results will be valuable in the study of controlled harvesting of pathogenic biofilms as well as in metabolites production for biotechnological purposes.
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Schulte M, Sterzenbach T, Miskiewicz K, Elpers L, Hensel M, Hansmeier N. A versatile remote control system for functional expression of bacterial virulence genes based on the tetA promoter. Int J Med Microbiol 2019; 309:54-65. [DOI: 10.1016/j.ijmm.2018.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 10/21/2018] [Accepted: 11/14/2018] [Indexed: 11/16/2022] Open
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Nhu NTK, Phan MD, Peters KM, Lo AW, Forde BM, Min Chong T, Yin WF, Chan KG, Chromek M, Brauner A, Chapman MR, Beatson SA, Schembri MA. Discovery of New Genes Involved in Curli Production by a Uropathogenic Escherichia coli Strain from the Highly Virulent O45:K1:H7 Lineage. mBio 2018; 9:e01462-18. [PMID: 30131362 PMCID: PMC6106082 DOI: 10.1128/mbio.01462-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 07/10/2018] [Indexed: 11/20/2022] Open
Abstract
Curli are bacterial surface-associated amyloid fibers that bind to the dye Congo red (CR) and facilitate uropathogenic Escherichia coli (UPEC) biofilm formation and protection against host innate defenses. Here we sequenced the genome of the curli-producing UPEC pyelonephritis strain MS7163 and showed it belongs to the highly virulent O45:K1:H7 neonatal meningitis-associated clone. MS7163 produced curli at human physiological temperature, and this correlated with biofilm growth, resistance of sessile cells to the human cationic peptide cathelicidin, and enhanced colonization of the mouse bladder. We devised a forward genetic screen using CR staining as a proxy for curli production and identified 41 genes that were required for optimal CR binding, of which 19 genes were essential for curli synthesis. Ten of these genes were novel or poorly characterized with respect to curli synthesis and included genes involved in purine de novo biosynthesis, a regulator that controls the Rcs phosphorelay system, and a novel repressor of curli production (referred to as rcpA). The involvement of these genes in curli production was confirmed by the construction of defined mutants and their complementation. The mutants did not express the curli major subunit CsgA and failed to produce curli based on CR binding. Mutation of purF (the first gene in the purine biosynthesis pathway) and rcpA also led to attenuated colonization of the mouse bladder. Overall, this work has provided new insight into the regulation of curli and the role of these amyloid fibers in UPEC biofilm formation and pathogenesis.IMPORTANCE Uropathogenic Escherichia coli (UPEC) strains are the most common cause of urinary tract infection, a disease increasingly associated with escalating antibiotic resistance. UPEC strains possess multiple surface-associated factors that enable their colonization of the urinary tract, including fimbriae, curli, and autotransporters. Curli are extracellular amyloid fibers that enhance UPEC virulence and promote biofilm formation. Here we examined the function and regulation of curli in a UPEC pyelonephritis strain belonging to the highly virulent O45:K1:H7 neonatal meningitis-associated clone. Curli expression at human physiological temperature led to increased biofilm formation, resistance of sessile cells to the human cationic peptide LL-37, and enhanced bladder colonization. Using a comprehensive genetic screen, we identified multiple genes involved in curli production, including several that were novel or poorly characterized with respect to curli synthesis. In total, this study demonstrates an important role for curli as a UPEC virulence factor that promotes biofilm formation, resistance, and pathogenesis.
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Affiliation(s)
- Nguyen Thi Khanh Nhu
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
- Australian Centre for Ecogenomics, the University of Queensland, Brisbane, Queensland, Australia
| | - Minh-Duy Phan
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
| | - Kate M Peters
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
| | - Alvin W Lo
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
| | - Brian M Forde
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
- Australian Centre for Ecogenomics, the University of Queensland, Brisbane, Queensland, Australia
| | - Teik Min Chong
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Wai-Fong Yin
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Sciences, University of Malaya, Kuala Lumpur, Malaysia
- International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Milan Chromek
- Department of Microbiology, Tumor and Cell Biology, Division of Clinical Microbiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
- Department of Pediatrics, CLINTEC, Karolinska University Hospital and Karolinska Institutet, Stockholm, Sweden
| | - Annelie Brauner
- Department of Microbiology, Tumor and Cell Biology, Division of Clinical Microbiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Matthew R Chapman
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Scott A Beatson
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
- Australian Centre for Ecogenomics, the University of Queensland, Brisbane, Queensland, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
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Propolis potentiates the effect of cranberry (Vaccinium macrocarpon) against the virulence of uropathogenic Escherichia coli. Sci Rep 2018; 8:10706. [PMID: 30013052 PMCID: PMC6048107 DOI: 10.1038/s41598-018-29082-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 06/29/2018] [Indexed: 01/08/2023] Open
Abstract
Uropathogenic Escherichia coli (UPEC), the most prevalent bacteria isolated in urinary tract infections (UTI), is now frequently resistant to antibiotics used to treat this pathology. The antibacterial properties of cranberry and propolis could reduce the frequency of UTIs and thus the use of antibiotics, helping in the fight against the emergence of antibiotic resistance. Transcriptomic profiles of a clinical UPEC strain exposed to cranberry proanthocyanidins alone (190 µg/mL), propolis alone (102.4 µg/mL) and a combination of both were determined. Cranberry alone, but more so cranberry + propolis combined, modified the expression of genes involved in different essential pathways: down-expression of genes involved in adhesion, motility, and biofilm formation, and up-regulation of genes involved in iron metabolism and stress response. Phenotypic assays confirmed the decrease of motility (swarming and swimming) and biofilm formation (early formation and formed biofilm). This study showed for the first time that propolis potentiated the effect of cranberry proanthocyanidins on adhesion, motility, biofilm formation, iron metabolism and stress response of UPEC. Cranberry + propolis treatment could represent an interesting new strategy to prevent recurrent UTI.
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Biofilm Lithography enables high-resolution cell patterning via optogenetic adhesin expression. Proc Natl Acad Sci U S A 2018; 115:3698-3703. [PMID: 29555779 PMCID: PMC5889658 DOI: 10.1073/pnas.1720676115] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Bacteria live in surface-attached communities known as biofilms, where spatial structure is tightly linked to community function. We have developed a genetically encoded biofilm patterning tool (“Biofilm Lithography”) by engineering bacteria such that the expression of membrane adhesion proteins responsible for surface attachment is optically regulated. Accordingly, these bacteria only form biofilm on illuminated surface regions. With this tool, we are able to use blue light to pattern Escherichia coli biofilms with 25 μm spatial resolution. We present an accompanying biophysical model to understand the mechanism behind light-regulated biofilm formation and to provide insight on related natural biofilm processes. Overall, this biofilm patterning tool can be applied to study natural microbial communities as well as to engineer living biomaterials. Bacterial biofilms represent a promising opportunity for engineering of microbial communities. However, our ability to control spatial structure in biofilms remains limited. Here we engineer Escherichia coli with a light-activated transcriptional promoter (pDawn) to optically regulate expression of an adhesin gene (Ag43). When illuminated with patterned blue light, long-term viable biofilms with spatial resolution down to 25 μm can be formed on a variety of substrates and inside enclosed culture chambers without the need for surface pretreatment. A biophysical model suggests that the patterning mechanism involves stimulation of transiently surface-adsorbed cells, lending evidence to a previously proposed role of adhesin expression during natural biofilm maturation. Overall, this tool—termed “Biofilm Lithography”—has distinct advantages over existing cell-depositing/patterning methods and provides the ability to grow structured biofilms, with applications toward an improved understanding of natural biofilm communities, as well as the engineering of living biomaterials and bottom–up approaches to microbial consortia design.
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Insights into the structure and assembly of a bacterial cellulose secretion system. Nat Commun 2017; 8:2065. [PMID: 29234007 PMCID: PMC5727187 DOI: 10.1038/s41467-017-01523-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 09/25/2017] [Indexed: 12/20/2022] Open
Abstract
Secreted exopolysaccharides present important determinants for bacterial biofilm formation, survival, and virulence. Cellulose secretion typically requires the concerted action of a c-di-GMP-responsive inner membrane synthase (BcsA), an accessory membrane-anchored protein (BcsB), and several additional Bcs components. Although the BcsAB catalytic duo has been studied in great detail, its interplay with co-expressed subunits remains enigmatic. Here we show that E. coli Bcs proteins partake in a complex protein interaction network. Electron microscopy reveals a stable, megadalton-sized macromolecular assembly, which encompasses most of the inner membrane and cytosolic Bcs components and features a previously unobserved asymmetric architecture. Heterologous reconstitution and mutational analyses point toward a structure-function model, where accessory proteins regulate secretion by affecting both the assembly and stability of the system. Altogether, these results lay the foundation for more comprehensive models of synthase-dependent exopolysaccharide secretion in biofilms and add a sophisticated secretory nanomachine to the diverse bacterial arsenal for virulence and adaptation.
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The Gut Microbiota Facilitates Drifts in the Genetic Diversity and Infectivity of Bacterial Viruses. Cell Host Microbe 2017; 22:801-808.e3. [PMID: 29174401 DOI: 10.1016/j.chom.2017.10.010] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/11/2017] [Accepted: 09/29/2017] [Indexed: 01/12/2023]
Abstract
The intestinal microbiota and human health are intimately linked, but interactions between bacteria and bacteriophages in the context of the mammalian intestine remain largely unexplored. We used comparative population genomics to study a tripartite network consisting of a virulent bacteriophage, its bacterial host, and a phage-insensitive bacterial strain both in vitro and within the murine gut. The bacteriophage adapted to infect the insensitive strain when the three partners co-existed in the gut of conventional mice, but not in dixenic mice or in planktonic cultures. The molecular changes associated with modifications in the bacteriophage host spectrum included single amino acid substitutions and an unusual homologous intragenomic recombination event within the genome of the bacteriophage. An intermediate bacterial host isolated from the murine microbiota mediated bacteriophage adaptation. Our data indicate that by offering access to new hosts, the microbiota shifts the genetic diversity of bacteriophages, thereby promoting long-term persistence of bacteriophage populations.
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Martinez-Gil M, Goh KGK, Rackaityte E, Sakamoto C, Audrain B, Moriel DG, Totsika M, Ghigo JM, Schembri MA, Beloin C. YeeJ is an inverse autotransporter from Escherichia coli that binds to peptidoglycan and promotes biofilm formation. Sci Rep 2017; 7:11326. [PMID: 28900103 PMCID: PMC5595812 DOI: 10.1038/s41598-017-10902-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 08/16/2017] [Indexed: 02/08/2023] Open
Abstract
Escherichia coli is a commensal or pathogenic bacterium that can survive in diverse environments. Adhesion to surfaces is essential for E. coli colonization, and thus it is important to understand the molecular mechanisms that promote this process in different niches. Autotransporter proteins are a class of cell-surface factor used by E. coli for adherence. Here we characterized the regulation and function of YeeJ, a poorly studied but widespread representative from an emerging class of autotransporter proteins, the inverse autotransporters (IAT). We showed that the yeeJ gene is present in ~40% of 96 completely sequenced E. coli genomes and that YeeJ exists as two length variants, albeit with no detectable functional differences. We demonstrated that YeeJ promotes biofilm formation in different settings through exposition at the cell-surface. We also showed that YeeJ contains a LysM domain that interacts with peptidoglycan and thus assists its localization into the outer membrane. Additionally, we identified the Polynucleotide Phosphorylase PNPase as a repressor of yeeJ transcription. Overall, our work provides new insight into YeeJ as a member of the recently defined IAT class, and contributes to our understanding of how commensal and pathogenic E. coli colonise their environments.
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Affiliation(s)
- Marta Martinez-Gil
- Institut Pasteur, Unité de Génétique des Biofilms, 28 rue du Dr. Roux, 75724, Paris, CEDEX 15, France
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias. Universidad de Málaga, Málaga, Spain
| | - Kelvin G K Goh
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Elze Rackaityte
- Institut Pasteur, Unité de Génétique des Biofilms, 28 rue du Dr. Roux, 75724, Paris, CEDEX 15, France
- University of California San Francisco, Department of Medicine, San Francisco, CA, USA
| | - Chizuko Sakamoto
- Institut Pasteur, Unité de Génétique des Biofilms, 28 rue du Dr. Roux, 75724, Paris, CEDEX 15, France
| | - Bianca Audrain
- Institut Pasteur, Unité de Génétique des Biofilms, 28 rue du Dr. Roux, 75724, Paris, CEDEX 15, France
| | - Danilo G Moriel
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
- GSK Vaccines Institute for Global Health S.r.l., 53100, Siena, Italy
| | - Makrina Totsika
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia
- Institute of Health and Biomedical Innovation, and School of Biomedical Sciences, Queensland University of Technology, Kelvin Grove, QLD, 4059, Australia
| | - Jean-Marc Ghigo
- Institut Pasteur, Unité de Génétique des Biofilms, 28 rue du Dr. Roux, 75724, Paris, CEDEX 15, France
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Christophe Beloin
- Institut Pasteur, Unité de Génétique des Biofilms, 28 rue du Dr. Roux, 75724, Paris, CEDEX 15, France.
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Echeverz M, García B, Sabalza A, Valle J, Gabaldón T, Solano C, Lasa I. Lack of the PGA exopolysaccharide in Salmonella as an adaptive trait for survival in the host. PLoS Genet 2017; 13:e1006816. [PMID: 28542593 PMCID: PMC5464674 DOI: 10.1371/journal.pgen.1006816] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/08/2017] [Accepted: 05/12/2017] [Indexed: 12/22/2022] Open
Abstract
Many bacteria build biofilm matrices using a conserved exopolysaccharide named PGA or PNAG (poly-β-1,6-N-acetyl-D-glucosamine). Interestingly, while E. coli and other members of the family Enterobacteriaceae encode the pgaABCD operon responsible for PGA synthesis, Salmonella lacks it. The evolutionary force driving this difference remains to be determined. Here, we report that Salmonella lost the pgaABCD operon after the divergence of Salmonella and Citrobacter clades, and previous to the diversification of the currently sequenced Salmonella strains. Reconstitution of the PGA machinery endows Salmonella with the capacity to produce PGA in a cyclic dimeric GMP (c-di-GMP) dependent manner. Outside the host, the PGA polysaccharide does not seem to provide any significant benefit to Salmonella: resistance against chlorine treatment, ultraviolet light irradiation, heavy metal stress and phage infection remained the same as in a strain producing cellulose, the main biofilm exopolysaccharide naturally produced by Salmonella. In contrast, PGA production proved to be deleterious to Salmonella survival inside the host, since it increased susceptibility to bile salts and oxidative stress, and hindered the capacity of S. Enteritidis to survive inside macrophages and to colonize extraintestinal organs, including the gallbladder. Altogether, our observations indicate that PGA is an antivirulence factor whose loss may have been a necessary event during Salmonella speciation to permit survival inside the host. During bacterial evolution, specific traits that optimize the organism’s fitness are selected. The production of exopolysaccharides is widespread among bacteria in which they play a protective shielding role as main constituents of biofilms. In contrast to closely related siblings, Salmonella has lost the capacity to produce the exopolysaccharide PGA. Our study reveals that Salmonella lost pga genes, and that the driving force for such a loss may have been the detrimental impact that PGA has during Salmonella invasion of internal organs where it augments the susceptibility to bile salts and oxygen radicals, reducing bacterial survival inside macrophages and rendering Salmonella avirulent. These results suggest that gene-loss has played an important role during Salmonella evolution.
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Affiliation(s)
- Maite Echeverz
- Navarrabiomed-Universidad Pública de Navarra-Departamento de Salud, IDISNA, Pamplona, Spain
| | - Begoña García
- Navarrabiomed-Universidad Pública de Navarra-Departamento de Salud, IDISNA, Pamplona, Spain
| | - Amaia Sabalza
- Navarrabiomed-Universidad Pública de Navarra-Departamento de Salud, IDISNA, Pamplona, Spain
| | - Jaione Valle
- Navarrabiomed-Universidad Pública de Navarra-Departamento de Salud, IDISNA, Pamplona, Spain
| | - Toni Gabaldón
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Cristina Solano
- Navarrabiomed-Universidad Pública de Navarra-Departamento de Salud, IDISNA, Pamplona, Spain
- * E-mail: (CS); (IL)
| | - Iñigo Lasa
- Navarrabiomed-Universidad Pública de Navarra-Departamento de Salud, IDISNA, Pamplona, Spain
- * E-mail: (CS); (IL)
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13
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The Stringent Response Promotes Antibiotic Resistance Dissemination by Regulating Integron Integrase Expression in Biofilms. mBio 2016; 7:mBio.00868-16. [PMID: 27531906 PMCID: PMC4992968 DOI: 10.1128/mbio.00868-16] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Class 1 integrons are genetic systems that enable bacteria to capture and express gene cassettes. These integrons, when isolated in clinical contexts, most often carry antibiotic resistance gene cassettes. They play a major role in the dissemination of antibiotic resistance among Gram-negative bacteria. The key element of integrons is the integrase, which allows gene cassettes to be acquired and shuffled. Planktonic culture experiments have shown that integrase expression is regulated by the bacterial SOS response. In natural settings, however, bacteria generally live in biofilms, which are characterized by strong antibiotic resilience and by increased expression of stress-related genes. Here, we report that under biofilm conditions, the stringent response, which is induced upon starvation, (i) increases basal integrase and SOS regulon gene expression via induction of the SOS response and (ii) exerts biofilm-specific regulation of the integrase via the Lon protease. This indicates that biofilm environments favor integron-mediated acquisition of antibiotic resistance and other adaptive functions encoded by gene cassettes. Multidrug-resistant bacteria are becoming a worldwide health problem. Integrons are bacterial genetic platforms that allow the bacteria to capture and express gene cassettes. In clinical settings, integrons play a major role in the dissemination of antibiotic resistance gene cassettes among Gram-negative bacteria. Cassette capture is catalyzed by the integron integrase, whose expression is induced by DNA damage and controlled by the bacterial SOS response in laboratory planktonic cultures. In natural settings, bacteria usually grow in heterogeneous environments known as biofilms, which have very different conditions than planktonic cultures. Integrase regulation has not been investigated in biofilms. Our results showed that in addition to the SOS response, the stringent response (induced upon starvation) is specifically involved in the regulation of class 1 integron integrases in biofilms. This study shows that biofilms are favorable environments for integron-mediated acquisition/exchange of antibiotic resistance genes by bacteria and for the emergence of multidrug-resistant bacteria.
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Johns BE, Purdy KJ, Tucker NP, Maddocks SE. Phenotypic and Genotypic Characteristics of Small Colony Variants and Their Role in Chronic Infection. Microbiol Insights 2015; 8:15-23. [PMID: 26448688 PMCID: PMC4581789 DOI: 10.4137/mbi.s25800] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 08/09/2015] [Accepted: 08/13/2015] [Indexed: 01/02/2023] Open
Abstract
Small colony variant (SCV) bacteria arise spontaneously within apparently homogeneous microbial populations, largely in response to environmental stresses, such as antimicrobial treatment. They display unique phenotypic characteristics conferred in part by heritable genetic changes. Characteristically slow growing, SCVs comprise a minor proportion of the population from which they arise but persist by virtue of their inherent resilience and host adaptability. Consequently, SCVs are problematic in chronic infection, where antimicrobial treatment is administered during the acute phase of infection but fails to eradicate SCVs, which remain within the host causing recurrent or chronic infection. This review discusses some of the phenotypic and genotypic changes that enable SCVs to successfully proliferate within the host environment as potential pathogens and strategies that could ameliorate the resolution of infection where SCVs are present.
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Affiliation(s)
- Benjamin E Johns
- Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Nicholas P Tucker
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Sarah E Maddocks
- Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
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15
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Abstract
Plants and bacteria synthesize the essential human micronutrient riboflavin (vitamin B2) via the same multi-step pathway. The early intermediates of this pathway are notoriously reactive and may be overproduced in vivo because riboflavin biosynthesis enzymes lack feedback controls. In the present paper, we demonstrate disposal of riboflavin intermediates by COG3236 (DUF1768), a protein of previously unknown function that is fused to two different riboflavin pathway enzymes in plants and bacteria (RIBR and RibA respectively). We present cheminformatic, biochemical, genetic and genomic evidence to show that: (i) plant and bacterial COG3236 proteins cleave the N-glycosidic bond of the first two intermediates of riboflavin biosynthesis, yielding relatively innocuous products; (ii) certain COG3236 proteins are in a multi-enzyme riboflavin biosynthesis complex that gives them privileged access to riboflavin intermediates; and (iii) COG3236 action in Arabidopsis thaliana and Escherichia coli helps maintain flavin levels. COG3236 proteins thus illustrate two emerging principles in chemical biology: directed overflow metabolism, in which excess flux is diverted out of a pathway, and the pre-emption of damage from reactive metabolites.
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16
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Jacquot A, Sakamoto C, Razafitianamarahavo A, Caillet C, Merlin J, Fahs A, Ghigo JM, Duval JFL, Beloin C, Francius G. The dynamics and pH-dependence of Ag43 adhesins' self-association probed by atomic force spectroscopy. NANOSCALE 2014; 6:12665-12681. [PMID: 25208582 DOI: 10.1039/c4nr03312d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Self-associating auto-transporter (SAAT) adhesins are two-domain cell surface proteins involved in bacteria auto-aggregation and biofilm formation. Antigen 43 (Ag43) is a SAAT adhesin commonly found in Escherichia coli whose variant Ag43a has been shown to promote persistence of uropathogenic E. coli within the bladder. The recent resolution of the tri-dimensional structure of the 499 amino-acids' β-domain in Ag43a has shed light on the possible mechanism governing the self-recognition of SAAT adhesins, in particular the importance of trans-interactions between the L shaped β-helical scaffold of two α-domains of neighboring adhesins. In this study, we use single-molecule force spectroscopy (SMFS) and dynamic force spectroscopy (DFS) to unravel the dynamics of Ag43-self association under various pH and molecular elongation rate conditions that mimic the situations encountered by E. coli in its natural environment. Results evidenced an important stretchability of Ag43α with unfolding of sub-domains leading to molecular extension as long as 150 nm. Nanomechanical analysis of molecular stretching data suggested that self-association of Ag43 can lead to the formation of dimers and tetramers driven by rapid and weak cis- as well as slow but strong trans-interaction forces with a magnitude as large as 100-250 pN. The dynamics of cis- and trans-interactions were demonstrated to be strongly influenced by pH and applied shear force, thus suggesting that environmental conditions can modulate Ag43-mediated aggregation of bacteria at the molecular level.
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Affiliation(s)
- Adrien Jacquot
- Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, Villers-lès-Nancy, F-54601, France
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17
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Biofilms formed by gram-negative bacteria undergo increased lipid a palmitoylation, enhancing in vivo survival. mBio 2014; 5:mBio.01116-14. [PMID: 25139899 PMCID: PMC4147861 DOI: 10.1128/mbio.01116-14] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Bacterial biofilm communities are associated with profound physiological changes that lead to novel properties compared to the properties of individual (planktonic) bacteria. The study of biofilm-associated phenotypes is an essential step toward control of deleterious effects of pathogenic biofilms. Here we investigated lipopolysaccharide (LPS) structural modifications in Escherichia coli biofilm bacteria, and we showed that all tested commensal and pathogenic E. coli biofilm bacteria display LPS modifications corresponding to an increased level of incorporation of palmitate acyl chain (palmitoylation) into lipid A compared to planktonic bacteria. Genetic analysis showed that lipid A palmitoylation in biofilms is mediated by the PagP enzyme, which is regulated by the histone-like protein repressor H-NS and the SlyA regulator. While lipid A palmitoylation does not influence bacterial adhesion, it weakens inflammatory response and enhances resistance to some antimicrobial peptides. Moreover, we showed that lipid A palmitoylation increases in vivo survival of biofilm bacteria in a clinically relevant model of catheter infection, potentially contributing to biofilm tolerance to host immune defenses. The widespread occurrence of increased lipid A palmitoylation in biofilms formed by all tested bacteria suggests that it constitutes a new biofilm-associated phenotype in Gram-negative bacteria. Bacterial communities called biofilms display characteristic properties compared to isolated (planktonic) bacteria, suggesting that some molecules could be more particularly produced under biofilm conditions. We investigated biofilm-associated modifications occurring in the lipopolysaccharide (LPS), a major component of all Gram-negative bacterial outer membrane. We showed that all tested commensal and pathogenic biofilm bacteria display high incorporation of a palmitate acyl chain into the lipid A part of LPS. This lipid A palmitoylation is mediated by the PagP enzyme, whose expression in biofilm is controlled by the regulatory proteins H-NS and SlyA. We also showed that lipid A palmitoylation in biofilm bacteria reduces host inflammatory response and enhances their survival in an animal model of biofilm infections. While these results provide new insights into the biofilm lifestyle, they also suggest that the level of lipid A palmitoylation could be used as an indicator to monitor the development of biofilm infections on medical surfaces.
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Marhova M, Kostadinova S, Stoitsova S. Biofilm-Forming Capabilities of UrinaryEscherichia ColiIsolates. BIOTECHNOL BIOTEC EQ 2014. [DOI: 10.1080/13102818.2010.10817903] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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19
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Lenahan M, Sheridan Á, Morris D, Duffy G, Fanning S, Burgess CM. Transcriptomic Analysis of Triclosan-Susceptible and -Tolerant Escherichia coli O157:H19 in Response to Triclosan Exposure. Microb Drug Resist 2014; 20:91-103. [DOI: 10.1089/mdr.2013.0063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Mary Lenahan
- Food Safety Department, Teagasc Food Research Centre, Dublin, Ireland
| | - Áine Sheridan
- Food Safety Department, Teagasc Food Research Centre, Dublin, Ireland
- UCD Centre for Food Safety and the Centre for Food-Borne Zoonomics, UCD Centre for Molecular Innovation and Drug Design, School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland
| | - Dermot Morris
- Teagasc Animal and Grassland Research and Innovation Centre, Athenry, Co. Galway, Ireland
| | - Geraldine Duffy
- Food Safety Department, Teagasc Food Research Centre, Dublin, Ireland
| | - Séamus Fanning
- UCD Centre for Food Safety and the Centre for Food-Borne Zoonomics, UCD Centre for Molecular Innovation and Drug Design, School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland
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20
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A new biofilm-associated colicin with increased efficiency against biofilm bacteria. ISME JOURNAL 2014; 8:1275-88. [PMID: 24451204 DOI: 10.1038/ismej.2013.238] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 11/26/2013] [Accepted: 11/30/2013] [Indexed: 11/08/2022]
Abstract
Formation of bacterial biofilm communities leads to profound physiological modifications and increased physical and metabolic exchanges between bacteria. It was previously shown that bioactive molecules produced within the biofilm environment contribute to bacterial interactions. Here we describe new pore-forming colicin R, specifically produced in biofilms formed by the natural isolate Escherichia coli ROAR029 but that cannot be detected under planktonic culture conditions. We demonstrate that an increased SOS stress response within mature biofilms induces SOS-dependent colicin R expression. We provide evidence that colicin R displays increased activity against E. coli strains that have a reduced lipopolysaccharide length, such as the pathogenic enteroaggregative E. coli LF82 clinical isolate, therefore pointing to lipopolysaccharide size as an important determinant for resistance to colicins. We show that colicin R toxicity toward E. coli LF82 is increased under biofilm conditions compared with planktonic susceptibility and that release of colicin R confers a strong competitive advantage in mixed biofilms by rapidly outcompeting sensitive neighboring bacteria. This work identifies the first biofilm-associated colicin that preferentially targets biofilm bacteria. Furthermore, it indicates that the study of antagonistic molecules produced in biofilm and multispecies contexts could reveal unsuspected, ecologically relevant bacterial interactions influencing population dynamics in natural environments.
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Aerial exposure to the bacterial volatile compound trimethylamine modifies antibiotic resistance of physically separated bacteria by raising culture medium pH. mBio 2014; 5:e00944-13. [PMID: 24399857 PMCID: PMC3884056 DOI: 10.1128/mbio.00944-13] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Bacteria release a wide diversity of small bioactive molecules that often correspond to secondary metabolites. Among them, volatile molecules produced under various growth conditions were shown to mediate cross-kingdom interactions with plants, nematodes, and fungi. Although the role of volatile compounds in bacterial biology is not well understood, recent reports indicated that they could play a role in airborne interactions between bacteria and influence antibiotic resistance, biofilm formation, and virulence. In this study, we investigated long-distance effects of 14 previously described Escherichia coli volatile compounds upon the bacteria E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis. We show that several of these molecules constitute chemical cues influencing growth, adhesion, and motility in exposed bacteria. Moreover, we show that aerial exposure to trimethylamine (TMA), a volatile compound produced in animal intestines and tissues upon biogenic reduction of trimethylamine oxide (TMAO), modifies the antibiotic resistance profiles of all tested Gram-positive and Gram-negative bacteria. We demonstrate that the TMA mode of action is distinct from that previously described for ammonia and results from nonspecific transient alteration of antibiotic uptake due to pH increase in the environment of bacteria aerially exposed to TMA. Our study therefore presents a new way by which volatile compounds can affect community behavior and structure in physically separated bacteria. It further demonstrates that bacterial gases and volatile compounds mediate chemical interactions, triggering functional responses that play an important role in the development of bacterial communities. IMPORTANCE Bacteria release many different volatile compounds during food transformation and fermentation. Here we sought to investigate the role of several bacterial volatile molecules released by Escherichia coli during long-distance airborne interactions with other bacteria. While several tested volatiles affect bacterial motility and surface adhesion, we show that aerial exposure to trimethylamine, a molecule produced by E. coli and many other Gram-negative bacteria in animal intestines and infected tissues, also modulates antibiotic resistance in all tested bacteria. We demonstrate that exposure to trimethylamine increases the pH of the growth medium of exposed bacteria, resulting in modifications in antibiotic uptake and transient alteration of antibiotic resistance. Our study therefore presents a new mechanism by which volatile compounds can affect community behavior and structure in physically separated bacteria, and it illustrates how airborne chemical interactions between bacteria contribute to the development of bacterial communities.
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22
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Chauhan A, Sakamoto C, Ghigo JM, Beloin C. Did I pick the right colony? Pitfalls in the study of regulation of the phase variable antigen 43 adhesin. PLoS One 2013; 8:e73568. [PMID: 24039985 PMCID: PMC3764049 DOI: 10.1371/journal.pone.0073568] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 07/21/2013] [Indexed: 11/27/2022] Open
Abstract
Ag43 is an abundant outer membrane autotransporter adhesin present in most commensal and pathogenic Escherichia coli. Expression of the agn43 gene is characterized by a regulated reversible switch or phase variation between the agn43 ON and agn43 OFF states. Although the agn43 regulatory switch leads to a heterogeneous population of ON and OFF bacteria, studies of Ag43 seldom consider potential biases associated with phase variation. We monitored agn43 ON/OFF phase-variation status genetically and phenotypically and we show that the use of populations with random agn43 ON or OFF status could result in misleading conclusions about Ag43 function or regulation. In particular, we demonstrate that Lrp and MqsR, previously identified as agn43 regulators, do not regulate agn43 expression or ON/OFF switch frequency. We also show that biofilm formation in dynamic flow conditions does not influence agn43 ON/OFF switching but physically selects aggregating agn43 ON cells. This indicates that misinterpretation is possible when studying gene expression within biofilms. Finally, we provide evidence that ignoring the initial agn43 ON/OFF status of the E. coli populations studied is likely to bias analyses of phenotypes associated with other E. coli adhesins. This study therefore emphasizes the importance of monitoring Ag43 phase variation and indicates that caution is required when interpreting experiments using strains that are neither deleted for agn43 nor carefully assessed for agn43 ON/OFF status.
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Affiliation(s)
- Ashwini Chauhan
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Chizuko Sakamoto
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, cellule Pasteur, Paris, France
| | - Jean-Marc Ghigo
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Christophe Beloin
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
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23
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Escherichia coli resistance to nonbiocidal antibiofilm polysaccharides is rare and mediated by multiple mutations leading to surface physicochemical modifications. Antimicrob Agents Chemother 2013; 57:3960-8. [PMID: 23733462 DOI: 10.1128/aac.02606-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antivirulence strategies targeting bacterial behavior, such as adhesion and biofilm formation, are expected to exert low selective pressure and have been proposed as alternatives to biocidal antibiotic treatments to avoid the rapid occurrence of bacterial resistance. Here, we tested this hypothesis using group 2 capsule polysaccharide (G2cps), a polysaccharidic molecule previously shown to impair bacterium-surface interactions, and we investigated the nature of bacterial resistance to a nonbiocidal antibiofilm strategy. We screened an Escherichia coli mutant library for an increased ability to form biofilm in the presence of G2cps, and we identified several mutants displaying partial but not total resistance to this antibiofilm polysaccharide. Our genetic analysis showed that partial resistance to G2cps results from multiple unrelated mutations leading to modifications in surface physicochemical properties that counteract the changes in ionic charge and Lewis base properties induced by G2cps. Moreover, some of the identified mutants harboring improved biofilm formation in the presence of G2cps were also partially resistant to other antibiofilm molecules. This study therefore shows that alterations of bacterial surface properties mediate only partial resistance to G2cps. It also experimentally validates the potential value of nonbiocidal antibiofilm strategies, since full resistance to antibiofilm compounds is rare and potentially unlikely to arise in clinical settings.
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Da Re S, Valle J, Charbonnel N, Beloin C, Latour-Lambert P, Faure P, Turlin E, Le Bouguénec C, Renauld-Mongénie G, Forestier C, Ghigo JM. Identification of commensal Escherichia coli genes involved in biofilm resistance to pathogen colonization. PLoS One 2013; 8:e61628. [PMID: 23667443 PMCID: PMC3646849 DOI: 10.1371/journal.pone.0061628] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 03/12/2013] [Indexed: 12/24/2022] Open
Abstract
Protection provided by host bacterial microbiota against microbial pathogens is a well known but ill-understood property referred to as the barrier effect, or colonization resistance. Despite recent genome-wide analyses of host microbiota and increasing therapeutic interest, molecular analysis of colonization resistance is hampered by the complexity of direct in vivo experiments. Here we developed an in vitro-to-in vivo approach to identification of genes involved in resistance of commensal bacteria to exogenous pathogens. We analyzed genetic responses induced in commensal Escherichia coli upon entry of a diarrheagenic enteroaggregative E. coli or an unrelated Klebsiella pneumoniae pathogen into a biofilm community. We showed that pathogens trigger specific responses in commensal bacteria and we identified genes involved in limiting colonization of incoming pathogens within commensal biofilm. We tested the in vivo relevance of our findings by comparing the extent of intestinal colonization by enteroaggregative E. coli and K. pneumoniae pathogens in mice pre-colonized with E. coli wild type commensal strain, or mutants corresponding to identified colonization resistance genes. We demonstrated that the absence of yiaF and bssS (yceP) differentially alters pathogen colonization in the mouse gut. This study therefore identifies previously uncharacterized colonization resistance genes and provides new approaches to unravelling molecular aspects of commensal/pathogen competitive interactions.
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Affiliation(s)
- Sandra Da Re
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Jaione Valle
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Nicolas Charbonnel
- Université d'Auvergne-Clermont 1, Laboratoire de Bactériologie, Clermont-Ferrand, France
| | - Christophe Beloin
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Patricia Latour-Lambert
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Philippe Faure
- Université Pierre et Marie Curie, Equipe Neurophysiologie et Comportement (NPC) - UMR 7102, Paris, France
| | - Evelyne Turlin
- Institut Pasteur, Unité des Membranes Bactériennes, Département de Microbiologie, Paris, France
| | - Chantal Le Bouguénec
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, Département de Microbiologie, Paris, France
| | | | - Christiane Forestier
- Université d'Auvergne-Clermont 1, Laboratoire de Bactériologie, Clermont-Ferrand, France
| | - Jean-Marc Ghigo
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
- * E-mail:
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25
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Bernier SP, Lebeaux D, DeFrancesco AS, Valomon A, Soubigou G, Coppée JY, Ghigo JM, Beloin C. Starvation, together with the SOS response, mediates high biofilm-specific tolerance to the fluoroquinolone ofloxacin. PLoS Genet 2013; 9:e1003144. [PMID: 23300476 PMCID: PMC3536669 DOI: 10.1371/journal.pgen.1003144] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 10/22/2012] [Indexed: 12/14/2022] Open
Abstract
High levels of antibiotic tolerance are a hallmark of bacterial biofilms. In contrast to well-characterized inherited antibiotic resistance, molecular mechanisms leading to reversible and transient antibiotic tolerance displayed by biofilm bacteria are still poorly understood. The physiological heterogeneity of biofilms influences the formation of transient specialized subpopulations that may be more tolerant to antibiotics. In this study, we used random transposon mutagenesis to identify biofilm-specific tolerant mutants normally exhibited by subpopulations located in specialized niches of heterogeneous biofilms. Using Escherichia coli as a model organism, we demonstrated, through identification of amino acid auxotroph mutants, that starved biofilms exhibited significantly greater tolerance towards fluoroquinolone ofloxacin than their planktonic counterparts. We demonstrated that the biofilm-associated tolerance to ofloxacin was fully dependent on a functional SOS response upon starvation to both amino acids and carbon source and partially dependent on the stringent response upon leucine starvation. However, the biofilm-specific ofloxacin increased tolerance did not involve any of the SOS-induced toxin–antitoxin systems previously associated with formation of highly tolerant persisters. We further demonstrated that ofloxacin tolerance was induced as a function of biofilm age, which was dependent on the SOS response. Our results therefore show that the SOS stress response induced in heterogeneous and nutrient-deprived biofilm microenvironments is a molecular mechanism leading to biofilm-specific high tolerance to the fluoroquinolone ofloxacin. Biofilm surface-attached communities have the capacity to tolerate high concentrations of antibiotics, and bacterial biofilms formed on indwelling medical devices are difficult to eradicate and often lead to the onset of chronic or systemic infections. The physiological heterogeneity of multicellular biofilms has been associated with development of subpopulations highly tolerant to multiple antibiotics. Here we demonstrate that, upon starvation for specific essential growth nutrients, biofilm bacteria become highly tolerant to fluoroquinolone ofloxacin. The SOS response plays a critical role in this phenomenon, while the stringent response plays only a minor role. Taken together, these results support the hypothesis that bacteria localized within nutrient-limited niches of the biofilm structure may temporarily enter a physiological state enabling them to tolerate bactericidal concentrations of antibiotics.
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Affiliation(s)
- Steve P. Bernier
- Institut Pasteur, Unité de Génétique des Biofilms, Paris, France
| | - David Lebeaux
- Institut Pasteur, Unité de Génétique des Biofilms, Paris, France
| | | | - Amandine Valomon
- Institut Pasteur, Unité de Génétique des Biofilms, Paris, France
| | - Guillaume Soubigou
- Institut Pasteur, Génopole, Plate-forme 2–Transcriptome et Epigénome, Paris, France
| | - Jean-Yves Coppée
- Institut Pasteur, Génopole, Plate-forme 2–Transcriptome et Epigénome, Paris, France
| | - Jean-Marc Ghigo
- Institut Pasteur, Unité de Génétique des Biofilms, Paris, France
| | - Christophe Beloin
- Institut Pasteur, Unité de Génétique des Biofilms, Paris, France
- * E-mail:
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26
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Robledo M, Rivera L, Jiménez-Zurdo JI, Rivas R, Dazzo F, Velázquez E, Martínez-Molina E, Hirsch AM, Mateos PF. Role of Rhizobium endoglucanase CelC2 in cellulose biosynthesis and biofilm formation on plant roots and abiotic surfaces. Microb Cell Fact 2012; 11:125. [PMID: 22970813 PMCID: PMC3520766 DOI: 10.1186/1475-2859-11-125] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 09/06/2012] [Indexed: 02/02/2023] Open
Abstract
Background The synthesis of cellulose is among the most important but poorly understood biochemical processes, especially in bacteria, due to its complexity and high degree of regulation. In this study, we analyzed both the production of cellulose by all known members of the Rhizobiaceae and the diversity of Rhizobium celABC operon predicted to be involved in cellulose biosynthesis. We also investigated the involvement in cellulose production and biofilm formation of celC gene encoding an endoglucanase (CelC2) that is required for canonical symbiotic root hair infection by Rhizobium leguminosarum bv. trifolii. Results ANU843 celC mutants lacking (ANU843ΔC2) or overproducing cellulase (ANU843C2+) produced greatly increased or reduced amounts of external cellulose micro fibrils, respectively. Calcofluor-stained cellulose micro fibrils were considerably longer when formed by ANU843ΔC2 bacteria rather than by the wild-type strain, in correlation with a significant increase in their flocculation in batch culture. In contrast, neither calcofluor-stained extracellular micro fibrils nor flocculation was detectable in ANU843C2+ cells. To clarify the role of cellulose synthesis in Rhizobium cell aggregation and attachment, we analyzed the ability of these mutants to produce biofilms on different surfaces. Alteration of wild-type CelC2 levels resulted in a reduced ability of bacteria to form biofilms both in abiotic surfaces and in planta. Conclusions Our results support a key role of the CelC2 cellulase in cellulose biosynthesis by modulating the length of the cellulose fibrils that mediate firm adhesion among Rhizobium bacteria leading to biofilm formation. Rhizobium cellulose is an essential component of the biofilm polysaccharidic matrix architecture and either an excess or a defect of this “building material” seem to collapse the biofilm structure. These results position cellulose hydrolytic enzymes as excellent anti-biofilm candidates.
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Affiliation(s)
- M Robledo
- Departamento de Microbiología y Genética and CIALE, Universidad de Salamanca, Salamanca, Spain
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Saragosti J, Silberzan P, Buguin A. Modeling E. coli tumbles by rotational diffusion. Implications for chemotaxis. PLoS One 2012; 7:e35412. [PMID: 22530021 PMCID: PMC3329434 DOI: 10.1371/journal.pone.0035412] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 03/15/2012] [Indexed: 11/18/2022] Open
Abstract
The bacterium Escherichia coli in suspension in a liquid medium swims by a succession of runs and tumbles, effectively describing a random walk. The tumbles randomize incompletely, i.e. with a directional persistence, the orientation taken by the bacterium. Here, we model these tumbles by an active rotational diffusion process characterized by a diffusion coefficient and a diffusion time. In homogeneous media, this description accounts well for the experimental reorientations. In shallow gradients of nutrients, tumbles are still described by a unique rotational diffusion coefficient. Together with an increase in the run length, these tumbles significantly contribute to the net chemotactic drift via a modulation of their duration as a function of the direction of the preceding run. Finally, we discuss the limits of this model in propagating concentration waves characterized by steep gradients. In that case, the effective rotational diffusion coefficient itself varies with the direction of the preceding run. We propose that this effect is related to the number of flagella involved in the reorientation process.
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Affiliation(s)
- Jonathan Saragosti
- Laboratoire Physico-chimie Curie - UMR 168, Institut Curie, Centre de Recherche – CNRS – UPMC, Paris, France
| | - Pascal Silberzan
- Laboratoire Physico-chimie Curie - UMR 168, Institut Curie, Centre de Recherche – CNRS – UPMC, Paris, France
| | - Axel Buguin
- Laboratoire Physico-chimie Curie - UMR 168, Institut Curie, Centre de Recherche – CNRS – UPMC, Paris, France
- * E-mail:
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Connecting environment and genome plasticity in the characterization of transformation-induced SOS regulation and carbon catabolite control of the Vibrio cholerae integron integrase. J Bacteriol 2012; 194:1659-67. [PMID: 22287520 DOI: 10.1128/jb.05982-11] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The human pathogen Vibrio cholerae carries a chromosomal superintegron (SI). The SI contains an array of hundreds of gene cassettes organized in tandem which are stable under conditions when no particular stress is applied to bacteria (such as during laboratory growth). Rearrangements of these cassettes are catalyzed by the activity of the associated integron integrase. Understanding the regulation of integrase expression is pivotal to fully comprehending the role played by this genetic reservoir for bacterial adaptation and its connection with the development of antibiotic resistance. Our previous work established that the integrase is regulated by the bacterial SOS response and that it is induced during bacterial conjugation. Here, we show that transformation, another horizontal gene transfer (HGT) mechanism, also triggers integrase expression through SOS induction, underlining the importance of HGT in genome plasticity. Moreover, we report a new cyclic AMP (cAMP)-cAMP receptor protein (CRP)-dependent regulation mechanism of the integrase, highlighting the influence of the extracellular environment on chromosomal gene content. Altogether, our data suggest an interplay between different stress responses and regulatory pathways for the modulation of the recombinase expression, thus showing how the SI remodeling mechanism is merged into bacterial physiology.
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Spagnolo J, Bigot S, Denis Y, Bordi C, de Bentzmann S. Development of a genetic tool for activating chromosomal expression of cryptic or tightly regulated loci in Pseudomonas aeruginosa. Plasmid 2011; 67:245-51. [PMID: 22212534 DOI: 10.1016/j.plasmid.2011.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 12/15/2011] [Accepted: 12/18/2011] [Indexed: 11/24/2022]
Abstract
A method for replacing endogenous promoter by a constitutive promoter in Pseudomonas aeruginosa is described. Plasmid pKNG101, a broadly used shuttle suicide vector in P. aeruginosa, was improved to allow chromosomal introduction of a Plac promoter in front of any kind of gene especially those with unknown function. Using this strategy alleviates the need for cloning difficulties encountered in this bacteria and antibiotic marker selection.
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Affiliation(s)
- Jennifer Spagnolo
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, CNRS-Aix Marseille Université, Marseille, France
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Saragosti J, Calvez V, Bournaveas N, Perthame B, Buguin A, Silberzan P. Directional persistence of chemotactic bacteria in a traveling concentration wave. Proc Natl Acad Sci U S A 2011; 108:16235-40. [PMID: 21918111 PMCID: PMC3182703 DOI: 10.1073/pnas.1101996108] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chemotactic bacteria are known to collectively migrate towards sources of attractants. In confined convectionless geometries, concentration "waves" of swimming Escherichia coli can form and propagate through a self-organized process involving hundreds of thousands of these microorganisms. These waves are observed in particular in microcapillaries or microchannels; they result from the interaction between individual chemotactic bacteria and the macroscopic chemical gradients dynamically generated by the migrating population. By studying individual trajectories within the propagating wave, we show that, not only the mean run length is longer in the direction of propagation, but also that the directional persistence is larger compared to the opposite direction. This modulation of the reorientations significantly improves the efficiency of the collective migration. Moreover, these two quantities are spatially modulated along the concentration profile. We recover quantitatively these microscopic and macroscopic observations with a dedicated kinetic model.
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Affiliation(s)
- J. Saragosti
- Laboratoire Physico-chimie Curie—Unité Mixte de Recherche (UMR) 168; Institut Curie, Centre de Recherche; Centre National de la Recherche Scientifique (CNRS); Université Pierre et Marie Curie (UPMC); F-75248 Paris, France
| | - V. Calvez
- Unité de Mathématiques pures et appliquées—Unité Mixte de Recherche (UMR) 5669; Ecole Normale Supérieure de Lyon; Centre National de la Recherche Scientifique (CNRS); F-69364 Lyon, France
| | - N. Bournaveas
- School of Mathematics, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom; and
| | - B. Perthame
- Laboratoire Jacques-Louis Lions—BC187; Centre National de la Recherche Scientifique (CNRS); UPMC; Institut Universitaire de France (IUF); F-75252 Paris, France
| | - A. Buguin
- Laboratoire Physico-chimie Curie—Unité Mixte de Recherche (UMR) 168; Institut Curie, Centre de Recherche; Centre National de la Recherche Scientifique (CNRS); Université Pierre et Marie Curie (UPMC); F-75248 Paris, France
| | - P. Silberzan
- Laboratoire Physico-chimie Curie—Unité Mixte de Recherche (UMR) 168; Institut Curie, Centre de Recherche; Centre National de la Recherche Scientifique (CNRS); Université Pierre et Marie Curie (UPMC); F-75248 Paris, France
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Molecular characterization of UpaB and UpaC, two new autotransporter proteins of uropathogenic Escherichia coli CFT073. Infect Immun 2011; 80:321-32. [PMID: 21930758 DOI: 10.1128/iai.05322-11] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) is the primary cause of urinary tract infection (UTI) in the developed world. The major factors associated with virulence of UPEC are fimbrial adhesins, which mediate specific attachment to host receptors and trigger innate host responses. Another group of adhesins is represented by the autotransporter (AT) subgroup of proteins. The genome-sequenced prototype UPEC strain CFT073 contains 11 putative AT-encoding genes. In this study, we have performed a detailed molecular characterization of two closely related AT adhesins from CFT073: UpaB (c0426) and UpaC (c0478). PCR screening revealed that the upaB and upaC AT-encoding genes are common in E. coli. The upaB and upaC genes were cloned and characterized in a recombinant E. coli K-12 strain background. This revealed that they encode proteins located at the cell surface but possess different functional properties: UpaB mediates adherence to several ECM proteins, while UpaC expression is associated with increased biofilm formation. In CFT073, upaB is expressed while upaC is transcriptionally repressed by the global regulator H-NS. In competitive colonization experiments employing the mouse UTI model, CFT073 significantly outcompeted its upaB (but not upaC) isogenic mutant strain in the bladder. This attenuated phenotype was also observed in single-challenge experiments, where deletion of the upaB gene in CFT073 significantly reduced early colonization of the bladder.
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Gerdes S, El Yacoubi B, Bailly M, Blaby IK, Blaby-Haas CE, Jeanguenin L, Lara-Núñez A, Pribat A, Waller JC, Wilke A, Overbeek R, Hanson AD, de Crécy-Lagard V. Synergistic use of plant-prokaryote comparative genomics for functional annotations. BMC Genomics 2011; 12 Suppl 1:S2. [PMID: 21810204 PMCID: PMC3223725 DOI: 10.1186/1471-2164-12-s1-s2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Identifying functions for all gene products in all sequenced organisms is a central challenge of the post-genomic era. However, at least 30-50% of the proteins encoded by any given genome are of unknown or vaguely known function, and a large number are wrongly annotated. Many of these 'unknown' proteins are common to prokaryotes and plants. We set out to predict and experimentally test the functions of such proteins. Our approach to functional prediction integrates comparative genomics based mainly on microbial genomes with functional genomic data from model microorganisms and post-genomic data from plants. This approach bridges the gap between automated homology-based annotations and the classical gene discovery efforts of experimentalists, and is more powerful than purely computational approaches to identifying gene-function associations. RESULTS Among Arabidopsis genes, we focused on those (2,325 in total) that (i) are unique or belong to families with no more than three members, (ii) occur in prokaryotes, and (iii) have unknown or poorly known functions. Computer-assisted selection of promising targets for deeper analysis was based on homology-independent characteristics associated in the SEED database with the prokaryotic members of each family. In-depth comparative genomic analysis was performed for 360 top candidate families. From this pool, 78 families were connected to general areas of metabolism and, of these families, specific functional predictions were made for 41. Twenty-one predicted functions have been experimentally tested or are currently under investigation by our group in at least one prokaryotic organism (nine of them have been validated, four invalidated, and eight are in progress). Ten additional predictions have been independently validated by other groups. Discovering the function of very widespread but hitherto enigmatic proteins such as the YrdC or YgfZ families illustrates the power of our approach. CONCLUSIONS Our approach correctly predicted functions for 19 uncharacterized protein families from plants and prokaryotes; none of these functions had previously been correctly predicted by computational methods. The resulting annotations could be propagated with confidence to over six thousand homologous proteins encoded in over 900 bacterial, archaeal, and eukaryotic genomes currently available in public databases.
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Affiliation(s)
- Svetlana Gerdes
- Fellowship for Interpretation of Genomes, Burr Ridge, IL, USA
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Francius G, Polyakov P, Merlin J, Abe Y, Ghigo JM, Merlin C, Beloin C, Duval JFL. Bacterial surface appendages strongly impact nanomechanical and electrokinetic properties of Escherichia coli cells subjected to osmotic stress. PLoS One 2011; 6:e20066. [PMID: 21655293 PMCID: PMC3105017 DOI: 10.1371/journal.pone.0020066] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 04/17/2011] [Indexed: 11/19/2022] Open
Abstract
The physicochemical properties and dynamics of bacterial envelope, play a major role in bacterial activity. In this study, the morphological, nanomechanical and electrohydrodynamic properties of Escherichia coli K-12 mutant cells were thoroughly investigated as a function of bulk medium ionic strength using atomic force microscopy (AFM) and electrokinetics (electrophoresis). Bacteria were differing according to genetic alterations controlling the production of different surface appendages (short and rigid Ag43 adhesins, longer and more flexible type 1 fimbriae and F pilus). From the analysis of the spatially resolved force curves, it is shown that cells elasticity and turgor pressure are not only depending on bulk salt concentration but also on the presence/absence and nature of surface appendage. In 1 mM KNO(3), cells without appendages or cells surrounded by Ag43 exhibit large Young moduli and turgor pressures (∼700-900 kPa and ∼100-300 kPa respectively). Under similar ionic strength condition, a dramatic ∼50% to ∼70% decrease of these nanomechanical parameters was evidenced for cells with appendages. Qualitatively, such dependence of nanomechanical behavior on surface organization remains when increasing medium salt content to 100 mM, even though, quantitatively, differences are marked to a much smaller extent. Additionally, for a given surface appendage, the magnitude of the nanomechanical parameters decreases significantly when increasing bulk salt concentration. This effect is ascribed to a bacterial exoosmotic water loss resulting in a combined contraction of bacterial cytoplasm together with an electrostatically-driven shrinkage of the surface appendages. The former process is demonstrated upon AFM analysis, while the latter, inaccessible upon AFM imaging, is inferred from electrophoretic data interpreted according to advanced soft particle electrokinetic theory. Altogether, AFM and electrokinetic results clearly demonstrate the intimate relationship between structure/flexibility and charge of bacterial envelope and propensity of bacterium and surface appendages to contract under hypertonic conditions.
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Affiliation(s)
- Grégory Francius
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, Nancy Université, CNRS UMR7564, Villers-lès-Nancy, France
| | - Pavel Polyakov
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, Nancy Université, CNRS UMR7564, Villers-lès-Nancy, France
| | - Jenny Merlin
- Laboratoire Environnement et Minéralurgie, Nancy Université, CNRS UMR7569, Vandoeuvre-lès-Nancy, France
| | - Yumiko Abe
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, Nancy Université, CNRS UMR7564, Villers-lès-Nancy, France
| | - Jean-Marc Ghigo
- Institut Pasteur, Unité de Génétique des Biofilms, Paris, France
- CNRS URA 2172, Paris, France
| | - Christophe Merlin
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, Nancy Université, CNRS UMR7564, Villers-lès-Nancy, France
| | - Christophe Beloin
- Institut Pasteur, Unité de Génétique des Biofilms, Paris, France
- CNRS URA 2172, Paris, France
| | - Jérôme F. L. Duval
- Laboratoire Environnement et Minéralurgie, Nancy Université, CNRS UMR7569, Vandoeuvre-lès-Nancy, France
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Polyakov P, Soussen C, Duan J, Duval JFL, Brie D, Francius G. Automated force volume image processing for biological samples. PLoS One 2011; 6:e18887. [PMID: 21559483 PMCID: PMC3084721 DOI: 10.1371/journal.pone.0018887] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 03/24/2011] [Indexed: 01/09/2023] Open
Abstract
Atomic force microscopy (AFM) has now become a powerful technique for investigating on a molecular level, surface forces, nanomechanical properties of deformable particles, biomolecular interactions, kinetics, and dynamic processes. This paper specifically focuses on the analysis of AFM force curves collected on biological systems, in particular, bacteria. The goal is to provide fully automated tools to achieve theoretical interpretation of force curves on the basis of adequate, available physical models. In this respect, we propose two algorithms, one for the processing of approach force curves and another for the quantitative analysis of retraction force curves. In the former, electrostatic interactions prior to contact between AFM probe and bacterium are accounted for and mechanical interactions operating after contact are described in terms of Hertz-Hooke formalism. Retraction force curves are analyzed on the basis of the Freely Jointed Chain model. For both algorithms, the quantitative reconstruction of force curves is based on the robust detection of critical points (jumps, changes of slope or changes of curvature) which mark the transitions between the various relevant interactions taking place between the AFM tip and the studied sample during approach and retraction. Once the key regions of separation distance and indentation are detected, the physical parameters describing the relevant interactions operating in these regions are extracted making use of regression procedure for fitting experiments to theory. The flexibility, accuracy and strength of the algorithms are illustrated with the processing of two force-volume images, which collect a large set of approach and retraction curves measured on a single biological surface. For each force-volume image, several maps are generated, representing the spatial distribution of the searched physical parameters as estimated for each pixel of the force-volume image.
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Affiliation(s)
- Pavel Polyakov
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - Charles Soussen
- Centre de Recherche en Automatique de Nancy, CRAN, UMR 7039, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - Junbo Duan
- Centre de Recherche en Automatique de Nancy, CRAN, UMR 7039, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - Jérôme F. L. Duval
- Laboratoire Environnement et Minéralurgie, LEM, UMR 7569, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
| | - David Brie
- Centre de Recherche en Automatique de Nancy, CRAN, UMR 7039, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
- * E-mail: (GF); (DB)
| | - Grégory Francius
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Nancy-Université, CNRS, Vandoeuvre lès Nancy, France
- * E-mail: (GF); (DB)
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A role for the universal Kae1/Qri7/YgjD (COG0533) family in tRNA modification. EMBO J 2011; 30:882-93. [PMID: 21285948 DOI: 10.1038/emboj.2010.363] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 12/21/2010] [Indexed: 11/09/2022] Open
Abstract
The YgjD/Kae1 family (COG0533) has been on the top-10 list of universally conserved proteins of unknown function for over 5 years. It has been linked to DNA maintenance in bacteria and mitochondria and transcription regulation and telomere homeostasis in eukaryotes, but its actual function has never been found. Based on a comparative genomic and structural analysis, we predicted this family was involved in the biosynthesis of N(6)-threonylcarbamoyl adenosine, a universal modification found at position 37 of tRNAs decoding ANN codons. This was confirmed as a yeast mutant lacking Kae1 is devoid of t(6)A. t(6)A(-) strains were also used to reveal that t(6)A has a critical role in initiation codon restriction to AUG and in restricting frameshifting at tandem ANN codons. We also showed that YaeZ, a YgjD paralog, is required for YgjD function in vivo in bacteria. This work lays the foundation for understanding the pleiotropic role of this universal protein family.
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Le Quéré B, Ghigo JM. BcsQ is an essential component of the Escherichia coli cellulose biosynthesis apparatus that localizes at the bacterial cell pole. Mol Microbiol 2010; 72:724-40. [PMID: 19400787 DOI: 10.1111/j.1365-2958.2009.06678.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Biofilms are microbial communities characterized by three-dimensional growth resulting from the ability of individual cells to adhere to each other as well as to produce an extracellular matrix that ensures biofilm physical cohesion. Numerous bacteria produce cellulose as a biofilm matrix polymer, a property relying on the expression of bacterial cellulose synthesis (Bcs) proteins and their post-translational activation upon binding of cyclic di-guanosine mono-phosphate second messenger (c-di-GMP) produced by diguanylate cyclases. In Escherichia coli and other Enterobacteriaceae, two genes of unknown function, yhjR and yhjQ, are located upstream of the bcs genes. Here, we show that yhjQ, but not yhjR, is essential for cellulose biosynthesis; it has therefore been renamed bcsQ. Using a green fluorescent protein (GFP) fusion approach, we demonstrate that BcsQ, a MinD homologue, displays a polar localization and that cell-to-cell adhesion is initiated through production of cellulose at the BcsQ-labelled pole. Although we did not detect a similar localization for other Bcs proteins, immunogold labelling of cellulose itself at the pole of individual bacteria indicates the localized activity of the cellulose biosynthesis apparatus. These results therefore suggest that BcsQ could participate in spatial restriction of cellulose biosynthesis activity in Enterobacteriaceae.
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Affiliation(s)
- Benjamin Le Quéré
- Institut Pasteur, Unité de Génétique des Biofilms, CNRS URA 2172, 25-28 rue du Dr Roux, Paris, France
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Upadhyayula VK, Gadhamshetty V. Appreciating the role of carbon nanotube composites in preventing biofouling and promoting biofilms on material surfaces in environmental engineering: A review. Biotechnol Adv 2010; 28:802-16. [DOI: 10.1016/j.biotechadv.2010.06.006] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 05/30/2010] [Accepted: 06/17/2010] [Indexed: 10/19/2022]
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May T, Tsuruta K, Okabe S. Exposure of conjugative plasmid carrying Escherichia coli biofilms to male-specific bacteriophages. ISME JOURNAL 2010; 5:771-5. [PMID: 20962879 DOI: 10.1038/ismej.2010.158] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Escherichia coli carrying a natural conjugative F-plasmid generates F-pili mating pairs, which is important for early biofilm formation. In this study, we investigated the effect of male-specific filamentous single stranded DNA bacteriophage (f1) and RNA bacteriophage (MS2) on the formation of biofilms by E. coli carrying a natural conjugative F-plasmid. We showed that the early biofilm formation was completely inhibited by addition of the f1 phage, but not the MS2 phage. This suggests that the tip of F-pili is the specific attachment site for mating pairs formation and the side of F-pili has a non-obligatory role during biofilm formation. The inhibitory effect of the f1 phage was dependent on the time of addition during the biofilm formation. No inhibitory effect was observed when the f1 phages were added to the mature biofilms. This resistant mechanism of the mature biofilms could be attributed to the biofilm-specific phenotypes representing that the F-pili mating pairs were already formed and then the curli production commenced during the biofilm maturation. The pre-formed mating pairs seemed to resist the f1 phages. Altogether, our results indicate a close relationship between the presence of conjugative plasmid and male-specific bacteriophages within sessile biofilm communities, as well as the possibility of using the male-specific bacteriophages to control biofilm formation.
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Affiliation(s)
- Thithiwat May
- Division of Environmental Engineering, Graduate School of Engineering, Hokkaido University, Kita-Ku, Kita-13, Nishi-8, Sapporo, Hokkaido, Japan
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Uropathogenic Escherichia coli modulates immune responses and its curli fimbriae interact with the antimicrobial peptide LL-37. PLoS Pathog 2010; 6:e1001010. [PMID: 20661475 PMCID: PMC2908543 DOI: 10.1371/journal.ppat.1001010] [Citation(s) in RCA: 175] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 06/17/2010] [Indexed: 01/22/2023] Open
Abstract
Bacterial growth in multicellular communities, or biofilms, offers many potential advantages over single-cell growth, including resistance to antimicrobial factors. Here we describe the interaction between the biofilm-promoting components curli fimbriae and cellulose of uropathogenic E. coli and the endogenous antimicrobial defense in the urinary tract. We also demonstrate the impact of this interplay on the pathogenesis of urinary tract infections. Our results suggest that curli and cellulose exhibit differential and complementary functions. Both of these biofilm components were expressed by a high proportion of clinical E. coli isolates. Curli promoted adherence to epithelial cells and resistance against the human antimicrobial peptide LL-37, but also increased the induction of the proinflammatory cytokine IL-8. Cellulose production, on the other hand, reduced immune induction and hence delayed bacterial elimination from the kidneys. Interestingly, LL-37 inhibited curli formation by preventing the polymerization of the major curli subunit, CsgA. Thus, even relatively low concentrations of LL-37 inhibited curli-mediated biofilm formation in vitro. Taken together, our data demonstrate that biofilm components are involved in the pathogenesis of urinary tract infections by E. coli and can be a target of local immune defense mechanisms. Most infections of the urinary tract are caused by uropathogenic E. coli. On abiotic surfaces, these bacteria are able to form biofilms, which protect them from various adverse environmental conditions. In this study, we sought to investigate whether two E. coli biofilm components, curli fimbriae and cellulose, provide a similar protection against innate immune defense mechanisms of the urinary tract. We put special emphasis on the interaction with the human antimicrobial peptide LL-37, which plays a crucial role in the protection against uropathogenic E. coli. We demonstrate that curli expression specifically reduces bacterial sensitivity to LL-37 by binding the peptide before reaching the bacterial cell membrane and exhibiting its bactericidal activity. A more general protection is mediated by cellulose, possibly by hiding immunogenic surface structures of the bacterium. In addition to providing protection, curli are also targeted by the immune system. The formation of new curli fibers is inhibited in the presence of LL-37. Moreover, curliated bacteria show higher immunogenicity than their non-curliated counterparts. Cellulose expression, on the other hand, appears to impair initial host colonization. In conclusion, our findings demonstrate an example of the tight interplay between bacterial virulence factors and the host immune defense.
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40
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Allsopp LP, Totsika M, Tree JJ, Ulett GC, Mabbett AN, Wells TJ, Kobe B, Beatson SA, Schembri MA. UpaH is a newly identified autotransporter protein that contributes to biofilm formation and bladder colonization by uropathogenic Escherichia coli CFT073. Infect Immun 2010; 78:1659-69. [PMID: 20145097 PMCID: PMC2849410 DOI: 10.1128/iai.01010-09] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 10/14/2009] [Accepted: 01/07/2010] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli is the primary cause of urinary tract infection (UTI) in the developed world. The major factors associated with virulence of uropathogenic E. coli (UPEC) are fimbrial adhesins, which mediate specific attachment to host receptors and trigger innate host responses. Another group of adhesins is represented by the autotransporter (AT) subgroup of proteins. In this study, we identified a new AT-encoding gene, termed upaH, present in a 6.5-kb unannotated intergenic region in the genome of the prototypic UPEC strain CFT073. Cloning and sequencing of the upaH gene from CFT073 revealed an intact 8.535-kb coding region, contrary to the published genome sequence. The upaH gene was widely distributed among a large collection of UPEC isolates as well as the E. coli Reference (ECOR) strain collection. Bioinformatic analyses suggest beta-helix as the predominant structure in the large N-terminal passenger (alpha) domain and a 12-strand beta-barrel for the C-terminal beta-domain of UpaH. We demonstrated that UpaH is expressed at the cell surface of CFT073 and promotes biofilm formation. In the mouse UTI model, deletion of the upaH gene in CFT073 and in two other UPEC strains did not significantly affect colonization of the bladder in single-challenge experiments. However, in competitive colonization experiments, CFT073 significantly outcompeted its upaH isogenic mutant strain in urine and the bladder.
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Affiliation(s)
- Luke P. Allsopp
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Makrina Totsika
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Jai J. Tree
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Glen C. Ulett
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Amanda N. Mabbett
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Timothy J. Wells
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Scott A. Beatson
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Mark A. Schembri
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane QLD 4072, Australia
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41
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Korea CG, Badouraly R, Prevost MC, Ghigo JM, Beloin C. Escherichia coli K-12 possesses multiple cryptic but functional chaperone-usher fimbriae with distinct surface specificities. Environ Microbiol 2010; 12:1957-77. [PMID: 20345943 DOI: 10.1111/j.1462-2920.2010.02202.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Commensal and pathogenic Escherichia coli adherence to host and environmental surfaces is mediated by a variety of adhesins. Although extensively studied as a model bacterium, 34% of the genes in the E. coli K-12 genome have no known function. We hypothesized that some of them may correspond to functional adhesins. We characterized E. coli K-12 ycb, ybg, yfc, yad, yra, sfm and yeh operons, which display sequence and organizational homologies to type 1 fimbriae exported by the chaperone/usher pathway. We showed that, although these operons are poorly expressed under laboratory conditions, six of them are nevertheless functional when expressed, and promote adhesion to abiotic and/or epithelial cell surfaces. While the studied fimbriae display different binding specificities, we obtained evidence of synergy/interference with other adhesins such as Ag43 or type 1 fimbriae. We showed that their expression is under the negative control of H-NS and, except for yad, subjected to cAMP receptor protein-mediated activation and carbon catabolite repression. These results therefore demonstrate that ycb, yfc, yad, yra, sfm and yeh operons encode cryptic but functional fimbriae adhesins whose expression following environmental modifications could contribute to E. coli's ability to adhere to and colonize a wide diversity of surfaces in its various ecological niches.
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Affiliation(s)
- Charalampia-Georgia Korea
- Institut Pasteur, Unité de Génétique des Biofilms, CNRS URA 2172, 25-28 rue du Dr Roux, 750724 Paris Cedex 15, France
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42
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Lakins MA, Marrison JL, O'Toole PJ, van der Woude MW. Exploiting advances in imaging technology to study biofilms by applying multiphoton laser scanning microscopy as an imaging and manipulation tool. J Microsc 2009; 235:128-37. [PMID: 19659907 DOI: 10.1111/j.1365-2818.2009.03190.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Biofilms are an important element of the natural ecosystems but can be detrimental in health care and industrial settings. To improve our ability to combat biofilms, we need to understand the processes that facilitate their formation and dispersal. One approach that has proven to be invaluable is to image biofilms as they grow. Here we describe tools and protocols to visualize biofilms with multiphoton laser scanning microscopy, compare this with single photon laser scanning confocal microscopy and highlight best working procedures. Furthermore, we describe how with multiphoton laser scanning microscopy the laser can be used to manipulate the biofilm, specifically to achieve localized bleaching, killing or ablation within the biofilm biomass. These applications open novel ways to study the dynamics of biofilm formation, regeneration and dispersal.
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Affiliation(s)
- M A Lakins
- Centre of Immunology and Infection, Department of Biology, University of York and The Hull York Medical School, York YO10 5YW, UK
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43
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Mikkelsen H, Ball G, Giraud C, Filloux A. Expression of Pseudomonas aeruginosa CupD fimbrial genes is antagonistically controlled by RcsB and the EAL-containing PvrR response regulators. PLoS One 2009; 4:e6018. [PMID: 19547710 PMCID: PMC2696094 DOI: 10.1371/journal.pone.0006018] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 05/11/2009] [Indexed: 12/16/2022] Open
Abstract
Pseudomonas aeruginosa is a gram-negative pathogenic bacterium with a high adaptive potential that allows proliferation in a broad range of hosts or niches. It is also the causative agent of both acute and chronic biofilm-related infections in humans. Three cup gene clusters (cupA-C), involved in the assembly of cell surface fimbriae, have been shown to be involved in biofilm formation by the P. aeruginosa strains PAO1 or PAK. In PA14 isolates, a fourth cluster, named cupD, was identified within a pathogenicity island, PAPI-I, and may contribute to the higher virulence of this strain. Expression of the cupA genes is controlled by the HNS-like protein MvaT, whereas the cupB and cupC genes are under the control of the RocS1A1R two-component system. In this study, we show that cupD gene expression is positively controlled by the response regulator RcsB. As a consequence, CupD fimbriae are assembled on the cell surface, which results in a number of phenotypes such as a small colony morphotype, increased biofilm formation and decreased motility. These behaviors are compatible with the sessile bacterial lifestyle. The balance between planktonic and sessile lifestyles is known to be linked to the intracellular levels of c-di-GMP with high levels favoring biofilm formation. We showed that the EAL domain-containing PvrR response regulator counteracts the activity of RcsB on cupD gene expression. The action of PvrR is likely to involve c-di-GMP degradation through phosphodiesterase activity, confirming the key role of this second messenger in the balance between bacterial lifestyles. The regulatory network between RcsB and PvrR remains to be elucidated, but it stands as a potential model system to study how the equilibrium between the two lifestyles could be influenced by therapeutic agents that favor the planktonic lifestyle. This would render the pathogen accessible for the immune system or conventional antibiotic treatment.
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Affiliation(s)
- Helga Mikkelsen
- Imperial College London, Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, South Kensington Campus, London, United Kingdom
| | - Geneviève Ball
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS-IBSM, Marseille, France
| | - Caroline Giraud
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS-IBSM, Marseille, France
| | - Alain Filloux
- Imperial College London, Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, South Kensington Campus, London, United Kingdom
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS-IBSM, Marseille, France
- * E-mail:
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44
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Beloin C, Houry A, Froment M, Ghigo JM, Henry N. A short-time scale colloidal system reveals early bacterial adhesion dynamics. PLoS Biol 2008; 6:e167. [PMID: 18613749 PMCID: PMC2443189 DOI: 10.1371/journal.pbio.0060167] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Accepted: 05/29/2008] [Indexed: 11/24/2022] Open
Abstract
The development of bacteria on abiotic surfaces has important public health and sanitary consequences. However, despite several decades of study of bacterial adhesion to inert surfaces, the biophysical mechanisms governing this process remain poorly understood, due, in particular, to the lack of methodologies covering the appropriate time scale. Using micrometric colloidal surface particles and flow cytometry analysis, we developed a rapid multiparametric approach to studying early events in adhesion of the bacterium Escherichia coli. This approach simultaneously describes the kinetics and amplitude of early steps in adhesion, changes in physicochemical surface properties within the first few seconds of adhesion, and the self-association state of attached and free-floating cells. Examination of the role of three well-characterized E. coli surface adhesion factors upon attachment to colloidal surfaces—curli fimbriae, F-conjugative pilus, and Ag43 adhesin—showed clear-cut differences in the very initial phases of surface colonization for cell-bearing surface structures, all known to promote biofilm development. Our multiparametric analysis revealed a correlation in the adhesion phase with cell-to-cell aggregation properties and demonstrated that this phenomenon amplified surface colonization once initial cell-surface attachment was achieved. Monitoring of real-time physico-chemical particle surface properties showed that surface-active molecules of bacterial origin quickly modified surface properties, providing new insight into the intricate relations connecting abiotic surface physicochemical properties and bacterial adhesion. Hence, the biophysical analytical method described here provides a new and relevant approach to quantitatively and kinetically investigating bacterial adhesion and biofilm development. When bacteria grow on solid surfaces, they can form three-dimensional communities called biofilms. Within these complex structures, bacteria can develop specific tolerance to different microbiocides, causing serious health and economic problems. Investigations of the key molecular events involved in biofilm formation have shown that surface-exposed adhesin proteins promote this process, but many questions remain regarding the mechanisms and biophysics of surface adhesion. We introduced an original approach to investigating the very early steps in bacterial adhesion that uses dispersed colloidal surfaces as microbial adhesion substrates. Using flow cytometry, we performed a quantitative real-time analysis of adhesion kinetics of several strains of the bacterium Escherichia coli, which were genetically engineered to produce well-characterized cell-surface adhesins that are known to promote biofilm development. We provide evidence for previously unknown adhesin-dependent behaviors, such as clear-cut differences in the very initial phases of surface colonization. We also demonstrate that initial adhesion correlates with almost instant surface property changes, and that cell-to-cell association might serve as an amplification mechanism for surface colonization. We therefore provide a new understanding of the intricate relationships between the physico-chemistry of abiotic surfaces and bacterial adhesion. Combining micrometric colloidal beads as adhesion substrates with flow cytometric analysis allows for a high-resolution analysis that reveals adhesin-dependent behavior in the very first steps of surface colonization by bacteria.
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Affiliation(s)
- Christophe Beloin
- Unité de Génétique des Biofilms, Institut Pasteur, CNRS URA 2172, Paris, France
| | - Ali Houry
- Laboratoire Physico-Chimie Curie, Institut Curie, CNRS UMR 168, Université Paris VI , Paris, France
| | - Manuel Froment
- Laboratoire Physico-Chimie Curie, Institut Curie, CNRS UMR 168, Université Paris VI , Paris, France
| | - Jean-Marc Ghigo
- Unité de Génétique des Biofilms, Institut Pasteur, CNRS URA 2172, Paris, France
| | - Nelly Henry
- Laboratoire Physico-Chimie Curie, Institut Curie, CNRS UMR 168, Université Paris VI , Paris, France
- * To whom correspondence should be addressed. E-mail:
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UpaG, a new member of the trimeric autotransporter family of adhesins in uropathogenic Escherichia coli. J Bacteriol 2008; 190:4147-61. [PMID: 18424525 DOI: 10.1128/jb.00122-08] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The ability of Escherichia coli to colonize both intestinal and extraintestinal sites is driven by the presence of specific virulence factors, among which are the autotransporter (AT) proteins. Members of the trimeric AT adhesin family are important virulence factors for several gram-negative pathogens and mediate adherence to eukaryotic cells and extracellular matrix (ECM) proteins. In this study, we characterized a new trimeric AT adhesin (UpaG) from uropathogenic E. coli (UPEC). Molecular analysis of UpaG revealed that it is translocated to the cell surface and adopts a multimeric conformation. We demonstrated that UpaG is able to promote cell aggregation and biofilm formation on abiotic surfaces in CFT073 and various UPEC strains. In addition, UpaG expression resulted in the adhesion of CFT073 to human bladder epithelial cells, with specific affinity to fibronectin and laminin. Prevalence analysis revealed that upaG is strongly associated with E. coli strains from the B2 and D phylogenetic groups, while deletion of upaG had no significant effect on the ability of CFT073 to colonize the mouse urinary tract. Thus, UpaG is a novel trimeric AT adhesin from E. coli that mediates aggregation, biofilm formation, and adhesion to various ECM proteins.
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46
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Abstract
Biofilms are structured communities characterized by distinctive gene expression patterns and profound physiological changes compared to those of planktonic cultures. Here, we show that many gram-negative bacterial biofilms secrete high levels of a small-molecular-weight compound, which inhibits the growth of only Escherichia coli K-12 and a rare few other natural isolates. We demonstrate both genetically and biochemically that this molecule is the amino acid valine, and we provide evidence that valine production within biofilms results from metabolic changes occurring within high-density biofilm communities when carbon sources are not limiting. This finding identifies a natural environment in which bacteria can encounter high amounts of valine, and we propose that in-biofilm valine secretion may be the long-sought reason for widespread but unexplained valine resistance found in most enterobacteria. Our results experimentally validate the postulated production of metabolites that is characteristic of the conditions associated with some biofilm environments. The identification of such molecules may lead to new approaches for biofilm monitoring and control.
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47
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Le Guyader D, Redd MJ, Colucci-Guyon E, Murayama E, Kissa K, Briolat V, Mordelet E, Zapata A, Shinomiya H, Herbomel P. Origins and unconventional behavior of neutrophils in developing zebrafish. Blood 2007; 111:132-41. [PMID: 17875807 DOI: 10.1182/blood-2007-06-095398] [Citation(s) in RCA: 294] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The first leukocytes that arise in the development of vertebrate embryos are the primitive macrophages, which differentiate in the yolk sac and then quickly invade embryonic tissues. These macrophages have been considered to constitute a separate lineage, giving rise to no other cell type. Using an in vivo photoactivatable cell tracer in the transparent zebrafish (Danio rerio) embryo, we demonstrated that this lineage also gave rise to an equal or higher number of neutrophilic granulocytes. We were surprised to find that the differentiation of these primitive neutrophils occurs only after primitive myeloid progenitors have dispersed in the tissues. By 2 days after fertilization, these neutrophils have become the major leukocyte type found wandering in the epidermis and mesenchyme. Like the primitive macrophages, all primitive and larval neutrophils express PU.1 and L-plastin and they are highly attracted to local infections, yet only a small fraction of them phagocytose microbes, and to a much lesser extent per cell than the macrophages. They are also attracted to variously stressed or malformed tissues, suggesting a wider role than antimicrobial defense.
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Affiliation(s)
- Dorothée Le Guyader
- Unité Macrophages et Développement de l'Immunité, Centre National de la Recherche Scientifique-Unité de Recherche Associée 2578, Institut Pasteur, Paris, France
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48
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Lu TK, Collins JJ. Dispersing biofilms with engineered enzymatic bacteriophage. Proc Natl Acad Sci U S A 2007; 104:11197-202. [PMID: 17592147 PMCID: PMC1899193 DOI: 10.1073/pnas.0704624104] [Citation(s) in RCA: 531] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Synthetic biology involves the engineering of biological organisms by using modular and generalizable designs with the ultimate goal of developing useful solutions to real-world problems. One such problem involves bacterial biofilms, which are crucial in the pathogenesis of many clinically important infections and are difficult to eradicate because they exhibit resistance to antimicrobial treatments and removal by host immune systems. To address this issue, we engineered bacteriophage to express a biofilm-degrading enzyme during infection to simultaneously attack the bacterial cells in the biofilm and the biofilm matrix, which is composed of extracellular polymeric substances. We show that the efficacy of biofilm removal by this two-pronged enzymatic bacteriophage strategy is significantly greater than that of nonenzymatic bacteriophage treatment. Our engineered enzymatic phage substantially reduced bacterial biofilm cell counts by approximately 4.5 orders of magnitude ( approximately 99.997% removal), which was about two orders of magnitude better than that of nonenzymatic phage. This work demonstrates the feasibility and benefits of using engineered enzymatic bacteriophage to reduce bacterial biofilms and the applicability of synthetic biology to an important medical and industrial problem.
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Affiliation(s)
- Timothy K. Lu
- *Harvard–MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Room E25–519, Cambridge, MA 02139; and
- Center for BioDynamics and Department of Biomedical Engineering, Boston University, 44 Cummington Street, Boston, MA 02215
| | - James J. Collins
- Center for BioDynamics and Department of Biomedical Engineering, Boston University, 44 Cummington Street, Boston, MA 02215
- To whom correspondence should be addressed. E-mail:
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