1
|
Berryhill BA, Burke KB, Fontaine J, Brink CE, Harvill MG, Goldberg DA, Konstantinidis KT, Levin BR, Woodworth MH. Enteric Populations of Escherichia coli are Likely to be Resistant to Phages Due to O Antigen Expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.08.566299. [PMID: 37986824 PMCID: PMC10659284 DOI: 10.1101/2023.11.08.566299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
There is a surfeit of bioinformatic data showing that bacteriophages abound in the enteric microbiomes of humans. What is the contribution of these viruses in shaping the bacterial strain and species composition of the gut microbiome and how are these phages maintained over time? To address these questions, we performed experiments with Escherichia coli and phages isolated from four fecal microbiota transplantation (FMT) doses as representative samples of non-dysbiotic enteric microbiota and develop and analyze the properties of a mathematical model of the population and evolutionary dynamics of bacteria and phage. Our models predict and experiments confirm that due to production of the O antigen, E. coli in the enteric microbiome are likely to be resistant to infection with co-occurring phages. Furthermore, our modeling suggests that the phages can be maintained in the population due to the high rates of host transition between resistant and sensitive states, which we call leaky resistance. Based on our observations and model predictions, we postulate that the phages found in the human gut are likely to play little role in shaping the composition of E. coli at the strain level in the enteric microbiome in healthy individuals. How general this is for other species of bacteria in the enteric flora is not yet clear, although O antigen expression is common across many taxa.
Collapse
Affiliation(s)
- Brandon A. Berryhill
- Department of Biology, Emory University; Atlanta, Georgia, 30322, USA
- Program in Microbiology and Molecular Genetics (MMG), Graduate Division of Biological and Biomedical Sciences (GDBBS), Laney Graduate School, Emory University; Atlanta, Georgia, 30322, USA
| | - Kylie B. Burke
- Department of Biology, Emory University; Atlanta, Georgia, 30322, USA
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine; Atlanta, Georgia, 30322, USA
| | - Jake Fontaine
- Department of Biology, Emory University; Atlanta, Georgia, 30322, USA
| | - Catherine E. Brink
- Ocean Science & Engineering, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- School of Civil & Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Mason G. Harvill
- Department of Biology, Emory University; Atlanta, Georgia, 30322, USA
| | - David A. Goldberg
- Department of Biology, Emory University; Atlanta, Georgia, 30322, USA
| | - Konstantinos T. Konstantinidis
- Ocean Science & Engineering, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- School of Civil & Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Bruce R. Levin
- Department of Biology, Emory University; Atlanta, Georgia, 30322, USA
| | - Michael H. Woodworth
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine; Atlanta, Georgia, 30322, USA
| |
Collapse
|
2
|
Letarov AV. Bacterial Virus Forcing of Bacterial O-Antigen Shields: Lessons from Coliphages. Int J Mol Sci 2023; 24:17390. [PMID: 38139217 PMCID: PMC10743462 DOI: 10.3390/ijms242417390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
In most Gram-negative bacteria, outer membrane (OM) lipopolysaccharide (LPS) molecules carry long polysaccharide chains known as the O antigens or O polysaccharides (OPS). The OPS structure varies highly from strain to strain, with more than 188 O serotypes described in E. coli. Although many bacteriophages recognize OPS as their primary receptors, these molecules can also screen OM proteins and other OM surface receptors from direct interaction with phage receptor-binding proteins (RBP). In this review, I analyze the body of evidence indicating that most of the E. coli OPS types robustly shield cells completely, preventing phage access to the OM surface. This shield not only blocks virulent phages but also restricts the acquisition of prophages. The available data suggest that OPS-mediated OM shielding is not merely one of many mechanisms of bacterial resistance to phages. Rather, it is an omnipresent factor significantly affecting the ecology, phage-host co-evolution and other related processes in E. coli and probably in many other species of Gram-negative bacteria. The phages, in turn, evolved multiple mechanisms to break through the OPS layer. These mechanisms rely on the phage RBPs recognizing the OPS or on using alternative receptors exposed above the OPS layer. The data allow one to forward the interpretation that, regardless of the type of receptors used, primary receptor recognition is always followed by the generation of a mechanical force driving the phage tail through the OPS layer. This force may be created by molecular motors of enzymatically active tail spikes or by virion structural re-arrangements at the moment of infection.
Collapse
Affiliation(s)
- Andrey V Letarov
- Winogradsky Institute of Micrbiology, Research Center Fundamentals of Biotechnology RAS, pr. 60-letiya Oktyabrya 7 bld. 2, Moscow 117312, Russia
| |
Collapse
|
3
|
Wegner T, Dombovski A, Gesing K, Köhrer A, Elinkmann M, Karst U, Glorius F, Jose J. Combining lipid-mimicking-enabled transition metal and enzyme-mediated catalysis at the cell surface of E. coli. Chem Sci 2023; 14:11896-11906. [PMID: 37920346 PMCID: PMC10619624 DOI: 10.1039/d3sc02960c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 10/06/2023] [Indexed: 11/04/2023] Open
Abstract
Being an essential multifunctional platform and interface to the extracellular environment, the cell membrane constitutes a valuable target for the modification and manipulation of cells and cellular behavior, as well as for the implementation of artificial, new-to-nature functionality. While bacterial cell surface functionalization via expression and presentation of recombinant proteins has extensively been applied, the corresponding application of functionalizable lipid mimetics has only rarely been reported. Herein, we describe an approach to equip E. coli cells with a lipid-mimicking, readily membrane-integrating imidazolium salt and a corresponding NHC-palladium complex that allows for flexible bacterial membrane surface functionalization and enables E. coli cells to perform cleavage of propargyl ethers present in the surrounding cell medium. We show that this approach can be combined with already established on-surface functionalization, such as bacterial surface display of enzymes, i.e. laccases, leading to a new type of cascade reaction. Overall, we envision the herein presented proof-of-concept studies to lay the foundation for a multifunctional toolbox that allows flexible and broadly applicable functionalization of bacterial membranes.
Collapse
Affiliation(s)
- Tristan Wegner
- University of Münster, Institute of Organic Chemistry Münster Germany
| | - Alexander Dombovski
- University of Münster, Institute of Pharmaceutical and Medicinal Chemistry Münster Germany
| | - Katrin Gesing
- University of Münster, Institute of Pharmaceutical and Medicinal Chemistry Münster Germany
| | - Alexander Köhrer
- University of Münster, Institute of Inorganic and Analytical Chemistry Münster Germany
| | - Matthias Elinkmann
- University of Münster, Institute of Inorganic and Analytical Chemistry Münster Germany
| | - Uwe Karst
- University of Münster, Institute of Inorganic and Analytical Chemistry Münster Germany
| | - Frank Glorius
- University of Münster, Institute of Organic Chemistry Münster Germany
| | - Joachim Jose
- University of Münster, Institute of Pharmaceutical and Medicinal Chemistry Münster Germany
| |
Collapse
|
4
|
Abstract
The first critical step in a virus’s infection cycle is attachment to its host. This interaction is precise enough to ensure the virus will be able to productively infect the cell, but some flexibility can be beneficial to enable coevolution and host range switching or expansion. Bacteriophage Sf6 utilizes a two-step process to recognize and attach to its host Shigella flexneri. Sf6 first recognizes the lipopolysaccharide (LPS) of S. flexneri and then binds outer membrane protein (Omp) A or OmpC. This phage infects serotype Y strains but can also form small, turbid plaques on serotype 2a2; turbid plaques appear translucent rather than transparent, indicating greater survival of bacteria. Reduced plating efficiency further suggested inefficient infection. To examine the interactions between Sf6 and this alternate host, phages were experimentally evolved using mixed populations of S. flexneri serotypes Y and 2a2. The recovered mutants could infect serotype 2a2 with greater efficiency than the ancestral Sf6, forming clear plaques on both serotypes. All mutations mapped to two distinct regions of the receptor-binding tailspike protein: (i) adjacent to the LPS binding site near the N terminus; and (ii) at the distal, C-terminal tip of the protein. Although we anticipated interactions between the Sf6 tailspike and 2a2 O-antigen to be weak, LPS of this serotype appears to inhibit infection through strong binding of particles, effectively removing them from the environment. The mutations of the evolved strains reduce the inhibitory effect by either reducing electrostatic interactions with the O-antigen or increasing reliance on the Omp secondary receptors. IMPORTANCE Viruses depend on host cells to propagate themselves. In mixed populations and communities of host cells, finding these susceptible host cells may have to be balanced with avoiding nonhost cells. Alternatively, being able to infect new cell types can increase the fitness of the virus. Many bacterial viruses use a two-step process to identify their hosts, binding first to an LPS receptor and then to a host protein. For Shigella virus Sf6, the tailspike protein was previously known to bind the LPS receptor. Genetic data from this work imply the tailspike also binds to the protein receptor. By experimentally evolving Sf6, we also show that point mutations in this protein can dramatically affect the binding of one or both receptors. This may provide Sf6 flexibility in identifying host cells and the ability to rapidly alter its host range under selective pressure.
Collapse
|
5
|
Phosphonate production by marine microbes: Exploring new sources and potential function. Proc Natl Acad Sci U S A 2022; 119:e2113386119. [PMID: 35254902 PMCID: PMC8931226 DOI: 10.1073/pnas.2113386119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Phosphonates are a class of phosphorus metabolites characterized by a highly stable C-P bond. Phosphonates accumulate to high concentrations in seawater, fuel a large fraction of marine methane production, and serve as a source of phosphorus to microbes inhabiting nutrient-limited regions of the oligotrophic ocean. Here, we show that 15% of all bacterioplankton in the surface ocean have genes phosphonate synthesis and that most belong to the abundant groups Prochlorococcus and SAR11. Genomic and chemical evidence suggests that phosphonates are incorporated into cell-surface phosphonoglycoproteins that may act to mitigate cell mortality by grazing and viral lysis. These results underscore the large global biogeochemical impact of relatively rare but highly expressed traits in numerically abundant groups of marine bacteria. Phosphonates are organophosphorus metabolites with a characteristic C-P bond. They are ubiquitous in the marine environment, their degradation broadly supports ecosystem productivity, and they are key components of the marine phosphorus (P) cycle. However, the microbial producers that sustain the large oceanic inventory of phosphonates as well as the physiological and ecological roles of phosphonates are enigmatic. Here, we show that phosphonate synthesis genes are rare but widely distributed among diverse bacteria and archaea, including Prochlorococcus and SAR11, the two major groups of bacteria in the ocean. In addition, we show that Prochlorococcus can allocate over 40% of its total cellular P-quota toward phosphonate production. However, we find no evidence that Prochlorococcus uses phosphonates for surplus P storage, and nearly all producer genomes lack the genes necessary to degrade and assimilate phosphonates. Instead, we postulate that phosphonates are associated with cell-surface glycoproteins, suggesting that phosphonates mediate ecological interactions between the cell and its surrounding environment. Our findings indicate that the oligotrophic surface ocean phosphonate pool is sustained by a relatively small fraction of the bacterioplankton cells allocating a significant portion of their P quotas toward secondary metabolism and away from growth and reproduction.
Collapse
|
6
|
Hermansen S, Linke D, Leo JC. Transmembrane β-barrel proteins of bacteria: From structure to function. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:113-161. [PMID: 35034717 DOI: 10.1016/bs.apcsb.2021.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The outer membrane of Gram-negative bacteria is a specialized organelle conferring protection to the cell against various environmental stresses and resistance to many harmful compounds. The outer membrane has a number of unique features, including an asymmetric lipid bilayer, the presence of lipopolysaccharides and an individual proteome. The vast majority of the integral transmembrane proteins in the outer membrane belongs to the family of β-barrel proteins. These evolutionarily related proteins share a cylindrical, anti-parallel β-sheet core fold spanning the outer membrane. The loops and accessory domains attached to the β-barrel allow for a remarkable versatility in function for these proteins, ranging from diffusion pores and transporters to enzymes and adhesins. We summarize the current knowledge on β-barrel structure and folding and give an overview of their functions, evolution, and potential as drug targets.
Collapse
Affiliation(s)
- Simen Hermansen
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Jack C Leo
- Antimicrobial resistance, Omics and Microbiota Group, Department of Biosciences, Nottingham Trent University, Nottingham, United Kingdom.
| |
Collapse
|
7
|
Lipidation of Class IV CdiA Effector Proteins Promotes Target Cell Recognition during Contact-Dependent Growth Inhibition. mBio 2021; 12:e0253021. [PMID: 34634941 PMCID: PMC8510554 DOI: 10.1128/mbio.02530-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Contact-dependent growth inhibition (CDI) systems enable the direct transfer of protein toxins between competing Gram-negative bacteria. CDI+ strains produce cell surface CdiA effector proteins that bind specific receptors on neighboring bacteria to initiate toxin delivery. Three classes of CdiA effectors that recognize different outer membrane protein receptors have been characterized in Escherichia coli to date. Here, we describe a fourth effector class that uses the lipopolysaccharide (LPS) core as a receptor to identify target bacteria. Selection for CDI-resistant target cells yielded waaF and waaP “deep-rough” mutants, which are unable to synthesize the full LPS core. The CDI resistance phenotypes of other waa mutants suggest that phosphorylated inner-core heptose residues form a critical CdiA recognition epitope. Class IV cdi loci also encode putative lysyl acyltransferases (CdiC) that are homologous to enzymes that lipidate repeats-in-toxin (RTX) cytolysins. We found that catalytically active CdiC is required for full target cell killing activity, and we provide evidence that the acyltransferase appends 3-hydroxydecanoate to a specific Lys residue within the CdiA receptor-binding domain. We propose that the lipid moiety inserts into the hydrophobic leaflet of lipid A to anchor CdiA interactions with the core oligosaccharide. Thus, LPS-binding CDI systems appear to have co-opted an RTX toxin-activating acyltransferase to increase the affinity of CdiA effectors for the target cell outer membrane.
Collapse
|
8
|
Diard M, Bakkeren E, Lentsch V, Rocker A, Bekele NA, Hoces D, Aslani S, Arnoldini M, Böhi F, Schumann-Moor K, Adamcik J, Piccoli L, Lanzavecchia A, Stadtmueller BM, Donohue N, van der Woude MW, Hockenberry A, Viollier PH, Falquet L, Wüthrich D, Bonfiglio F, Loverdo C, Egli A, Zandomeneghi G, Mezzenga R, Holst O, Meier BH, Hardt WD, Slack E. A rationally designed oral vaccine induces immunoglobulin A in the murine gut that directs the evolution of attenuated Salmonella variants. Nat Microbiol 2021; 6:830-841. [PMID: 34045711 PMCID: PMC7611113 DOI: 10.1038/s41564-021-00911-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 04/14/2021] [Indexed: 12/12/2022]
Abstract
The ability of gut bacterial pathogens to escape immunity by antigenic variation-particularly via changes to surface-exposed antigens-is a major barrier to immune clearance1. However, not all variants are equally fit in all environments2,3. It should therefore be possible to exploit such immune escape mechanisms to direct an evolutionary trade-off. Here, we demonstrate this phenomenon using Salmonella enterica subspecies enterica serovar Typhimurium (S.Tm). A dominant surface antigen of S.Tm is its O-antigen: a long, repetitive glycan that can be rapidly varied by mutations in biosynthetic pathways or by phase variation4,5. We quantified the selective advantage of O-antigen variants in the presence and absence of O-antigen-specific immunoglobulin A and identified a set of evolutionary trajectories allowing immune escape without an associated fitness cost in naive mice. Through the use of rationally designed oral vaccines, we induced immunoglobulin A responses blocking all of these trajectories. This selected for Salmonella mutants carrying deletions of the O-antigen polymerase gene wzyB. Due to their short O-antigen, these evolved mutants were more susceptible to environmental stressors (detergents or complement) and predation (bacteriophages) and were impaired in gut colonization and virulence in mice. Therefore, a rationally induced cocktail of intestinal antibodies can direct an evolutionary trade-off in S.Tm. This lays the foundations for the exploration of mucosal vaccines capable of setting evolutionary traps as a prophylactic strategy.
Collapse
Affiliation(s)
- Médéric Diard
- Biozentrum, University of Basel, Basel, Switzerland.
| | - Erik Bakkeren
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland.,Department of Zoology, University of Oxford, Oxford, UK
| | - Verena Lentsch
- Institute of Food, Nutrition and Health, D-HEST, ETH Zürich, Zürich, Switzerland
| | | | | | - Daniel Hoces
- Institute of Food, Nutrition and Health, D-HEST, ETH Zürich, Zürich, Switzerland
| | - Selma Aslani
- Institute of Food, Nutrition and Health, D-HEST, ETH Zürich, Zürich, Switzerland
| | - Markus Arnoldini
- Institute of Food, Nutrition and Health, D-HEST, ETH Zürich, Zürich, Switzerland
| | - Flurina Böhi
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland.,Department of Molecular Mechanisms of Disease, University of Zürich, Zürich, Switzerland
| | - Kathrin Schumann-Moor
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland.,Division of Surgical Research, University Hospital of Zürich, Zürich, Switzerland
| | - Jozef Adamcik
- Institute of Food, Nutrition and Health, D-HEST, ETH Zürich, Zürich, Switzerland
| | - Luca Piccoli
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Bellinzona, Switzerland
| | - Antonio Lanzavecchia
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Bellinzona, Switzerland
| | - Beth M Stadtmueller
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Nicholas Donohue
- York Biomedical Research Institute, Hull York Medical School, University of York, York, UK.,Department of Orthopedics and Trauma, Medical University of Graz, Graz, Austria
| | - Marjan W van der Woude
- York Biomedical Research Institute, Hull York Medical School, University of York, York, UK
| | - Alyson Hockenberry
- Department of Environmental Microbiology, Eawag, Dubendorf, Switzerland.,Department of Environmental Sciences, ETH Zürich, Zürich, Switzerland
| | - Patrick H Viollier
- Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Laurent Falquet
- Department of Biology, University of Fribourg, Fribourg, Switzerland.,Swiss Institute of Bioinformatics, Fribourg, Switzerland
| | - Daniel Wüthrich
- Infection Biology, University Hospital of Basel, Basel, Switzerland
| | | | - Claude Loverdo
- Department of Materials, ETH Zürich, Zürich, Switzerland
| | - Adrian Egli
- Infection Biology, University Hospital of Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | | | - Raffaele Mezzenga
- Institute of Food, Nutrition and Health, D-HEST, ETH Zürich, Zürich, Switzerland.,Department of Materials, ETH Zürich, Zürich, Switzerland
| | - Otto Holst
- Forschungszentrum Borstel, Borstel, Germany
| | - Beat H Meier
- Institute for Physical Chemistry, ETH Zürich, Zürich, Switzerland
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland.
| | - Emma Slack
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland. .,Institute of Food, Nutrition and Health, D-HEST, ETH Zürich, Zürich, Switzerland.
| |
Collapse
|
9
|
Chaudhry W, Lee E, Worthy A, Weiss Z, Grabowicz M, Vega N, Levin B. Mucoidy, a general mechanism for maintaining lytic phage in populations of bacteria. FEMS Microbiol Ecol 2021; 96:5897354. [PMID: 32845324 PMCID: PMC7532286 DOI: 10.1093/femsec/fiaa162] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 08/11/2020] [Indexed: 12/19/2022] Open
Abstract
We present evidence that phage resistance resulting from overproduction of exopolysaccharides, mucoidy, provides a general answer to the longstanding question of how lytic viruses are maintained in populations dominated by bacteria upon which they cannot replicate. In serial transfer culture, populations of mucoid Escherichia coli MG1655 that are resistant to lytic phages with different receptors, and thereby requiring independent mutations for surface resistance, are capable of maintaining these phages with little effect on their total density. Based on the results of our analysis of a mathematical model, we postulate that the maintenance of phage in populations dominated by mucoid cells can be attributed primarily to high rates of transition from the resistant mucoid states to susceptible non-mucoid states. Our tests with both population dynamic and single cell experiments as well as genomic analysis are consistent with this hypothesis. We discuss reasons for the generalized resistance of these mucoid E. coli, and the genetic and molecular mechanisms responsible for the high rate of transition from mucoid to sensitive states responsible for the maintenance of lytic phage in mucoid populations of E. coli.
Collapse
Affiliation(s)
- Waqas Chaudhry
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Esther Lee
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Andrew Worthy
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Zoe Weiss
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Marcin Grabowicz
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA.,Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.,Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Nicole Vega
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Bruce Levin
- Department of Biology, Emory University, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA
| |
Collapse
|
10
|
Golomidova AK, Efimov AD, Kulikov EE, Kuznetsov AS, Belalov IS, Letarov AV. O antigen restricts lysogenization of non-O157 Escherichia coli strains by Stx-converting bacteriophage phi24B. Sci Rep 2021; 11:3035. [PMID: 33542282 PMCID: PMC7862636 DOI: 10.1038/s41598-021-82422-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 01/18/2021] [Indexed: 11/23/2022] Open
Abstract
Acquisition of new prophages that are able to increase the bacterial fitness by the lysogenic conversion is believed to be an important strategy of bacterial adaptation to the changing environment. However, in contrast to the factors determining the range of bacteriophage lytic activity, little is known about the factors that define the lysogenization host range. Bacteriophage phi24B is the paradigmal model of Stx-converting phages, encoding the toxins of the Shiga-toxigenic E. coli (STEC). This virus has been shown to lysogenize a wide range of E. coli strains that is much broader than the range of the strains supporting its lytic growth. Therefore, phages produced by the STEC population colonizing the small or large intestine are potentially able to lysogenize symbiotic E. coli in the hindgut, and these secondary lysogens may contribute to the overall patient toxic load and to lead to the emergence of new pathogenic STEC strains. We demonstrate, however, that O antigen effectively limit the lysogenization of the wild E. coli strains by phi24B phage. The lysogens are formed from the spontaneous rough mutants and therefore have increased sensitivity to other bacteriophages and to the bactericidal activity of the serum if compared to their respective parental strains.
Collapse
Affiliation(s)
- A K Golomidova
- Winogradsky Institute of Microbiology, RC Biotechnology RAS, Prospekt 60-letiya Oktyabrya 7 bld. 2, Moscow, Russia, 117312
| | - A D Efimov
- Winogradsky Institute of Microbiology, RC Biotechnology RAS, Prospekt 60-letiya Oktyabrya 7 bld. 2, Moscow, Russia, 117312
| | - E E Kulikov
- Winogradsky Institute of Microbiology, RC Biotechnology RAS, Prospekt 60-letiya Oktyabrya 7 bld. 2, Moscow, Russia, 117312.,Phystech School of Biological and Medical Physics, Moscow Institute of Physics and Technology, Moscow, Russia
| | - A S Kuznetsov
- Winogradsky Institute of Microbiology, RC Biotechnology RAS, Prospekt 60-letiya Oktyabrya 7 bld. 2, Moscow, Russia, 117312.,Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - I Sh Belalov
- Winogradsky Institute of Microbiology, RC Biotechnology RAS, Prospekt 60-letiya Oktyabrya 7 bld. 2, Moscow, Russia, 117312
| | - A V Letarov
- Winogradsky Institute of Microbiology, RC Biotechnology RAS, Prospekt 60-letiya Oktyabrya 7 bld. 2, Moscow, Russia, 117312. .,Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
| |
Collapse
|
11
|
The Role of Pseudomonas aeruginosa Lipopolysaccharide in Bacterial Pathogenesis and Physiology. Pathogens 2019; 9:pathogens9010006. [PMID: 31861540 PMCID: PMC7168646 DOI: 10.3390/pathogens9010006] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/15/2019] [Accepted: 12/17/2019] [Indexed: 12/13/2022] Open
Abstract
The major constituent of the outer membrane of Gram-negative bacteria is lipopolysaccharide (LPS), which is comprised of lipid A, core oligosaccharide, and O antigen, which is a long polysaccharide chain extending into the extracellular environment. Due to the localization of LPS, it is a key molecule on the bacterial cell wall that is recognized by the host to deploy an immune defence in order to neutralize invading pathogens. However, LPS also promotes bacterial survival in a host environment by protecting the bacteria from these threats. This review explores the relationship between the different LPS glycoforms of the opportunistic pathogen Pseudomonas aeruginosa and the ability of this organism to cause persistent infections, especially in the genetic disease cystic fibrosis. We also discuss the role of LPS in facilitating biofilm formation, antibiotic resistance, and how LPS may be targeted by new antimicrobial therapies.
Collapse
|
12
|
Kulikov EE, Golomidova AK, Prokhorov NS, Ivanov PA, Letarov AV. High-throughput LPS profiling as a tool for revealing of bacteriophage infection strategies. Sci Rep 2019; 9:2958. [PMID: 30814597 PMCID: PMC6393563 DOI: 10.1038/s41598-019-39590-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/25/2019] [Indexed: 12/25/2022] Open
Abstract
O-antigens of Gram-negative bacteria modulate the interactions of bacterial cells with diverse external factors, including the components of the immune system and bacteriophages. Some phages need to acquire specific adhesins to overcome the O-antigen layer. For other phages, O-antigen is required for phage infection. In this case, interaction of phage receptor binding proteins coupled with enzymatic degradation or modification of the O-antigen is followed by phage infection. Identification of the strategies used by newly isolated phages may be of importance in their consideration for various applications. Here we describe an approach based on screening for host LPS alterations caused by selection by bacteriophages. We describe an optimized LPS profiling procedure that is simple, rapid and suitable for mass screening of mutants. We demonstrate that the phage infection strategies identified using a set of engineered E. coli 4 s mutants with impaired or altered LPS synthesis are in good agreement with the results of simpler tests based on LPS profiling of phage-resistant spontaneous mutants.
Collapse
Affiliation(s)
- Eugene E Kulikov
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, prosp. 60-letiya Oktyabrya, 7 bld. 2, 117312, Moscow, Russian Federation
- Moscow Institute of Physics and Technology, Institutskiy per., 9, Dolgoprudny, Moscow Region, 141701, Russian Federation
| | - Alla K Golomidova
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, prosp. 60-letiya Oktyabrya, 7 bld. 2, 117312, Moscow, Russian Federation
| | - Nikolai S Prokhorov
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, prosp. 60-letiya Oktyabrya, 7 bld. 2, 117312, Moscow, Russian Federation
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, 301 University Bulevard, Galveston, TX, USA
| | - Pavel A Ivanov
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, prosp. 60-letiya Oktyabrya, 7 bld. 2, 117312, Moscow, Russian Federation
| | - Andrey V Letarov
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, prosp. 60-letiya Oktyabrya, 7 bld. 2, 117312, Moscow, Russian Federation.
- Moscow Institute of Physics and Technology, Institutskiy per., 9, Dolgoprudny, Moscow Region, 141701, Russian Federation.
- Faculty of Biology, Lomonosov Moscow State University, ul. Leninskie Gory, 1, 119991, Moscow, Russia.
| |
Collapse
|
13
|
Sharp C, Boinett C, Cain A, Housden NG, Kumar S, Turner K, Parkhill J, Kleanthous C. O-Antigen-Dependent Colicin Insensitivity of Uropathogenic Escherichia coli. J Bacteriol 2019; 201:e00545-18. [PMID: 30510143 PMCID: PMC6351738 DOI: 10.1128/jb.00545-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/05/2018] [Indexed: 11/20/2022] Open
Abstract
The outer membrane of Gram-negative bacteria presents a significant barrier for molecules entering the cell. Nevertheless, colicins, which are antimicrobial proteins secreted by Escherichia coli, can target other E. coli cells by binding to cell surface receptor proteins and activating their import, resulting in cell death. Previous studies have documented high rates of nonspecific resistance (insensitivity) of various E. coli strains toward colicins that is independent of colicin-specific immunity and is instead associated with lipopolysaccharide (LPS) in the outer membrane. This observation poses a contradiction: why do E. coli strains have colicin-expressing plasmids, which are energetically costly to retain, if cells around them are likely to be naturally insensitive to the colicin they produce? Here, using a combination of transposon sequencing and phenotypic microarrays, we show that colicin insensitivity of uropathogenic E. coli sequence type 131 (ST131) is dependent on the production of its O-antigen but that minor changes in growth conditions render the organism sensitive toward colicins. The reintroduction of O-antigen into E. coli K-12 demonstrated that it is the density of O-antigen that is the dominant factor governing colicin insensitivity. We also show, by microscopy of fluorescently labelled colicins, that growth conditions affect the degree of occlusion by O-antigen of outer membrane receptors but not the clustered organization of receptors. The result of our study demonstrate that environmental conditions play a critical role in sensitizing E. coli toward colicins and that O-antigen in LPS is central to this role.IMPORTANCEEscherichia coli infections can be a major health burden, especially with the organism becoming increasingly resistant to "last-resort" antibiotics such as carbapenems. Although colicins are potent narrow-spectrum antimicrobials with potential as future antibiotics, high levels of naturally occurring colicin insensitivity have been documented which could limit their efficacy. We identify O-antigen-dependent colicin insensitivity in a clinically relevant uropathogenic E. coli strain and show that this insensitivity can be circumvented by minor changes to growth conditions. The results of our study suggest that colicin insensitivity among E. coli organisms has been greatly overestimated, and as a consequence, colicins could in fact be effective species-specific antimicrobials targeting pathogenic E. coli such as uropathogenic E. coli (UPEC).
Collapse
Affiliation(s)
- Connor Sharp
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | | | - Amy Cain
- Wellcome Sanger Institute, Hinxton, United Kingdom
- Macquarie University, Sydney, Australia
| | - Nicholas G Housden
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Sandip Kumar
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Keith Turner
- Quadram Institute Bioscience, Norwich, United Kingdom
| | | | - Colin Kleanthous
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
14
|
O’Donoghue EJ, Sirisaengtaksin N, Browning DF, Bielska E, Hadis M, Fernandez-Trillo F, Alderwick L, Jabbari S, Krachler AM. Lipopolysaccharide structure impacts the entry kinetics of bacterial outer membrane vesicles into host cells. PLoS Pathog 2017; 13:e1006760. [PMID: 29186191 PMCID: PMC5724897 DOI: 10.1371/journal.ppat.1006760] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 12/11/2017] [Accepted: 11/17/2017] [Indexed: 11/19/2022] Open
Abstract
Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections.
Collapse
Affiliation(s)
- Eloise J. O’Donoghue
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Natalie Sirisaengtaksin
- Department of Microbiology and Molecular Genetics, University of Texas McGovern Medical School at Houston, Houston, Texas, United States of America
| | - Douglas F. Browning
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Ewa Bielska
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Mohammed Hadis
- Institute of Microbiology and Infection, School of Chemistry, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Francisco Fernandez-Trillo
- Institute of Microbiology and Infection, School of Chemistry, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Luke Alderwick
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Sara Jabbari
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- School of Mathematics, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Anne Marie Krachler
- Department of Microbiology and Molecular Genetics, University of Texas McGovern Medical School at Houston, Houston, Texas, United States of America
- * E-mail:
| |
Collapse
|
15
|
Mills A, Duong F. Lipopolysaccharides promote binding and unfolding of the antibacterial colicin E3 rRNAse domain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2454-2460. [PMID: 28888366 DOI: 10.1016/j.bbamem.2017.08.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 11/17/2022]
Abstract
Nuclease colicins are antibacterial proteins produced by certain strains of E. coli to reduce competition from rival strains. These colicins are generally organized with an N-terminal transport (T)-domain, a central receptor binding (R)-domain, and a C-terminal cytotoxic nuclease domain. These colicins are always produced in complex with an inhibitory immunity protein, which dissociates prior entrance of the cytotoxic domain in the target cell. How exactly colicins traverse the cell envelope is not understood, yet this knowledge is important for the design of new antibacterial therapies. In this report, we find that the cytotoxic rRNAse domain of colicin E3, lacking both T- and R-domains, is sufficient to inhibit cell growth provided the immunity protein Im3 has been removed. Thus, while the T-domain is needed for dissociation of Im3, the rRNAse alone can associate to the cell surface without R-domain. Accordingly, we find a high affinity interaction (Kd ~1-2μM) between the rRNAse domain and lipopolysaccharides (LPS). Furthermore, we show that binding of ColE3 to LPS destabilizes the secondary structure of the toxin, which is expectedly crucial for transport through the narrow pore of the porin OmpF. The effect of LPS on binding and unfolding of ColE3 may be indicative of a broader role of LPS for transport of colicins in general.
Collapse
Affiliation(s)
- Allan Mills
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Franck Duong
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
| |
Collapse
|
16
|
Putker F, Bos MP, Tommassen J. Transport of lipopolysaccharide to the Gram-negative bacterial cell surface. FEMS Microbiol Rev 2015; 39:985-1002. [DOI: 10.1093/femsre/fuv026] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2015] [Indexed: 12/15/2022] Open
|
17
|
Nath P, Morona R. Mutational analysis of the major periplasmic loops of Shigella flexneri Wzy: identification of the residues affecting O antigen modal chain length control, and Wzz-dependent polymerization activity. MICROBIOLOGY-SGM 2015; 161:774-85. [PMID: 25627441 DOI: 10.1099/mic.0.000042] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 01/19/2015] [Indexed: 01/10/2023]
Abstract
The O antigen (Oag) component of LPS is a major Shigella flexneri virulence determinant. Oag is polymerized by WzySf, and its modal chain length is determined by WzzSf and WzzpHS2. Site-directed mutagenesis was performed on wzySf in pWaldo-wzySf-TEV-GFP to alter Arg residues in WzySf's two large periplasmic loops (PLs) (PL3 and PL5). Analysis of the LPS profiles conferred by mutated WzySf proteins in the wzySf deficient (Δwzy) strain identified residues that affect WzySf activity. The importance of the guanidium group of the Arg residues was investigated by altering the Arg residues to Lys and Glu, which generated WzySf mutants conferring altered LPS Oag modal chain lengths. The dependence of these WzySf mutants on WzzSf was investigated by expressing them in a wzySf and wzzSf deficient (Δwzy Δwzz) strain. Comparison of the LPS profiles identified a role for the Arg residues in the association of WzySf and WzzSf during Oag polymerization. Colicin E2 and bacteriophage Sf6c susceptibility supported this conclusion. Comparison of the expression levels of different mutant WzySf-GFPs with the wild-type WzySf-GFP showed that certain Arg residues affected production levels of WzySf in a WzzSf-dependent manner. To our knowledge, this is the first report of S. flexneri WzySf mutants having an effect on LPS Oag modal chain length, and identified functionally significant Arg residues in WzySf.
Collapse
Affiliation(s)
- Pratiti Nath
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
| | - Renato Morona
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
| |
Collapse
|
18
|
Variations in O-antigen biosynthesis and O-acetylation associated with altered phage sensitivity in Escherichia coli 4s. J Bacteriol 2014; 197:905-12. [PMID: 25512310 DOI: 10.1128/jb.02398-14] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The O polysaccharide of the lipopolysaccharide (O antigen) of Gram-negative bacteria often serves as a receptor for bacteriophages that can make the phage dependent on a given O-antigen type, thus supporting the concept of the adaptive significance of the O-antigen variability in bacteria. The O-antigen layer also modulates interactions of many bacteriophages with their hosts, limiting the access of the viruses to other cell surface receptors. Here we report variations of O-antigen synthesis and structure in an environmental Escherichia coli isolate, 4s, obtained from horse feces, and its mutants selected for resistance to bacteriophage G7C, isolated from the same fecal sample. The 4s O antigen was found to be serologically, structurally, and genetically related to the O antigen of E. coli O22, differing only in side-chain α-D-glucosylation in the former, mediated by a gtr locus on the chromosome. Spontaneous mutations of E. coli 4s occurring with an unusually high frequency affected either O-antigen synthesis or O-acetylation due to the inactivation of the gene encoding the putative glycosyltransferase WclH or the putative acetyltransferase WclK, respectively, by the insertion of IS1-like elements. These mutations induced resistance to bacteriophage G7C and also modified interactions of E. coli 4s with several other bacteriophages conferring either resistance or sensitivity to the host. These findings suggest that O-antigen synthesis and O-acetylation can both ensure the specific recognition of the O-antigen receptor following infection by some phages and provide protection of the host cells against attack by other phages.
Collapse
|
19
|
Mutational analysis of the Shigella flexneri O-antigen polymerase Wzy: identification of Wzz-dependent Wzy mutants. J Bacteriol 2014; 197:108-19. [PMID: 25313393 DOI: 10.1128/jb.01885-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The O-antigen (Oag) component of lipopolysaccharide (LPS) is a major virulence determinant of Shigella flexneri and is synthesized by the O-antigen polymerase, WzySf. Oag chain length is regulated by chromosomally encoded WzzSf and pHS-2 plasmid-encoded WzzpHS2. To identify functionally important amino acid residues in WzySf, random mutagenesis was performed on the wzySf gene in a pWaldo-TEV-GFP plasmid, followed by screening with colicin E2. Analysis of the LPS conferred by mutated WzySf proteins in the wzySf-deficient (Δwzy) strain identified 4 different mutant classes, with mutations found in periplasmic loop 1 (PL1), PL2, PL3, and PL6, transmembrane region 2 (TM2), TM4, TM5, TM7, TM8, and TM9, and cytoplasmic loop 1 (CL1) and CL5. The association of WzySf and WzzSf was investigated by transforming these mutated wzySf plasmids into a wzySf- and wzzSf-deficient (Δwzy Δwzz) strain. Comparison of the LPS profiles in the Δwzy and Δwzy Δwzz backgrounds identified WzySf mutants whose polymerization activities were WzzSf dependent. Colicin E2 and bacteriophage Sf6c sensitivities were consistent with the LPS profiles. Analysis of the expression levels of the WzySf-GFP mutants in the Δwzy and Δwzy Δwzz backgrounds identified a role for WzzSf in WzySf stability. Hence, in addition to its role in regulating Oag modal chain length, WzzSf also affects WzySf activity and stability.
Collapse
|
20
|
Tran ENH, Papadopoulos M, Morona R. Relationship between O-antigen chain length and resistance to colicin E2 in Shigella flexneri. MICROBIOLOGY-SGM 2014; 160:589-601. [PMID: 24425769 DOI: 10.1099/mic.0.074955-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Shigella flexneri polysaccharide co-polymerase class 1a (PCP1a) protein, WzzBSF, regulates LPS O-antigen (Oag) chain length to confer short (S)-type Oag chains of ~10-17 Oag repeat units (RUs). The S-type Oag chains affect Shigella flexneri virulence as they influence IcsA-mediated actin-based motility. However, they do not confer resistance to complement; this is conferred by the very-long (VL)-type Oag chains determined by WzzB(pHS2). Colicins are bacterial proteins produced by some Escherichia coli strains to kill related strains. While the presence of Oag chains has been shown to shield outer-membrane proteins from colicins, the impact of Oag chain length against colicins is unknown. In this study, initial testing indicated that a Shigella flexneri Y wzz : : kan(r) mutant was more sensitive to colicin E2 compared with the WT strain. Plasmids encoding Wzz mutant and WT PCP1a proteins conferring different Oag modal chain lengths were then expressed in the mutant background, and tested against purified colicin E2. Analysis of swab and spot sensitivity assays showed that strains expressing either S-type or long (L)-type Oag chains (16-28 Oag RUs) conferred greater resistance to colicin E2 compared with strains having very-short-type (2-8 Oag RUs), intermediate-short-type (8-14 Oag RUs) or VL-type (>80 Oag RUs) Oag chains. These results suggest a novel role for LPS Oag chain length control that may have evolved due to selection pressure from colicins in the environment.
Collapse
Affiliation(s)
- Elizabeth Ngoc Hoa Tran
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
| | - Magdalene Papadopoulos
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
| | - Renato Morona
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia
| |
Collapse
|
21
|
Core lipopolysaccharide-specific phage SSU5 as an Auxiliary Component of a Phage Cocktail for Salmonella biocontrol. Appl Environ Microbiol 2013; 80:1026-34. [PMID: 24271179 DOI: 10.1128/aem.03494-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Salmonella spp. are among the major food-borne pathogens that cause mild diarrhea to severe bacteremia. The use of bacteriophages to control various food-borne pathogens, including Salmonella, has emerged as a promising alternative to traditional chemotherapy. We isolated the Siphoviridae family phage SSU5, which can infect only rough strains of Salmonella. The blocking of SSU5 adsorption by periodate treatment of host Salmonella cells and spotting and adsorption assays with mutants that contain various truncations in their lipopolysaccharide (LPS) cores revealed that the outer core region of the LPS is a receptor of SSU5. SSU5 could infect O-antigen (O-Ag)-deficient Salmonella mutants that developed by challenging of O-Ag-specific phages, and consequently, it delayed the emergence of the phage-resistant Salmonella population in broth culture when treated together with phages using O-Ag as a receptor. Therefore, these results suggested that phage SSU5 would be a promising auxiliary component of a phage cocktail to control rough strains of Salmonella enterica serovar Typhimurium, which might emerge as resistant mutants upon infection by phages using O-Ag as a receptor.
Collapse
|
22
|
Tran ENH, Doyle MT, Morona R. LPS unmasking of Shigella flexneri reveals preferential localisation of tagged outer membrane protease IcsP to septa and new poles. PLoS One 2013; 8:e70508. [PMID: 23936222 PMCID: PMC3723647 DOI: 10.1371/journal.pone.0070508] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/18/2013] [Indexed: 11/29/2022] Open
Abstract
The Shigella flexneri outer membrane (OM) protease IcsP (SopA) is a member of the enterobacterial Omptin family of proteases which cleaves the polarly localised OM protein IcsA that is essential for Shigella virulence. Unlike IcsA however, the specific localisation of IcsP on the cell surface is unknown. To determine the distribution of IcsP, a haemagglutinin (HA) epitope was inserted into the non-essential IcsP OM loop 5 using Splicing by Overlap Extension (SOE) PCR, and IcsP(HA) was characterised. Quantum Dot (QD) immunofluorescence (IF) surface labelling of IcsP(HA) was then undertaken. Quantitative fluorescence analysis of S. flexneri 2a 2457T treated with and without tunicaymcin to deplete lipopolysaccharide (LPS) O antigen (Oag) showed that IcsP(HA) was asymmetrically distributed on the surface of septating and non-septating cells, and that this distribution was masked by LPS Oag in untreated cells. Double QD IF labelling of IcsP(HA) and IcsA showed that IcsP(HA) preferentially localised to the new pole of non-septating cells and to the septum of septating cells. The localisation of IcsP(HA) in a rough LPS S. flexneri 2457T strain (with no Oag) was also investigated and a similar distribution of IcsP(HA) was observed. Complementation of the rough LPS strain with rmlD resulted in restored LPS Oag chain expression and loss of IcsP(HA) detection, providing further support for LPS Oag masking of surface proteins. Our data presents for the first time the distribution for the Omptin OM protease IcsP, relative to IcsA, and the effect of LPS Oag masking on its detection.
Collapse
Affiliation(s)
- Elizabeth Ngoc Hoa Tran
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia
| | - Matthew Thomas Doyle
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia
| | - Renato Morona
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia
| |
Collapse
|
23
|
|
24
|
Localization of the domains of the Haemophilus ducreyi trimeric autotransporter DsrA involved in serum resistance and binding to the extracellular matrix proteins fibronectin and vitronectin. Infect Immun 2008; 77:657-66. [PMID: 19015257 DOI: 10.1128/iai.00819-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Resisting the bactericidal activity of naturally occurring antibodies and complement of normal human serum is an important element in the evasion of innate immunity by bacteria. In the gram-negative mucosal pathogen Haemophilus ducreyi, serum resistance is mediated primarily by the trimeric autotransporter DsrA. DsrA also functions as an adhesin for the extracellular matrix proteins fibronectin and vitronectin and mediates attachment of H. ducreyi to keratinocytes. We sought to determine the domain(s) of the 236-residue DsrA protein required for serum resistance and extracellular matrix protein binding. A 140-amino-acid truncated protein containing only the C-terminal portion of the passenger domain and the entire translocator domain of DsrA exhibited binding to fibronectin and vitronectin and conferred serum resistance to an H. ducreyi serum-sensitive strain. A shorter DsrA construct consisting of only 128 amino acids was unable to bind to extracellular matrix proteins but was serum resistant. We concluded that neither fibronectin binding nor vitronectin binding is required for high-level serum resistance in H. ducreyi.
Collapse
|
25
|
Baboolal TG, Conroy MJ, Gill K, Ridley H, Visudtiphole V, Bullough PA, Lakey JH. Colicin N binds to the periphery of its receptor and translocator, outer membrane protein F. Structure 2008; 16:371-9. [PMID: 18334212 PMCID: PMC2581486 DOI: 10.1016/j.str.2007.12.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 11/24/2022]
Abstract
Colicins kill Escherichia coli after translocation across the outer membrane. Colicin N displays an unusually simple translocation pathway, using the outer membrane protein F (OmpF) as both receptor and translocator. Studies of this binary complex may therefore reveal a significant component of the translocation pathway. Here we show that, in 2D crystals, colicin is found outside the porin trimer, suggesting that translocation may occur at the protein-lipid interface. The major lipid of the outer leaflet interface is lipopolysaccharide (LPS). It is further shown that colicin N binding displaces OmpF-bound LPS. The N-terminal helix of the pore-forming domain, which is not required for pore formation, rearranges and binds to OmpF. Colicin N also binds artificial OmpF dimers, indicating that trimeric symmetry plays no part in the interaction. The data indicate that colicin is closely associated with the OmpF-lipid interface, providing evidence that this peripheral pathway may play a role in colicin transmembrane transport.
Collapse
Affiliation(s)
- Thomas G Baboolal
- The Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
26
|
Smith DL, James CE, Sergeant MJ, Yaxian Y, Saunders JR, McCarthy AJ, Allison HE. Short-tailed stx phages exploit the conserved YaeT protein to disseminate Shiga toxin genes among enterobacteria. J Bacteriol 2007; 189:7223-33. [PMID: 17693515 PMCID: PMC2168440 DOI: 10.1128/jb.00824-07] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 07/17/2007] [Indexed: 11/20/2022] Open
Abstract
Infection of Escherichia coli by Shiga toxin-encoding bacteriophages (Stx phages) was the pivotal event in the evolution of the deadly Shiga toxin-encoding E. coli (STEC), of which serotype O157:H7 is the most notorious. The number of different bacterial species and strains reported to produce Shiga toxin is now more than 500, since the first reported STEC infection outbreak in 1982. Clearly, Stx phages are spreading rapidly, but the underlying mechanism for this dissemination has not been explained. Here we show that an essential and highly conserved gene product, YaeT, which has an essential role in the insertion of proteins in the gram-negative bacterial outer membrane, is the surface molecule recognized by the majority (ca. 70%) of Stx phages via conserved tail spike proteins associated with a short-tailed morphology. The yaeT gene was initially identified through complementation, and its role was confirmed in phage binding assays with and without anti-YaeT antiserum. Heterologous cloning of E. coli yaeT to enable Stx phage adsorption to Erwinia carotovora and the phage adsorption patterns of bacterial species possessing natural yaeT variants further supported this conclusion. The use of an essential and highly conserved protein by the majority of Stx phages is a strategy that has enabled and promoted the rapid spread of shigatoxigenic potential throughout multiple E. coli serogroups and related bacterial species. Infection of commensal bacteria in the mammalian gut has been shown to amplify Shiga toxin production in vivo, and the data from this study provide a platform for the development of a therapeutic strategy to limit this YaeT-mediated infection of the commensal flora.
Collapse
Affiliation(s)
- Darren L Smith
- Microbiology Research Group, BioSciences Building, School of Biological Sciences, University of Liverpool, Crown Street, Liverpool, Merseyside, UK
| | | | | | | | | | | | | |
Collapse
|
27
|
Wolfe DN, Goebel EM, Bjornstad ON, Restif O, Harvill ET. The O antigen enables Bordetella parapertussis to avoid Bordetella pertussis-induced immunity. Infect Immun 2007; 75:4972-9. [PMID: 17698566 PMCID: PMC2044517 DOI: 10.1128/iai.00763-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella pertussis and Bordetella parapertussis are closely related endemic human pathogens which cause whooping cough, a disease that is reemerging in human populations. Despite how closely related these pathogens are, their coexistence and the limited efficacy of B. pertussis vaccines against B. parapertussis suggest a lack of cross-protective immunity between the two. We sought to address the ability of infection-induced immunity against one of these pathogens to protect against subsequent infection by the other using a mouse model of infection. Immunity induced by B. parapertussis infection protected against subsequent infections by either species. However, immunity induced by B. pertussis infection prevented subsequent B. pertussis infections but did not protect against B. parapertussis infections. The O antigen of B. parapertussis inhibited binding of antibodies to the bacterial surface and was required for B. parapertussis to colonize mice convalescent from B. pertussis infection. Thus, the O antigen of B. parapertussis confers asymmetrical cross-immunity between the causative agents of whooping cough. We propose that these findings warrant investigation of the relative role of B. parapertussis in the resurgence of whooping cough.
Collapse
Affiliation(s)
- Daniel N Wolfe
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 115 Henning Building, University Park, PA 16802, USA
| | | | | | | | | |
Collapse
|
28
|
Iguchi A, Iyoda S, Watanabe H, Osawa R. O Side Chain Deficiency Enhances Sensitivity of Escherichia coli to Shiga Toxin 2-Converting Bacteriophages. Curr Microbiol 2007; 54:14-9. [PMID: 17171471 DOI: 10.1007/s00284-006-0139-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 08/04/2006] [Indexed: 10/23/2022]
Abstract
We investigated the relationship between expression of the O side chain of outer membrane lipopolysaccharide (LPS) and infection by a Shiga toxin 2 (Stx2)-converting phage in normal and benign strains of Escherichia coli. Of 19 wild-type E. coli strains isolated from the feces of healthy subjects, those with low-molecular-weight LPS showed markedly higher susceptibility to lytic and lysogenic infection by Stx2 phages than those with high-molecular-weight LPS. All lysogens produced infectious phage particles and Stx2. The Stx-negative E. coli O157:H7 strain ATCC43888 with an intact O side chain was found to be resistant to lysis by an Stx2 phage and lysogenic infection by a recombinant Stx2 phage, whereas a rfbE mutant deficient in the expression of the O side chain was readily infected by the phage and yielded stable lysogens. The evidence suggests that an O side chain deficiency leads to the creation of new pathotypes of Shiga toxin-producing E. coli (STEC) within the intestinal microflora.
Collapse
Affiliation(s)
- Atsushi Iguchi
- Department of Bioscience, Graduate School of Science and Technology, Kobe University, Rokko-dai 1-1, Kobe, 657-8501, Japan
| | | | | | | |
Collapse
|
29
|
Scholl D, Adhya S, Merril C. Escherichia coli K1's capsule is a barrier to bacteriophage T7. Appl Environ Microbiol 2005; 71:4872-4. [PMID: 16085886 PMCID: PMC1183359 DOI: 10.1128/aem.71.8.4872-4874.2005] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Escherichia coli strains that produce the K1 polysaccharide capsule have long been associated with pathogenesis. This capsule is believed to increase the cell's invasiveness, allowing the bacteria to avoid phagocytosis and inactivation by complement. It is also recognized as a receptor by some phages, such as K1F and K1-5, which have virion-associated enzymes that degrade the polysaccharide. In this report we show that expression of the K1 capsule in E. coli physically blocks infection by T7, a phage that recognizes lipopolysaccharide as the primary receptor. Enzymatic removal of the K1 antigen from the cell allows T7 to adsorb and replicate. This observation suggests that the capsule plays an important role as a defense against some phages that recognize structures beneath it and that the K1-specific phages evolved to counter this physical barrier.
Collapse
Affiliation(s)
- Dean Scholl
- The National Institute of Mental Health, National Institutes of Health, Building 36, Room 3D20, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | | | | |
Collapse
|
30
|
Morona R, Van Den Bosch L. Lipopolysaccharide O antigen chains mask IcsA (VirG) in Shigella flexneri. FEMS Microbiol Lett 2003; 221:173-80. [PMID: 12725923 DOI: 10.1016/s0378-1097(03)00210-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Shigella flexneri 2a strain 2457T lipopolysaccharide (LPS) has O antigen (Oag) chains with two modal lengths (S-type and VL-type), and has IcsA apparently located at one pole on its cell surface. Treatment of Y serotype derivatives of 2457T and RMA696 (2457T wzz(SF)) with Sf6 tailspike protein (TSP) resulted in hydrolysis of Oag chains, and an increase in detection of IcsA by indirect immunofluorescence staining on both the lateral and polar regions of the cell surface. Newly synthesised IcsA expressed from a pBAD promoter in a S. flexneri Y strain was also detected on both the lateral and polar regions of the cell when incubated with TSP prior to immunofluorescence staining. We conclude that IcsA is actually located on both lateral and polar regions of the S. flexneri cell surface, and that LPS Oag chains mask the presence of IcsA by hindering its detection with antibodies. These results have implications for the mechanism of IcsA export. They suggest that while IcsA export is predominantly targeted to the old cell pole, it can also occur on the lateral regions of the cell surface.
Collapse
Affiliation(s)
- Renato Morona
- Department of Molecular and Biomedical Science, University of Adelaide, SA, Australia.
| | | |
Collapse
|
31
|
de Cock H, Pasveer M, Tommassen J, Bouveret E. Identification of phospholipids as new components that assist in the in vitro trimerization of a bacterial pore protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:865-75. [PMID: 11168429 DOI: 10.1046/j.1432-1327.2001.01975.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The in vitro trimerization of folded monomers of the bacterial pore protein PhoE, into its native-like, heat- and SDS-stable form requires incubations with isolated cell envelopes and Triton X-100. The possibility that membranes could be isolated that are enriched in assembly factors required for assembly of the pore protein was now investigated. Fractionation of total cell envelopes of Escherichia coli via various techniques indeed revealed the existence of membrane fractions with different capacities to support assembly in vitro. Fractions containing mainly inner membrane vesicles supported the formation of trimers that were associated with these membrane vesicles. However, only a proportion of these trimers were heat- and SDS-stable and these were formed with slow kinetics. In contrast, fractions containing mainly outer membrane vesicles supported formation of high amounts of heat-stable trimers with fast kinetics. We identified phospholipids as active assembly components in these membranes that support trimerization of folded monomers in a process with similar characteristics as observed with inner membrane vesicles. Furthermore, phospholipids strongly stimulate the kinetics of trimerization and increase the final yield of heat-stable trimers in the context of outer membranes. We propose that lipopolysaccharides stabilize the assembly competent state of folded monomers as a lipochaperone. Phospholipids are involved in converting the folded monomer into new assembly competent intermediate with a short half-life that will form heat-stable trimers most efficiently in the context of outer membrane vesicles. These results provide biochemical evidence for the involvement of different lipidic components at distinct stages of the porin assembly process.
Collapse
Affiliation(s)
- H de Cock
- Molecular Microbiology and Institute of Biomembranes, Utrecht University, the Netherlands.
| | | | | | | |
Collapse
|
32
|
Shtatland T, Gill SC, Javornik BE, Johansson HE, Singer BS, Uhlenbeck OC, Zichi DA, Gold L. Interactions of Escherichia coli RNA with bacteriophage MS2 coat protein: genomic SELEX. Nucleic Acids Res 2000; 28:E93. [PMID: 11058143 PMCID: PMC113162 DOI: 10.1093/nar/28.21.e93] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Genomic SELEX is a method for studying the network of nucleic acid-protein interactions within any organism. Here we report the discovery of several interesting and potentially biologically important interactions using genomic SELEX. We have found that bacteriophage MS2 coat protein binds several Escherichia coli mRNA fragments more tightly than it binds the natural, well-studied, phage mRNA site. MS2 coat protein binds mRNA fragments from rffG (involved in formation of lipopolysaccharide in the bacterial outer membrane), ebgR (lactose utilization repressor), as well as from several other genes. Genomic SELEX may yield experimentally induced artifacts, such as molecules in which the fixed sequences participate in binding. We describe several methods (annealing of oligonucleotides complementary to fixed sequences or switching fixed sequences) to eliminate some, or almost all, of these artifacts. Such methods may be useful tools for both randomized sequence SELEX and genomic SELEX.
Collapse
MESH Headings
- Artifacts
- Bacteriophages
- Base Sequence
- Binding Sites
- Capsid/metabolism
- Capsid Proteins
- Computational Biology
- Consensus Sequence
- Genes, Bacterial/genetics
- Genome, Bacterial
- Genomic Library
- Nucleic Acid Conformation
- Nucleic Acid Hybridization
- Oligodeoxyribonucleotides/genetics
- Oligodeoxyribonucleotides/metabolism
- Polymerase Chain Reaction
- Protein Binding
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/genetics
- RNA, Viral/metabolism
- RNA-Binding Proteins/metabolism
- Sensitivity and Specificity
- Substrate Specificity
- Transcription, Genetic
Collapse
Affiliation(s)
- T Shtatland
- Department of Molecular, University of Colorado, Boulder, CO 80309-0347, USA
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Bunikis J, Barbour AG. Access of antibody or trypsin to an integral outer membrane protein (P66) of Borrelia burgdorferi is hindered by Osp lipoproteins. Infect Immun 1999; 67:2874-83. [PMID: 10338494 PMCID: PMC96595 DOI: 10.1128/iai.67.6.2874-2883.1999] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The outer membrane of Borrelia burgdorferi, the Lyme disease agent, contains lipoproteins anchored by their lipid moieties and integral proteins with membrane-spanning regions. We used the techniques of in situ proteolysis, immunofluorescence, in vitro growth inhibition, and cross-linking with formaldehyde to characterize topological relationships between P66, an integral membrane protein, and selected Osp lipoproteins of B. burgdorferi. Protease treatment of intact spirochetes cleaved P66 and Osp proteins but not the periplasmic flagellin or the BmpA protein of the cytoplasmic membrane. P66 of cells lacking OspA, OspB, and OspC was more susceptible to trypsin cleavage than was P66 of cells with these Osp proteins. A monoclonal antibody against the surface loop of P66 bound, agglutinated, and inhibited the growth of viable spirochetes lacking OspA, OspB, OspC, and OspD but not of the cells that expressed OspA, OspC, and/or OspD. When cells were fixed, the antibody bound to cells that express OspD and OspC but still not to cells with OspA. The close association of OspA and P66 was confirmed by the crosslinking of the two proteins by formaldehyde. These results show that Osp proteins, particularly OspA, limit the access of antibody or trypsin to the surface loop region of P66. The proximity and possible contact between P66 and OspA (or other Osp proteins) may hinder the effectiveness of antibodies to what otherwise would be an appropriate vaccine target.
Collapse
Affiliation(s)
- J Bunikis
- Departments of Microbiology & Molecular Genetics and Medicine, University of California Irvine, Irvine, California 92697, USA
| | | |
Collapse
|
34
|
De Cock H, Schäfer U, Potgeter M, Demel R, Müller M, Tommassen J. Affinity of the periplasmic chaperone Skp of Escherichia coli for phospholipids, lipopolysaccharides and non-native outer membrane proteins. Role of Skp in the biogenesis of outer membrane protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 259:96-103. [PMID: 9914480 DOI: 10.1046/j.1432-1327.1999.00010.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Skp protein of Escherichia coli has been proposed to be a periplasmic molecular chaperone involved in the biogenesis of outer membrane proteins. In this study, evidence is obtained that Skp exists in two different states characterized by their different sensitivity to proteases. The conversion between these states can be modulated in vitro by phospholipids, lipopolysaccharides and bivalent cations. Skp is able to associate with and insert into phospholipid membranes in vitro, indicating that it may associate with phospholipids in the inner and/or outer membrane in vivo. In addition, it interacts specifically with outer membrane proteins that are in their non-native state. We propose that Skp is required in vivo for the efficient targeting of unfolded outer membrane proteins to the membrane.
Collapse
Affiliation(s)
- H De Cock
- Department of Molecular Cell Biology, Utrecht University, The Netherlands
| | | | | | | | | | | |
Collapse
|
35
|
Zirk NM, Hashmi SF, Ziegler HK. The polysaccharide portion of lipopolysaccharide regulates antigen-specific T-cell activation via effects on macrophage-mediated antigen processing. Infect Immun 1999; 67:319-26. [PMID: 9864232 PMCID: PMC96313 DOI: 10.1128/iai.67.1.319-326.1999] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/1998] [Accepted: 10/16/1998] [Indexed: 11/20/2022] Open
Abstract
The lipopolysaccharide (LPS) structure of Salmonella typhimurium has been correlated with the virulence of wild-type strain LT2. Mutants of LT2 with truncated polysaccharide portions of LPS are less virulent than strains with a complete LPS structure. Polyclonal T cells and monoclonal T-cell hybridomas were more reactive to heat-killed rough mutants than to heat-killed smooth strains, as measured by interleukin-2 (IL-2) production. Using a large panel of strains with truncated LPS molecules, we found that T-cell reactivity decreased with certain lengths of polysaccharide. The decreased response was not due to differential phagocytic uptake, IL-12 production, or major histocompatibility complex class II surface expression by macrophages. Also, LT2 did not mediate any global suppression since addition of LT2 did not diminish the response of T cells specific for antigens unrelated to Salmonella. In an experiment in which processing times were varied, we found that antigens from rough strains were processed and presented more quickly than those associated with smooth strains. At longer processing times, epitopes from LT2 were presented well. We hypothesize that the slower antigen processing and presentation of wild-type Salmonella may be caused by masking of surface antigens by the longer polysaccharide portion of smooth LPS. This blocking of effective antigen presentation may contribute to the virulence of Salmonella.
Collapse
Affiliation(s)
- N M Zirk
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
| | | | | |
Collapse
|
36
|
Rubirés X, Saigi F, Piqué N, Climent N, Merino S, Albertí S, Tomás JM, Regué M. A gene (wbbL) from Serratia marcescens N28b (O4) complements the rfb-50 mutation of Escherichia coli K-12 derivatives. J Bacteriol 1997; 179:7581-6. [PMID: 9393727 PMCID: PMC179713 DOI: 10.1128/jb.179.23.7581-7586.1997] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A cosmid-based genomic library of Serratia marcescens N28b was introduced into Escherichia coli DH5alpha, and clones were screened for serum resistance. One clone was found resistant to serum, to bacteriocin 28b, and to bacteriophages TuIa and TuIb. This clone also showed O antigen in its lipopolysaccharide. Subcloning and sequencing experiments showed that a 2,124-bp DNA fragment containing the rmlD and wbbL genes was responsible for the observed phenotypes. On the basis of amino acid similarity, we suggest that the 288-residue RmlD protein is a dTDP-L-rhamnose synthase. Plasmid pJT102, containing only the wbbL gene, was able to induce O16-antigen production and serum resistance in E. coli DH5alpha. These results suggest that the 282-residue WbbL protein is a rhamnosyltransferase able to complement the rJb-50 mutation in E. coli K-12 derivatives, despite the low level of amino acid identity between WbbL and the E. coli rhamnosyltransferase (24.80%). S. marcescens N28b rmlD and wbbL mutants were constructed by mobilization of suicide plasmids containing a portion of rmlD or wbbL. These insertion mutants were unable to produce O antigen; since strain N28b produces O4 antigen, these results suggest that both genes are involved in O4-antigen biosynthesis.
Collapse
Affiliation(s)
- X Rubirés
- Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Spain
| | | | | | | | | | | | | | | |
Collapse
|
37
|
de Cock H, Struyvé M, Kleerebezem M, van der Krift T, Tommassen J. Role of the carboxy-terminal phenylalanine in the biogenesis of outer membrane protein PhoE of Escherichia coli K-12. J Mol Biol 1997; 269:473-8. [PMID: 9217252 DOI: 10.1006/jmbi.1997.1069] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Most bacterial outer membrane proteins contain a phenylalanine at their C terminus. It has been shown that this residue has an important role in the efficient and correct assembly of PhoE protein into the Escherichia coli outer membrane, since its substitution or deletion resulted in the accumulation of trypsin-sensitive monomers of this normally trimeric protein. Here, the role of the C-terminal Phe in the assembly of PhoE was studied in further detail. Immunocytochemical labelling on ultrathin cryosections revealed that a mutant PhoE protein that lacks the C-terminal Phe accumulates in the periplasm. However, when the expression levels of the altered species were reduced, the efficiency of outer membrane incorporation was increased and the lethal effects were alleviated. The role of the C-terminal Phe in protein folding, trimerization and outer membrane incorporation was further studied in vitro. Deletion of this residue interfered with the efficiency of the formation of an assembly-competent folded monomer, and the stability of this PhoE form was affected. The in vitro trimerization and insertion into outer membranes were not affected by the mutation.
Collapse
Affiliation(s)
- H de Cock
- Department of Molecular Cell Biology and Institute of Biomembranes, Utrecht University, The Netherlands
| | | | | | | | | |
Collapse
|
38
|
Owen P, Meehan M, de Loughry-Doherty H, Henderson I. Phase-variable outer membrane proteins in Escherichia coli. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 1996; 16:63-76. [PMID: 8988388 DOI: 10.1111/j.1574-695x.1996.tb00124.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Escherichia coli contains at least two phase-variable proteins in its outer membrane. One, termed antigen 43 (Ag43), is the product of the metastable flu gene located at min 43.6 on the E. coli chromosome and is responsible for colony form variation and for autoaggregation in liquid media. Ag43 is composed of two proteinaceous subunits, alpha 43 and beta 43 in 1:1 stoichiometry. alpha 43 (apparent M(r) 60,000) is surface expressed, extends beyond the O-side chains of smooth lipopolysaccharide and is bound to the cell surface through an interaction with beta 43 (apparent M(r) 53,000), itself an integral, heat-modifiable, outer membrane protein. alpha 43 shows limited N-terminal sequence homology with certain enterobacterial adhesins, and notable sequence homology with AIDA-1, an adhesin of diffuse-adhering E. coli. In addition, alpha 43 contains an RGD motif and a consensus sequence for an (autoproteolytic?) aspartyl protease active site. Expression of Ag43 is subject to reversible phase variation-in liquid minimal medium, the rates of variation from Ag43+ to Ag43- states and from Ag43- to Ag43+ states being approximately 2.2 x 10(-3) and approximately 1 x 10(-3), respectively. Phase switching of Ag43 is regulated by DNA methylation (deoxyadenosine methylase (dam) mutants being 'locked OFF') and by OxyR (oxyR mutants being 'locked ON'). It is proposed that OxyR acts as a repressor of Ag43 transcription by binding to unmethylated GATC sites in the regulatory region of the gene. In some strains, Ag43 may also undergo antigenic variation. A 94 kDa immunocrossreactive outer membrane protein, showing similar rates of phase variation, has additionally been detected for some enteropathogenic and uropathogenic strains of E. coli. This 94 kDa protein can be proteolytically cleaved in situ with trypsin to yield two membrane-bound products with M(r)s and properties similar to those of alpha 43 and beta 43. Results suggest that Ag43 may represent one of a family of antigenically-related high-M(r) adhesins which are synthesized as polyprotein precursors. Some members may be processed and presented on the cell surface as bipartite protein complexes (as Ag43). Others can remain uncleaved.
Collapse
Affiliation(s)
- P Owen
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Ireland
| | | | | | | |
Collapse
|
39
|
de Cock H, Tommassen J. Lipopolysaccharides and divalent cations are involved in the formation of an assembly-competent intermediate of outer-membrane protein PhoE of E.coli. EMBO J 1996; 15:5567-73. [PMID: 8896450 PMCID: PMC452301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
To identify the requirements for the biogenesis of outer-membrane proteins in Gram-negative bacteria, the sorting and assembly of the trimeric, pore-forming protein PhoE was studied in vitro. Purified lipopolysaccharide (LPS) in combination with low amounts of Triton X-100 and divalent cations induced the formation of folded monomers. LPS of deep-rough strains was far less efficient in the formation of folded monomers than wild-type LPS was. These folded monomers could be converted into heat-stable trimers upon addition of outer membranes and higher amounts of Triton X-100. Trimerization could precede the insertion step. These in vitro data suggest that the assembly in vivo proceeds sequentially by (i) formation of a folded monomer by interaction with LPS; (ii) sorting of the folded monomers to assembly sites in the outer membrane; (iii) trimerization; and (iv) insertion.
Collapse
Affiliation(s)
- H de Cock
- Department of Molecular Cell Biology, Utrecht University, The Netherlands
| | | |
Collapse
|
40
|
Doolittle MM, Cooney JJ, Caldwell DE. Tracing the interaction of bacteriophage with bacterial biofilms using fluorescent and chromogenic probes. JOURNAL OF INDUSTRIAL MICROBIOLOGY 1996; 16:331-41. [PMID: 8987490 DOI: 10.1007/bf01570111] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Phages T4 and E79 were fluorescently-labeled with rhodamine isothiocyanate (RITC), fluoroscein isothiocyanate (FITC), and by the addition of 4'6-diamidino-2-phenylindole (DAPI) to phage-infected host cells of Escherichia coli and Pseudomonas aeruginosa. Comparisons of electron micrographs with scanning confocal laser microscope (SCLM) images indicated that single RITC-labeled phage particles could be visualized. Biofilms of each bacterium were infected by labeled phage. SCLM and epifluorescence microscopy were used to observe adsorption of phage to single-layer surface-attached bacteria and thicker biofilms. The spread of the recombinant T4 phage, YZA1 (containing an rII-LacZ fusion), within a lac E. coli biofilm could be detected in the presence of chromogenic and fluorogenic homologs of galactose. Infected cells exhibited blue pigmentation and fluorescence from the cleavage products produced by the phage-encoded beta-galactosidase activity. Fluorescent antibodies were used to detect non-labeled progeny phage. Phage T4 infected both surface-attached and surface-associated E. coli while phage E79 adsorbed to P. aeruginosa cells on the surface of the biofilm, but access to cells deep in biofilms was somewhat restricted. Temperature and nutrient concentration did not affect susceptibility to phage infection, but lower temperature and low nutrients extended the time-to-lysis and slowed the spread of infection within the biofilm.
Collapse
Affiliation(s)
- M M Doolittle
- Environmental Sciences Program, University of Massachusetts, Boston 02125-3393, USA
| | | | | |
Collapse
|
41
|
de Cock H, van Blokland S, Tommassen J. In vitro insertion and assembly of outer membrane protein PhoE of Escherichia coli K-12 into the outer membrane. Role of Triton X-100. J Biol Chem 1996; 271:12885-90. [PMID: 8662743 DOI: 10.1074/jbc.271.22.12885] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The assembly of the in vitro synthesized outer membrane protein PhoE into purified outer membranes was investigated. The assembly appeared to be strongly stimulated by the presence of low amounts of Triton X-100 (optimal 0.08%, w/v). The role of Triton X-100 in the in vitro system was further examined. Pretreating outer membranes with Triton X-100 did not make the membranes competent for correct assembly, indicating that the detergent did not act on the membrane but at the protein level. PhoE became assembly-incompetent with a half-life of approximately 12 min and 90 s at 37 degrees C in the absence and presence, respectively, of 0.08% Triton X-100. Apparently, Triton X-100 induces an assembly-competent state in the PhoE protein with a very short half-life. Furthermore, the efficiency of correct assembly of PhoE was greatly reduced when outer membranes of deep rough lipopolysaccharide mutants were used, indicating an important role of lipopolysaccharides in the assembly of the porin.
Collapse
Affiliation(s)
- H de Cock
- Institute of Biomembranes and the Department of Molecular Cell Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | | | | |
Collapse
|
42
|
Shi W, Stocker BA, Adler J. Effect of the surface composition of motile Escherichia coli and motile Salmonella species on the direction of galvanotaxis. J Bacteriol 1996; 178:1113-9. [PMID: 8576046 PMCID: PMC177773 DOI: 10.1128/jb.178.4.1113-1119.1996] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have reported that motile Escherichia coli K-12 placed in an electric field swims toward the anode but that motile Salmonella typhimurium strains swim toward the cathode, a phenomenon called galvanotaxis (J. Adler and W. Shi, Cold Spring Harbor Symp. Quant. Biol. 53:23-25, 1988). In the present study, we isolated mutants with an altered direction of galvanotaxis. By further analyses of these mutants and by examination of E. coli and Salmonella strains with altered cell surface structure, we have now established a correlation between the direction of galvanotaxis and the surface structure of the cell: motile rough bacteria (that is, those without O polysaccharide; for example, E. coli K-12 and S. typhimurium mutants of classes galE and rfa) swam toward the anode, whereas motile smooth bacteria (that is, those with O polysaccharide; for example, wild-type S. typhimurium LT2) swam toward the cathode. However, smooth bacteria with acidic polysaccharide capsules (K1 in E. coli and Vi in Salmonella typhi) swam toward the anode. Measurements of passive electrophoretic mobility of strains representative of each set were made. We propose that the different directions of galvanotaxis of rough (or capsulate) bacteria and of smooth bacteria are explicable if the negative electrophoretic mobility of flagellar filaments is less than that of rough bodies but greater than that of smooth bodies.
Collapse
Affiliation(s)
- W Shi
- Department of Biochemistry, University of Wisconsin-Madison 53706, USA
| | | | | |
Collapse
|
43
|
van der Wal FJ, Luirink J, Oudega B. Bacteriocin release proteins: mode of action, structure, and biotechnological application. FEMS Microbiol Rev 1995; 17:381-99. [PMID: 8845188 DOI: 10.1111/j.1574-6976.1995.tb00221.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The mechanism by which Gram-negative bacteria like Escherichia coli secrete bacteriocins into the culture medium is unique and quite different from the mechanism by which other proteins are translocated across the two bacterial membranes, namely through the known branches of the general secretory pathway. The release of bacteriocins requires the expression and activity of a so-called bacteriocin release protein and the presence of the detergent-resistant phospholipase A in the outer membrane. The bacteriocin release proteins are highly expressed small lipoproteins which are synthesized with a signal peptide that remains stable and which accumulates in the cytoplasmic membrane after cleavage. The combined action of these stable, accumulated signal peptides, the lipid-modified mature bacteriocin release proteins (BRPs) and phospholipase A cause the release of bacteriocins. The structure and mode of action of these BRPs as well as their application in the release of heterologous proteins by E. coli is described in this review.
Collapse
Affiliation(s)
- F J van der Wal
- Department of Molecular Microbiology, IMBW, BioCentrum Amsterdam, Faculty of Biology, The Netherlands
| | | | | |
Collapse
|
44
|
Hernández-Allés S, Albertí S, Rubires X, Merino S, Tomás JM, Benedí VJ. Isolation of FC3-11, a bacteriophage specific for theKlebsiella pneumoniaeporin OmpK36, and its use for the isolation of porin-deficient mutants. Can J Microbiol 1995. [DOI: 10.1139/m95-053] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
FC3-11, a bacteriophage specific for the Klebsiella pneumoniae porin OmpK36, was isolated by its ability to infect Escherichia coli strains expressing the cloned OmpK36 porin. Porin OmpK36 was shown to be the receptor for phage FC3-11 by the observations that K. pneumoniae and E. coli strains that do not express OmpK36 were resistant to phage FC3-11, the purified porin inactivated the phage, and mutants selected for FC3-11 resistance had lost OmpK36. The outer membrane protein OmpK35 was isolated from a K. pneumoniae phage-resistant mutant by using porin isolation methods and was shown to contain an N-terminal sequence typical of enterobacterial porins. Bacteriophage FC3-11, alone or in combination with previously described lipopolysaccharide-specific phages, is a valuable tool to obtain OmpK36-porinless mutants.Key words: Klebsiella pneumoniae, porins, bacteriophage.
Collapse
|
45
|
Gadó I, Pászti J, László VG. Effect of precultivation conditions on colicin susceptibility in Escherichia coli. J Chemother 1995; 7:100-5. [PMID: 7545223 DOI: 10.1179/joc.1995.7.2.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The effect of 20 colicins and cloacin was studied after various precultivations. Nutrient agar supplemented with subinhibitory concentration of EDTA used for precultivation or elevating the growth-temperature of the inoculum from 37 degrees C to 42 degrees C increased the susceptibility of wild-type (smooth) Escherichia coli strains to the inhibitory action of some colicins. There were great differences among the colicins in respect to these effects. In case of rough mutants, their sensitivities did not change or eventually decrease after EDTA or heat pretreatment. The LPS pattern in SDS-PAGE of smooth cells grown in EDTA-containing nutrient medium changed in some degree towards the rough character. In case of precultivation at 42 degrees C this change was less considerable. It is supposed that both factors applied during precultivation have influence on colicin sensitivity by means of the change of receptor activity caused by LPS modification.
Collapse
Affiliation(s)
- I Gadó
- B. Johan National Institute of Hygiene, Budapest, Hungary
| | | | | |
Collapse
|
46
|
Van Gelder P, De Cock H, Tommassen J. Detergent-induced folding of the outer-membrane protein PhoE, a pore protein induced by phosphate limitation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:783-7. [PMID: 7813467 DOI: 10.1111/j.1432-1033.1994.00783.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The folding of the in vitro synthesized outer-membrane protein PhoE, a protein induced by phosphate limitation, has previously been studied using immunoprecipitation experiments with monoclonal antibodies that recognize conformational epitopes [De Cock, H., Hendricks, R., de Vrije, T. & Tommassen, J. (1990) J. Biol. Chem. 265, 4646-4651]. A folded monomer of the protein was detected in this way, while the addition of outer membranes was required to induce trimerization. In this study, we demonstrate that the folding of the in vitro synthesized PhoE protein did not occur spontaneously, but was dependent on the detergent that was present in the immunoprecipitation buffer. A remarkable specificity of phenyl-containing detergents on the efficient in vitro folding of PhoE molecules was observed. Furthermore, trimerization was detected in the absence of outer membranes when such detergents were present. However, the rate of trimerization was increased by the addition of crude cell envelopes containing outer membranes. The outer membranes probably enhanced trimerization by concentrating the folded PhoE molecules.
Collapse
Affiliation(s)
- P Van Gelder
- Department of Molecular Cell Biology, Utrecht University, The Netherlands
| | | | | |
Collapse
|
47
|
Zaat SA, Slegtenhorst-Eegdeman K, Tommassen J, Geli V, Wijffelman CA, Lugtenberg BJ. Construction of phoE-caa, a novel PCR- and immunologically detectable marker gene for Pseudomonas putida. Appl Environ Microbiol 1994; 60:3965-73. [PMID: 7993086 PMCID: PMC201923 DOI: 10.1128/aem.60.11.3965-3973.1994] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In this paper we describe the construction and use in Pseudomonas putida WCS358 of phoE-caa, a novel hybrid marker gene, which allows monitoring both at the protein level by immunological methods and at the DNA level by PCR. The marker is based on the Escherichia coli outer membrane protein gene phoE and 75 bp of E. coli caa, which encode a nonbacteriocinic fragment of colicin A. This fragment contains an epitope which is recognized by monoclonal antibody (MAb) 1C11. As the epitope is contained in one of the cell surface-exposed loops of PhoE, whole cells of bacteria expressing the protein can be detected by using the MAb. The marker gene contains only E. coli sequences not coding for toxins and therefore can be considered environmentally safe. The hybrid PhoE-ColA protein was expressed in E. coli under conditions of phosphate starvation, and single cells could be detected by immunofluorescence microscopy with MAb 1C11. Using a wide-host-range vector the phoE-caa gene was introduced into P. putida WCS358. The gene appeared to be expressed under phosphate limitation in this species, and the gene product was present in the membrane fraction and reacted with MAb 1C11. The hybrid PhoE-ColA protein could be detected on whole cells of WCS358 mutant strains lacking (part of) the O-antigen of the lipopolysaccharide but not on wild-type WCS358 cells, unless these cells had previously been washed with 10 mM EDTA. In addition to immunodetection, the phoE-caa marker gene could be specifically detected by PCR with one primer directed to a part of the phoE sequence and a second primer that annealed to the caa insert.
Collapse
Affiliation(s)
- S A Zaat
- Leiden University, Institute of Molecular Plant Sciences, The Netherlands
| | | | | | | | | | | |
Collapse
|
48
|
Abstract
Lactoferrin (Lf) is an iron-binding antimicrobial protein present in milk and on mucosal surfaces, with a suggested role in preimmune host defense. Certain strains of Escherichia coli (bacterial whole cells) demonstrate specific interaction with 125I-labeled Lf. A band with a mass of approximately 37 kDa, which was reactive with horseradish peroxidase-labeled Lf, was identified in the boiled cell envelope and outer membrane preparations of an Lf-binding E. coli strain, E34663, and a non-Lf-binding strain, HH45, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting (immunoblotting). Such a band was not detected in the unboiled native cell envelope and outer membrane preparations. The molecular mass and the property of heat modifiability suggested that the Lf-binding proteins were porins. The native trimeric form of porin OmpF isolated from strain B6 and its dissociated monomeric form both reacted with horseradish peroxidase-labeled Lf and with monoclonal antibodies specific for OmpF. Furthermore, by using E. coli constructs with defined porin phenotypes, OmpF and OmpC were identified as the Lf-binding proteins by urea-SDS-PAGE and Western blotting and by 125I-Lf binding studies with intact bacteria. These data establish that Lf binds to porins, a class of well-conserved molecules common in E. coli and many other gram-negative bacteria. However, in certain strains of E. coli these pore-forming proteins are shielded from Lf interaction.
Collapse
Affiliation(s)
- J Erdei
- Department of Medical Microbiology, Malmö General Hospital, University of Lund, Sweden
| | | | | |
Collapse
|
49
|
Abstract
Colicins are unusual bacterial toxins because they are directed against close relatives of the producing strain. They kill their targets in one of three distinct ways; via a ribonuclease or deoxyribonuclease activity or by forming pores in the target cell's membrane. This review deals with the steps involved in pore-forming colicin activity including, initial synthesis of the toxin, toxin release, receptor binding, translocation across the periplasm and pore formation in the cytoplasmic membrane. Special reference is made to the role of colicin in vivo, the structural changes occurring during pore formation and the role of the immunity protein.
Collapse
Affiliation(s)
- J H Lakey
- European Molecular Biology Laboratory, Heidelberg, Germany
| | | | | |
Collapse
|
50
|
Russo TA, Guenther JE, Wenderoth S, Frank MM. Generation of isogenic K54 capsule-deficient Escherichia coli strains through TnphoA-mediated gene disruption. Mol Microbiol 1993; 9:357-64. [PMID: 8412686 DOI: 10.1111/j.1365-2958.1993.tb01696.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Transposon mutagenesis, using IS50L::phoA(Tn-phoA), was performed in a K54/O4/H5 blood isolate of Escherichia coli (CP9), to generate a library of random mutants. Five hundred and twenty-six independent CP9 TnphoA mutants were isolated with active gene fusions to alkaline phosphatase. From this mutant library, eight capsule-deficient strains were detected and were found to have a single copy of TnphoA. Sixteen additional capsule deficient mutants with TnphoA inserts were subsequently obtained that did not possess active PhoA fusions. In conjunction with the initial eight capsule-deficient isolates we have defined genes on three different XbaI fragments as being involved in capsule production. Generalized transduction with the bacteriophage T4 established that these insertions were responsible for the loss of capsule and that they are linked. These capsule-deficient strains can be used to assess the pathogenic role of the K54 capsular polysaccharide.
Collapse
Affiliation(s)
- T A Russo
- Bacterial Pathogenesis Unit, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland 20892
| | | | | | | |
Collapse
|