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Zeng X, Wang N, Xiang C, Liu Q, Li D, Zhou Y, Zhang X, Xie Y, Zhang W, Yang H, Jiang M, Zong X, Zou Q, Shi Y. Peptidoglycan-associated lipoprotein contributes to the virulence of Acinetobacter baumannii and serves as a vaccine candidate. Genomics 2023; 115:110590. [PMID: 36868326 DOI: 10.1016/j.ygeno.2023.110590] [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: 08/09/2022] [Revised: 01/20/2023] [Accepted: 02/22/2023] [Indexed: 03/05/2023]
Abstract
The role of peptidoglycan-associated lipoprotein (Pal) in A. baumannii pathogenesis remains unclear. Here, we illustrated its role by constructing a pal deficient A. baumannii mutant and its complementary strain.Transcriptome analysis of the WT and pal mutant revealed a total of 596 differentially expressed genes. Gene Ontology analysis revealed that pal deficiency caused the downregulation of genes related to material transport and metabolic processes. The pal mutant showed a slower growth and was sensitive to detergent and serum killing compared to WT strain, whereas, the complemented pal mutant showed rescued phenotype. The pal mutant caused decreased mortality in mice pneumonia infection compared to WT strain, while the complemented pal mutant showed increased mortality. Mice immunized with recombinant Pal showed 40% protection against A. baumannii-mediated pneumonia. Collectively, these data indicate Pal is a virulence factor of A. baumannii and may serve as a potential target for preventive or therapeutic interventions.
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Affiliation(s)
- Xi Zeng
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China; National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, China; Department of Phamacy, the 78th Group Army Hospital of Chinese PLA, Mudanjiang, Heilongjiang, China
| | - Ning Wang
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Chuanying Xiang
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Qiang Liu
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Daiyu Li
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yangyang Zhou
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xiaomin Zhang
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yu Xie
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Weijun Zhang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, China
| | - Hong Yang
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ming Jiang
- College of Life Science and Technology, Mudanjiang Normal University, Mudanjiang, Heilongjiang, China
| | - Xianchun Zong
- College of Life Science and Technology, Mudanjiang Normal University, Mudanjiang, Heilongjiang, China
| | - Quanming Zou
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, China
| | - Yun Shi
- West China Biopharmaceutical Research Institute, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
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2
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Lipopolysaccharide -mediated resistance to host antimicrobial peptides and hemocyte-derived reactive-oxygen species are the major Providencia alcalifaciens virulence factors in Drosophila melanogaster. PLoS Pathog 2022; 18:e1010825. [PMID: 36084158 PMCID: PMC9491580 DOI: 10.1371/journal.ppat.1010825] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 09/21/2022] [Accepted: 08/23/2022] [Indexed: 02/07/2023] Open
Abstract
Bacteria from the genus Providencia are ubiquitous Gram-negative opportunistic pathogens, causing “travelers’ diarrhea”, urinary tract, and other nosocomial infections in humans. Some Providencia strains have also been isolated as natural pathogens of Drosophila melanogaster. Despite clinical relevance and extensive use in Drosophila immunity research, little is known about Providencia virulence mechanisms and the corresponding insect host defenses. To close this knowledge gap, we investigated the virulence factors of a representative Providencia species—P. alcalifaciens which is highly virulent to fruit flies and amenable to genetic manipulations. We generated a P. alcalifaciens transposon mutant library and performed an unbiased forward genetics screen in vivo for attenuated mutants. Our screen uncovered 23 mutants with reduced virulence. The vast majority of them had disrupted genes linked to lipopolysaccharide (LPS) synthesis or modifications. These LPS mutants were sensitive to cationic antimicrobial peptides (AMPs) in vitro and their virulence was restored in Drosophila mutants lacking most AMPs. Thus, LPS-mediated resistance to host AMPs is one of the virulence strategies of P. alcalifaciens. Another subset of P. alcalifaciens attenuated mutants exhibited increased susceptibility to reactive oxygen species (ROS) in vitro and their virulence was rescued by chemical scavenging of ROS in flies prior to infection. Using genetic analysis, we found that the enzyme Duox specifically in hemocytes is the source of bactericidal ROS targeting P. alcalifaciens. Consistently, the virulence of ROS-sensitive P. alcalifaciens mutants was rescued in flies with Duox knockdown in hemocytes. Therefore, these genes function as virulence factors by helping bacteria to counteract the ROS immune response. Our reciprocal analysis of host-pathogen interactions between D. melanogaster and P. alcalifaciens identified that AMPs and hemocyte-derived ROS are the major defense mechanisms against P. alcalifaciens, while the ability of the pathogen to resist these host immune responses is its major virulence mechanism. Thus, our work revealed a host-pathogen conflict mediated by ROS and AMPs. Pathogens express special molecules or structures called virulence factors to successfully infect a host. By identifying these factors, we can learn how hosts fight and how pathogens cause infections. Here, we identified virulence factors of the human and fruit fly pathogen Providencia alcalifaciens, by infecting flies with a series of mutants of this pathogen. In this way, we detected 23 mutants that were less virulent. Some of these less virulent mutants were hypersensitive to fruit fly immune defense molecules called antimicrobial peptides (AMPs), while others were sensitive to reactive oxygen species (ROS) produced by the immune cells. Notably, AMPs-sensitive mutants remained virulent in a Drosophila mutant that lacks AMPs, while pathogens sensitive to oxidative stress retained their virulence in a fruit fly mutant devoid of oxidative species. These results suggest that the ability of P. alcalifaciens to resist two major host immune molecules, namely AMPs and ROS, is the major virulence mechanism. Overall, our systematic analysis of P. alcalifaciens virulence factors has identified the major defense mechanisms of the fruit fly against this pathogen and the bacterial mechanisms to combat these immune responses.
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3
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Lipopolysaccharide-Induced Immunological Tolerance in Monocyte-Derived Dendritic Cells. IMMUNO 2022. [DOI: 10.3390/immuno2030030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Bacterial lipopolysaccharides (LPS), also referred to as endotoxins, are major outer surface membrane components present on almost all Gram-negative bacteria and are major determinants of sepsis-related clinical complications including septic shock. LPS acts as a strong stimulator of innate or natural immunity in a wide variety of eukaryotic species ranging from insects to humans including specific effects on the adaptive immune system. However, following immune stimulation, lipopolysaccharide can induce tolerance which is an essential immune-homeostatic response that prevents overactivation of the inflammatory response. The tolerance induced by LPS is a state of reduced immune responsiveness due to persistent and repeated challenges, resulting in decreased expression of pro-inflammatory modulators and up-regulation of antimicrobials and other mediators that promote a reduction of inflammation. The presence of environmental-derived LPS may play a key role in decreasing autoimmune diseases and gut tolerance to the plethora of ingested antigens. The use of LPS may be an important immune adjuvant as demonstrated by the promotion of IDO1 increase when present in the fusion protein complex of CTB-INS (a chimera of the cholera toxin B subunit linked to proinsulin) that inhibits human monocyte-derived DC (moDC) activation, which may act through an IDO1-dependent pathway. The resultant state of DC tolerance can be further enhanced by the presence of residual E. coli lipopolysaccharide (LPS) which is almost always present in partially purified CTB-INS preparations. The approach to using an adjuvant with an autoantigen in immunotherapy promises effective treatment for devastating tissue-specific autoimmune diseases like multiple sclerosis (MS) and type 1 diabetes (T1D).
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4
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Yeow J, Chng SS. Of zones, bridges and chaperones - phospholipid transport in bacterial outer membrane assembly and homeostasis. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35384832 DOI: 10.1099/mic.0.001177] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The outer membrane (OM) is a formidable permeability barrier that protects Gram-negative bacteria from detergents and antibiotics. It possesses exquisite lipid asymmetry, requiring the placement and retention of lipopolysaccharides (LPS) in the outer leaflet, and phospholipids (PLs) in the inner leaflet. To establish OM lipid asymmetry, LPS are transported from the inner membrane (IM) directly to the outer leaflet of the OM. In contrast, mechanisms for PL trafficking across the cell envelope are much less understood. In this review, we summarize and discuss recent advances in our understanding of PL transport, making parallel comparisons to well-established pathways for OM lipoprotein (Lol) and LPS (Lpt). Insights into putative PL transport systems highlight possible connections back to the 'Bayer bridges', adhesion zones between the IM and the OM that had been observed more than 50 years ago, and proposed as passages for export of OM components, including LPS and PLs.
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Affiliation(s)
- Jiang Yeow
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
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5
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Ashraf KU, Nygaard R, Vickery ON, Erramilli SK, Herrera CM, McConville TH, Petrou VI, Giacometti SI, Dufrisne MB, Nosol K, Zinkle AP, Graham CLB, Loukeris M, Kloss B, Skorupinska-Tudek K, Swiezewska E, Roper DI, Clarke OB, Uhlemann AC, Kossiakoff AA, Trent MS, Stansfeld PJ, Mancia F. Structural basis of lipopolysaccharide maturation by the O-antigen ligase. Nature 2022; 604:371-376. [PMID: 35388216 PMCID: PMC9884178 DOI: 10.1038/s41586-022-04555-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 02/16/2022] [Indexed: 01/31/2023]
Abstract
The outer membrane of Gram-negative bacteria has an external leaflet that is largely composed of lipopolysaccharide, which provides a selective permeation barrier, particularly against antimicrobials1. The final and crucial step in the biosynthesis of lipopolysaccharide is the addition of a species-dependent O-antigen to the lipid A core oligosaccharide, which is catalysed by the O-antigen ligase WaaL2. Here we present structures of WaaL from Cupriavidus metallidurans, both in the apo state and in complex with its lipid carrier undecaprenyl pyrophosphate, determined by single-particle cryo-electron microscopy. The structures reveal that WaaL comprises 12 transmembrane helices and a predominantly α-helical periplasmic region, which we show contains many of the conserved residues that are required for catalysis. We observe a conserved fold within the GT-C family of glycosyltransferases and hypothesize that they have a common mechanism for shuttling the undecaprenyl-based carrier to and from the active site. The structures, combined with genetic, biochemical, bioinformatics and molecular dynamics simulation experiments, offer molecular details on how the ligands come in apposition, and allows us to propose a mechanistic model for catalysis. Together, our work provides a structural basis for lipopolysaccharide maturation in a member of the GT-C superfamily of glycosyltransferases.
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Affiliation(s)
- Khuram U Ashraf
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Rie Nygaard
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Owen N Vickery
- School of Life Sciences, University of Warwick, Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Carmen M Herrera
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Thomas H McConville
- Department of Medicine, Division of Infectious Diseases, Columbia University Medical Center, New York, NY, USA
| | - Vasileios I Petrou
- Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers Biomedical Health Sciences, Newark, NJ, USA
- Center for Immunity and Inflammation, New Jersey Medical School, Rutgers Biomedical Health Sciences, Newark, NJ, USA
| | - Sabrina I Giacometti
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Meagan Belcher Dufrisne
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Kamil Nosol
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Allen P Zinkle
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | | | - Michael Loukeris
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY, USA
| | - Brian Kloss
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY, USA
| | | | - Ewa Swiezewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - David I Roper
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
- Department of Anesthesiology, Columbia University Irving Medical Center, New York, NY, USA
| | - Anne-Catrin Uhlemann
- Department of Medicine, Division of Infectious Diseases, Columbia University Medical Center, New York, NY, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - M Stephen Trent
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
| | - Phillip J Stansfeld
- School of Life Sciences, University of Warwick, Coventry, UK.
- Department of Chemistry, University of Warwick, Coventry, UK.
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA.
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6
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Martorana AM, Moura ECCM, Sperandeo P, Di Vincenzo F, Liang X, Toone E, Zhou P, Polissi A. Degradation of Components of the Lpt Transenvelope Machinery Reveals LPS-Dependent Lpt Complex Stability in Escherichia coli. Front Mol Biosci 2022; 8:758228. [PMID: 35004843 PMCID: PMC8727689 DOI: 10.3389/fmolb.2021.758228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
Lipopolysaccharide (LPS) is a peculiar component of the outer membrane (OM) of many Gram-negative bacteria that renders these bacteria highly impermeable to many toxic molecules, including antibiotics. LPS is assembled at the OM by a dedicated intermembrane transport system, the Lpt (LPS transport) machinery, composed of seven essential proteins located in the inner membrane (IM) (LptB2CFG), periplasm (LptA), and OM (LptDE). Defects in LPS transport compromise LPS insertion and assembly at the OM and result in an overall modification of the cell envelope and its permeability barrier properties. LptA is a key component of the Lpt machine. It connects the IM and OM sub-complexes by interacting with the IM protein LptC and the OM protein LptD, thus enabling the LPS transport across the periplasm. Defects in Lpt system assembly result in LptA degradation whose stability can be considered a marker of an improperly assembled Lpt system. Indeed, LptA recruitment by its IM and OM docking sites requires correct maturation of the LptB2CFG and LptDE sub-complexes, respectively. These quality control checkpoints are crucial to avoid LPS mistargeting. To further dissect the requirements for the complete Lpt transenvelope bridge assembly, we explored the importance of LPS presence by blocking its synthesis using an inhibitor compound. Here, we found that the interruption of LPS synthesis results in the degradation of both LptA and LptD, suggesting that, in the absence of the LPS substrate, the stability of the Lpt complex is compromised. Under these conditions, DegP, a major chaperone–protease in Escherichia coli, is responsible for LptD but not LptA degradation. Importantly, LptD and LptA stability is not affected by stressors disturbing the integrity of LPS or peptidoglycan layers, further supporting the notion that the LPS substrate is fundamental to keeping the Lpt transenvelope complex assembled and that LptA and LptD play a major role in the stability of the Lpt system.
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Affiliation(s)
- Alessandra M Martorana
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università Degli Studi di Milano, Milan, Italy
| | - Elisabete C C M Moura
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università Degli Studi di Milano, Milan, Italy
| | - Paola Sperandeo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università Degli Studi di Milano, Milan, Italy
| | - Flavia Di Vincenzo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università Degli Studi di Milano, Milan, Italy
| | - Xiaofei Liang
- Department of Chemistry, Duke University, Durham, NC, United States
| | - Eric Toone
- Department of Chemistry, Duke University, Durham, NC, United States
| | - Pei Zhou
- Department of Chemistry, Duke University, Durham, NC, United States.,Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Alessandra Polissi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università Degli Studi di Milano, Milan, Italy
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7
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Marchant P, Carreño A, Vivanco E, Silva A, Nevermann J, Otero C, Araya E, Gil F, Calderón IL, Fuentes JA. "One for All": Functional Transfer of OMV-Mediated Polymyxin B Resistance From Salmonella enterica sv. Typhi Δ tolR and Δ degS to Susceptible Bacteria. Front Microbiol 2021; 12:672467. [PMID: 34025627 PMCID: PMC8131662 DOI: 10.3389/fmicb.2021.672467] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/12/2021] [Indexed: 12/22/2022] Open
Abstract
The appearance of multi-resistant strains has contributed to reintroducing polymyxin as the last-line therapy. Although polymyxin resistance is based on bacterial envelope changes, other resistance mechanisms are being reported. Outer membrane vesicles (OMVs) are nanosized proteoliposomes secreted from the outer membrane of Gram-negative bacteria. In some bacteria, OMVs have shown to provide resistance to diverse antimicrobial agents either by sequestering and/or expelling the harmful agent from the bacterial envelope. Nevertheless, the participation of OMVs in polymyxin resistance has not yet been explored in S. Typhi, and neither OMVs derived from hypervesiculating mutants. In this work, we explored whether OMVs produced by the hypervesiculating strains Salmonella Typhi ΔrfaE (LPS synthesis), ΔtolR (bacterial envelope) and ΔdegS (misfolded proteins and σ E activation) exhibit protective properties against polymyxin B. We found that the OMVs extracted from S. Typhi ΔtolR and ΔdegS protect S. Typhi WT from polymyxin B in a concentration-depending manner. By contrast, the protective effect exerted by OMVs from S. Typhi WT and S. Typhi ΔrfaE is much lower. This effect is achieved by the sequestration of polymyxin B, as assessed by the more positive Zeta potential of OMVs with polymyxin B and the diminished antibiotic's availability when coincubated with OMVs. We also found that S. Typhi ΔtolR exhibited an increased MIC of polymyxin B. Finally, we determined that S. Typhi ΔtolR and S. Typhi ΔdegS, at a lesser level, can functionally and transiently transfer the OMV-mediated polymyxin B resistance to susceptible bacteria in cocultures. This work shows that mutants in genes related to OMVs biogenesis can release vesicles with improved abilities to protect bacteria against membrane-active agents. Since mutations affecting OMV biogenesis can involve the bacterial envelope, mutants with increased resistance to membrane-acting agents that, in turn, produce protective OMVs with a high vesiculation rate (e.g., S. Typhi ΔtolR) can arise. Such mutants can functionally transfer the resistance to surrounding bacteria via OMVs, diminishing the effective concentration of the antimicrobial agent and potentially favoring the selection of spontaneous resistant strains in the environment. This phenomenon might be considered the source for the emergence of polymyxin resistance in an entire bacterial community.
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Affiliation(s)
- Pedro Marchant
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alexander Carreño
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Eduardo Vivanco
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Andrés Silva
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Jan Nevermann
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Carolina Otero
- Escuela de Química y Farmacia, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Eyleen Araya
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Santiago, Chile
| | - Fernando Gil
- Microbiota-Host Interactions and Clostridia Research Group, Universidad Andres Bello, Santiago, Chile.,ANID-Millennium Science Initiative Program-Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Iván L Calderón
- Laboratorio de RNAs Bacterianos, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Juan A Fuentes
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
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8
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Wong S, Alattas H, Slavcev RA. A snapshot of the λ T4rII exclusion (Rex) phenotype in Escherichia coli. Curr Genet 2021; 67:739-745. [PMID: 33877398 DOI: 10.1007/s00294-021-01183-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/20/2021] [Accepted: 03/25/2021] [Indexed: 10/21/2022]
Abstract
The lambda (λ) T4rII exclusion (Rex) phenotype is defined as the inability of T4rII to propagate in Escherichia coli lysogenized by bacteriophage λ. The Rex system requires the presence of two lambda immunity genes, rexA and rexB, to exclude T4 (rIIA-rIIB) from plating on a lawn of E. coli λ lysogens. The onset of the Rex phenotype by T4rII infection imparts a harsh cellular environment that prevents T4rII superinfection while killing the majority of the cell population. Since the discovery of this powerful exclusion system in 1955 by Seymour Benzer, few mechanistic models have been proposed to explain the process of Rex activation and the physiological manifestations associated with Rex onset. For the first time, key host proteins have recently been linked to Rex, including σE, σS, TolA, and other membrane proteins. Together with the known Rex system components, the RII proteins of bacteriophage T4 and the Rex proteins from bacteriophage λ, we are closer than ever to solving the mystery that has eluded investigators for over six decades. Here, we review the fundamental Rex components in light of this new knowledge.
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Affiliation(s)
- Shirley Wong
- School of Pharmacy, University of Waterloo, ON, N2L 3G1, Canada
| | - Hibah Alattas
- School of Pharmacy, University of Waterloo, ON, N2L 3G1, Canada.
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9
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Reimer SL, Beniac DR, Hiebert SL, Booth TF, Chong PM, Westmacott GR, Zhanel GG, Bay DC. Comparative Analysis of Outer Membrane Vesicle Isolation Methods With an Escherichia coli tolA Mutant Reveals a Hypervesiculating Phenotype With Outer-Inner Membrane Vesicle Content. Front Microbiol 2021; 12:628801. [PMID: 33746922 PMCID: PMC7973035 DOI: 10.3389/fmicb.2021.628801] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/08/2021] [Indexed: 12/14/2022] Open
Abstract
Outer membrane vesicles (OMVs) produced by Gram-negative bacteria are mediators of cell survival and pathogenesis by facilitating virulence factor dissemination and resistance to antimicrobials. Studies of OMV properties often focus on hypervesiculating Escherichia coli mutants that have increased OMV production when compared to their corresponding wild-type (WT) strains. Currently, two conventional techniques, ultracentrifugation (UC) and ultradiafiltration (UF), are used interchangeably to isolate OMVs, however, there is concern that each technique may inadvertently alter the properties of isolated OMVs during study. To address this concern, we compared two OMV isolation methods, UC and UF, with respect to final OMV quantities, size distributions, and morphologies using a hypervesiculating Escherichia coli K-12 ΔtolA mutant. Nanoparticle tracking analysis (NTA) indicated that UC techniques result in lower vesicle yields compared to UF. However, UF permitted isolation of OMVs with smaller average sizes than UC, highlighting a potential OMV isolation size bias by each technique. Cryo-transmission electron microscopy (cryo-TEM) visualization of isolated OMVs revealed distinct morphological differences between WT and ΔtolA OMVs, where ΔtolA OMVs isolated by either UC or UF method possessed a greater proportion of OMVs with two or more membranes. Proteomic OMV analysis of WT and ΔtolA OMVs confirmed that ΔtolA enhances inner plasma membrane carryover in multi-lamellar OMVs. This study demonstrates that UC and UF are useful techniques for OMV isolation, where UF may be preferable due to faster isolation, higher OMV yields and enrichment of smaller sized vesicles.
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Affiliation(s)
- Shelby L Reimer
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
| | - Daniel R Beniac
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Shannon L Hiebert
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Timothy F Booth
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Patrick M Chong
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Garrett R Westmacott
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - George G Zhanel
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
| | - Denice C Bay
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
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10
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Szczepaniak J, Press C, Kleanthous C. The multifarious roles of Tol-Pal in Gram-negative bacteria. FEMS Microbiol Rev 2021; 44:490-506. [PMID: 32472934 PMCID: PMC7391070 DOI: 10.1093/femsre/fuaa018] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 05/28/2020] [Indexed: 12/15/2022] Open
Abstract
In the 1960s several groups reported the isolation and preliminary genetic mapping of
Escherichia coli strains tolerant towards the
action of colicins. These pioneering studies kick-started two new fields in bacteriology;
one centred on how bacteriocins like colicins exploit the Tol (or more commonly Tol-Pal)
system to kill bacteria, the other on the physiological role of this cell
envelope-spanning assembly. The following half century has seen significant advances in
the first of these fields whereas the second has remained elusive, until recently. Here,
we review work that begins to shed light on Tol-Pal function in Gram-negative bacteria.
What emerges from these studies is that Tol-Pal is an energised system with fundamental,
interlinked roles in cell division – coordinating the re-structuring of peptidoglycan at
division sites and stabilising the connection between the outer membrane and underlying
cell wall. This latter role is achieved by Tol-Pal exploiting the proton motive force to
catalyse the accumulation of the outer membrane peptidoglycan associated lipoprotein Pal
at division sites while simultaneously mobilising Pal molecules from around the cell.
These studies begin to explain the diverse phenotypic outcomes of tol-pal
mutations, point to other cell envelope roles Tol-Pal may have and raise many new
questions.
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Affiliation(s)
- Joanna Szczepaniak
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Cara Press
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
| | - Colin Kleanthous
- Department of Biochemistry, South Parks Road, University of Oxford, Oxford OX1 3QU, UK
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11
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Micoli F, MacLennan CA. Outer membrane vesicle vaccines. Semin Immunol 2020; 50:101433. [PMID: 33309166 DOI: 10.1016/j.smim.2020.101433] [Citation(s) in RCA: 105] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/16/2020] [Accepted: 11/19/2020] [Indexed: 10/22/2022]
Abstract
Outer Membrane Vesicles (OMV) have received increased attention in recent years as a vaccine platform against bacterial pathogens. OMV from Neisseria meningitidis serogroup B have been extensively explored. Following the success of the MeNZB OMV vaccine in controlling an outbreak of N. meningitidis B in New Zealand, additional research and development resulted in the licensure of the OMV-containing four-component 4CMenB vaccine, Bexsero. This provided broader protection against multiple meningococcal B strains. Advances in the field of genetic engineering have permitted further improvements in the platform resulting in increased yields, reduced endotoxicity and decoration with homologous and heterologous antigens to enhance immuno genicity and provide broader protection. The OMV vaccine platform has been extended to many other pathogens. In this review, we discuss progress in the development of the OMV vaccine delivery platform, highlighting successful applications, together with potential challenges and gaps.
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Affiliation(s)
| | - Calman A MacLennan
- Bill & Melinda Gates Foundation, 62 Buckingham Gate, London, United Kingdom; Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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12
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Guo L, Wang J, Gou Y, Tan L, Liu H, Pan Y, Zhao Y. Comparative proteomics reveals stress responses of Vibrio parahaemolyticus biofilm on different surfaces: Internal adaptation and external adjustment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 731:138386. [PMID: 32417469 DOI: 10.1016/j.scitotenv.2020.138386] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/27/2020] [Accepted: 03/31/2020] [Indexed: 06/11/2023]
Abstract
Vibrio parahaemolyticus is a kind of gram-negative marine pathogen, which usually adheres to stainless steel (SS), glass (GS) and other abiotic surfaces in aquaculture and food processing in the form of biofilm and causes the spread of gastrointestinal illness. However, the deeply survival adaptation mechanism of V. parahaemolyticus biofilm cells on these contact surface remained unclear. Here, proteomics was used to investigated the physiological response of the V. parahaemolyticus biofilms cells to different abiotic surfaces (SS, GS and polystyrene (PS)). In addition, the effect of contact materials on the physical-chemical properties of biofilms are also characterized. Results showed that the expression of proteins of biofilm cells established on the SS surface were mainly related to the alleviation of metal ion stress and toxicity. The up-regulated proteins in the biofilm cells formed on the GS surface were mainly involved in the biological processes of sugar uptake, protein synthesis and bacterial chemotaxis. Meanwhile, the significantly expressed proteins in the biofilm cells formed on the PS surface were mainly involved in the cellular physiological activity of aromatic compound metabolism, osmotic stress and nutrient transport. All functional proteins mentioned above were closely related to the interaction characteristics of the contact surface and biofilm. This study provided an in-depth comparison of V. parahaemolyticus biofilm formation on these three abiotic surfaces, and presented a model in first time for the adaptation behavior of biofilm cells on different surfaces as affected by metal ion stress, nutrition, osmotic stress, and sugar utilization, which could facilitate an efficient control strategy for biofilm formation in industrial field.
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Affiliation(s)
- Linxia Guo
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China
| | - Jingjing Wang
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China; Department of Food Science, Foshan University, Foshan, 528000, China
| | - Yi Gou
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China
| | - Ling Tan
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China
| | - Haiquan Liu
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China; Engineering Research Center of Food Thermal-processing Technology, Shanghai Ocean University, Shanghai 201306, China
| | - Yingjie Pan
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China
| | - Yong Zhao
- College of Food Science & Technology, Shanghai Ocean University, Shanghai, China; Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China; Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai, China.
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13
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Multicopy Suppressor Analysis of Strains Lacking Cytoplasmic Peptidyl-Prolyl cis/trans Isomerases Identifies Three New PPIase Activities in Escherichia coli That Includes the DksA Transcription Factor. Int J Mol Sci 2020; 21:ijms21165843. [PMID: 32823955 PMCID: PMC7461557 DOI: 10.3390/ijms21165843] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 11/17/2022] Open
Abstract
Consistent with a role in catalyzing rate-limiting step of protein folding, removal of genes encoding cytoplasmic protein folding catalysts belonging to the family of peptidyl-prolyl cis/trans isomerases (PPIs) in Escherichia coli confers conditional lethality. To address the molecular basis of the essentiality of PPIs, a multicopy suppressor approach revealed that overexpression of genes encoding chaperones (DnaK/J and GroL/S), transcriptional factors (DksA and SrrA), replication proteins Hda/DiaA, asparatokinase MetL, Cmk and acid resistance regulator (AriR) overcome some defects of Δ6ppi strains. Interestingly, viability of Δ6ppi bacteria requires the presence of transcriptional factors DksA, SrrA, Cmk or Hda. DksA, MetL and Cmk are for the first time shown to exhibit PPIase activity in chymotrypsin-coupled and RNase T1 refolding assays and their overexpression also restores growth of a Δ(dnaK/J/tig) strain, revealing their mechanism of suppression. Mutagenesis of DksA identified that D74, F82 and L84 amino acid residues are critical for its PPIase activity and their replacement abrogated multicopy suppression ability. Mutational studies revealed that DksA-mediated suppression of either Δ6ppi or ΔdnaK/J is abolished if GroL/S and RpoE are limiting, or in the absence of either major porin regulatory sensory kinase EnvZ or RNase H, transporter TatC or LepA GTPase or Pi-signaling regulator PhoU.
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14
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Nakkarach A, Foo HL, Song AAL, Nitisinprasert S, Withayagiat U. Promising discovery of beneficial Escherichia coli in the human gut. 3 Biotech 2020; 10:296. [PMID: 32550113 DOI: 10.1007/s13205-020-02289-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 06/01/2020] [Indexed: 01/03/2023] Open
Abstract
Ingested dietary fibres are hydrolysed by colon microbiota to produce energy-providing short-chain fatty acids (SCFA) that stimulate anti-inflammatory effects. SCFA-producing bacteria were screened from bacteria isolated from human faeces using bromothymol blue as an acid indicator and gas chromatography for SCFA profiling. The beneficial functions (antagonistic activity, haemolytic activities, antibiotic susceptibility, mucus adherent percentage and toxin gene detection) were evaluated for the top five SCFA-producing bacteria isolated from three healthy volunteers that identified as Escherichia coli strains. They produced acetic, propionic, isobutyric, butyric, isovaleric, valeric and caproic acids at average concentrations of 15.9, 1.8, 1.1, 1.9, 1.8, 2.7 and 3.4 mM, respectively. The SCFA production by E. coli strains was rapidly increased during the first 8 h of incubation and gradually decreased after 16 h of incubation. All E. coli strains showed acid and bile tolerance, resulting in a survival rate greater than 70% with no haemolytic activity, mucus adherence greater than 40% and susceptibility to conventional antibiotics. Hence, the selected E. coli strains exhibited promising probiotic properties with neither enterotoxin nor LPS producibility was detected. The present results confirm the existence of friendly and harmless E. coli strains in human microbiota as potential probiotics.
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Affiliation(s)
- Atchareeya Nakkarach
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
- Department of Bioprocess, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Hooi Ling Foo
- Department of Bioprocess, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Adelene Ai-Lian Song
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Sunee Nitisinprasert
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
| | - Ulaiwan Withayagiat
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
- Fermentation Technology Research Center, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
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15
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Ruan X, Monjarás Feria J, Hamad M, Valvano MA. Escherichia coli and Pseudomonas aeruginosa lipopolysaccharide O-antigen ligases share similar membrane topology and biochemical properties. Mol Microbiol 2018; 110:95-113. [PMID: 30047569 DOI: 10.1111/mmi.14085] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
WaaL is an inner membrane glycosyltransferase that catalyzes the transfer of O-antigen polysaccharide from its lipid-linked intermediate to a terminal sugar of the lipid A-core oligosaccharide, a conserved step in lipopolysaccharide biosynthesis. Ligation occurs at the periplasmic side of the bacterial cell membrane, suggesting the catalytic region of WaaL faces the periplasm. Establishing the membrane topology of the WaaL protein family will enable understanding its mechanism and exploit it as a potential antimicrobial target. Applying oxidative labeling of native methionine/cysteine residues, we previously validated a topological model for Escherichia coli WaaL, which differs substantially from the reported topology of the Pseudomonas aeruginosa WaaL, derived from the analysis of truncated protein reporter fusions. Here, we examined the topology of intact E. coli and P. aeruginosa WaaL proteins by labeling engineered cysteine residues with the membrane-impermeable sulfhydryl reagent polyethylene glycol maleimide (PEG-Mal). The accessibility of PEG-Mal to targeted engineered cysteine residues in both E. coli and P. aeruginosa WaaL proteins demonstrates that both ligases share similar membrane topology. Further, we also demonstrate that P. aeruginosa WaaL shares similar functional properties with E. coli WaaL and that E. coli WaaL may adopt a functional dimer conformation.
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Affiliation(s)
- Xiang Ruan
- Department of Microbiology and Immunology, University of Western Ontario, London, N6A 5C1, Canada
| | - Julia Monjarás Feria
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, United Kingdom
| | - Mohamad Hamad
- Department of Medical Laboratory Sciences, College of Health Sciences, University of Sharjah, Sharjah, United Arab Emirates
| | - Miguel A Valvano
- Department of Microbiology and Immunology, University of Western Ontario, London, N6A 5C1, Canada.,Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, United Kingdom
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16
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Shoji M, Sato K, Yukitake H, Kamaguchi A, Sasaki Y, Naito M, Nakayama K. Identification of genes encoding glycosyltransferases involved in lipopolysaccharide synthesis inPorphyromonas gingivalis. Mol Oral Microbiol 2017; 33:68-80. [DOI: 10.1111/omi.12200] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2017] [Indexed: 12/16/2022]
Affiliation(s)
- M. Shoji
- Department of Microbiology and Oral Infection; Nagasaki University Graduate School of Biomedical Sciences; Nagasaki Japan
| | - K. Sato
- Department of Microbiology and Oral Infection; Nagasaki University Graduate School of Biomedical Sciences; Nagasaki Japan
| | - H. Yukitake
- Department of Microbiology and Oral Infection; Nagasaki University Graduate School of Biomedical Sciences; Nagasaki Japan
| | - A. Kamaguchi
- Department of Oral Microbiology; School of Dentistry; Health Sciences University of Hokkaido; Hokkaido Japan
| | - Y. Sasaki
- Department of Microbiology and Oral Infection; Nagasaki University Graduate School of Biomedical Sciences; Nagasaki Japan
| | - M. Naito
- Department of Microbiology and Oral Infection; Nagasaki University Graduate School of Biomedical Sciences; Nagasaki Japan
| | - K. Nakayama
- Department of Microbiology and Oral Infection; Nagasaki University Graduate School of Biomedical Sciences; Nagasaki Japan
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17
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The Production of Curli Amyloid Fibers Is Deeply Integrated into the Biology of Escherichia coli. Biomolecules 2017; 7:biom7040075. [PMID: 29088115 PMCID: PMC5745457 DOI: 10.3390/biom7040075] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/13/2017] [Accepted: 10/23/2017] [Indexed: 12/29/2022] Open
Abstract
Curli amyloid fibers are the major protein component of the extracellular matrix produced by Enterobacteriaceae during biofilm formation. Curli are required for proper biofilm development and environmental persistence by Escherichia coli. Here, we present a complete and vetted genetic analysis of functional amyloid fiber biogenesis. The Keio collection of single gene deletions was screened on Congo red indicator plates to identify E. coli mutants that had defective amyloid production. We discovered that more than three hundred gene products modulated curli production. These genes were involved in fundamental cellular processes such as regulation, environmental sensing, respiration, metabolism, cell envelope biogenesis, transport, and protein turnover. The alternative sigma factors, σS and σE, had opposing roles in curli production. Mutations that induced the σE or Cpx stress response systems had reduced curli production, while mutant strains with increased σS levels had increased curli production. Mutations in metabolic pathways, including gluconeogenesis and the biosynthesis of lipopolysaccharide (LPS), produced less curli. Regulation of the master biofilm regulator, CsgD, was diverse, and the screen revealed several proteins and small RNAs (sRNA) that regulate csgD messenger RNA (mRNA) levels. Using previously published studies, we found minimal overlap between the genes affecting curli biogenesis and genes known to impact swimming or swarming motility, underlying the distinction between motile and sessile lifestyles. Collectively, the diversity and number of elements required suggest curli production is part of a highly regulated and complex developmental pathway in E. coli.
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18
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Mandal RK, Kwon YM. Global Screening of Salmonella enterica Serovar Typhimurium Genes for Desiccation Survival. Front Microbiol 2017; 8:1723. [PMID: 28943871 PMCID: PMC5596212 DOI: 10.3389/fmicb.2017.01723] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/24/2017] [Indexed: 01/13/2023] Open
Abstract
Salmonella spp., one of the most common foodborne bacterial pathogens, has the ability to survive under desiccation conditions in foods and food processing facilities for years. This raises the concerns of Salmonella infection in humans associated with low water activity foods. Salmonella responds to desiccation stress via complex pathways involving immediate physiological actions as well as coordinated genetic responses. However, the exact mechanisms of Salmonella to resist desiccation stress remain to be fully elucidated. In this study, we screened a genome-saturating transposon (Tn5) library of Salmonella Typhimurium (S. Typhimurium) 14028s under the in vitro desiccation stress using transposon sequencing (Tn-seq). We identified 61 genes and 6 intergenic regions required to overcome desiccation stress. Salmonella desiccation resistance genes were mostly related to energy production and conversion; cell wall/membrane/envelope biogenesis; inorganic ion transport and metabolism; regulation of biological process; DNA metabolic process; ABC transporters; and two component system. More than 20% of the Salmonella desiccation resistance genes encode either putative or hypothetical proteins. Phenotypic evaluation of 12 single gene knockout mutants showed 3 mutants (atpH, atpG, and corA) had significantly (p < 0.02) reduced survival as compared to the wild type during desiccation survival. Thus, our study provided new insights into the molecular mechanisms utilized by Salmonella for survival against desiccation stress. The findings might be further exploited to develop effective control strategies against Salmonella contamination in low water activity foods and food processing facilities.
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Affiliation(s)
- Rabindra K Mandal
- Department of Poultry Science, University of ArkansasFayetteville, AR, United States
| | - Young M Kwon
- Department of Poultry Science, University of ArkansasFayetteville, AR, United States.,Cell and Molecular Biology Program, University of ArkansasFayetteville, AR, United States
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19
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Shrivastava R, Jiang X, Chng SS. Outer membrane lipid homeostasis via retrograde phospholipid transport in Escherichia coli. Mol Microbiol 2017; 106:395-408. [PMID: 28815827 DOI: 10.1111/mmi.13772] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2017] [Indexed: 01/21/2023]
Abstract
Biogenesis of the outer membrane (OM) in Gram-negative bacteria, which is essential for viability, requires the coordinated transport and assembly of proteins and lipids, including lipopolysaccharides (LPS) and phospholipids (PLs), into the membrane. While pathways for LPS and OM protein assembly are well-studied, how PLs are transported to and from the OM is not clear. Mechanisms that ensure OM stability and homeostasis are also unknown. The trans-envelope Tol-Pal complex, whose physiological role has remained elusive, is important for OM stability. Here, we establish that the Tol-Pal complex is required for PL transport and OM lipid homeostasis in Escherichia coli. Cells lacking the complex exhibit defects in lipid asymmetry and accumulate excess PLs in the OM. This imbalance in OM lipids is due to defective retrograde PL transport in the absence of a functional Tol-Pal complex. Thus, cells ensure the assembly of a stable OM by maintaining an excess flux of PLs to the OM only to return the surplus to the inner membrane. Our findings also provide insights into the mechanism by which the Tol-Pal complex may promote OM invagination during cell division.
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Affiliation(s)
- Rahul Shrivastava
- Department of Chemistry, National University of Singapore, Singapore 117543
| | - Xiang'Er Jiang
- Department of Chemistry, National University of Singapore, Singapore 117543
| | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore 117543.,Singapore Center for Environmental Life Sciences Engineering, National University of Singapore (SCELSE-NUS), Singapore 117456
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20
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Volgers C, Savelkoul PHM, Stassen FRM. Gram-negative bacterial membrane vesicle release in response to the host-environment: different threats, same trick? Crit Rev Microbiol 2017; 44:258-273. [PMID: 28741415 DOI: 10.1080/1040841x.2017.1353949] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Bacteria are confronted with a multitude of stressors when occupying niches within the host. These stressors originate from host defense mechanisms, other bacteria during niche competition or result from physiological challenges such as nutrient limitation. To counteract these stressors, bacteria have developed a stress-induced network to mount the adaptations required for survival. These stress-induced adaptations include the release of membrane vesicles from the bacterial envelope. Membrane vesicles can provide bacteria with a plethora of immediate and ultimate benefits for coping with environmental stressors. This review addresses how membrane vesicles aid Gram-negative bacteria to cope with host-associated stress factors, focusing on vesicle biogenesis and the physiological functions. As many of the pathways, that drive vesicle biogenesis, confer we propose that shedding of membrane vesicles by Gram-negative bacteria entails an integrated part of general stress responses.
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Affiliation(s)
- Charlotte Volgers
- a Department of Medical Microbiology, School of Nutrition and Translational Research in Metabolism (NUTRIM) , Maastricht University Medical Centre , Maastricht , The Netherlands
| | - Paul H M Savelkoul
- a Department of Medical Microbiology, School of Nutrition and Translational Research in Metabolism (NUTRIM) , Maastricht University Medical Centre , Maastricht , The Netherlands.,b Department of Medical Microbiology and Infection Control , VU University Medical Center , Amsterdam , The Netherlands
| | - Frank R M Stassen
- a Department of Medical Microbiology, School of Nutrition and Translational Research in Metabolism (NUTRIM) , Maastricht University Medical Centre , Maastricht , The Netherlands
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21
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Baron F, Bonnassie S, Alabdeh M, Cochet MF, Nau F, Guérin-Dubiard C, Gautier M, Andrews SC, Jan S. Global Gene-expression Analysis of the Response of Salmonella Enteritidis to Egg White Exposure Reveals Multiple Egg White-imposed Stress Responses. Front Microbiol 2017; 8:829. [PMID: 28553268 PMCID: PMC5428311 DOI: 10.3389/fmicb.2017.00829] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 04/24/2017] [Indexed: 12/20/2022] Open
Abstract
Chicken egg white protects the embryo from bacterial invaders by presenting an assortment of antagonistic activities that combine together to both kill and inhibit growth. The key features of the egg white anti-bacterial system are iron restriction, high pH, antibacterial peptides and proteins, and viscosity. Salmonella enterica serovar Enteritidis is the major pathogen responsible for egg-borne infection in humans, which is partly explained by its exceptional capacity for survival under the harsh conditions encountered within egg white. However, at temperatures up to 42°C, egg white exerts a much stronger bactericidal effect on S. Enteritidis than at lower temperatures, although the mechanism of egg white-induced killing is only partly understood. Here, for the first time, the impact of exposure of S. Enteritidis to egg white under bactericidal conditions (45°C) is explored by global-expression analysis. A large-scale (18.7% of genome) shift in transcription is revealed suggesting major changes in specific aspects of S. Enteritidis physiology: induction of egg white related stress-responses (envelope damage, exposure to heat and alkalinity, and translation shutdown); shift in energy metabolism from respiration to fermentation; and enhanced micronutrient provision (due to iron and biotin restriction). Little evidence of DNA damage or redox stress was obtained. Instead, data are consistent with envelope damage resulting in cell death by lysis. A surprise was the high degree of induction of hexonate/hexuronate utilization genes, despite no evidence indicating the presence of these substrates in egg white.
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Affiliation(s)
- Florence Baron
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Sylvie Bonnassie
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- Science de la Vie et de la Terre, Université de Rennes IRennes, France
| | - Mariah Alabdeh
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Marie-Françoise Cochet
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Françoise Nau
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Catherine Guérin-Dubiard
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Michel Gautier
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | | | - Sophie Jan
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
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22
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Dennehy R, Romano M, Ruggiero A, Mohamed YF, Dignam SL, Mujica Troncoso C, Callaghan M, Valvano MA, Berisio R, McClean S. The Burkholderia cenocepacia peptidoglycan-associated lipoprotein is involved in epithelial cell attachment and elicitation of inflammation. Cell Microbiol 2016; 19. [PMID: 27886433 DOI: 10.1111/cmi.12691] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 10/18/2016] [Accepted: 11/03/2016] [Indexed: 12/26/2022]
Abstract
The Burkholderia cepacia complex (Bcc) is a group of Gram-negative opportunistic pathogens causing infections in people with cystic fibrosis (CF). Bcc is highly antibiotic resistant, making conventional antibiotic treatment problematic. The identification of novel targets for anti-virulence therapies should improve therapeutic options for infected CF patients. We previously identified that the peptidoglycan-associated lipoprotein (Pal) was immunogenic in Bcc infected CF patients; however, its role in Bcc pathogenesis is unknown. The virulence of a pal deletion mutant (Δpal) in Galleria mellonella was 88-fold reduced (p < .001) compared to wild type. The lipopolysaccharide profiles of wild type and Δpal were identical, indicating no involvement of Pal in O-antigen transport. However, Δpal was more susceptible to polymyxin B. Structural elucidation by X-ray crystallography and calorimetry demonstrated that Pal binds peptidoglycan fragments. Δpal showed a 1.5-fold reduced stimulation of IL-8 in CF epithelial cells relative to wild type (p < .001), demonstrating that Pal is a significant driver of inflammation. The Δpal mutant had reduced binding to CFBE41o- cells, but adhesion of Pal-expressing recombinant E. coli to CFBE41o- cells was enhanced compared to wild-type E. coli (p < .0001), confirming that Pal plays a direct role in host cell attachment. Overall, Bcc Pal mediates host cell attachment and stimulation of cytokine secretion, contributing to Bcc pathogenesis.
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Affiliation(s)
- Ruth Dennehy
- Centre of Microbial Host Interactions, Institute of Technology Tallaght, Dublin, Ireland
| | - Maria Romano
- National Research Council, Institute of Biostructures and Bioimaging, Naples, Italy
| | - Alessia Ruggiero
- National Research Council, Institute of Biostructures and Bioimaging, Naples, Italy
| | - Yasmine F Mohamed
- Centre for Experimental Medicine, Queen's University, Belfast, Northern Ireland.,Faculty of Pharmacy, Department of Microbiology, Alexandria University, Alexandria, Egypt
| | - Simon L Dignam
- Centre of Microbial Host Interactions, Institute of Technology Tallaght, Dublin, Ireland
| | | | - Máire Callaghan
- Centre of Microbial Host Interactions, Institute of Technology Tallaght, Dublin, Ireland
| | - Miguel A Valvano
- Centre for Experimental Medicine, Queen's University, Belfast, Northern Ireland
| | - Rita Berisio
- National Research Council, Institute of Biostructures and Bioimaging, Naples, Italy
| | - Siobhán McClean
- Centre of Microbial Host Interactions, Institute of Technology Tallaght, Dublin, Ireland
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23
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Santos CA, Janissen R, Toledo MAS, Beloti LL, Azzoni AR, Cotta MA, Souza AP. Characterization of the TolB-Pal trans-envelope complex from Xylella fastidiosa reveals a dynamic and coordinated protein expression profile during the biofilm development process. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1372-81. [PMID: 26049080 DOI: 10.1016/j.bbapap.2015.05.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/22/2015] [Accepted: 05/28/2015] [Indexed: 01/09/2023]
Abstract
The intriguing roles of the bacterial Tol-Pal trans-envelope protein complex range from maintenance of cell envelope integrity to potential participation in the process of cell division. In this study, we report the characterization of the XfTolB and XfPal proteins of the Tol-Pal complex of Xylella fastidiosa. X. fastidiosa is a major plant pathogen that forms biofilms inside xylem vessels, triggering the development of diseases in important cultivable plants around the word. Based on functional complementation experiments in Escherichia coli tolB and pal mutant strains, we confirmed the role of xftolB and xfpal in outer membrane integrity. In addition, we observed a dynamic and coordinated protein expression profile during the X. fastidiosa biofilm development process. Using small-angle X-ray scattering (SAXS), the low-resolution structure of the isolated XfTolB-XfPal complex in solution was solved for the first time. Finally, the localization of the XfTolB and XfPal polar ends was visualized via immunofluorescence labeling in vivo during bacterial cell growth. Our results highlight the major role of the components of the cell envelope, particularly the TolB-Pal complex, during the different phases of bacterial biofilm development.
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Affiliation(s)
- Clelton A Santos
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Richard Janissen
- Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Marcelo A S Toledo
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Lilian L Beloti
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Adriano R Azzoni
- Departamento de Engenharia Química, Escola Politécnica, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Monica A Cotta
- Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Anete P Souza
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, SP, Brazil; Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil.
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24
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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
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25
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Dor-On E, Solomon B. Targeting glioblastoma via intranasal administration of Ff bacteriophages. Front Microbiol 2015; 6:530. [PMID: 26074908 PMCID: PMC4445050 DOI: 10.3389/fmicb.2015.00530] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 05/14/2015] [Indexed: 01/29/2023] Open
Abstract
Bacteriophages (phages) are ubiquitous viruses that control the growth and diversity of bacteria. Although they have no tropism to mammalian cells, accumulated evidence suggests that phages are not neutral to the mammalian macro-host and can promote immunomodulatory and anti-tumorigenic activities. Here we demonstrate that Ff phages that do not display any proteins or peptides could inhibit the growth of subcutaneous glioblastoma tumors in mice and that this activity is mediated in part by lipopolysaccharide molecules attached to their virion. Using the intranasal route, a non-invasive approach to deliver therapeutics directly to the CNS, we further show that phages rapidly accumulate in the brains of mice and could attenuate progression of orthotopic glioblastoma. Taken together, this study provides new insight into phages non-bacterial activities and demonstrates the feasibility of delivering Ff phages intranasally to treat brain malignancies.
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Affiliation(s)
- Eyal Dor-On
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University Tel-Aviv, Israel
| | - Beka Solomon
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University Tel-Aviv, Israel
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26
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Martínez E, Paly E, Barre FX. CTXφ Replication Depends on the Histone-Like HU Protein and the UvrD Helicase. PLoS Genet 2015; 11:e1005256. [PMID: 25992634 PMCID: PMC4439123 DOI: 10.1371/journal.pgen.1005256] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/29/2015] [Indexed: 02/06/2023] Open
Abstract
The Vibrio cholerae bacterium is the agent of cholera. The capacity to produce the cholera toxin, which is responsible for the deadly diarrhea associated with cholera epidemics, is encoded in the genome of a filamentous phage, CTXφ. Rolling-circle replication (RCR) is central to the life cycle of CTXφ because amplification of the phage genome permits its efficient integration into the genome and its packaging into new viral particles. A single phage-encoded HUH endonuclease initiates RCR of the proto-typical filamentous phages of enterobacteriaceae by introducing a nick at a specific position of the double stranded DNA form of the phage genome. The rest of the process is driven by host factors that are either essential or crucial for the replication of the host genome, such as the Rep SF1 helicase. In contrast, we show here that the histone-like HU protein of V. cholerae is necessary for the introduction of a nick by the HUH endonuclease of CTXφ. We further show that CTXφ RCR depends on a SF1 helicase normally implicated in DNA repair, UvrD, rather than Rep. In addition to CTXφ, we show that VGJφ, a representative member of a second family of vibrio integrative filamentous phages, requires UvrD and HU for RCR while TLCφ, a satellite phage, depends on Rep and is independent from HU. One of the major strategies to prevent Cholera epidemics is the development of oral vaccines based on live attenuated Vibrio cholerae strains. The most promising vaccine strains have been obtained by deletion of the cholera toxin genes, which are harboured in the genome of an integrated phage, CTXϕ. However, they can re-acquire the cholera toxin genes when re-infected by CTXϕ or by hybrid phages between CTXϕ and other vibrio phages, which raised safety concerns about their use. Here, we developed a screening strategy to identify non-essential host factors implicated in CTXϕ replication. We show that the histone-like HU protein and the UvrD helicase are both absolutely required for its replication. We further show that they are essential for the replication of VGJϕ, a representative member of a family of phages that can form hybrids with CTXϕ. Accordingly, we demonstrate that the disruption of the two subunits of HU and/or of UvrD prevents infection of the V. cholerae by CTXϕ and VGJϕ. In addition, we show that it limits CTXϕ horizontal transmission. Taken together, these results indicate that HU- and/or UvrD- cells are promising candidates for the development of safer live attenuated cholera vaccine.
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Affiliation(s)
- Eriel Martínez
- Institute for Integrative Biology of the Cell (I2BC), Université Paris Saclay, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France
| | - Evelyne Paly
- Institute for Integrative Biology of the Cell (I2BC), Université Paris Saclay, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France
| | - François-Xavier Barre
- Institute for Integrative Biology of the Cell (I2BC), Université Paris Saclay, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France
- * E-mail:
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27
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Meloni E, Colucci AM, Micoli F, Sollai L, Gavini M, Saul A, Di Cioccio V, MacLennan CA. Simplified low-cost production of O-antigen from Salmonella Typhimurium Generalized Modules for Membrane Antigens (GMMA). J Biotechnol 2015; 198:46-52. [PMID: 25659926 DOI: 10.1016/j.jbiotec.2015.01.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 01/16/2015] [Accepted: 01/26/2015] [Indexed: 10/24/2022]
Abstract
The Novartis Vaccines Institute for Global Health is developing vaccines using outer membrane particles, known as Generalized Modules for Membrane Antigens (GMMA). These are blebs of outer membrane and periplasm, shed from the surface of living Gram-negative bacteria following the targeted deletion of proteins involved in maintaining the integrity of the inner and outer membranes. The current study investigates the use of GMMA as starting material for extraction of membrane components, focusing on the O-antigen polysaccharide portion of lipopolysaccharide from Salmonella Typhimurium. We show that the amount of O-antigen extracted from GMMA by acid hydrolysis is comparable to the quantity extracted from whole wild type bacteria, but with less protein and DNA contaminants. Compared to conventional purification, GMMA enabled a reduction in the number of purification steps required to obtain the O-antigen polysaccharide with the same purity. Purification processes from GMMA and bacteria were characterised by similar final yields. Use of GMMA as starting material provides the possibility to simplify the purification process of O-antigen, with a consequent decrease in manufacturing costs of O-antigen-based glyconjugate vaccines against Salmonella strains and potentially other Gram-negative bacteria.
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Affiliation(s)
- Eleonora Meloni
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Anna Maria Colucci
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Francesca Micoli
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Luigi Sollai
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Massimiliano Gavini
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Allan Saul
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Vito Di Cioccio
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Calman A MacLennan
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy.
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Morgan JK, Ortiz JA, Riordan JT. The role for TolA in enterohemorrhagic Escherichia coli pathogenesis and virulence gene transcription. Microb Pathog 2014; 77:42-52. [DOI: 10.1016/j.micpath.2014.10.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/14/2014] [Accepted: 10/21/2014] [Indexed: 01/16/2023]
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29
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Escherichia coli genes and pathways involved in surviving extreme exposure to ionizing radiation. J Bacteriol 2014; 196:3534-45. [PMID: 25049088 DOI: 10.1128/jb.01589-14] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To further an improved understanding of the mechanisms used by bacterial cells to survive extreme exposure to ionizing radiation (IR), we broadly screened nonessential Escherichia coli genes for those involved in IR resistance by using transposon-directed insertion sequencing (TraDIS). Forty-six genes were identified, most of which become essential upon heavy IR exposure. Most of these were subjected to direct validation. The results reinforced the notion that survival after high doses of ionizing radiation does not depend on a single mechanism or process, but instead is multifaceted. Many identified genes affect either DNA repair or the cellular response to oxidative damage. However, contributions by genes involved in cell wall structure/function, cell division, and intermediary metabolism were also evident. About half of the identified genes have not previously been associated with IR resistance or recovery from IR exposure, including eight genes of unknown function.
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30
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Black SL, Dawson A, Ward FB, Allen RJ. Genes required for growth at high hydrostatic pressure in Escherichia coli K-12 identified by genome-wide screening. PLoS One 2013; 8:e73995. [PMID: 24040140 PMCID: PMC3770679 DOI: 10.1371/journal.pone.0073995] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 08/01/2013] [Indexed: 11/28/2022] Open
Abstract
Despite the fact that much of the global microbial biosphere is believed to exist in high pressure environments, the effects of hydrostatic pressure on microbial physiology remain poorly understood. We use a genome-wide screening approach, combined with a novel high-throughput high-pressure cell culture method, to investigate the effects of hydrostatic pressure on microbial physiology in vivo. The Keio collection of single-gene deletion mutants in Escherichia coli K-12 was screened for growth at a range of pressures from 0.1 MPa to 60 MPa. This led to the identification of 6 genes, rodZ, holC, priA, dnaT, dedD and tatC, whose products were required for growth at 30 MPa and a further 3 genes, tolB, rffT and iscS, whose products were required for growth at 40 MPa. Our results support the view that the effects of pressure on cell physiology are pleiotropic, with DNA replication, cell division, the cytoskeleton and cell envelope physiology all being potential failure points for cell physiology during growth at elevated pressure.
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Affiliation(s)
- S. Lucas Black
- SUPA School of Physics and Astronomy, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - Angela Dawson
- SUPA School of Physics and Astronomy, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - F. Bruce Ward
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - Rosalind J. Allen
- SUPA School of Physics and Astronomy, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
- * E-mail:
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31
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Teleha MA, Miller AC, Larsen RA. Overexpression of the Escherichia coli TolQ protein leads to a null-FtsN-like division phenotype. Microbiologyopen 2013; 2:618-32. [PMID: 23818486 PMCID: PMC3831626 DOI: 10.1002/mbo3.101] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/27/2013] [Accepted: 06/03/2013] [Indexed: 11/25/2022] Open
Abstract
Mutations involving the Tol-Pal complex of Escherichia coli result in a subtle phenotype in which cells chain when grown under low-salt conditions. Here, the nonpolar deletion of individual genes encoding the cytoplasmic membrane-associated components of the complex (TolQ, TolR, TolA) produced a similar phenotype. Surprisingly, the overexpression of one of these proteins, TolQ, resulted in a much more overt phenotype in which cells occurred as elongated rods coupled in long chains when grown under normal salt conditions. Neither TolR nor TolA overexpression produced a phenotype, nor was the presence of either protein required for the TolQ-dependent phenotype. Consistent with their native membrane topology, the amino-terminal domain of TolQ specifically associated in vivo with the periplasmic domain of FtsN in a cytoplasm-based two-hybrid analysis. Further, the concomitant overexpression of FtsN rescued the TolQ-dependent phenotype, suggesting a model wherein the overexpression of TolQ sequesters FtsN, depleting this essential protein from the divisome during Gram-negative cell division. The role of the Tol-Pal system in division is discussed. Over-expression of the cytoplasmic membrane protein TolQ resulted in a division phenotype similar to that seen in cells depleted for FtsN. Two hybrid analysis suggested that TolQ and FtsN physically interact through domains that localize in the periplasmic space; while the concurrent over-expression of FtsN alleviated the TolQ over-expression phenotype. Together these results suggest a model wherein over-expressed TolQ sequesters FtsN, disrupting normal cell division.
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Affiliation(s)
- Mary A Teleha
- Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio, 43403; Division of Science and Math, Lorain County Community College, Elyria, Ohio, 44035
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Shoji M, Yukitake H, Sato K, Shibata Y, Naito M, Aduse-Opoku J, Abiko Y, Curtis MA, Nakayama K. Identification of an O-antigen chain length regulator, WzzP, in Porphyromonas gingivalis. Microbiologyopen 2013; 2:383-401. [PMID: 23509024 PMCID: PMC3684754 DOI: 10.1002/mbo3.84] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/11/2013] [Accepted: 02/19/2013] [Indexed: 01/22/2023] Open
Abstract
The periodontal pathogen Porphyromonas gingivalis has two different lipopolysaccharides (LPSs) designated O-LPS and A-LPS, which are a conventional O-antigen polysaccharide and an anionic polysaccharide that are both linked to lipid A-cores, respectively. However, the precise mechanisms of LPS biosynthesis remain to be determined. In this study, we isolated a pigment-less mutant by transposon mutagenesis and identified that the transposon was inserted into the coding sequence PGN_2005, which encodes a hypothetical protein of P. gingivalis ATCC 33277. We found that (i) LPSs purified from the PGN_2005 mutant were shorter than those of the wild type; (ii) the PGN_2005 protein was located in the inner membrane fraction; and (iii) the PGN_2005 gene conferred Wzz activity upon an Escherichia coli wzz mutant. These results indicate that the PGN_2005 protein, which was designated WzzP, is a functional homolog of the Wzz protein in P. gingivalis. Comparison of amino acid sequences among WzzP and conventional Wzz proteins indicated that WzzP had an additional fragment at the C-terminal region. In addition, we determined that the PGN_1896 and PGN_1233 proteins and the PGN_1033 protein appear to be WbaP homolog proteins and a Wzx homolog protein involved in LPS biosynthesis, respectively.
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Affiliation(s)
- Mikio Shoji
- Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, 852-8588, Japan
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Zhou K, Michiels CW, Aertsen A. Variation of intragenic tandem repeat tract of tolA modulates Escherichia coli stress tolerance. PLoS One 2012; 7:e47766. [PMID: 23094082 PMCID: PMC3477136 DOI: 10.1371/journal.pone.0047766] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 09/20/2012] [Indexed: 11/18/2022] Open
Abstract
In recent work we discovered that the intragenic tandem repeat (TR) region of the tolA gene is highly variable among different Escherichia coli strains. The aim of this study was therefore to investigate the biological function and dynamics of TR variation in E. coli tolA. The biological impact of TR variation was examined by comparing the ability of a set of synthetic tolA variants with in frame repeat copies varying from 2 to 39 to rescue the altered susceptibility of an E. coli ΔtolA mutant to deoxycholic acid, sodium dodecyl sulfate, hyperosmolarity, and infection with filamentous bacteriophage. Interestingly, although each of the TolA variants was able to at least partly rescue the ΔtolA mutant, the extent was clearly dependent on both the repeat number and the type of stress imposed, indicating the existence of opposing selective forces with regard to the optimal TR copy number. Subsequently, TR dynamics in a clonal population were assayed, and we could demonstrate that TR contractions are RecA dependent and enhanced in a DNA repair deficient uvrD background, and can occur at a frequency of 6.9×10−5.
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Affiliation(s)
- Kai Zhou
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Department of Microbial and Molecular Systems (MS), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Chris W. Michiels
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Department of Microbial and Molecular Systems (MS), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Abram Aertsen
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Department of Microbial and Molecular Systems (MS), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
- * E-mail:
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Vonkavaara M, Pavel STI, Hölzl K, Nordfelth R, Sjöstedt A, Stöven S. Francisella is sensitive to insect antimicrobial peptides. J Innate Immun 2012; 5:50-9. [PMID: 23037919 DOI: 10.1159/000342468] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 08/01/2012] [Indexed: 12/24/2022] Open
Abstract
Francisella tularensis causes the zoonotic disease tularemia. Arthropod vectors are important transmission routes for the disease, although it is not known how Francisella survives the efficient arthropod immune response. Here, we used Drosophila melanogaster as a model host for Francisella infections and investigated whether the bacteria are resistant to insect humoral immune responses, in particular to the antimicrobial peptides (AMPs) secreted into the insect hemolymph. Moreover, we asked to what extent such resistance might depend on lipopolysaccharide (LPS) structure and surface characteristics of the bacteria. We analyzed Francisella novicida mutant strains in genes, directly or indirectly involved in specific steps of LPS biosynthesis, for virulence in wild-type and Relish(E20) immune-deficient flies, and tested selected mutants for sensitivity to AMPs in vitro. We demonstrate that Francisella is sensitive to specific fly AMPs, i.e. Attacin, Cecropin, Drosocin and Drosomycin. Furthermore, six bacterial genes, kpsF, manB, lpxF, slt, tolA and pal, were found to be required for resistance to Relish-dependent immune responses, illustrating the importance of structural details of Francisella lipid A and Kdo core for interactions with AMPs. Interestingly, a more negative surface charge and lack of O-antigen did not render mutant bacteria more sensitive to cationic AMPs and did not attenuate virulence in flies.
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Affiliation(s)
- Malin Vonkavaara
- Department of Clinical Microbiology, Umeå University, Umeå, Sweden
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35
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Ihnatko R, Shaw E, Toman R. Proteome of Coxiella burnetii. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 984:105-30. [DOI: 10.1007/978-94-007-4315-1_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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36
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Ruan X, Loyola DE, Marolda CL, Perez-Donoso JM, Valvano MA. The WaaL O-antigen lipopolysaccharide ligase has features in common with metal ion-independent inverting glycosyltransferases. Glycobiology 2011; 22:288-99. [PMID: 21983211 DOI: 10.1093/glycob/cwr150] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
WaaL is a membrane enzyme that catalyzes a key step in lipopolysaccharide (LPS) synthesis: the glycosidic bonding of a sugar at the proximal end of the undecaprenyl-diphosphate (Und-PP) O-antigen with a terminal sugar of the lipid A-core oligosaccharide (OS). Utilizing an in vitro assay, we demonstrate here that ligation with purified Escherichia coli WaaL occurs without adenosine-5'-triphosphate (ATP) and magnesium ions. Furthermore, E. coli and Pseudomonas aeruginosa WaaL proteins cannot catalyze ATP hydrolysis in vitro. We also show that a lysine substitution of the arginine (Arg)-215 residue renders an active protein, whereas WaaL mutants with alanine replacements in the periplasmic-exposed residues Arg-215, Arg-288 and histidine (His)-338 and also the membrane-embedded aspartic acid-389 are nonfunctional. An in silico approach, combining predicted topological information with the analysis of sequence conservation, confirms the importance of a positive charge at the small periplasmic loop of WaaL, since an Arg corresponding to Arg-215 was found at a similar position in all the WaaL homologs. Also, a universally conserved H[NSQ]X(9)GXX[GTY] motif spanning the C-terminal end of the predicted large periplasmic loop and the membrane boundary of the transmembrane helix was identified. The His residue in this motif corresponds to His-338. A survey of LPS structures in which the linkage between O-antigen and lipid A-core OS was elucidated reveals that it is always in the β-configuration, whereas the sugars bound to Und-PP are in the α-configuration. Together, our biochemical and in silico data argue that WaaL proteins use a common reaction mechanism and share features of metal ion-independent inverting glycosyltransferases.
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Affiliation(s)
- Xiang Ruan
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, ON, Canada
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37
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Varying dependency of periplasmic peptidylprolyl cis–trans isomerases in promoting Yersinia pseudotuberculosis stress tolerance and pathogenicity. Biochem J 2011; 439:321-32. [DOI: 10.1042/bj20110767] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Periplasmic PPIases (peptidylprolyl cis–trans isomerases) catalyse the cis–trans isomerization of peptidyl-prolyl bonds, which is a rate-limiting step during protein folding. We demonstrate that the surA, ppiA, ppiD, fkpA and fklB alleles each encode a periplasmic PPIase in the bacterial pathogen Yersinia pseudotuberculosis. Of these, four were purified to homogeneity. Purified SurA, FkpA and FklB, but not PpiD, displayed detectable PPIase activity in vitro. Significantly, only Y. pseudotuberculosis lacking surA caused drastic alterations to the outer membrane protein profile and FA (fatty acid) composition. They also exhibited aberrant cellular morphology, leaking LPS (lipopolysaccharide) into the extracellular environment. The SurA PPIase is therefore most critical for maintaining Y. pseudotuberculosis envelope integrity during routine culturing. On the other hand, bacteria lacking either surA or all of the genes ppiA, ppiD, fkpA and fklB were sensitive to hydrogen peroxide and were attenuated in mice infections. Thus Y. pseudotuberculosis exhibits both SurA-dependent and -independent requirements for periplasmic PPIase activity to ensure in vivo survival and a full virulence effect in a mammalian host.
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38
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Structure-guided investigation of lipopolysaccharide O-antigen chain length regulators reveals regions critical for modal length control. J Bacteriol 2011; 193:3710-21. [PMID: 21642455 DOI: 10.1128/jb.00059-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The O-antigen component of the lipopolysaccharide (LPS) represents a population of polysaccharide molecules with nonrandom (modal) chain length distribution. The number of the repeat O units in each individual O-antigen polymer depends on the Wzz chain length regulator, an inner membrane protein belonging to the polysaccharide copolymerase (PCP) family. Different Wzz proteins confer vastly different ranges of modal lengths (4 to >100 repeat units), despite having remarkably conserved structural folds. The molecular mechanism responsible for the selective preference for a certain number of O units is unknown. Guided by the three-dimensional structures of PCPs, we constructed a panel of chimeric molecules containing parts of two closely related Wzz proteins from Salmonella enterica and Shigella flexneri which confer different O-antigen chain length distributions. Analysis of the O-antigen length distribution imparted by each chimera revealed the region spanning amino acids 67 to 95 (region 67 to 95), region 200 to 255, and region 269 to 274 as primarily affecting the length distribution. We also showed that there is no synergy between these regions. In particular, region 269 to 274 also influenced chain length distribution mediated by two distantly related PCPs, WzzB and FepE. Furthermore, from the 3 regions uncovered in this study, region 269 to 274 appeared to be critical for the stability of the oligomeric form of Wzz, as determined by cross-linking experiments. Together, our data suggest that chain length determination depends on regions that likely contribute to stabilize a supramolecular complex.
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Vanderkelen L, Van Herreweghe JM, Vanoirbeek KGA, Baggerman G, Myrnes B, Declerck PJ, Nilsen IW, Michiels CW, Callewaert L. Identification of a bacterial inhibitor against g-type lysozyme. Cell Mol Life Sci 2011; 68:1053-64. [PMID: 20734102 PMCID: PMC11115080 DOI: 10.1007/s00018-010-0507-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/12/2010] [Accepted: 08/10/2010] [Indexed: 01/17/2023]
Abstract
Lysozymes are antibacterial effectors of the innate immune system in animals that hydrolyze peptidoglycan. Bacteria have evolved protective mechanisms that contribute to lysozyme tolerance such as the production of lysozyme inhibitors, but only inhibitors of chicken (c-) and invertebrate (i-) type lysozyme have been identified. We here report the discovery of a novel Escherichia coli inhibitor specific for goose (g-) type lysozymes, which we designate PliG (periplasmic lysozyme inhibitor of g-type lysozyme). Although it does not inhibit c- or i-type lysozymes, PliG shares a structural sequence motif with the previously described PliI and MliC/PliC lysozyme inhibitor families, suggesting a common ancestry and mode of action. Deletion of pliG increased the sensitivity of E. coli to g-type lysozyme. The existence of inhibitors against all major types of animal lysozyme and their contribution to lysozyme tolerance suggest that lysozyme inhibitors may play a role in bacterial interactions with animal hosts.
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Affiliation(s)
- L. Vanderkelen
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium
| | - J. M. Van Herreweghe
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium
| | - K. G. A. Vanoirbeek
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium
| | - G. Baggerman
- Prometa, Interfaculty Centre for Proteomics and Metabolomics, Katholieke Universiteit Leuven, O&N II Herestraat 49, 3000 Leuven, Belgium
| | - B. Myrnes
- Fish Health and Marine Bioprospecting, Nofima Marin, P.O. Box 6122, 9291 Tromsø, Norway
| | - P. J. Declerck
- Laboratory for Pharmaceutical Biology, Katholieke Universiteit Leuven, O&N II Herestraat 49, 3000 Leuven, Belgium
| | - I. W. Nilsen
- Fish Health and Marine Bioprospecting, Nofima Marin, P.O. Box 6122, 9291 Tromsø, Norway
| | - C. W. Michiels
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium
| | - L. Callewaert
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Belgium
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Membrane topology and identification of critical amino acid residues in the Wzx O-antigen translocase from Escherichia coli O157:H4. J Bacteriol 2010; 192:6160-71. [PMID: 20870764 DOI: 10.1128/jb.00141-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Wzx belongs to a family of membrane proteins involved in the translocation of isoprenoid lipid-linked glycans, which is loosely related to members of the major facilitator superfamily. Despite Wzx homologs performing a conserved function, it has been difficult to pinpoint specific motifs of functional significance in their amino acid sequences. Here, we elucidate the topology of the Escherichia coli O157 Wzx (Wzx(EcO157)) by a combination of bioinformatics and substituted cysteine scanning mutagenesis, as well as targeted deletion-fusions to green fluorescent protein and alkaline phosphatase. We conclude that Wzx(EcO157) consists of 12 transmembrane (TM) helices and six periplasmic and five cytosolic loops, with N and C termini facing the cytoplasm. Four TM helices (II, IV, X, and XI) contain polar residues (aspartic acid or lysine), and they may form part of a relatively hydrophilic core. Thirty-five amino acid replacements to alanine or serine were targeted to five native cysteines and most of the aspartic acid, arginine, and lysine residues. From these, only replacements of aspartic acid-85, aspartic acid-326, arginine-298, and lysine-419 resulted in a protein unable to support O-antigen production. Aspartic acid-85 and lysine-419 are located in TM helices II and XI, while arginine-298 and aspartic acid-326 are located in periplasmic and cytosolic loops 4, respectively. Further analysis revealed that the charge at these positions is required for Wzx function since conservative substitutions maintaining the same charge polarity resulted in a functional protein, whereas those reversing or eliminating polarity abolished function. We propose that the functional requirement of charged residues at both sides of the membrane and in two TM helices could be important to allow the passage of the Und-PP-linked saccharide substrate across the membrane.
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Identification of Brucella abortus genes in elk (Cervus elaphus) using in vivo-induced antigen technology (IVIAT) reveals novel markers of infection. Vet Microbiol 2010; 142:367-72. [DOI: 10.1016/j.vetmic.2009.10.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 10/12/2009] [Accepted: 10/13/2009] [Indexed: 01/11/2023]
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Reguera M, Lloret J, Margaret I, Vinardell JM, Martín M, Buendía A, Rivilla R, Ruiz-Sainz JE, Bonilla I, Bolaños L. GeneSMb21071of plasmid pSymB is required for osmoadaptation ofSinorhizobium meliloti1021 and is implicated in modifications of cell surface polysaccharides structure in response to hyperosmotic stress. Can J Microbiol 2009; 55:1145-52. [DOI: 10.1139/w09-073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Megaplasmid pSymB of the nitrogen-fixing symbiont Sinorhizobium meliloti , implicated in adaptation to hyperosmotic stress, contains 11 gene clusters that apparently encode surface polysaccharides. However, only 2 of these clusters, containing the exo and exp genes, have been associated with the synthesis of the acidic exopolysaccharides succinoglycan and galactoglucan, respectively. The functions of the other 9 clusters remain unsolved. The involvement of one of those regions, pSymB cluster 3, on surface polysaccharide synthesis and its possible implication in osmoadaptation were investigated. In silico analysis of cluster 3 showed that it putatively encodes for the synthesis and transport of a methylated surface polysaccharide. Mutants affected in this cluster were symbiotically effective but showed defects in growth under saline and nonsaline osmotic stress. The gene SMb21071, encoding a putative initiating glycosyltransferase, is transcriptionally induced under hyperosmotic conditions. Sodium dodecyl sulfate – polyacrylamide gel electrophoresis and silver staining showed that osmotic stresses changed the profiles of surface polysaccharides of wild-type and mutants strains in different ways. The overall results suggest that cluster 3 is important for growth under saline stress and essential for growth under nonsaline hyperosmotic stress, and it appears to be implicated in maintaining and (or) modifying surface polysaccharides in response to osmotic stress.
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Affiliation(s)
- María Reguera
- Departamento de Biologia, Facultad de Ciencias, Universidad Autonoma de Madrid, Darwin 2, 28049-Madrid, Spain
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Novoa-Garrido M, Novoa-Garrido M, Steinum TM, Novoa-Garrido M, Steinum TM, Marolda CL, Valvano MA, Sørum H. Reduced lipopolysaccharide O antigen expression, increased acid susceptibility and multicellular behaviour in an Escherichia coliisolate after long-term in vitroexposure to formic acid. MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2009. [DOI: 10.1080/08910600902948966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Margarita Novoa-Garrido
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
| | - Margarita Novoa-Garrido
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
| | - Terje M. Steinum
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
| | - Margarita Novoa-Garrido
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
| | - Terje M. Steinum
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
| | - Cristina L. Marolda
- Infectious Diseases Research Group, Siebens-Drake Medical Research Institute, Department of Microbiology and Immunology
| | - Miguel A. Valvano
- Infectious Diseases Research Group, Siebens-Drake Medical Research Institute, Department of Microbiology and Immunology
- Department of Medicine, University of Western Ontario, London, ON, Canada
| | - Henning Sørum
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway
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Cell envelope perturbation induces oxidative stress and changes in iron homeostasis in Vibrio cholerae. J Bacteriol 2009; 191:5398-408. [PMID: 19542276 DOI: 10.1128/jb.00092-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Vibrio cholerae type II secretion (T2S) machinery is a multiprotein complex that spans the cell envelope. When the T2S system is inactivated, cholera toxin and other exoproteins accumulate in the periplasmic compartment. Additionally, loss of secretion via the T2S system leads to a reduced growth rate, compromised outer membrane integrity, and induction of the extracytoplasmic stress factor RpoE (A. E. Sikora, S. R. Lybarger, and M. Sandkvist, J. Bacteriol. 189:8484-8495, 2007). In this study, gene expression profiling reveals that inactivation of the T2S system alters the expression of genes encoding cell envelope components and proteins involved in central metabolism, chemotaxis, motility, oxidative stress, and iron storage and acquisition. Consistent with the gene expression data, molecular and biochemical analyses indicate that the T2S mutants suffer from internal oxidative stress and increased levels of intracellular ferrous iron. By using a tolA mutant of V. cholerae that shares a similar compromised membrane phenotype but maintains a functional T2S machinery, we show that the formation of radical oxygen species, induction of oxidative stress, and changes in iron physiology are likely general responses to cell envelope damage and are not unique to T2S mutants. Finally, we demonstrate that disruption of the V. cholerae cell envelope by chemical treatment with polymyxin B similarly results in induction of the RpoE-mediated stress response, increased sensitivity to oxidants, and a change in iron metabolism. We propose that many types of extracytoplasmic stresses, caused either by genetic alterations of outer membrane constituents or by chemical or physical damage to the cell envelope, induce common signaling pathways that ultimately lead to internal oxidative stress and misregulation of iron homeostasis.
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Godlewska R, Wiśniewska K, Pietras Z, Jagusztyn-Krynicka EK. Peptidoglycan-associated lipoprotein (Pal) of Gram-negative bacteria: function, structure, role in pathogenesis and potential application in immunoprophylaxis. FEMS Microbiol Lett 2009; 298:1-11. [PMID: 19519769 DOI: 10.1111/j.1574-6968.2009.01659.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The protein Pal (peptidoglycan-associated lipoprotein) is anchored in the outer membrane (OM) of Gram-negative bacteria and interacts with Tol proteins. Tol-Pal proteins form two complexes: the first is composed of three inner membrane Tol proteins (TolA, TolQ and TolR); the second consists of the TolB and Pal proteins linked to the cell's OM. These complexes interact with one another forming a multiprotein membrane-spanning system. It has recently been demonstrated that Pal is essential for bacterial survival and pathogenesis, although its role in virulence has not been clearly defined. This review summarizes the available data concerning the structure and function of Pal and its role in pathogenesis.
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Affiliation(s)
- Renata Godlewska
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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Paterson GK, Northen H, Cone DB, Willers C, Peters SE, Maskell DJ. Deletion of tolA in Salmonella Typhimurium generates an attenuated strain with vaccine potential. Microbiology (Reading) 2009; 155:220-228. [DOI: 10.1099/mic.0.021576-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The Gram-negative Tol-Pal system of envelope proteins plays a key role in maintaining outer membrane integrity and contributes to the virulence of several pathogens. We have investigated the role of one of these proteins, TolA, in the biology of Salmonella enterica serovar Typhimurium. Deletion of tolA rendered strain SL1344 more susceptible to killing by bile and human serum. In addition the mutant had impaired membrane integrity and displayed alterations in LPS production. The tolA mutant was highly attenuated in mouse infections via the oral and intravenous routes. Importantly, each phenotype displayed by the mutant was complemented by provision of tolA
in trans. The tolA gene therefore contributes to virulence, membrane integrity, LPS production and bile and serum resistance in S. enterica serovar Typhimurium SL1344. Finally, immunization with the tolA mutant provided significant protection against subsequent challenge with wild-type SL1344. The Tol-Pal system is therefore a potential target in the development of novel attenuated live vaccines against Salmonella and other Gram-negative pathogens.
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Affiliation(s)
- G. K. Paterson
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - H. Northen
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - D. B. Cone
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - C. Willers
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - S. E. Peters
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - D. J. Maskell
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
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Pérez JM, McGarry MA, Marolda CL, Valvano MA. Functional analysis of the large periplasmic loop of theEscherichia coliK-12 WaaL O-antigen ligase. Mol Microbiol 2008; 70:1424-40. [DOI: 10.1111/j.1365-2958.2008.06490.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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48
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Liu Y, Fratamico P, Debroy C, Bumbaugh AC, Allen JW. DNA sequencing and identification of serogroup-specific genes in the Escherichia coli O118 O antigen gene cluster and demonstration of antigenic diversity but only minor variation in DNA sequence of the O antigen clusters of E. coli O118 and O151. Foodborne Pathog Dis 2008; 5:449-57. [PMID: 18673069 DOI: 10.1089/fpd.2008.0096] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The DNA sequence of the O antigen gene cluster of an Escherichia coli serogroup O118 strain was determined, and 13 open reading frames (ORFs) were identified, encoding genes required for O antigen sugar biosynthesis, transfer, and processing. Polymerase chain reaction (PCR) assays targeting the wzx (O antigen flippase) and wzy (O antigen polymerase) genes in the O antigen gene cluster of E. coli O118 were designed for identification of these serogroups. Specificity testing using strains belonging to E. coli O118 isolated from various sources, representative strains of 167 other E. coli O serogroups, and 20 non-E. coli bacteria revealed that the PCR assays were specific for E. coli O118. Thus, the PCR assays can be used for rapid identification of E. coli O118 as an alterative to typing using antisera. However, the PCR assays targeting the E. coli O118 wzx and wzy genes were also positive using E. coli serogroup O151 DNA. Therefore, the sequence of the O antigen gene cluster of E. coli O151 was determined, and it was very similar to that of E. coli O118, with only three nucleotide differences. Although the lipopolysaccharide profiles of O118 and O151 showed differences, multilocus sequence typing of E. coli O118 and O151 strains only revealed minor variation at the nucleotide level. Since E. coli O118 strains are more frequently isolated from humans, animals, and the environment than E. coli O151, serogroup O151 may likely be a minor variant of E. coli O118. Further studies are needed to elucidate this possibility.
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Affiliation(s)
- Yanhong Liu
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, Pennsylvania 19038, USA.
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Kintz E, Goldberg JB. Regulation of lipopolysaccharide O antigen expression in Pseudomonas aeruginosa. Future Microbiol 2008; 3:191-203. [DOI: 10.2217/17460913.3.2.191] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative bacterium that is ubiquitously found in the environment. It is an important opportunistic pathogen in immunocompromised patients and causes life-threatening lung infections in individuals with cystic fibrosis. A prominent virulence factor for many Gram-negative bacteria, including P. aeruginosa, is lipopolysaccharide (LPS), which is an immunodominant antigen located in the outer portion of the outer membrane. P. aeruginosa produces two O antigens that are attached to lipid A + core: a B-band O antigen and an A-band O polysaccharide. The B-band O antigen-repeating unit of LPS is responsible for serotype specificity; strains lacking O antigen have been shown to be less virulent in animal models of infection. What is less well understood is how the O antigen chain length is regulated and why P. aeruginosa and some other bacteria show two preferred O antigen lengths. P. aeruginosa encodes two genes encoding O antigen chain length regulators. These genes, wzz1 and wzz2, influence the expression of the long and very long chain lengths, respectively. The long chain length appears more important for resistance to the action of sera and virulence in a mouse model of infection, while the very long chain length appears to be more sensitive to environmental stress conditions. Studies in other bacteria point to regulation at the level of transcription and complex formation as being involved in determining the O antigen chain length and may provide clues to the regulation in P. aeruginosa.
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Affiliation(s)
- Erica Kintz
- Department of Microbiology, University of Virginia Health System, 1300 Jefferson Park Avenue, 7230 Jordan Hall, Charlottesville, VA 22908-0734, USA
| | - Joanna B Goldberg
- Department of Microbiology, University of Virginia Health System, 1300 Jefferson Park Avenue, 7230 Jordan Hall, Charlottesville, VA 22908-0734, USA
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Chang J, Pang E, He H, Kwang J. Identification of novel attenuated Salmonella Enteritidis mutants. ACTA ACUST UNITED AC 2008; 53:26-34. [PMID: 18355292 DOI: 10.1111/j.1574-695x.2008.00394.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Salmonella Enteritidis is a major food-borne pathogen that causes nontyphoidal diarrhoea in humans. Infection of adult egg-laying hens usually results in symptomless carriage but in young chicks it may cause paratyphoid disease. It is not known whether S. Enteritidis requires genes additional to known virulence genes for systemic infection of young chickens. A transposon insertion library was created using S. Enteritidis 10/02, which yielded 1246 mutants. Of 384 mutants screened in chickens for attenuation (30.8% of insertion library), 12 (3.1%) had a 50% lethal dose at least 100 times that of the parental strain. Sequencing revealed insertions in genes involved in the biosynthesis of lipopolysaccharide, cell membrane, ATP biosynthesis, transcriptional regulation of virulence and the yhbC gene, which has an unknown function. Evaluation of in vitro virulence characteristics of a Delta yhbC mutant revealed that its ability to invade HeLa cells and survive within a chicken macrophage cell line (HD11) was significantly reduced. It was also less resistant to reactive oxygen and nitrogen intermediates and had a retarded growth rate. Chickens challenged with the Delta yhbC mutant cleared the organism from the liver and spleen 1 week faster than the parental strain and were able to develop specific serum IgG antibodies against the Delta yhbC mutant.
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Affiliation(s)
- Jason Chang
- Animal Health Biotechnology Group, Temasek Life Sciences Laboratory, National University of Singapore, Singapore
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