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Singh PK, Sharma P, Afanzar O, Goldfarb MH, Maklashina E, Eisenbach M, Cecchini G, Iverson TM. CryoEM structures reveal how the bacterial flagellum rotates and switches direction. Nat Microbiol 2024; 9:1271-1281. [PMID: 38632342 PMCID: PMC11087270 DOI: 10.1038/s41564-024-01674-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 03/12/2024] [Indexed: 04/19/2024]
Abstract
Bacterial chemotaxis requires bidirectional flagellar rotation at different rates. Rotation is driven by a flagellar motor, which is a supercomplex containing multiple rings. Architectural uncertainty regarding the cytoplasmic C-ring, or 'switch', limits our understanding of how the motor transmits torque and direction to the flagellar rod. Here we report cryogenic electron microscopy structures for Salmonella enterica serovar typhimurium inner membrane MS-ring and C-ring in a counterclockwise pose (4.0 Å) and isolated C-ring in a clockwise pose alone (4.6 Å) and bound to a regulator (5.9 Å). Conformational differences between rotational poses include a 180° shift in FliF/FliG domains that rotates the outward-facing MotA/B binding site to inward facing. The regulator has specificity for the clockwise pose by bridging elements unique to this conformation. We used these structures to propose how the switch reverses rotation and transmits torque to the flagellum, which advances the understanding of bacterial chemotaxis and bidirectional motor rotation.
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Affiliation(s)
- Prashant K Singh
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Pankaj Sharma
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Oshri Afanzar
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Margo H Goldfarb
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Elena Maklashina
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA, USA
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
| | - Michael Eisenbach
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA, USA
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA.
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA.
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA.
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2
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Gaudet RG, Zhu S, Halder A, Kim BH, Bradfield CJ, Huang S, Xu D, Mamiñska A, Nguyen TN, Lazarou M, Karatekin E, Gupta K, MacMicking JD. A human apolipoprotein L with detergent-like activity kills intracellular pathogens. Science 2021; 373:eabf8113. [PMID: 34437126 PMCID: PMC8422858 DOI: 10.1126/science.abf8113] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 04/29/2021] [Accepted: 06/03/2021] [Indexed: 12/11/2022]
Abstract
Activation of cell-autonomous defense by the immune cytokine interferon-γ (IFN-γ) is critical to the control of life-threatening infections in humans. IFN-γ induces the expression of hundreds of host proteins in all nucleated cells and tissues, yet many of these proteins remain uncharacterized. We screened 19,050 human genes by CRISPR-Cas9 mutagenesis and identified IFN-γ-induced apolipoprotein L3 (APOL3) as a potent bactericidal agent protecting multiple non-immune barrier cell types against infection. Canonical apolipoproteins typically solubilize mammalian lipids for extracellular transport; APOL3 instead targeted cytosol-invasive bacteria to dissolve their anionic membranes into human-bacterial lipoprotein nanodiscs detected by native mass spectrometry and visualized by single-particle cryo-electron microscopy. Thus, humans have harnessed the detergent-like properties of extracellular apolipoproteins to fashion an intracellular lysin, thereby endowing resident nonimmune cells with a mechanism to achieve sterilizing immunity.
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Affiliation(s)
- Ryan G Gaudet
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shiwei Zhu
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Anushka Halder
- Yale Nanobiology Institute, West Haven, CT 06477, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Bae-Hoon Kim
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Clinton J Bradfield
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shuai Huang
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Dijin Xu
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Agnieszka Mamiñska
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Thanh Ngoc Nguyen
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne 3800, Australia
| | - Michael Lazarou
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne 3800, Australia
| | - Erdem Karatekin
- Yale Nanobiology Institute, West Haven, CT 06477, USA
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA
- Saints-Pères Paris Institute for the Neurosciences, Centre National de la Recherche Scientifique (CNRS), Université de Paris, F-75006 Paris, France
| | - Kallol Gupta
- Yale Nanobiology Institute, West Haven, CT 06477, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - John D MacMicking
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA.
- Yale Systems Biology Institute, West Haven, CT 06477, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
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Liu D, Chen Q, Zhang L, Hu H, Yin C. AgsA oligomer acts as a functional unit. Biochem Biophys Res Commun 2020; 530:22-28. [PMID: 32828289 DOI: 10.1016/j.bbrc.2020.07.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 11/18/2022]
Abstract
AgsA (aggregation-suppressing protein) is an ATP-independent molecular chaperone machine belonging to the family of small heat shock proteins (sHSP), and it can prevent the aggregation of non-natural proteins. However, the substrate-binding site of AgsA and the functional unit that captures and binds the substrate remain unknown. In this study, different N-terminal and C-terminal deletion mutants of AgsA were constructed and their effects on AgsA oligomer assembly and chaperone activity were investigated. We found that the IXI motif at the C-terminus and the α-helix at the N-terminus affected the oligomerization and molecular chaperone activity of AgsA. In this work, we obtained a 6.8 Å resolution structure of AgsA using Electron cryo-microscopy (cryo-EM), and found that the functional form of AgsA was an 18-mer with D3 symmetry. Through amino acid mutations, disulfide bonds were introduced into two oligomeric interfaces, namely dimeric interface and non-partner interface. Under oxidation and reduction conditions, the chaperone activity of the disulfide-bonded AgsA did not change significantly, indicating that AgsA would not dissociate to achieve chaperone activity. Therefore, we concluded that the oligomer, especially 18-mer, was the primary functional unit.
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Affiliation(s)
- Dongmei Liu
- Department of Biochemistry and Biophysics, The Health Science Center, Peking University, Beijing, 100191, China.
| | - Qiang Chen
- The Chinese University of Hong Kong, Shenzhen, Shenzhen, Guangdong, 518172, PR China.
| | - Lei Zhang
- Department of Biochemistry and Biophysics, The Health Science Center, Peking University, Beijing, 100191, China; Electron Microscopy Analysis Laboratory, Center of Medical and Health Analysis, Peking University, Beijing, 100191, China.
| | - Hongli Hu
- The Chinese University of Hong Kong, Shenzhen, Shenzhen, Guangdong, 518172, PR China.
| | - Changcheng Yin
- Department of Biochemistry and Biophysics, The Health Science Center, Peking University, Beijing, 100191, China; Electron Microscopy Analysis Laboratory, Center of Medical and Health Analysis, Peking University, Beijing, 100191, China.
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Guimarães AC, Meireles LM, Lemos MF, Guimarães MCC, Endringer DC, Fronza M, Scherer R. Antibacterial Activity of Terpenes and Terpenoids Present in Essential Oils. Molecules 2019; 24:molecules24132471. [PMID: 31284397 PMCID: PMC6651100 DOI: 10.3390/molecules24132471] [Citation(s) in RCA: 285] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/10/2019] [Accepted: 05/25/2019] [Indexed: 11/25/2022] Open
Abstract
Background: The antimicrobial activity of essential oils has been reported in hundreds of studies, however, the great majority of these studies attribute the activity to the most prevalent compounds without analyzing them independently. Therefore, the aim was to investigate the antibacterial activity of 33 free terpenes commonly found in essential oils and evaluate the cellular ultrastructure to verify possible damage to the cellular membrane. Methods: Screening was performed to select substances with possible antimicrobial activity, then the minimal inhibitory concentrations, bactericidal activity and 24-h time-kill curve studies were evaluated by standard protocols. In addition, the ultrastructure of control and death bacteria were evaluated by scanning electron microscopy. Results: Only 16 of the 33 compounds had antimicrobial activity at the initial screening. Eugenol exhibited rapid bactericidal action against Salmonella enterica serovar Typhimurium (2 h). Terpineol showed excellent bactericidal activity against S. aureus strains. Carveol, citronellol and geraniol presented a rapid bactericidal effect against E. coli. Conclusions: The higher antimicrobial activity was related to the presence of hydroxyl groups (phenolic and alcohol compounds), whereas hydrocarbons resulted in less activity. The first group, such as carvacrol, l-carveol, eugenol, trans-geraniol, and thymol, showed higher activity when compared to sulfanilamide. Images obtained by scanning electron microscopy indicate that the mechanism causing the cell death of the evaluated bacteria is based on the loss of cellular membrane integrity of function. The present study brings detailed knowledge about the antimicrobial activity of the individual compounds present in essential oils, that can provide a greater understanding for the future researches.
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Affiliation(s)
- Aline Cristina Guimarães
- Pharmaceutical Sciences Graduate Program, Universidade Vila Velha, Espírito Santo 29102-770, Brazil
| | - Leandra Martins Meireles
- Pharmaceutical Sciences Graduate Program, Universidade Vila Velha, Espírito Santo 29102-770, Brazil
| | - Mayara Fumiere Lemos
- Pharmaceutical Sciences Graduate Program, Universidade Vila Velha, Espírito Santo 29102-770, Brazil
| | | | | | - Marcio Fronza
- Pharmaceutical Sciences Graduate Program, Universidade Vila Velha, Espírito Santo 29102-770, Brazil
| | - Rodrigo Scherer
- Pharmaceutical Sciences Graduate Program, Universidade Vila Velha, Espírito Santo 29102-770, Brazil.
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Abstract
Metabolic engineers seek to produce high-value products from inexpensive starting materials in a sustainable and cost-effective manner by using microbes as cellular factories. However, pathway development and optimization can be arduous tasks, complicated by pathway bottlenecks and toxicity. Pathway organization has emerged as a potential solution to these issues, and the use of protein- or DNA-based scaffolds has successfully increased the production of several industrially relevant compounds. These efforts demonstrate the usefulness of pathway colocalization and spatial organization for metabolic engineering applications. In particular, scaffolding within an enclosed, subcellular compartment shows great promise for pathway optimization, offering benefits such as increased local enzyme and substrate concentrations, sequestration of toxic or volatile intermediates, and alleviation of cofactor and resource competition with the host. Here, we describe the 1,2-propanediol utilization (Pdu) bacterial microcompartment (MCP) as an enclosed scaffold for pathway sequestration and organization. We first describe methods for controlling Pdu MCP formation, expressing and encapsulating heterologous cargo, and tuning cargo loading levels. We further describe assays for analyzing Pdu MCPs and assessing encapsulation levels. These methods will enable the repurposing of MCPs as tunable nanobioreactors for heterologous pathway encapsulation.
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Affiliation(s)
- Taylor M Nichols
- Department of Chemical and Biological Engineering, Northwestern University, Technological Institute, Evanston, IL, United States
| | - Nolan W Kennedy
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, IL, United States
| | - Danielle Tullman-Ercek
- Department of Chemical and Biological Engineering, Northwestern University, Technological Institute, Evanston, IL, United States; Center for Synthetic Biology, Northwestern University, Technological Institute, Evanston, IL, United States.
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6
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Abstract
The Salmonella typhimurium trans-membrane FliF MS ring templates assembly of the rotary bacterial flagellar motor, which also contains a cytoplasmic C-ring. A full-frame fusion of FliF with the rotor protein FliG assembles rings in non-motile expression hosts. 3D electron microscopy reconstructions of these FliFFliG rings show three high electron-density sub-volumes. 3D-classification revealed heterogeneity of the assigned cytoplasmic volume consistent with FliG lability. We used residue coevolution to construct homodimer building blocks for ring assembly, with X-ray crystal structures from other species and injectisome analogs. The coevolution signal validates folds and, importantly, indicates strong homodimer contacts for three ring building motifs (RBMs), initially identified in injectisome structures. It also indicates that the cofolded domains of the FliG N-terminal domain (FliG_N) with embedded α-helical FliF carboxy-terminal tail homo-oligomerize. The FliG middle and C-terminal domains (FliG_MC) have a weak signal for homo-dimerization but have coevolved to conserve their stacking contact. The homodimers and their ring models fit well into the 3D reconstruction. We hypothesize that a stable FliF periplasmic hub provides a platform for FliG ring self-assembly, but the FliG_MC ring has only limited stability without the C-ring. We also present a mechanical model for torque transmission in the FliFFliG ring.
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Affiliation(s)
- Shahid Khan
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
- Molecular Biology Consortium, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Tai Wei Guo
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Saurav Misra
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, KS, 66506, USA
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Kato J, Dey S, Soto JE, Butan C, Wilkinson MC, De Guzman RN, Galan JE. A protein secreted by the Salmonella type III secretion system controls needle filament assembly. eLife 2018; 7:e35886. [PMID: 30015613 PMCID: PMC6066329 DOI: 10.7554/elife.35886] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 07/16/2018] [Indexed: 12/14/2022] Open
Abstract
Type III protein secretion systems (T3SS) are encoded by several pathogenic or symbiotic bacteria. The central component of this nanomachine is the needle complex. Here we show in a Salmonella Typhimurium T3SS that assembly of the needle filament of this structure requires OrgC, a protein encoded within the T3SS gene cluster. Absence of OrgC results in significantly reduced number of needle substructures but does not affect needle length. We show that OrgC is secreted by the T3SS and that exogenous addition of OrgC can complement a ∆orgC mutation. We also show that OrgC interacts with the needle filament subunit PrgI and accelerates its polymerization into filaments in vitro. The structure of OrgC shows a novel fold with a shared topology with a domain from flagellar capping proteins. These findings identify a novel component of T3SS and provide new insight into the assembly of the type III secretion machine.
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Affiliation(s)
- Junya Kato
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Supratim Dey
- Department of Molecular BiosciencesUniversity of KansasLawrenceUnited States
| | - Jose E Soto
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Carmen Butan
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Mason C Wilkinson
- Department of Molecular BiosciencesUniversity of KansasLawrenceUnited States
| | - Roberto N De Guzman
- Department of Molecular BiosciencesUniversity of KansasLawrenceUnited States
| | - Jorge E Galan
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
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Hansmeier N, Miskiewicz K, Elpers L, Liss V, Hensel M, Sterzenbach T. Functional expression of the entire adhesiome of Salmonella enterica serotype Typhimurium. Sci Rep 2017; 7:10326. [PMID: 28871183 PMCID: PMC5583245 DOI: 10.1038/s41598-017-10598-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 08/10/2017] [Indexed: 12/21/2022] Open
Abstract
Adhesins are crucial virulence factors of pathogenic bacteria involved in colonization, transmission and pathogenesis. Many bacterial genomes contain the information for a surprisingly large number of diverse adhesive structures. One prominent example is the invasive and facultative intracellular pathogen Salmonella enterica with an adhesiome of up to 20 adhesins. Such large repertoire of adhesins contributes to colonization of a broad range of host species and may allow adaptation to various environments within the host, as well as in non-host environments. For S. enterica, only few members of the adhesiome are functionally expressed under laboratory conditions, and accordingly the structural and functional understanding of the majority of adhesins is sparse. We have devised a simple and versatile approach to functionally express all adhesins of S. enterica serotype Typhimurium, either within Salmonella or within heterologous hosts such as Escherichia coli. We demonstrate the surface expression of various so far cryptic adhesins and show ultrastructural features using atomic force microscopy and transmission electron microscopy. In summary, we report for the first time the expression of the entire adhesiome of S. enterica serotype Typhimurium.
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Affiliation(s)
- Nicole Hansmeier
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastr. 11, 49076, Osnabrück, Germany
| | - Katarzyna Miskiewicz
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastr. 11, 49076, Osnabrück, Germany
| | - Laura Elpers
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastr. 11, 49076, Osnabrück, Germany
| | - Viktoria Liss
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastr. 11, 49076, Osnabrück, Germany
| | - Michael Hensel
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastr. 11, 49076, Osnabrück, Germany.
| | - Torsten Sterzenbach
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Barbarastr. 11, 49076, Osnabrück, Germany.
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Dietsche T, Tesfazgi Mebrhatu M, Brunner MJ, Abrusci P, Yan J, Franz-Wachtel M, Schärfe C, Zilkenat S, Grin I, Galán JE, Kohlbacher O, Lea S, Macek B, Marlovits TC, Robinson CV, Wagner S. Structural and Functional Characterization of the Bacterial Type III Secretion Export Apparatus. PLoS Pathog 2016; 12:e1006071. [PMID: 27977800 PMCID: PMC5158082 DOI: 10.1371/journal.ppat.1006071] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 11/17/2016] [Indexed: 02/04/2023] Open
Abstract
Bacterial type III protein secretion systems inject effector proteins into eukaryotic host cells in order to promote survival and colonization of Gram-negative pathogens and symbionts. Secretion across the bacterial cell envelope and injection into host cells is facilitated by a so-called injectisome. Its small hydrophobic export apparatus components SpaP and SpaR were shown to nucleate assembly of the needle complex and to form the central “cup” substructure of a Salmonella Typhimurium secretion system. However, the in vivo placement of these components in the needle complex and their function during the secretion process remained poorly defined. Here we present evidence that a SpaP pentamer forms a 15 Å wide pore and provide a detailed map of SpaP interactions with the export apparatus components SpaQ, SpaR, and SpaS. We further refine the current view of export apparatus assembly, consolidate transmembrane topology models for SpaP and SpaR, and present intimate interactions of the periplasmic domains of SpaP and SpaR with the inner rod protein PrgJ, indicating how export apparatus and needle filament are connected to create a continuous conduit for substrate translocation. Many Gram-negative bacteria use type III secretion systems to inject bacterial proteins into eukaryotic host cells in order to promote their own survival and colonization. These systems are large molecular machines with the ability to transport proteins across three cell membranes in one step. It is believed that the only gated barrier of these systems lies in the bacterial cytoplasmic membrane but it was unclear so far how this gate looks like and of which components it is composed. Here we present evidence based on in depth biochemical and genetic characterization that an assembly of five SpaP proteins forms this gate in the cytoplasmic membrane of the type III secretion system of Salmonella pathogenicity island 1. We further show that one subunit each of the proteins SpaQ, SpaR, and SpaS are closely associated to the SpaP gate and may function in the gating mechanism, and that the protein PrgJ is attached to this gate on the outside to connect it to the hollow needle filament projecting towards the host cell. Our findings elucidate a hitherto ill-defined aspect of type III secretion systems and may help to develop novel antiinfective therapies targeting these virulence-associated molecular devices.
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Affiliation(s)
- Tobias Dietsche
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Mehari Tesfazgi Mebrhatu
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Matthias J. Brunner
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE) and German Electron Synchrotron Centre (DESY), Hamburg, Germany
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Patrizia Abrusci
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Jun Yan
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | | | | | - Susann Zilkenat
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Iwan Grin
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Jorge E. Galán
- Yale University School of Medicine, Department of Microbial Pathogenesis, New Haven, Connecticut, United States of America
| | - Oliver Kohlbacher
- University of Tübingen, Center for BioinformaticsTübingen, Germany
- Max Planck Institute for Developmental Biology, Biomolecular Interactions, Tübingen, Germany
| | - Susan Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Boris Macek
- University of Tübingen, Proteome Center Tübingen, Tübingen, Germany
| | - Thomas C. Marlovits
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE) and German Electron Synchrotron Centre (DESY), Hamburg, Germany
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Carol V. Robinson
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Samuel Wagner
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner-site Tübingen, Tübingen, Germany
- * E-mail:
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10
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Bhargava K, Conti DS, da Rocha SRP, Zhang Y. Application of an oregano oil nanoemulsion to the control of foodborne bacteria on fresh lettuce. Food Microbiol 2015; 47:69-73. [PMID: 25583339 DOI: 10.1016/j.fm.2014.11.007] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/11/2014] [Accepted: 11/18/2014] [Indexed: 11/25/2022]
Abstract
Although antimicrobial activities of plant essential oils are well documented, challenges remain as to their application in fresh produce due to the hydrophobic nature of essential oils. Oregano oil nanoemulsions were formulated with a food-grade emulsifier and evaluated for their efficacy in inactivating the growth of foodborne bacteria on fresh lettuce. Lettuce was artificially inoculated with Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli O157:H7, followed by a one-minute dipping in oregano oil nanoemulsions (0.05% or 0.1%). Samples were stored at 4 °C and enumerated for bacteria at fixed intervals (0 h, 3 h, 24 h, and 72 h). Compared to control, 0.05% nanoemulsion showed an up to 3.44, 2.31, and 3.05 log CFU/g reductions in L. monocytogenes, S. Typhimurium, and E. coli O157:H7, respectively. Up to 3.57, 3.26, and 3.35 log CFU/g reductions were observed on the same bacteria by the 0.1% treatment. Scanning Electron Microscopy (SEM) demonstrated disrupted bacterial membranes due to the oregano oil treatment. The data suggest that applying oregano oil nanoemulsions to fresh produce may be an effective antimicrobial control strategy.
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Affiliation(s)
- Kanika Bhargava
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI, USA; Department of Human Environmental Sciences, University of Central Oklahoma, Edmond, OK, USA
| | - Denise S Conti
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, MI, USA
| | - Sandro R P da Rocha
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, MI, USA
| | - Yifan Zhang
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI, USA.
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11
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Amro AA, Neama AJ, Hussein A, Hashish EA, Sheweita SA. Evaluation the surface antigen of the Salmonella typhimurium ATCC 14028 ghosts prepared by "SLRP". ScientificWorldJournal 2014; 2014:840863. [PMID: 24772035 PMCID: PMC3977473 DOI: 10.1155/2014/840863] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 02/25/2014] [Indexed: 11/17/2022] Open
Abstract
Recently, bacterial ghosts (BGs) were prepared using a protocol based on critical chemical concentrations. It has been given the name "sponge like" (SL) protocol and used in its reduced form "sponge like reduced protocol" (SLRP). While specific antibody for Salmonella is available on the market under the commercial names (of some kits) such as Febrile Antigen Kit (N.S. BIO-TEC), we used the described Kit to investigate the validity of the SLRP. In this study, using SLRP we succeeded to prepare STGs with correct surface antigens could interact with their specific antibodies. Additionally the study has included oral vaccination with STGs with challenge test. The rats serums have been evaluated against both of the O and H antigens. The antigen-antibody interaction (agglutination) results of both the SLRP and the animal experiments prove that we have correct STGs able to immunize the rats against viable Salmonella. STGs could be used as vaccine and as adjuvant and in the antibodies and in the diagnostic kits production. This study is an additional step for the establishment of correct BGs for immunological purposes.
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Affiliation(s)
- Amara A. Amro
- Department of Protein Research, Genetic Engineering and Biotechnology Research Institute, City for Scientific Research and Technology Applications, New Borg Al-Arab, P.O. Box. 21934, Alexandria, Egypt
- Biotechnology Department, Institute of Graduate Studies & Research, Alexandria University, 163 El Horreya Avenu, P.O. Box 832, Alexandria 21526, Egypt
| | - Ahmed J. Neama
- Zoonoses Research Unit, Faculty of Veterinary Medicine, Alqadisya University, Alqadisya, Iraq
| | - Ahmed Hussein
- Biotechnology Department, Institute of Graduate Studies & Research, Alexandria University, 163 El Horreya Avenu, P.O. Box 832, Alexandria 21526, Egypt
| | - Emad A. Hashish
- Department of Clinical Pathology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Salah A. Sheweita
- Biotechnology Department, Institute of Graduate Studies & Research, Alexandria University, 163 El Horreya Avenu, P.O. Box 832, Alexandria 21526, Egypt
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12
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Horiuchi S, Inagaki Y, Okamura N, Nakaya R, Yamamoto N. Type 1 Pili Enhance the Invasion ofSalmonella braenderupandSalmonella typhimuriumto HeLa Cells. Microbiol Immunol 2013; 36:593-602. [PMID: 1355852 DOI: 10.1111/j.1348-0421.1992.tb02059.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The relationship between type 1 pili-associated adhesion and invasion to HeLa cells by Salmonella braenderup and S. typhimurium was studied. When the clinical isolates of these strains were grown in L-broth, they showed both type 1 pili formation and mannose-sensitive adhesion to HeLa cells. On the other hand, the type 1 pili-defective mutants, which were obtained either by repeated subcultures on L-agar plates or by the transposon Tn1-insertion mutagenesis of the S. braenderup and S. typhimurium strains, concomitantly lost mannose-sensitive adhesion to HeLa cells. When the HeLa cells were incubated with Salmonella, the type 1 piliated strains invaded the HeLa cells with much higher infection rate than did the type 1 pili-defective strains. The invasion of type 1 piliated strains to HeLa cells was markedly inhibited in the presence of D-mannose. The infectivity of the strain, which lost type 1 pili but still had mannose-resistant adhesion, was slightly higher than that of the strains defective in both mannose-sensitive and mannose-resistant adhesion. These results suggested that type 1 pili have a role in enhancing the invasion of S. braenderup and S. typhimurium to HeLa cells.
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Affiliation(s)
- S Horiuchi
- Department of Microbiology, Faculty of Medicine, Tokyo Medical and Dental University, Japan
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13
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Abstract
Frequent and indiscriminate use of existing battery of antibiotics has led to the development of multi drug resistant (MDR) strains of pathogens. As decreasing the concentration of the antibiotic required to treat Salmonellosis might help in combating the development of resistant strains, the present study was designed to assess the synergistic effects, if any, of nisin, in combination with conventional anti-Salmonella antibiotics against Salmonella enterica serovar Typhimurium. Minimum inhibitory concentrations (MICs) of the selected antimicrobial agents were determined by micro and macro broth dilution assays. In-vitro synergy between the agents was evaluated by radial diffusion assay, fractional inhibitory concentration (FIC) index (checkerboard test) and time-kill assay. Scanning electron microscopy (SEM) was also performed to substantiate the effect of the combinations. In-vivo synergistic efficacy of the combinations selected on the basis of in-vitro results was also evaluated in the murine model, in terms of reduction in the number of Salmonellae in liver, spleen and intestine. Nisin-ampicillin and nisin-EDTA combinations were observed to have additive effects, whereas the combinations of nisin-ceftriaxone and nisin-cefotaxime were found to be highly synergistic against serovar Typhimurium as evident by checkerboard test and time-kill assay. SEM results revealed marked changes on the outer membrane of the bacterial cells treated with various combinations. In-vivo synergy was evident from the larger log unit decreases in all the target organs of mice treated with the combinations than in those treated with drugs alone. This study thus highlights that nisin has the potential to act in conjunction with conventional antibiotics at much lower MICs. These observations seem to be significant, as reducing the therapeutic concentrations of antibiotics may be a valuable strategy for avoiding/reducing the development of emerging antibiotic resistance. Value added potential of nisin in the efficacy of conventional antibiotics may thus be exploited not only against Salmonella but against other Gram-negative infections as well.
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Affiliation(s)
- Aman Preet Singh
- Department of Microbiology, Basic Medical Sciences Block, Panjab University, Chandigarh, India
| | - Vijay Prabha
- Department of Microbiology, Basic Medical Sciences Block, Panjab University, Chandigarh, India
| | - Praveen Rishi
- Department of Microbiology, Basic Medical Sciences Block, Panjab University, Chandigarh, India
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14
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Kim S, Ghafoor K, Lee J, Feng M, Hong J, Lee DU, Park J. Bacterial inactivation in water, DNA strand breaking, and membrane damage induced by ultraviolet-assisted titanium dioxide photocatalysis. Water Res 2013; 47:4403-4411. [PMID: 23764591 DOI: 10.1016/j.watres.2013.05.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 04/03/2013] [Accepted: 05/04/2013] [Indexed: 06/02/2023]
Abstract
The effects of UV-assisted TiO2-photocatalytic oxidation (PCO) inactivation of pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium) in a liquid culture using different domains of UV irradiation (A, B and C) were evaluated. Structural changes in super-coiled plasmid DNA (pUC19) and genomic DNA of E. coli were observed using gel electrophoresis to demonstrate the photodynamic DNA strand breaking activity of UV-assisted TiO2-PCO. Membrane damage in bacterial cells was observed using both a scanning electron microscope (SEM) and a confocal laser scanning microscope (CLSM). Both UVC-TiO2-PCO and UVC alone resulted in an earlier bactericidal phase (initial counts of approximately 6 log CFU/mL) in 60 s and 90 s, respectively, in liquid culture. UVC-TiO2-PCO treatment for 6 min converted all plasmid DNA to the linear form; however, under UVC irradiation alone, super-coiled DNA remained. Prolonged UVC-TiO2-PCO treatment resulted in structural changes in genomic DNA from E. coli. SEM observations revealed that bacteria suffered severe visible cell damage after UVC-TiO2-PCO treatment for 30-60 min. S. typhimurium cells showed visible damage after 30 min, which was confirmed using CLSM. All treated cells were stained red using propidium iodide under a fluorescent light.
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Affiliation(s)
- Soohyun Kim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-479, Republic of Korea
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15
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Demers JP, Sgourakis NG, Gupta R, Loquet A, Giller K, Riedel D, Laube B, Kolbe M, Baker D, Becker S, Lange A. The common structural architecture of Shigella flexneri and Salmonella typhimurium type three secretion needles. PLoS Pathog 2013; 9:e1003245. [PMID: 23555258 PMCID: PMC3605151 DOI: 10.1371/journal.ppat.1003245] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/23/2013] [Indexed: 11/25/2022] Open
Abstract
The Type Three Secretion System (T3SS), or injectisome, is a macromolecular infection machinery present in many pathogenic Gram-negative bacteria. It consists of a basal body, anchored in both bacterial membranes, and a hollow needle through which effector proteins are delivered into the target host cell. Two different architectures of the T3SS needle have been previously proposed. First, an atomic model of the Salmonella typhimurium needle was generated from solid-state NMR data. The needle subunit protein, PrgI, comprises a rigid-extended N-terminal segment and a helix-loop-helix motif with the N-terminus located on the outside face of the needle. Second, a model of the Shigella flexneri needle was generated from a high-resolution 7.7-Å cryo-electron microscopy density map. The subunit protein, MxiH, contains an N-terminal α-helix, a loop, another α-helix, a 14-residue-long β-hairpin (Q51–Q64) and a C-terminal α-helix, with the N-terminus facing inward to the lumen of the needle. In the current study, we carried out solid-state NMR measurements of wild-type Shigella flexneri needles polymerized in vitro and identified the following secondary structure elements for MxiH: a rigid-extended N-terminal segment (S2-T11), an α-helix (L12-A38), a loop (E39-P44) and a C-terminal α-helix (Q45-R83). Using immunogold labeling in vitro and in vivo on functional needles, we located the N-terminus of MxiH subunits on the exterior of the assembly, consistent with evolutionary sequence conservation patterns and mutagenesis data. We generated a homology model of Shigella flexneri needles compatible with both experimental data: the MxiH solid-state NMR chemical shifts and the state-of-the-art cryoEM density map. These results corroborate the solid-state NMR structure previously solved for Salmonella typhimurium PrgI needles and establish that Shigella flexneri and Salmonella typhimurium subunit proteins adopt a conserved structure and orientation in their assembled state. Our study reveals a common structural architecture of T3SS needles, essential to understand T3SS-mediated infection and develop treatments. Gram-negative bacteria use a molecular machinery called the Type Three Secretion System (T3SS) to deliver toxic proteins to the host cell. Our research group has recently solved the structure of the extracellular T3SS needle of Salmonella typhimurium. Employing solid-state NMR, we could determine local structure parameters such as dihedral angles and inter-nuclear proximities for this supramolecular assembly. Concurrently, a high-resolution cryo-electron microscopy density map of the T3SS needle of Shigella flexneri was obtained by Fujii et al. Modeling of the Shigella needle subunit protein to fit the EM density produced a model incompatible with the atomic model of the Salmonella needle in terms of secondary structure and subunit orientation. Here, we determined directly the secondary structure of the Shigella needle subunit using solid-state NMR, and its orientation using in vitro and in vivo immunogold labeling in functional needles. We found that Shigella subunits adopt the same secondary structure and orientation as in the atomic model of Salmonella, and we generated a homology model of the Shigella needle consistent with the EM density. Knowing the common T3SS needle architecture is essential for understanding the secretion mechanism and interactions of the needle with other components of the T3SS, and to develop therapeutics.
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Affiliation(s)
- Jean-Philippe Demers
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Nikolaos G. Sgourakis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rashmi Gupta
- Department for Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Antoine Loquet
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Karin Giller
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dietmar Riedel
- Laboratory for Electron Microscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Britta Laube
- Core Facility Microscopy, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Michael Kolbe
- Department for Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin, Germany
- * E-mail: (MK); (DB); (SB); (AL)
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- * E-mail: (MK); (DB); (SB); (AL)
| | - Stefan Becker
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- * E-mail: (MK); (DB); (SB); (AL)
| | - Adam Lange
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- * E-mail: (MK); (DB); (SB); (AL)
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16
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Staniewicz L, Donald AM, Stokes DJ, Thomson N, Sivaniah E, Grant A, Bulmer D, Khan A. The application of STEM and in situ controlled dehydration to bacterial systems using ESEM. Scanning 2012; 34:237-246. [PMID: 22689513 DOI: 10.1002/sca.21000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 10/19/2011] [Indexed: 06/01/2023]
Abstract
Transmission imaging with an environmental scanning electron microscope (ESEM) (Wet STEM) is a recent development in the field of electron microscopy, combining the simple preparation inherent to ESEM work with an alternate form of contrast available through a STEM detector. Because the technique is relatively new, there is little information available on how best to apply this technique and which samples it is best suited for. This work is a description of the sample preparation and microscopy employed by the authors for imaging bacteria with Wet STEM (scanning transmission electron microscopy). Three different bacterial samples will be presented in this study: first, used as a model system, is Escherichia coli for which the contrast mechanisms of STEM are demonstrated along with the visual effects of a dehydration-induced collapse. This collapse, although clearly in some sense artifactual, is thought to lead to structurally meaningful morphological information. Second, Wet STEM is applied to two distinct bacterial systems to demonstrate the novel types of information accessible by this approach: the plastic-producing Cupriavidus necator along with wild-type and ΔmreC knockout mutants of Salmonella enterica serovar Typhimurium. Cupriavidus necator is shown to exhibit clear internal differences between bacteria with and without plastic granules, while the ΔmreC mutant of S. Typhimurium has an internal morphology distinct from that of the wild type.
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Affiliation(s)
- Lech Staniewicz
- Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom.
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17
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Jennings ME, Quick LN, Ubol N, Shrom S, Dollahon N, Wilson JW. Characterization of Salmonella type III secretion hyper-activity which results in biofilm-like cell aggregation. PLoS One 2012; 7:e33080. [PMID: 22412985 PMCID: PMC3297627 DOI: 10.1371/journal.pone.0033080] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 02/07/2012] [Indexed: 01/06/2023] Open
Abstract
We have previously reported the cloning of the Salmonella enterica serovar Typhimurium SPI-1 secretion system and the use of this clone to functionally complement a ΔSPI-1 strain for type III secretion activity. In the current study, we discovered that S. Typhimurium cultures containing cloned SPI-1 display an adherent biofilm and cell clumps in the media. This phenotype was associated with hyper-expression of SPI-1 type III secretion functions. The biofilm and cell clumps were associated with copious amounts of secreted SPI-1 protein substrates SipA, SipB, SipC, SopB, SopE, and SptP. We used a C-terminally FLAG-tagged SipA protein to further demonstrate SPI-1 substrate association with the cell aggregates using fluorescence microscopy and immunogold electron microscopy. Different S. Typhimurium backgrounds and both flagellated and nonflagellated strains displayed the biofilm phenotype. Mutations in genes essential for known bacterial biofilm pathways (bcsA, csgBA, bapA) did not affect the biofilms formed here indicating that this phenomenon is independent of established biofilm mechanisms. The SPI-1-mediated biofilm was able to massively recruit heterologous non-biofilm forming bacteria into the adherent cell community. The results indicate a bacterial aggregation phenotype mediated by elevated SPI-1 type III secretion activity with applications for engineered biofilm formation, protein purification strategies, and antigen display.
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Affiliation(s)
- Matthew E. Jennings
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Laura N. Quick
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Nicha Ubol
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
| | - Sally Shrom
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
| | - Norman Dollahon
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
| | - James W. Wilson
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
- * E-mail:
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18
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Alvarez-Ordóñez A, Prieto M. Changes in ultrastructure and Fourier transform infrared spectrum of Salmonella enterica serovar typhimurium cells after exposure to stress conditions. Appl Environ Microbiol 2010; 76:7598-607. [PMID: 20851964 PMCID: PMC2976207 DOI: 10.1128/aem.00312-10] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 09/08/2010] [Indexed: 11/20/2022] Open
Abstract
The effect of exposure to acid (pH 2.5), alkaline (pH 11.0), heat (55°C), and oxidative (40 mM H₂O₂) lethal conditions on the ultrastructure and global chemical composition of Salmonella enterica serovar Typhimurium CECT 443 cells was studied using transmission electron microscopy and Fourier transform infrared spectroscopy (FT-IR) combined with multivariate statistical methods (hierarchical cluster analysis and factor analysis). Infrared spectra exhibited marked differences in the five spectral regions for all conditions tested compared to those of nontreated control cells, which suggests the existence of a complex bacterial stress response in which modifications in a wide variety of cellular compounds are involved. The visible spectral changes observed in all of the spectral regions, together with ultrastructural changes observed by transmission electron microscopy and data obtained from membrane integrity tests, indicate the existence of membrane damage or alterations in membrane composition after heat, acid, alkaline, and oxidative treatments. Results obtained in this study indicate the potential of FT-IR spectroscopy to discriminate between intact and injured bacterial cells and between treatment technologies, and they show the adequacy of this technique to study the molecular aspects of bacterial stress response.
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Affiliation(s)
- A. Alvarez-Ordóñez
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, 24071 León, Spain
| | - M. Prieto
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, 24071 León, Spain
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19
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Al-Bahry S, Mahmoud I, Elshafie A, Al-Harthy A, Al-Ghafri S, Al-Amri I, Alkindi A. Bacterial flora and antibiotic resistance from eggs of green turtles Chelonia mydas: an indication of polluted effluents. Mar Pollut Bull 2009; 58:720-725. [PMID: 19185323 DOI: 10.1016/j.marpolbul.2008.12.018] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 12/12/2008] [Accepted: 12/31/2008] [Indexed: 05/27/2023]
Abstract
Sea turtles migrate to various habitats where they can be exposed to different pollutants. Bacteria were collected from turtle eggs and their resistance to antibiotics was used as pollutant bio-indicators of contaminated effluents. Eggs were collected randomly from turtles when they were laying their eggs. A total of 90 eggs were collected and placed into sterile plastic bags (3 eggs/turtle) during June-December of 2003. The bacteria located in the eggshell, albumen and yolk were examined, and 42% of the eggs were contaminated with 10 genera of bacteria. Pseudomonas spp. were the most frequent isolates. The albumen was found to be the part of the egg to be the least contaminated by bacterial infection. Bacterial isolates tested with 14 antibiotics showed variations in resistance. Resistance to ampicillin was the highest. The presence of antibiotic resistant bacteria in eggs indicates that the green turtle populations were subjected to polluted effluents during some of their migratory routes and feeding habitats. Scanning electron microscopy revealed that Salmonella typhimurium penetrated all eggshell layers.
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Affiliation(s)
- Saif Al-Bahry
- Department of Biology, College of Science, Sultan Qaboos University, PO Box 36, PC 123, Al-Khodh, Oman.
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20
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Dai JG, Xie HW, Jin G, Wang WG, Zhang Y, Guo Y. Preliminary study on high-level expression of tandem-arranged tachyplesin-encoding gene in Bacillus subtilis Wb800 and its antibacterial activity. Mar Biotechnol (NY) 2009; 11:109-117. [PMID: 18670810 DOI: 10.1007/s10126-008-9125-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 06/10/2008] [Indexed: 05/26/2023]
Abstract
To produce tachyplesin, an antimicrobial peptide, by a stable and efficient gene engineering approach, cDNAs containing single tachyplesin gene sequence (tac)(1) and tandem repeat of tachyplesin gene sequence (tac2) were respectively developed by annealing two synthesized complementary single-stranded DNAs and constructed into pSBPTQ shuttle vector under the control of the SacB.p.s promoter. The vectors containing the target gene sequence were then transformed into Bacillus subtilis WB800, respectively. Both expression of tac and tac2 were induced by 2% sucrose. The fermentation supernatant was purified by regenerated cellulose membrane tubing (MWCO 2000) and the secreted TAC(2) and TAC2 were about 5 and 10 mg/l of supernatant, respectively. The antimicrobial activities of TAC and TAC2 were measured by the size of bacteriostatic circle of the fermentation supernatants against Escherichia coli K88. Ultrastructural alteration of E. coli K88 and Salmonella typhimurium was observed under scanning electron microscope and transmission electron microscopy. The results showed that in comparison with TAC, TAC2 was expressed at a higher level and also indicating strong antimicrobial activity both in vitro and in vivo.
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Affiliation(s)
- Jian-guo Dai
- School of Applied Chemistry and Biological Technology, Shenzhen Polytechnic, Shenzhen 518055, China.
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21
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Chu H, Huang Y, Zhao Y. Silver nanorod arrays as a surface-enhanced Raman scattering substrate for foodborne pathogenic bacteria detection. Appl Spectrosc 2008; 62:922-931. [PMID: 18702867 DOI: 10.1366/000370208785284330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Surface-enhanced Raman scattering (SERS) using novel silver nanorod array substrates has been used for the detection of pathogenic bacteria. The substrate consists of a base layer of 500 nm silver film on a glass slide and a layer of silver nanorod array with a length of approximately 1 microm produced by the oblique angle deposition method at a vapor incident angle of 86 degrees . Spectra from whole cell bacteria, Generic Escherichia coli, E. coli O157:H7, E. coli DH 5alpha, Staphylococcus aureus, S. epidermidis, and Salmonella typhimurium, and bacteria mixtures have been obtained. This SERS active substrate can detect spectral differences between Gram types, different species, their mixture, and strains. Principal component analysis (PCA) has been applied to classify the spectra. Viable and nonviable cells have also been examined, and significantly reduced SERS responses were observed for nonviable cells. SERS detection of bacteria at the single cell level, excited at low incident laser power (12 micro W) and short collection time (10 s), has also been demonstrated. These results indicate that the SERS-active silver nanorod array substrate is a potential analytical sensor for rapid identification of microorganisms with a minimum of sample preparation.
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Affiliation(s)
- Hsiaoyun Chu
- Department of Food Science and Technology, The University of Georgia, Athens, Georgia 30602, USA.
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22
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Veldhuizen EJA, Rijnders M, Claassen EA, van Dijk A, Haagsman HP. Porcine beta-defensin 2 displays broad antimicrobial activity against pathogenic intestinal bacteria. Mol Immunol 2007; 45:386-94. [PMID: 17658606 DOI: 10.1016/j.molimm.2007.06.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 06/05/2007] [Accepted: 06/07/2007] [Indexed: 01/14/2023]
Abstract
Defensins are small antimicrobial peptides that play an important role in the innate immune system of mammals. Here, we describe the antimicrobial activity of pBD-2, a recently discovered new porcine defensin that is produced in the intestine. A synthetic peptide corresponding to the mature protein showed high antimicrobial activity against a broad range of pathogenic bacteria, while it only showed limited hemolytic activity against porcine red blood cells. Highest activity was observed against Salmonella typhimurium, Listeria monocytogenes and Erysipelothrix rhusiopathiae. pBD-2 (4-8microM) killed these pathogens within 3h. The activity of pBD-2 against S. typhimurium was studied in more detail. At the minimum bactericidal concentration (MBC) of pBD-2, complete killing of S. typhimurium was relatively fast with no viable bacteria left after 90 min. However, antimicrobial activity of pBD-2 was decreased at higher ionic strengths with no residual activity at 150mM NaCl. Transmission electron microscopy of pBD-2 treated S. typhimurium indicated that relatively low doses of pBD-2 caused a retraction of the cytoplasmic membrane, while pBD-2 concentrations close to the MBC led to cytoplasm leakage and complete lysis of bacterial cells. Considering the site of production and the activity, pBD-2 may be an important defense molecule for intestinal health.
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Affiliation(s)
- Edwin J A Veldhuizen
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
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23
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Kim SR, Rhee MS, Kim BC, Lee H, Kim KH. Modeling of the inactivation of Salmonella typhimurium by supercritical carbon dioxide in physiological saline and phosphate-buffered saline. J Microbiol Methods 2007; 70:132-41. [PMID: 17509706 DOI: 10.1016/j.mimet.2007.04.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 04/04/2007] [Accepted: 04/09/2007] [Indexed: 11/15/2022]
Abstract
In this study, we used supercritical carbon dioxide (SC-CO(2)) to inactivate Salmonella typhimurium suspended in physiological saline (PS) or phosphate-buffered saline (PBS). The colony forming activity of S. typhimurium was completely lost (i.e., 8-log reduction) under the following condition ranges: pressures of 80-150 bar, temperatures of 35-45 degrees C and 10-50 min treatment times. The microbial inactivation process had three distinct phases and was modeled by the modified Gompertz model. Generally, an increase in pressure at constant temperature, and an increase in temperature at a constant pressure, both enhanced S. typhimurium inactivation. When the cells were suspended in PBS rather than PS, the length of time for the complete inactivation significantly increased. We observed the surface and internal morphological changes of the cells by SEM and TEM, respectively. The extraction of proteinous substances, nucleic acids and outer membrane proteins into the suspension during SC-CO(2) treatment was also observed. Through SDS-PAGE analysis of the total proteins and major outer membrane proteins (OMPs) of SC-CO(2)-treated cells, we found that a substantial amount of the total soluble proteins had converted into insoluble protein.
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Affiliation(s)
- Soo Rin Kim
- Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea
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24
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Di Pasqua R, Betts G, Hoskins N, Edwards M, Ercolini D, Mauriello G. Membrane toxicity of antimicrobial compounds from essential oils. J Agric Food Chem 2007; 55:4863-70. [PMID: 17497876 DOI: 10.1021/jf0636465] [Citation(s) in RCA: 359] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Natural antimicrobial compounds perform their action mainly against cell membranes. The aim of this work was to evaluate the interaction, meant as a mechanism of action, of essential oil antimicrobial compounds with the microbial cell envelope. The lipid profiles of Escherichia coli O157:H7, Staphylococcus aureus, Salmonella enterica serovar Typhimurium, Pseudomonas fluorescens, and Brochothrix thermosphacta cells treated with thymol, carvacrol, limonene, eugenol, and cinnamaldehyde have been analyzed by gas chromatography. In line with the fatty acids analysis, the treated cells were also observed by scanning electron microscopy (SEM) to evaluate structural alterations. The overall results showed a strong decrease of the unsaturated fatty acids (UFAs) for the treated cells; in particular, the C18:2trans and C18:3cis underwent a notable reduction contributing to the total UFA decreases, while the saturated fatty acid C17:0 raised the highest concentration in cinnamaldehyde-treated cells. SEM images showed that the used antimicrobial compounds quickly exerted their antimicrobial activities, determining structural alterations of the cell envelope.
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Affiliation(s)
- Rosangela Di Pasqua
- Department of Food Science, Division of Microbiology, University of Naples Federico II, Via Università 100, 80055 Portici, Italy
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25
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Abstract
A wide variety of microorganisms are able to form biofilms at the interface between air and liquid (pellicles). In this study changes during the maturation of the pellicle of Salmonella Typhimurium were analysed and the role of cellulose in the pellicle structure and morphology evaluated. The morphology of both sides of the pellicle was characterised using atomic force microscopy and scanning electron microscopy. Overall, there was a marked difference in the morphology of the water-facing (WF) and air-facing (AF) biofilm surfaces. While the AF side appeared to be uniform, and extensively covered with an exocellular coating, cells in the WF side were distributed into clusters and were less covered. However, the similarity in size and shape of single cells from both sides of the pellicle may indicate that the bacterial cells across the pellicle have a similar physiological status. During maturation, porous structures with multiple cracks and channels were created in the pellicle, leading to disintegration. By comparison with the structure of pellicles of a cellulose-deficient mutant, it was demonstrated that the observed disintegration of mature pellicles probably occurred in part by self-hydrolysis of components of the matrix.
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Affiliation(s)
- Keren Scher
- Department of Biotechnology and Food Engineering, Technion, Haifa, Israel
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26
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Isoda R, Simanski SP, Pathangey L, Stone AES, Brown TA. Expression of a Porphyromonas gingivalis hemagglutinin on the surface of a Salmonella vaccine vector. Vaccine 2007; 25:117-26. [PMID: 16942819 DOI: 10.1016/j.vaccine.2006.06.085] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 06/19/2006] [Accepted: 06/23/2006] [Indexed: 10/24/2022]
Abstract
Live, attenuated Salmonella strains can serve as vectors for the delivery of recombinant vaccine antigens for development of oral mucosal vaccines. Various vaccine parameters can affect the immune responses elicited by Salmonella vectors, including the expression level, location and timing of expressed antigens. We have previously established immunogenic Salmonella enterica serovar Typhimurium strains which cytoplasmically express hemagglutinin B (HagB) of Porphyromonas gingivalis, a putative periodontal pathogen. In this study, we sought to determine whether the 39 kDa HagB protein could be stably expressed on the surface of an avirulent Salmonella vaccine strain. The hagB gene was cloned into an expression plasmid as a C-terminal fusion with Lpp-OmpA, a hybrid surface display system. High expression of Lpp-OmpA-HagB proved to be toxic to the vaccine strain, and it was necessary to introduce attenuating mutations in the trc promoter. Stable expression was obtained in transformants with promoter mutations that resulted in low levels of expression. The expression of Lpp-OmpA-HagB was confirmed by ELISA and Western blot. Localization to the outer membrane/periplasm was confirmed by transmission electron microscopy using immunogold labeling, surface labeling of whole mounts using electron microscopy, flow cytometry, and by quantitation of HagB in cytoplasmic, as well as inner and outer cell membrane fractions. When delivered orally in mice, the surface-expressing strain induced higher serum IgG and IgA responses to HagB than a cytoplasmic expressing strain, while responses in secretions were comparable. These results suggest that surface localization may differentially enhance the immunogenicity of antigens expressed by live, avirulent Salmonella vaccine vectors.
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Affiliation(s)
- Ryutaro Isoda
- Department of Oral Biology, P.O. Box 100424, University of Florida, Gainesville, FL 32610, United States
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27
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Trachtenberg S, Cohen-Krausz S. The archaeabacterial flagellar filament: a bacterial propeller with a pilus-like structure. J Mol Microbiol Biotechnol 2006; 11:208-20. [PMID: 16983196 DOI: 10.1159/000094055] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Common prokaryotic motility modes are swimming by means of rotating internal or external flagellar filaments or gliding by means of retracting pili. The archaeabacterial flagellar filament differs significantly from the eubacterial flagellum: (1) Its diameter is 10-14 nm, compared to 18-24 nm for eubacterial flagellar filaments. (2) It has 3.3 subunits/turn of a 1.9 nm pitch left-handed helix compared to 5.5 subunits/turn of a 2.6 nm pitch right-handed helix for plain eubacterial flagellar filaments. (3) The archaeabacterial filament is glycosylated, which is uncommon in eubacterial flagella and is believed to be one of the key elements for stabilizing proteins under extreme conditions. (4) The amino acid composition of archaeabacterial flagellin, although highly conserved within the group, seems unrelated to the highly conserved eubacterial flagellins. On the other hand, the archaeabacterial flagellar filament shares some fundamental properties with type IV pili: (1) The hydrophobic N termini are largely homologous with the oligomerization domain of pilin. (2) The flagellin monomers follow a different mode of transport and assembly. They are synthesized as pre-flagellin and have a cleavable signal peptide, like pre-pilin and unlike eubacterial flagellin. (3) The archaeabacterial flagellin, like pilin, is glycosylated. (4) The filament lacks a central channel, consistent with polymerization occurring at the cell-proximal end. (5) The diameter of type IV pili, 6-9 nm, is closer to that of the archaeabacterial filament, 10-14 nm. A large body of data on the biochemistry and molecular biology of archaeabacterial flagella has accumulated in recent years. However, their structure and symmetry is only beginning to unfold. Here, we review the structure of the archaeabacterial flagellar filament in reference to the structures of type IV pili and eubacterial flagellar filaments, with which it shares structural and functional similarities, correspondingly.
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Affiliation(s)
- Shlomo Trachtenberg
- Department of Membrane and Ultrastructure Research, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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28
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Thomas DR, Francis NR, Xu C, DeRosier DJ. The three-dimensional structure of the flagellar rotor from a clockwise-locked mutant of Salmonella enterica serovar Typhimurium. J Bacteriol 2006; 188:7039-48. [PMID: 17015643 PMCID: PMC1636246 DOI: 10.1128/jb.00552-06] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Three-dimensional reconstructions from electron cryomicrographs of the rotor of the flagellar motor reveal that the symmetry of individual M rings varies from 24-fold to 26-fold while that of the C rings, containing the two motor/switch proteins FliM and FliN, varies from 32-fold to 36-fold, with no apparent correlation between the symmetries of the two rings. Results from other studies provided evidence that, in addition to the transmembrane protein FliF, at least some part of the third motor/switch protein, FliG, contributes to a thickening on the face of the M ring, but there was no evidence as to whether or not any portion of FliG also contributes to the C ring. Of the four morphological features in the cross section of the C ring, the feature closest to the M ring is not present with the rotational symmetry of the rest of the C ring, but instead it has the symmetry of the M ring. We suggest that this inner feature arises from a domain of FliG. We present a hypothetical docking in which the C-terminal motor domain of FliG lies in the C ring, where it can interact intimately with FliM.
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Affiliation(s)
- Dennis R Thomas
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
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29
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Abstract
Electron tomography of frozen-hydrated bacteria, combined with single particle averaging, has produced stunning images of the intact bacterial flagellum, revealing features of the rotor, stator and export apparatus.
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Affiliation(s)
- David DeRosier
- Department of Life Sciences, MS029 Brandeis University, Waltham, Massachusetts 02454-9110, USA.
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30
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Veldhuizen EJA, Hendriks HGCJM, Hogenkamp A, van Dijk A, Gaastra W, Tooten PCJ, Haagsman HP. Differential regulation of porcine beta-defensins 1 and 2 upon Salmonella infection in the intestinal epithelial cell line IPI-2I. Vet Immunol Immunopathol 2006; 114:94-102. [PMID: 16938353 DOI: 10.1016/j.vetimm.2006.07.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 07/12/2006] [Accepted: 07/25/2006] [Indexed: 12/22/2022]
Abstract
Intestinal epithelial cells represent the first line of defence against pathogenic bacteria in the lumen of the gut. Besides acting as a physical barrier, epithelial cells orchestrate the immune response through the production of several innate immune mediator molecules including beta-defensins. Here, we establish the porcine intestinal cell line IPI-2I as a new model system to test the regulation of porcine beta-defensins 1 and 2. Gene expression of both defensins was highly upregulated by foetal calf serum components in normal growth medium. In serum-free medium, baseline expression remained low, but pBD-2 gene expression was increased 10-fold upon infection with Salmonella Typhimurium. Arcobacter cryaerophilus and Salmonella Enteritidis, pathogenic bacteria with comparable adhesion and invasion characteristics, failed to increase pBD-2 mRNA levels. Heat killed or colistin-treated Salmonella Typhimurium had no effect, showing that the upregulation of pBD-2 was dependent on the viability of the Salmonella Typhimurium. Gene expression of pBD-1 was regulated differently since an increase in pBD-1 mRNA was observed by Salmonella Enteritidis infection. We conclude that the IPI-2I cells can serve as a new model to study porcine beta-defensin regulation and that pBD-1 and pBD-2 are differentially regulated in this cell line.
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Affiliation(s)
- Edwin J A Veldhuizen
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, The Netherlands.
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31
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Jolivet-Gougeon A, Sauvager F, Bonnaure-Mallet M, Colwell RR, Cormier M. Virulence of viable but nonculturable S. Typhimurium LT2 after peracetic acid treatment. Int J Food Microbiol 2006; 112:147-52. [PMID: 16876276 DOI: 10.1016/j.ijfoodmicro.2006.06.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 01/31/2006] [Accepted: 06/03/2006] [Indexed: 11/16/2022]
Abstract
S. Typhimurium LT2 cells suspended in sterilized sewage effluent water (SEW) and in distilled water microcosms were exposed to 0, 7, 15 and 20 mg/l peracetic acid, and tested for viability and virulence. After treatment for one hour, colony forming units decreased by at least 5 log units at peracetic acid concentration of 7 mg/l. In SEW, at peracetic acid concentration of 15 mg/l, the cells were nonculturable (VNC), but retained virulence as demonstrated by invasion assays of HeLa cells. Higher concentrations (greater than or equal to 20 mg/l) resulted in bacterial death, i.e. substrate non-responsive cells. Despite morphological alterations of the bacteria after peracetic acid treatment, visualized by transmission electronic microscopy, conservation of both adhesive and invasive capacities was confirmed by scanning electron microscopy after exposure to 0-15 mg/l peracetic acid. Public health professionals need to recognize that peracetic acid-treated Salmonella is capable of modifying its physiological characteristics, including entering and recovering from the viable but nonculturable state, and may remain virulent after a stay in SEW followed by peracetic acid treatment.
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Affiliation(s)
- A Jolivet-Gougeon
- Equipe Microbiologie, UPRES-EA 1254, Faculté des Sciences Pharmaceutiques et Biologiques, Université de Rennes I, 2 Avenue du Professeur Léon Bernard, 35043 RENNES, France.
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32
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Robbe-Saule V, Jaumouillé V, Prévost MC, Guadagnini S, Talhouarne C, Mathout H, Kolb A, Norel F. Crl activates transcription initiation of RpoS-regulated genes involved in the multicellular behavior of Salmonella enterica serovar Typhimurium. J Bacteriol 2006; 188:3983-94. [PMID: 16707690 PMCID: PMC1482930 DOI: 10.1128/jb.00033-06] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Salmonella enterica serovar Typhimurium, the stationary-phase sigma factor sigma(S) (RpoS) is required for virulence, stress resistance, biofilm formation, and development of the rdar morphotype. This morphotype is a multicellular behavior characterized by expression of the adhesive extracellular matrix components cellulose and curli fimbriae. The Crl protein of Escherichia coli interacts with sigma(S) and activates expression of sigma(S)-regulated genes, such as the csgBAC operon encoding the subunit of the curli proteins, by an unknown mechanism. Here, we showed using in vivo and in vitro experiments that the Crl protein of Salmonella serovar Typhimurium is required for development of a typical rdar morphotype and for maximal expression of the csgD, csgB, adrA, and bcsA genes, which are involved in curli and cellulose biosynthesis. In vitro transcription assays and potassium permanganate reactivity experiments with purified His(6)-Crl showed that Crl directly activated sigma(S)-dependent transcription initiation at the csgD and adrA promoters. We observed no effect of Crl on sigma(70)-dependent transcription. Crl protein levels increased during the late exponential and stationary growth phases in Luria-Beratani medium without NaCl at 28 degrees C. We obtained complementation of the crl mutation by increasing sigma(S) levels. This suggests that Crl has a major physiological impact at low concentrations of sigma(S).
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Affiliation(s)
- Véronique Robbe-Saule
- Institut Pasteur, Unité des Régulations Transcriptionnelles, URA-CNRS 2172, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
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33
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Romanova IM, Smirnova TA, Andreev AL, Il'ina TS, Didenko LV, Gintsburg AL. [Formation of biofilms as an example of the social behavior of bacteria]. Mikrobiologiia 2006; 75:556-61. [PMID: 17025184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
This paper is a brief review of data on bacterial biofilms that occur inside and outside of host organisms. Such biofilms are of great ecological and clinical importance. The role of interspecies communications in the development of bacterial biofilms and infectious diseases is particularly emphasized. Considerable attention is given to the electron microscopic study of biofilms formed by Salmonella typhimurium cells incubated as a broth culture in microtubes without aeration. Bacterial samples taken from the biofilm and planktonic culture grown in the same microtube were comparatively investigated by transmission electron microscopy.
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Marlovits TC, Kubori T, Lara-Tejero M, Thomas D, Unger VM, Galán JE. Assembly of the inner rod determines needle length in the type III secretion injectisome. Nature 2006; 441:637-40. [PMID: 16738660 DOI: 10.1038/nature04822] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Accepted: 04/19/2006] [Indexed: 11/09/2022]
Abstract
Assembly of multi-component supramolecular machines is fundamental to biology, yet in most cases, assembly pathways and their control are poorly understood. An example is the type III secretion machine, which mediates the transfer of bacterial virulence proteins into host cells. A central component of this nanomachine is the needle complex or injectisome, an organelle associated with the bacterial envelope that is composed of a multi-ring base, an inner rod, and a protruding needle. Assembly of this organelle proceeds in sequential steps that require the reprogramming of the secretion machine. Here we provide evidence that, in Salmonella typhimurium, completion of the assembly of the inner rod determines the size of the needle substructure. Assembly of the inner rod, which is regulated by the InvJ protein, triggers conformational changes on the cytoplasmic side of the injectisome, reprogramming the secretion apparatus to stop secretion of the needle protein.
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Affiliation(s)
- Thomas C Marlovits
- Section of Microbial Pathogenesis, Yale University School of Medicine, Boyer Center for Molecular Medicine, New Haven, Connecticut 06536, USA
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35
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Abstract
Salmonellae can use ethanolamine (EA) as a sole source of carbon and nitrogen. This ability is encoded by an operon (eut) containing 17 genes, only 6 of which are required under standard conditions (37 degrees C; pH 7.0). Five of the extra genes (eutM, -N, -L, -K, and -G) become necessary under conditions that favor loss of the volatile intermediate, acetaldehyde, which escapes as a gas during growth on EA and is lost at a higher rate from these mutants. The eutM, -N, -L, and -K genes encode homologues of shell proteins of the carboxysome, an organelle shown (in other organisms) to concentrate CO(2). We propose that carboxysome-like organelles help bacteria conserve certain volatile metabolites-CO(2) or acetaldehyde-perhaps by providing a low-pH compartment. The EutG enzyme converts acetaldehyde to ethanol, which may improve carbon retention by forming acetals; alternatively, EutG may recycle NADH within the carboxysome.
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Affiliation(s)
- Joseph T Penrod
- Microbiology Section, Division of Biological Sciences, University of California-Davis, Davis, CA, USA
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36
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Abstract
Filaments of bacterial flagella are perfect tubular stackings polymerized out of just one kind of building block: the flagellin protein. Surprisingly, they do not form straight tubes, but exhibit a symmetry-breaking coiling into helical shapes which is essential for their biological function as cell "propeller''. The co-existence of two conformational states for flagellin within the filament is believed to be responsible for the helical shapes by producing local misfit which results in curvature and twist. In this paper, we present a coarse-grained description with an elastic energy functional for the filament derived from its microscopic structure. By minimising this functional we can answer the question of spatial distribution of flagellin states which is crucial for the observed coupling of curvature and twist. Our approach extends a classical theory of Calladine, which had to assume this spatial distribution from the outset.
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Affiliation(s)
- Benjamin Friedrich
- Max-Planck-Institute for Mathematics in the Sciences, Inselstrasse 22, 04103, Leipzig, Germany.
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Di Pasqua R, Hoskins N, Betts G, Mauriello G. Changes in membrane fatty acids composition of microbial cells induced by addiction of thymol, carvacrol, limonene, cinnamaldehyde, and eugenol in the growing media. J Agric Food Chem 2006; 54:2745-9. [PMID: 16569070 DOI: 10.1021/jf052722l] [Citation(s) in RCA: 281] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Major active compounds from essential oils are well-known to possess antimicrobial activity against both pathogen and spoilage microorganisms. The aim of this work was to determine the alteration of the membrane fatty acid profile as an adaptive mechanism of the cells in the presence of a sublethal concentration of antimicrobial compound in response to a stress condition. Methanolic solutions of thymol, carvacrol, limonene, cinnamaldehyde, and eugenol were added into growth media of Escherichia coli O157:H7, Salmonella enterica serovar typhimurium, Pseudomonas fluorescens, Brochothrix thermosphacta, and Staphylococcus aureus strains. Fatty acid extraction and gas chromatographic analysis were performed to assess changes in membrane fatty acid composition. Substantial changes were observed on the long chain unsaturated fatty acids when the E. coli and Salmonella strains grew in the presence of limonene and cinnamaldehyde and carvacrol and eugenol, respectively. All compounds influenced the fatty acid profile of B. thermosphacta, while Pseudomonas and S. aureus strains did not show substantial changes in their fatty acid compositions.
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Affiliation(s)
- Rosangela Di Pasqua
- Department of Food Science, Division of Microbiology, University of Naples Federico II, Via Università 100, 80055 Portici, Italy
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Fadl AA, Galindo CL, Sha J, Klimpel GR, Popov VL, Chopra AK. Global gene expression of a murein (Braun) lipoprotein mutant of Salmonella enterica serovar Typhimurium by microarray analysis. Gene 2006; 374:121-7. [PMID: 16574345 DOI: 10.1016/j.gene.2006.01.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 01/23/2006] [Accepted: 01/25/2006] [Indexed: 12/15/2022]
Abstract
Braun/murein lipoprotein (Lpp) is one of the major outer membrane components of gram-negative enteric bacteria involved in inflammatory responses and septic shock. In previous studies, we reported that two copies of the lipoprotein (lpp) gene (designated as lppA and lppB) existed on the chromosome of Salmonella enterica serovar Typhimurium. Deletion of both lppA and lppB genes rendered Salmonella defective in invasion, motility, induction of cytotoxicity, and production of inflammatory cytokines/chemokines. The lppAB double-knockout (DKO) mutant was attenuated in mice, and animals immunized with this mutant were protected against subsequent challenge with lethal doses of wild-type (wt) S. Typhimurium. To better understand how deletion of the lpp gene might affect Salmonella virulence, we performed global transcriptional profiling of the genes in the wt and the lppAB DKO mutant of S. Typhimurium using microarrays. Our data revealed alterations in the expression of flagellar genes, invasion-associated type III secretion system genes, and transcriptional virulence gene regulators in the lppAB DKO mutant compared to wt S. Typhimurium. These data correlated with the lppAB DKO mutant phenotype and provided possible mechanism(s) of Lpp-associated attenuation in S. Typhimurium. Although these studies were performed in in vitro grown bacteria, our future research will be targeted at global transcriptional profiling of the genes in in vivo grown wt S. Typhimurium and its Lpp mutant.
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Affiliation(s)
- A A Fadl
- Department of Microbiology and Immunology, 301 University Blvd, University of Texas Medical Branch, Galveston, Texas 77555-1070, United States
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de Rezende CE, Anriany Y, Carr LE, Joseph SW, Weiner RM. Capsular polysaccharide surrounds smooth and rugose types of Salmonella enterica serovar Typhimurium DT104. Appl Environ Microbiol 2005; 71:7345-51. [PMID: 16269777 PMCID: PMC1287654 DOI: 10.1128/aem.71.11.7345-7351.2005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The biofilms and rugose colony morphology of Salmonella enterica serovar Typhimurium strains are usually associated with at least two different exopolymeric substances (EPS), curli and cellulose. In this study, another EPS, a capsular polysaccharide (CP) synthesized constitutively in S. enterica serovar Typhimurium strain DT104 at 25 and 37 degrees C, has been recognized as a biofilm matrix component as well. Fluorophore-assisted carbohydrate electrophoresis (FACE) analysis indicated that the CP is comprised principally of glucose and mannose, with galactose as a minor constituent. The composition differs from that of known colanic acid-containing CP that is isolated from cells of Escherichia coli and other enteric bacteria grown at 37 degrees C. The reactivity of carbohydrate-specific lectins conjugated to fluorescein isothiocyanate or gold particles with cellular carbohydrates demonstrated the cell surface localization of CP. Further, lectin binding also correlated with the FACE analysis of CP. Immunoelectron microscopy, using specific antibodies against CP, confirmed that CP surrounds the cells. Confocal microscopy of antibody-labeled cells showed greater biofilm formation at 25 degrees C than at 37 degrees C. Since the CP was shown to be produced at both 37 degrees C and 25 degrees C, it does not appear to be significantly involved in attachment during the early formation of the biofilm matrix. Although the attachment of S. enterica serovar Typhimurium DT104 does not appear to be mediated by its CP, the capsule does contribute to the biofilm matrix and may have a role in other features of this organism, such as virulence, as has been shown previously for the capsules of other gram-negative and gram-positive bacteria.
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Affiliation(s)
- C Eriksson de Rezende
- Department of Cell Biology and Molecular Genetics, Microbiology Building, University of Maryland, College Park, MD 20742, USA
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Whitworth T, Popov VL, Yu XJ, Walker DH, Bouyer DH. Expression of the Rickettsia prowazekii pld or tlyC gene in Salmonella enterica serovar Typhimurium mediates phagosomal escape. Infect Immun 2005; 73:6668-73. [PMID: 16177343 PMCID: PMC1230948 DOI: 10.1128/iai.73.10.6668-6673.2005] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of the genus Rickettsia possess the ability to invade host cells and promptly escape from phagosomal vacuoles into the host cell cytosol, thereby avoiding destruction within the endosomal pathway. The mechanism underlying rickettsial phagosomal escape remains unknown, although the genomic sequences of several rickettsial species have allowed for the identification of four genes with potential membranolytic activities (tlyA, tlyC, pat1, and pld). This study was undertaken to determine which of the selected genes of Rickettsia prowazekii mediate the escape process. Quantitative ultrastructural analyses indicated that the period of active phagosomal escape was between 30 and 50 min postinfection. Reverse transcriptase PCR analyses determined that tlyC and pld were transcribed during the period of active phagosomal escape but that tlyA and pat1 were not. The functionality of both tlyC and pld was determined by complementation studies of Salmonella, which replicates within endosomes. Complementation of Salmonella organisms with either tlyC or pld resulted in the escape of transformants from endosomal vacuoles into the host cell cytosol demonstrated by quantitative ultrastructural analyses. These data suggest a role for tlyC and pld in the process of phagosomal escape by R. prowazekii.
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Affiliation(s)
- Ted Whitworth
- Department of Pathology, University of Texas Medical Branch at Galveston, 77555-0609, USA
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Shibata S, Alam M, Aizawa SI. Flagellar Filaments of the Deep-sea Bacteria Idiomarina loihiensis Belong to a Family Different from those of Salmonella typhimurium. J Mol Biol 2005; 352:510-6. [PMID: 16120444 DOI: 10.1016/j.jmb.2005.07.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 06/27/2005] [Accepted: 07/08/2005] [Indexed: 11/17/2022]
Abstract
The helical filaments of the bacterial flagella so far studied seem to be universal in the bacterial kingdom. Despite the variation in flagellin molecular masses, which range from 24 kDa to 62 kDa in different species, there are only two forms: either the so-called Normal (left-handed) or the Curly (right-handed). The Normal and Curly helical forms are asymmetric; the two characteristic helical parameters, which are the pitch and diameter, of Normal filaments are twice those of Curly filaments. Both the universality of these two helical forms and their asymmetry are biological puzzles. We found that the marine bacteria Idiomarina loihiensis have flagella with left-handed Curly-like filaments. Analysis of the polymorphic forms under different pH conditions showed that the Curly-like filaments are actually Normal filaments having a smaller pitch and diameter than those of Salmonella typhimurium. A minor modification of Calladine's model for a filament lattice can explain the variant helical forms. Pseudomonas aeruginosa filaments also belong to the family of I.loihiensis filaments. Thus, there are at least two families of flagella filaments.
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Affiliation(s)
- Satoshi Shibata
- Soft Nano-Machine Project, JST, 3-10-23 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
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Chakravortty D, Rohde M, Jäger L, Deiwick J, Hensel M. Formation of a novel surface structure encoded by Salmonella Pathogenicity Island 2. EMBO J 2005; 24:2043-52. [PMID: 15889142 PMCID: PMC1142609 DOI: 10.1038/sj.emboj.7600676] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Accepted: 04/15/2005] [Indexed: 12/28/2022] Open
Abstract
The type III secretion system (T3SS) encoded by Salmonella Pathogenicity Island 2 (SPI2) is essential for virulence and intracellular proliferation of Salmonella enterica. We have previously identified SPI2-encoded proteins that are secreted and function as a translocon for the injection of effector proteins. Here, we describe the formation of a novel SPI2-dependent appendage structure in vitro as well as on the surface of bacteria that reside inside a vacuole of infected host cells. In contrast to the T3SS of other pathogens, the translocon encoded by SPI2 is only present singly or in few copies at one pole of the bacterial cell. Under in vitro conditions, appendages are composed of a filamentous needle-like structure with a diameter of 10 nm that was sheathed with secreted protein. The formation of the appendage in vitro is dependent on acidic media conditions. We analyzed SPI2-encoded appendages in infected cells and observed that acidic vacuolar pH was not required for induction of SPI2 gene expression, but was essential for the assembly of these structures and their function as translocon for delivery of effector proteins.
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Affiliation(s)
- Dipshikha Chakravortty
- Institut für Klinische Mikrobiologie, Immunologie und Hygiene, FAU Erlangen-Nürnberg, Erlangen, Germany
| | - Manfred Rohde
- Department of Microbial Pathogenesis and Vaccine Research, Division of Microbiology, German Centre for Biotechnology (GBF), Braunschweig, Germany
| | - Lorenz Jäger
- Institut für Klinische Mikrobiologie, Immunologie und Hygiene, FAU Erlangen-Nürnberg, Erlangen, Germany
| | - Jörg Deiwick
- Institut für Biochemie, Universität zu Lübeck, Germany
| | - Michael Hensel
- Institut für Klinische Mikrobiologie, Immunologie und Hygiene, FAU Erlangen-Nürnberg, Erlangen, Germany
- Institut für Klinische Mikrobiologie, Immunologie und Hygiene, FAU Erlangen-Nürnberg, Wasserturmstrasse 3–5, Erlangen 91054, Germany. Tel.: +49 9131 852 3640; Fax: +49 9131 852 2531; E-mail:
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Wang Q, Suzuki A, Mariconda S, Porwollik S, Harshey RM. Sensing wetness: a new role for the bacterial flagellum. EMBO J 2005; 24:2034-42. [PMID: 15889148 PMCID: PMC1142604 DOI: 10.1038/sj.emboj.7600668] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Accepted: 04/11/2005] [Indexed: 12/17/2022] Open
Abstract
We have uncovered a new role for the bacterial flagellum in sensing external wetness. An investigation into why mutants in the chemotaxis signaling pathway of Salmonella typhimurium exhibit fewer and shorter flagella than wild-type when propagated on a surface, first showed that the mutants downregulate only a small set of genes on swarm media--class 3 or 'late' motility genes, and genes associated with the pathogenicity island SPI-1 TTSS (type three secretion system). Based on observations that swarm colonies of the mutants appear less hydrated, we tested a model in which the flagellum itself is a sensor: suboptimal external hydration interferes with secretion of flagellin subunits, inhibiting filament growth and blocking normal export of the class 3 transcription inhibitor FlgM. We provide strong experimental support for the model. In addition, the data show that the flagellar and SPI-1 TTSS are coupled via regulatory proteins. These studies implicate the flagellum, a bacterial organ for motility, in sensing the external environment to modulate not only its own biogenesis but other physiological functions as well.
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Affiliation(s)
- Qingfeng Wang
- Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
| | - Asaka Suzuki
- Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
| | - Susana Mariconda
- Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
| | | | - Rasika M Harshey
- Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
- Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA. Tel.: +1 512 471 6881; Fax: +1 512 471 7088; E-mail:
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Abstract
The mammalian serine protease plasmin, which has an important role in extracellular matrix degradation during cell migration, is regulated by the plasma antiprotease alpha(2)-antiplasmin (alpha(2)AP). The surface protease PgtE of Salmonella enterica serovar Typhimurium proteolytically inactivated alpha(2)AP. PgtE also activates the plasma zymogen plasminogen to plasmin, and bacteria expressing PgtE promoted degradation of extracellular matrix laminin in the presence of plasminogen and alpha(2)AP. alpha(2)AP inactivation was detected with the rough derivative of S. enterica 14028, but not with the smooth wild-type strain, suggesting that the O-antigen of lipopolysaccharide prevented contact of PgtE with the substrate molecule. After growth of S. enterica 14028 in murine J774A.1 macrophage-like cells, the infected cell lysate as well as bacteria from isolated Salmonella-containing vacuoles (SCVs) cleaved alpha(2)AP. Bacteria from SCVs produced an elevated level of PgtE and had a reduced O-antigen chain length. The lysate from S. enterica 14028-infected macrophages promoted formation of plasmin in the presence of alpha(2)AP, whereas plasmin formation by lysates from uninfected macrophages, or from macrophages infected with the pgtE-negative derivative of 14028, was inhibited by alpha(2)AP. Salmonella disseminates in the host within macrophages, which utilize plasmin for migration through tissue barriers. The results suggest that intracellular enhancement of PgtE activity in Salmonella may promote macrophage-associated proteolysis and cellular migration by altering the balance between host plasmin and alpha(2)AP.
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Affiliation(s)
- Kaarina Lähteenmäki
- General Microbiology, Faculty of Biosciences, University of Helsinki, Helsinki, Finland.
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Abstract
Type III secretion systems (TTSSs) mediate translocation of virulence factors into host cells. We report the 17-angstrom resolution structures of a central component of Salmonella typhimurium TTSS, the needle complex, and its assembly precursor, the bacterial envelope-anchored base. Both the base and the fully assembled needle complex adopted multiple oligomeric states in vivo, and needle assembly was accompanied by recruitment of the protein PrgJ as a structural component of the base. Moreover, conformational changes during needle assembly created scaffolds for anchoring both PrgJ and the needle substructure and may provide the basis for substrate-specificity switching during type III secretion.
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Affiliation(s)
- Thomas C. Marlovits
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520–8024, USA
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Tomoko Kubori
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Anand Sukhan
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Dennis R. Thomas
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Jorge E. Galán
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Vinzenz M. Unger
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520–8024, USA
- †To whom correspondence should be addressed., E-mail:
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Pavlova IB, Zuev VS. [Salmonella typhimurium population in water environment under the influence of temperature]. Zh Mikrobiol Epidemiol Immunobiol 2004:16-9. [PMID: 15554306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The strategy of the adaptation of S. typhimurium population to water environment under the influence of temperature factor was studied by scanning electron microscopy. Salmonellae were found to adhere to the surface of the Daphnia chitin covering. The study revealed that S. typhimurium population existed in water in the form of covered microcolonies as well as in the form of spheroplast-type cells and small cells in the L-form, joined with bands. The viability of salmonellae in water environment was studied without interaction and following interaction with Daphnia.
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Venza Colon CJ, Vasquez Leon AY, Villafañe RJ. Initial interaction of the P22 phage with the Salmonella typhimurium surface. P R Health Sci J 2004; 23:95-101. [PMID: 15377056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
OBJECTIVES The goals of these studies were to characterize the interaction of the P22 phage particle with the Salmonella cell surface and to determine the phage elements involved in this interaction by mutational analysis. BACKGROUND The phage P22 has been characterized extensively. The gene and protein for the phage P22 tailspike, which is the phage adsorption organelle, have been intensively studied. The kinetics of the interaction of the tailspike protein with the cell surface has been studied in detail, surprisingly no mutational analysis has ever been reported that has defined these components and their interaction between themselves and the cell surface. The main and perhaps only component needed for this cell surface interaction is the tailspike protein. METHODS Adsorption to the cell surface has been measured in the wild type phage and in mutant derivatives, isolated in this study. Phage mutants have been isolated after hydroxylamine mutagenesis. RESULTS The adsorption of P22 to the cell surface is a temperature-independent event. Forty putative phage adsorption mutants have been isolated. A sample of them have been further analyzed. These divide the adsorption process into at least two stages. One stage contains mutants that absorb with essential wild type phage kinetics to the cell surface while the other stage with delayed adsorption kinetics. CONCLUSIONS The interaction of the phage P22 with the Salmonella cell surface has been shown to be a complicated one which is temperature-independent and multi-stage. Mutants isolated in this study may help dissect this process even further.
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Rodríguez E, Seguer J, Rocabayera X, Manresa A. Cellular effects of monohydrochloride of l-arginine, Nalpha-lauroyl ethylester (LAE) on exposure to Salmonella typhimurium and Staphylococcus aureus. J Appl Microbiol 2004; 96:903-12. [PMID: 15078505 DOI: 10.1111/j.1365-2672.2004.02207.x] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AIMS Here we study the effect of monohydrochloride of L-arginine, N(alpha)-lauroyl ethylester (LAE), a cationic preservative derived from lauric acid and arginine, on the cell envelopes of Salmonella typhimurium and Staphylococcus aureus at sub-lethal concentration such as their respective minimal inhibitory concentrations, 32 and 8 microg ml(-1), respectively. METHODS AND RESULTS Bacterial populations were studied by using transmission electron and fluorescence microscopy (TEM and FM), flow cytometry (FC) and ion-flux across the cellular membrane. Cell integrity was altered mainly in the outer membrane of S. typhimurium, but there was no significant change in the cytoplasm. However, in Staph. aureus, clear zones, abnormal septation and mesosome-like structures were observed in the cytoplasm. Bacterial populations were double-stained with propidium iodide (PI) and SYTO-13 for FC analysis. In S. typhimurium the proportion of damaged cells after 24 h was 97% and in Staph. aureus 56.3%. LAE induced transmembrane ion flux, the increase of potassium leakage after 30 min of contact was 7.7 and 3.34 microg ml(-1) for Staph. aureus and S. typhimurium, respectively. Membrane disruption was detected by measuring the proton flow across the membrane. CONCLUSIONS Disturbance in membrane potential and structural changes was caused by LAE, although cells were not disrupted. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first time the cellular effects of LAE on bacterial cells were studied.
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Affiliation(s)
- E Rodríguez
- Laboratori de Microbiologia, Facultat de Farmacia, Universitat de Barcelona, Barcelona, Spain
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Perrin AJ, Jiang X, Birmingham CL, So NSY, Brumell JH. Recognition of Bacteria in the Cytosol of Mammalian Cells by the Ubiquitin System. Curr Biol 2004; 14:806-11. [PMID: 15120074 DOI: 10.1016/j.cub.2004.04.033] [Citation(s) in RCA: 233] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Revised: 03/12/2004] [Accepted: 03/17/2004] [Indexed: 11/30/2022]
Abstract
Recent studies have suggested the existence of innate host surveillance systems for the detection of bacteria in the cytosol of mammalian cells. The molecular details of how bacteria are recognized in the cytosol, however, remain unclear. Here we examined the fate of Salmonella typhimurium, a gram-negative bacterial pathogen that can infect a variety of hosts, in the cytosol of mammalian cells. These bacteria typically occupy a membrane bound compartment, the Salmonella-containing vacuole (SCV), in host cells. We show that some wild-type bacteria escape invasion vacuoles and are released into the cytosol. Subsequently, polyubiquitinated proteins accumulate on the bacterial surface, a response that was witnessed in several cell types. In macrophages but not epithelial cells, the proteasome was observed to undergo a dramatic subcellular relocalization and become associated with the surface of bacteria in the cytosol. Proteasome inhibition promoted replication of S. typhimurium in the cytosol of both cell types, in part through destabilization of the SCV. Surprisingly, the cytosol-adapted pathogen Listeria monocytogenes avoided recognition by the ubiquitin system by using actin-based motility. Our findings indicate that the ubiquitin system plays a major role in the recognition of bacterial pathogens in the cytosol of mammalian cells.
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Affiliation(s)
- Andrew J Perrin
- Infection, Immunity, Injury, and Repair Program, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
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Reis BP, Zhang S, Tsolis RM, Bäumler AJ, Adams LG, Santos RL. The attenuated sopB mutant of Salmonella enterica serovar Typhimurium has the same tissue distribution and host chemokine response as the wild type in bovine Peyer's patches. Vet Microbiol 2004; 97:269-77. [PMID: 14654296 DOI: 10.1016/j.vetmic.2003.09.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Salmonella enterica serovar Typhimurium is an important cause of enteric infections in farm animals and it is one of the most frequent food borne infections worldwide. Serovar Typhimurium lacking the sopB gene is attenuated for induction of host inflammatory response and fluid accumulation into the intestinal lumen, which correlates with clinical diarrhea. SopB is an inositol phosphate phosphatase, but its exact role in the pathogenesis of salmonellosis is still unclear. We employed the bovine ileal ligated loop model to compare the tissue distribution of a sopB mutant and its wild type parent serovar Typhimurium. Sections of the Peyer's patches were histologically processed and immuno-stained for detection of serovar Typhimurium. In addition, samples were processed for transmission electron microscopy, and the profile of expression of host chemokine and cytokine responses was assessed. Ultrastructurally both strains had the same ability to invade intestinal epithelial cells. No differences were detected in the tissue distribution of the sopB mutant and the wild type organism and both strains elicited the same profile of chemokines and pro-inflammatory cytokines. In conclusion, our results indicate that the attenuation of the sopB mutant is associated with pathogenic mechanisms other than invasion and distribution in host intestinal tissues.
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Affiliation(s)
- Bruno P Reis
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária da Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil
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