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Jønsson R, Björling A, Midtgaard SR, Jensen GV, Skar-Gislinge N, Arleth L, Matthews S, Krogfelt KA, Jenssen H. Aggregative adherence fimbriae form compact structures as seen by SAXS. Sci Rep 2023; 13:16516. [PMID: 37783694 PMCID: PMC10545799 DOI: 10.1038/s41598-023-42079-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 09/05/2023] [Indexed: 10/04/2023] Open
Abstract
Bacterial colonization is mediated by fimbriae, which are thin hair-like appendages dispersed from the bacterial surface. The aggregative adherence fimbriae from enteroaggregative E. coli are secreted through the outer membrane and consist of polymerized minor and major pilin subunits. Currently, the understanding of the structural morphology and the role of the minor pilin subunit in the polymerized fimbriae are limited. In this study we use small-angle X-ray scattering to reveal the structural morphology of purified fimbriae in solution. We show that the aggregative fimbriae are compact arrangements of subunit proteins Agg5A + Agg3B which are assembled pairwise on a flexible string rather than extended in relatively straight filaments. Absence of the minor subunit leads to less compact fimbriae, but did not affect the length. The study provides novel insights into the structural morphology and assembly of the aggregative adherence fimbriae. Our study suggests that the minor subunit is not located at the tip of the fimbriae as previously speculated but has a higher importance for the assembled fimbriae by affecting the global structure.
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Affiliation(s)
- Rie Jønsson
- Department of Science and Environment, Roskilde University, 4000, Roskilde, Denmark.
| | | | | | | | | | - Lise Arleth
- Niels Bohr Institute, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Steve Matthews
- Department of Life Sciences, Centre for Structural Biology, Imperial College London, South Kensington, London, UK
| | | | - Håvard Jenssen
- Department of Science and Environment, Roskilde University, 4000, Roskilde, Denmark.
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2
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Gahlot DK, Taheri N, MacIntyre S. Diversity in Genetic Regulation of Bacterial Fimbriae Assembled by the Chaperone Usher Pathway. Int J Mol Sci 2022; 24:ijms24010161. [PMID: 36613605 PMCID: PMC9820224 DOI: 10.3390/ijms24010161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 12/24/2022] Open
Abstract
Bacteria express different types of hair-like proteinaceous appendages on their cell surface known as pili or fimbriae. These filamentous structures are primarily involved in the adherence of bacteria to both abiotic and biotic surfaces for biofilm formation and/or virulence of non-pathogenic and pathogenic bacteria. In pathogenic bacteria, especially Gram-negative bacteria, fimbriae play a key role in bacteria-host interactions which are critical for bacterial invasion and infection. Fimbriae assembled by the Chaperone Usher pathway (CUP) are widespread within the Enterobacteriaceae, and their expression is tightly regulated by specific environmental stimuli. Genes essential for expression of CUP fimbriae are organised in small blocks/clusters, which are often located in proximity to other virulence genes on a pathogenicity island. Since these surface appendages play a crucial role in bacterial virulence, they have potential to be harnessed in vaccine development. This review covers the regulation of expression of CUP-assembled fimbriae in Gram-negative bacteria and uses selected examples to demonstrate both dedicated and global regulatory mechanisms.
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Affiliation(s)
- Dharmender K. Gahlot
- School of Biological Sciences, University of Reading, Reading RG6 6EX, UK
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, 901 87 Umeå, Sweden
- Correspondence: (D.K.G.); (S.M.)
| | - Nayyer Taheri
- APC Microbiome Institute, University College Cork, T12 K8AF Cork, Ireland
| | - Sheila MacIntyre
- School of Biological Sciences, University of Reading, Reading RG6 6EX, UK
- Correspondence: (D.K.G.); (S.M.)
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3
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Gaines MC, Isupov MN, Sivabalasarma S, Haque RU, McLaren M, Mollat CL, Tripp P, Neuhaus A, Gold VAM, Albers SV, Daum B. Electron cryo-microscopy reveals the structure of the archaeal thread filament. Nat Commun 2022; 13:7411. [PMID: 36456543 PMCID: PMC9715654 DOI: 10.1038/s41467-022-34652-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 11/02/2022] [Indexed: 12/05/2022] Open
Abstract
Pili are filamentous surface extensions that play roles in bacterial and archaeal cellular processes such as adhesion, biofilm formation, motility, cell-cell communication, DNA uptake and horizontal gene transfer. The model archaeaon Sulfolobus acidocaldarius assembles three filaments of the type-IV pilus superfamily (archaella, archaeal adhesion pili and UV-inducible pili), as well as a so-far uncharacterised fourth filament, named "thread". Here, we report on the cryo-EM structure of the archaeal thread. The filament is highly glycosylated and consists of subunits of the protein Saci_0406, arranged in a head-to-tail manner. Saci_0406 displays structural similarity, but low sequence homology, to bacterial type-I pilins. Thread subunits are interconnected via donor strand complementation, a feature reminiscent of bacterial chaperone-usher pili. However, despite these similarities in overall architecture, archaeal threads appear to have evolved independently and are likely assembled by a distinct mechanism.
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Affiliation(s)
- Matthew C Gaines
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Michail N Isupov
- Henry Wellcome Building for Biocatalysis, Department of Biosciences, Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, Exeter, UK
| | - Shamphavi Sivabalasarma
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Risat Ul Haque
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Mathew McLaren
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Clara L Mollat
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
| | - Patrick Tripp
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
| | - Alexander Neuhaus
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK
| | - Sonja-Verena Albers
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Schänzlestraße 1, 79104, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
- Signalling Research Centres BIOSS and CIBBS, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, Exeter, UK.
- Department of Biosciences, Faculty of Health and Life Sciences, Stocker Road, EX4 4QD, Exeter, UK.
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4
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Molecular Epidemiology of Plasmid-Mediated Types 1 and 3 Fimbriae Associated with Biofilm Formation in Multidrug Resistant Escherichia coli from Diseased Food Animals in Guangdong, China. Microbiol Spectr 2022; 10:e0250321. [PMID: 35969065 PMCID: PMC9603762 DOI: 10.1128/spectrum.02503-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Types 1 and 3 fimbriae in Enterobacteriaceae play versatile roles in bacterial physiology including attachment, invasion, cell motility as well as with biofilm formation and urinary tract infections. Herein, we investigated the prevalence and transmission of plasmid-mediated types 1 and 3 fimbriae from 1753 non-duplicate Enterobacteriaceae from diseased food Animals. We identified 123 (7.01%) strong biofilm producers and all was identified as E. coli. WGS analysis of 43 selected strong biofilm producers revealed that they harbored multiple ARGs, including ESBLs, PMQR and mcr-1. The gene clusters mrkABCDF and fimACDH encoding types 1 and 3 fimbriae, respectively, were identified among 43 (34.96%) and 7 (5.7%) of 123 strong biofilm isolates, respectively. These two operons were able to confer strong biofilm-forming ability to an E. coli weak-biofilm forming laboratory strain. Plasmid analysis revealed that mrk and fim operons were found to co-exist with ARGs and were primarily located on IncX1 and IncFII plasmids with similar backbones, respectively. mrkABCDF operons was present in all of 9457 Klebsiella pneumoniae using archived WGS data, and shared high homology to those on plasmids of 8 replicon types and chromosomes from 6 Enterobacteriaceae species from various origins and countries. In contrast, fimACDH operons was present in most of Enterobacter cloacae (62.15%), and shared high homology to those with only a small group of plasmids and Enterobacteriaceae species. This is the first comprehensive report of the prevalence, transmission and homology of plasmid-encoded type 1 and 3 fimbriae among the Enterobacteriaceae. Our findings indicated that plasmid-encoded mrkABCDF and fimACDH were major contributors to enhanced biofilm formation among E. coli and these two operons, in particular mrk could be as a potential anti-biofilm target. IMPORTANCE Biofilms allow bacteria to tolerate disinfectants and antimicrobials, as well as mammalian host defenses, and are therefore difficult to treat clinically. Most research concerning biofilm-related infections is typically focused on chromosomal biofilm-associated factors, including types 1 and 3 fimbriae of biofilm-forming Enterobacterium. However, the transmission and homology of the mobile types 1 and 3 fimbriae among Enterobacteriaceae is largely unknown. The findings revealed that the plasmid-encoded type 3 fimbriae encoded by mrkABCDF and type 1 fimbriae encoded by fimACDH were major contributors to enhancing biofilm formation among strong biofilm E. coli from diseased food producing animals. Additionally, mrk operon with high homology at an amino acid sequence was present both on plasmids of various replicon types and on chromosomes from diverse Enterobacteriaceae species from numerous origins and countries. These findings provide important information on the transmission of the mobile types 1 and 3 fimbriae among Enterobacteriaceae, indicating a potential antibiofilm target.
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5
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Tsoumtsa Meda LL, Landraud L, Petracchini S, Descorps-Declere S, Perthame E, Nahori MA, Ramirez Finn L, Ingersoll MA, Patiño-Navarrete R, Glaser P, Bonnet R, Dussurget O, Denamur E, Mettouchi A, Lemichez E. The cnf1 gene is associated with an expanding Escherichia coli ST131 H30Rx/C2 subclade and confers a competitive advantage for gut colonization. Gut Microbes 2022; 14:2121577. [PMID: 36154446 PMCID: PMC9519008 DOI: 10.1080/19490976.2022.2121577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Epidemiological projections point to acquisition of ever-expanding multidrug resistance (MDR) by Escherichia coli, a commensal of the digestive tract and a source of urinary tract pathogens. Bioinformatics analyses of a large collection of E. coli genomes from EnteroBase, enriched in clinical isolates of worldwide origins, suggest the Cytotoxic Necrotizing Factor 1 (CNF1)-toxin encoding gene, cnf1, is preferentially distributed in four common sequence types (ST) encompassing the pandemic E. coli MDR lineage ST131. This lineage is responsible for a majority of extraintestinal infections that escape first-line antibiotic treatment, with known enhanced capacities to colonize the gastrointestinal tract. Statistical projections based on this dataset point to a global expansion of cnf1-positive multidrug-resistant ST131 strains from subclade H30Rx/C2, accounting for a rising prevalence of cnf1-positive strains in ST131. Despite the absence of phylogeographical signals, cnf1-positive isolates segregated into clusters in the ST131-H30Rx/C2 phylogeny, sharing a similar profile of virulence factors and the same cnf1 allele. The suggested dominant expansion of cnf1-positive strains in ST131-H30Rx/C2 led us to uncover the competitive advantage conferred by cnf1 for gut colonization to the clinical strain EC131GY ST131-H30Rx/C2 versus cnf1-deleted isogenic strain. Complementation experiments showed that colon tissue invasion was compromised in the absence of deamidase activity on Rho GTPases by CNF1. Hence, gut colonization factor function of cnf1 was confirmed for another clinical strain ST131-H30Rx/C2. In addition, functional analysis of the cnf1-positive clinical strain EC131GY ST131-H30Rx/C2 and a cnf1-deleted isogenic strain showed no detectable impact of the CNF1 gene on bacterial fitness and inflammation during the acute phase of bladder monoinfection. Together these data argue for an absence of role of CNF1 in virulence during UTI, while enhancing gut colonization capacities of ST131-H30Rx/C2 and suggested expansion of cnf1-positive MDR isolates in subclade ST131-H30Rx/C2.
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Affiliation(s)
- Landry L. Tsoumtsa Meda
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité des Toxines Bactériennes, Département de Microbiologie, Paris, France
| | - Luce Landraud
- Université Paris Cité et Université Sorbonne Paris Nord, INSERM U1137, IAME, Paris, France,Laboratoire Microbiologie-hygiène, AP-HP, Hôpital Louis Mourier, Colombes, France
| | - Serena Petracchini
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité des Toxines Bactériennes, Département de Microbiologie, Paris, France
| | - Stéphane Descorps-Declere
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité des Toxines Bactériennes, Département de Microbiologie, Paris, France,Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, Paris, France
| | - Emeline Perthame
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, Paris, France
| | - Marie-Anne Nahori
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité des Toxines Bactériennes, Département de Microbiologie, Paris, France
| | - Laura Ramirez Finn
- Institut Pasteur, Department of Immunology, Mucosal Inflammation and Immunity group, Paris, France,Université Paris Cité, Institut Cochin, CNRS UMR8104, INSERM U1016, Paris, France
| | - Molly A. Ingersoll
- Institut Pasteur, Department of Immunology, Mucosal Inflammation and Immunity group, Paris, France,Université Paris Cité, Institut Cochin, CNRS UMR8104, INSERM U1016, Paris, France
| | - Rafael Patiño-Navarrete
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Unité Ecologie et Evolution de la Résistance aux Antibiotiques, Département de Microbiologie, Paris, France
| | - Philippe Glaser
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Unité Ecologie et Evolution de la Résistance aux Antibiotiques, Département de Microbiologie, Paris, France
| | - Richard Bonnet
- UMR INSERM U1071, INRA USC-2018, Université Clermont Auvergne, Clermont-Ferrand, France,Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire, Clermont-Ferrand, France
| | - Olivier Dussurget
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Unité de Recherche Yersinia, Département de Microbiologie, Paris, France
| | - Erick Denamur
- Université Paris Cité et Université Sorbonne Paris Nord, INSERM U1137, IAME, Paris, France,AP-HP, Laboratoire de Génétique Moléculaire, Hôpital Bichat, Paris, France
| | - Amel Mettouchi
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité des Toxines Bactériennes, Département de Microbiologie, Paris, France,Amel Mettouchi Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité des Toxines Bactériennes, Département de Microbiologie, 75015Paris, France
| | - Emmanuel Lemichez
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité des Toxines Bactériennes, Département de Microbiologie, Paris, France,CONTACT Emmanuel Lemichez
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6
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Hermansen S, Linke D, Leo JC. Transmembrane β-barrel proteins of bacteria: From structure to function. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:113-161. [PMID: 35034717 DOI: 10.1016/bs.apcsb.2021.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The outer membrane of Gram-negative bacteria is a specialized organelle conferring protection to the cell against various environmental stresses and resistance to many harmful compounds. The outer membrane has a number of unique features, including an asymmetric lipid bilayer, the presence of lipopolysaccharides and an individual proteome. The vast majority of the integral transmembrane proteins in the outer membrane belongs to the family of β-barrel proteins. These evolutionarily related proteins share a cylindrical, anti-parallel β-sheet core fold spanning the outer membrane. The loops and accessory domains attached to the β-barrel allow for a remarkable versatility in function for these proteins, ranging from diffusion pores and transporters to enzymes and adhesins. We summarize the current knowledge on β-barrel structure and folding and give an overview of their functions, evolution, and potential as drug targets.
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Affiliation(s)
- Simen Hermansen
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Jack C Leo
- Antimicrobial resistance, Omics and Microbiota Group, Department of Biosciences, Nottingham Trent University, Nottingham, United Kingdom.
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7
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Du M, Yuan Z, Werneburg GT, Henderson NS, Chauhan H, Kovach A, Zhao G, Johl J, Li H, Thanassi DG. Processive dynamics of the usher assembly platform during uropathogenic Escherichia coli P pilus biogenesis. Nat Commun 2021; 12:5207. [PMID: 34471127 PMCID: PMC8410936 DOI: 10.1038/s41467-021-25522-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 08/12/2021] [Indexed: 11/25/2022] Open
Abstract
Uropathogenic Escherichia coli assemble surface structures termed pili or fimbriae to initiate infection of the urinary tract. P pili facilitate bacterial colonization of the kidney and pyelonephritis. P pili are assembled through the conserved chaperone-usher pathway. Much of the structural and functional understanding of the chaperone-usher pathway has been gained through investigations of type 1 pili, which promote binding to the bladder and cystitis. In contrast, the structural basis for P pilus biogenesis at the usher has remained elusive. This is in part due to the flexible and variable-length P pilus tip fiber, creating structural heterogeneity, and difficulties isolating stable P pilus assembly intermediates. Here, we circumvent these hindrances and determine cryo-electron microscopy structures of the activated PapC usher in the process of secreting two- and three-subunit P pilus assembly intermediates, revealing processive steps in P pilus biogenesis and capturing new conformational dynamics of the usher assembly machine. Escherichia coli form pili structures in order to initiate infection of the urinary tract. Here, Thanassi et al., have solved the structures of pili assembly intermediates and provided insights into their biogenesis and assembly.
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Affiliation(s)
- Minge Du
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Zuanning Yuan
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Glenn T Werneburg
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, NY, USA.,Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY, USA.,Department of Urology, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Nadine S Henderson
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, NY, USA.,Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY, USA
| | - Hemil Chauhan
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, NY, USA.,Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY, USA.,SUNY Downstate College of Medicine, Brooklyn, New York, NY, USA
| | - Amanda Kovach
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Gongpu Zhao
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Jessica Johl
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, NY, USA.,Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY, USA
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA.
| | - David G Thanassi
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, NY, USA. .,Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, NY, USA.
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8
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González-Montalvo MA, Tavares-Carreón F, González GM, Villanueva-Lozano H, García-Romero I, Zomosa-Signoret VC, Valvano MA, Andrade A. Defining chaperone-usher fimbriae repertoire in Serratia marcescens. Microb Pathog 2021; 154:104857. [PMID: 33762200 DOI: 10.1016/j.micpath.2021.104857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/12/2021] [Indexed: 11/28/2022]
Abstract
Chaperone-usher (CU) fimbriae are surface organelles particularly prevalent among the Enterobacteriaceae. Mainly associated to their adhesive properties, CU fimbriae play key roles in biofilm formation and host cell interactions. Little is known about the fimbriome composition of the opportunistic human pathogen Serratia marcescens. Here, by using a search based on consensus fimbrial usher protein (FUP) sequences, we identified 421 FUPs across 39 S. marcescens genomes. Further analysis of the FUP-containing loci allowed us to classify them into 20 conserved CU operons, 6 of which form the S. marcescens core CU fimbriome. A new systematic nomenclature is proposed according to FUP sequence phylogeny. We also established an in vivo transcriptional assay comparing CU promoter expression between an environmental and a clinical isolate of S. marcescens, which revealed that promoters from 3 core CU operons (referred as fgov, fpo, and fps) are predominantly expressed in the two strains and might represent key core adhesion appendages contributing to S. marcescens pathogenesis.
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Affiliation(s)
- Martín A González-Montalvo
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico
| | - Faviola Tavares-Carreón
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, San Nicolás de los Garza, Nuevo León, 66455, Mexico
| | - Gloria M González
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico
| | - Hiram Villanueva-Lozano
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico
| | - Inmaculada García-Romero
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, United Kingdom
| | - Viviana C Zomosa-Signoret
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Bioquímica y Medicina Molecular, Monterrey, Nuevo León, 64460, Mexico
| | - Miguel A Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, United Kingdom
| | - Angel Andrade
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico.
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9
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Francius G, Petit F, Clément E, Chekli Y, Ghigo JM, Beloin C, Duval JFL. On the strong connection between nanoscale adhesion of Yad fimbriae and macroscale attachment of Yad-decorated bacteria to glycosylated, hydrophobic and hydrophilic surfaces. NANOSCALE 2021; 13:1257-1272. [PMID: 33404575 DOI: 10.1039/d0nr06840c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Yad fimbriae are currently viewed as versatile bacterial adhesins able to significantly mediate host or plant-pathogen recognition and contribute to the persistence of Escherichia coli in both the environment and within hosts. To date, however, the underlying adhesion process of Yad fimbriae on surfaces defined by controlled coating chemistries has not been evaluated on the relevant molecular scale. In this work, the interaction forces operational between Yad fimbriae expressed by genetically modified E. coli and self-assembled monolayers (SAM) differing in terms of charge, hydrophobicity or the nature of decorating sugar units are quantified by Single Molecule Force Spectroscopy (SMFS) on the nanoscale. It is found that the adhesion of Yad fimbriae onto probes functionalized with xylose is as strong as that measured with probes decorated with anti-Yad antibodies (ca. 80 to 300 pN). In contrast, the interactions of Yad with galactose, lactose, mannose, -OH, -NH2, -COOH and -CH3 terminated SAMs are clearly non-specific. Interpretation of SMFS measurements on the basis of worm-like-chain modeling for polypeptide nanomechanics further leads to the estimates of the maximal extension of Yad fimbriae upon stretching, of their persistence length and of their polydispersity. Finally, we show for the first time a strong correlation between the adhesion properties of Yad-decorated bacteria determined from conventional macroscopic counting methods and the molecular adhesion capacity of Yad fimbriae. This demonstration advocates the effort that should be made to understand on the nanoscale level the interactions between fimbriae and their cognate ligands. The results could further help the design of potential anti-adhesive molecules or surfaces to better fight against the virulence of bacterial pathogens.
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Affiliation(s)
- Grégory Francius
- Université de Lorraine, LCPME, UMR 7564, Villers-lès-Nancy, F-54600, France.
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10
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Pandey NK, Verma G, Kushwaha GS, Suar M, Bhavesh NS. Crystal structure of the usher chaperone YadV reveals a monomer with the proline lock in closed conformation suggestive of an intermediate state. FEBS Lett 2020; 594:3057-3066. [DOI: 10.1002/1873-3468.13883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/15/2020] [Accepted: 07/02/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Nishant Kumar Pandey
- Transcription Regulation Group International Centre for Genetic Engineering and Biotechnology (ICGEB) New Delhi India
- School of Biotechnology Kalinga Institute of Industrial Technology (KIIT), (Deemed to be University) Bhubaneswar India
| | - Garima Verma
- Transcription Regulation Group International Centre for Genetic Engineering and Biotechnology (ICGEB) New Delhi India
| | - Gajraj Singh Kushwaha
- Transcription Regulation Group International Centre for Genetic Engineering and Biotechnology (ICGEB) New Delhi India
| | - Mrutyunjay Suar
- School of Biotechnology Kalinga Institute of Industrial Technology (KIIT), (Deemed to be University) Bhubaneswar India
| | - Neel Sarovar Bhavesh
- Transcription Regulation Group International Centre for Genetic Engineering and Biotechnology (ICGEB) New Delhi India
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11
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Legros N, Ptascheck S, Pohlentz G, Karch H, Dobrindt U, Müthing J. PapG subtype-specific binding characteristics of Escherichia coli towards globo-series glycosphingolipids of human kidney and bladder uroepithelial cells. Glycobiology 2020; 29:789-802. [PMID: 31361021 DOI: 10.1093/glycob/cwz059] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/02/2019] [Accepted: 07/24/2019] [Indexed: 12/17/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) are the primary cause of urinary tract infections (UTIs) in humans. P-fimbriae are key players for bacterial adherence to the uroepithelium through the Galα1-4Gal-binding PapG adhesin. The three identified classes I, II and III of PapG are supposed to adhere differently to host cell glycosphingolipids (GSLs) of the uroepithelial tract harboring a distal or internal Galα1-4Gal sequence. In this study, GSL binding characteristics were obtained in a nonradioactive adhesion assay using biotinylated E. coli UTI and urine isolates combined with enzyme-linked NeutrAvidin for detection. Initial experiments with reference globotriaosylceramide (Gb3Cer, Galα1-4Galβ1-4Glcβ1-1Cer), globotetraosylceramide (Gb4Cer, GalNAcβ1-3Galα1-4Galβ1-4Glcβ1-1Cer) and Forssman GSL (GalNAcα1-3GalNAcβ1-3Galα1-4Galβ1-4Glcβ1-1Cer) revealed balanced adhesion toward the three GSLs for PapG I-mediated attachment. In contrast, E. coli carrying PapG II or PapG III increasingly adhered to growing oligosaccharide chain lengths of Gb3Cer, Gb4Cer and Forssman GSL. Binding studies with GSLs from human A498 kidney and human T24 bladder epithelial cells, both being negative for the Forssman GSL, revealed the less abundant Gb4Cer vs. Gb3Cer as the prevalent receptor in A498 cells of E. coli expressing PapG II or PapG III. On the other hand, T24 cells exhibited a higher relative content of Gb4Cer vs. Gb3Cer alongside dominant binding of PapG II- or PapG III-harboring E. coli toward Gb4Cer and vastly lowered attachment to minor Gb3Cer. Further studies on PapG-mediated interaction with cell surface-exposed GSLs will improve our knowledge on the molecular mechanisms of P-fimbriae-mediated adhesion and may contribute to the development of antiadhesion therapeutics to combat UTIs.
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Affiliation(s)
- Nadine Legros
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany
| | | | | | - Helge Karch
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany
| | - Ulrich Dobrindt
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany
| | - Johannes Müthing
- Institute of Hygiene, University of Münster, Robert-Koch-Str. 41, D-48149 Münster, Germany.,Institute of Hygiene, University of Münster, D-48149 Münster, Germany
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12
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Cheng YI, Chou L, Chiu YF, Hsueh HT, Kuo CH, Chu HA. Comparative Genomic Analysis of a Novel Strain of Taiwan Hot-Spring Cyanobacterium Thermosynechococcus sp. CL-1. Front Microbiol 2020; 11:82. [PMID: 32082292 PMCID: PMC7005997 DOI: 10.3389/fmicb.2020.00082] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 01/15/2020] [Indexed: 11/22/2022] Open
Abstract
Thermosynechococcus is a genus of thermophilic unicellular cyanobacteria that are dominant in microbial mats at about 50–65°C in alkaline hot springs of eastern Asia. We used PacBio SMRT Sequencing to sequence the complete genome of a novel strain of thermophilic cyanobacterium, Thermosynechococcus sp. CL-1, isolated from the Chin-Lun hot spring (pH 9.3, 62°C) in Taiwan. Genome-scale phylogenetic analysis and average nucleotide identity (ANI) results suggested that CL-1 is a new species in the genus Thermosynechococcus. Comparative genome analysis revealed divergent genome structures of Thermosynechococcus strains. In addition, the distinct genetic differences between CL-1 and the other Thermosynechococcus strains are related to photosynthesis, transporters, signal transduction, the chaperone/usher system, nitric oxide protection, antibiotic resistance, prokaryotic immunity systems, and other physiological processes. This study suggests that Thermosynechococcus strains have actively acquired many putative horizontally transferred genes from other bacteria that enabled them to adapt to different ecological niches and stressful conditions in hot springs.
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Affiliation(s)
- Yen-I Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Lin Chou
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Yi-Fang Chiu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Hsin-Ta Hsueh
- Sustainable Environment Research Laboratories, National Cheng Kung University, Tainan, Taiwan
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Hsiu-An Chu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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13
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Zalewska-Piątek B, Olszewski M, Lipniacki T, Błoński S, Wieczór M, Bruździak P, Skwarska A, Nowicki B, Nowicki S, Piątek R. A shear stress micromodel of urinary tract infection by the Escherichia coli producing Dr adhesin. PLoS Pathog 2020; 16:e1008247. [PMID: 31917805 PMCID: PMC7004390 DOI: 10.1371/journal.ppat.1008247] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 02/06/2020] [Accepted: 11/28/2019] [Indexed: 11/25/2022] Open
Abstract
In this study, we established a dynamic micromodel of urinary tract infection to analyze the impact of UT-segment-specific urinary outflow on the persistence of E. coli colonization. We found that the adherence of Dr+ E. coli to bladder T24 transitional cells and type IV collagen is maximal at lowest shear stress and is reduced by any increase in flow velocity. The analyzed adherence was effective in the whole spectrum of physiological shear stress and was almost irreversible over the entire range of generated shear force. Once Dr+ E. coli bound to host cells or collagen, they did not detach even in the presence of elevated shear stress or of chloramphenicol, a competitive inhibitor of binding. Investigating the role of epithelial surface architecture, we showed that the presence of budding cells–a model microarchitectural obstacle–promotes colonization of the urinary tract by E. coli. We report a previously undescribed phenomenon of epithelial cell “rolling-shedding” colonization, in which the detached epithelial cells reattach to the underlying cell line through a layer of adherent Dr+ E. coli. This rolling-shedding colonization progressed continuously due to “refilling” induced by the flow-perturbing obstacle. The shear stress of fluid containing free-floating bacteria fueled the rolling, while providing an uninterrupted supply of new bacteria to be trapped by the rolling cell. The progressive rolling allows for transfer of briefly attached bacteria onto the underlying monolayer in a repeating cascading event. Uropathogenic E. coli (UPEC) equipped with Dr fimbriae are associated with recurrent and chronic urinary tract infections (UTIs). The fimbriae assembled by the chaperone-usher pathway provide strong host-specific adherence which is, however, strongly modulated by the dynamically changing urine flow in the urinary tract (UT). In this paper, we use a dynamic in vitro micro-model of UTI to analyze the UT segment-specific impact of urinary outflow on the persistence and spread of Dr+ E. coli during host colonization. We conclude that the adhesive envelope formed by Dr fimbriae promotes strong and irreversible multivalent adherence of Dr+ E. coli to host receptors under flow conditions. We also observed that budding host cells–a model of any form of epithelial roughness, including carcinogenesis or physical injuries–facilitate the adherence of bacteria at flow conditions typically found in the UT, and our numerical simulations provided a mechanistic explanation for this effect. Finally, we combined the results to propose a rolling-shedding-refilling colonization model that shows how the wash off of detached colonized host cells may provoke a massive spread of UPEC. Our findings shed new light on UTI development and may be instrumental in the development of novel therapeutics.
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Affiliation(s)
- Beata Zalewska-Piątek
- Department of Molecular Microbiology and Biotechnology, Gdańsk University of Technology, Gdańsk, Poland
| | - Marcin Olszewski
- Department of Molecular Microbiology and Biotechnology, Gdańsk University of Technology, Gdańsk, Poland
| | - Tomasz Lipniacki
- Department of Biosystems and Soft Matter, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
| | - Sławomir Błoński
- Department of Biosystems and Soft Matter, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
| | - Miłosz Wieczór
- Department of Physical Chemistry, Gdańsk University of Technology, Gdańsk, Poland
| | - Piotr Bruździak
- Department of Physical Chemistry, Gdańsk University of Technology, Gdańsk, Poland
| | - Anna Skwarska
- Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Bogdan Nowicki
- Nowicki Institute for Woman’s Health Research, Brentwood, Tennessee, United States of America
| | - Stella Nowicki
- Nowicki Institute for Woman’s Health Research, Brentwood, Tennessee, United States of America
| | - Rafał Piątek
- Department of Molecular Microbiology and Biotechnology, Gdańsk University of Technology, Gdańsk, Poland
- * E-mail:
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14
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Psonis JJ, Chahales P, Henderson NS, Rigel NW, Hoffman PS, Thanassi DG. The small molecule nitazoxanide selectively disrupts BAM-mediated folding of the outer membrane usher protein. J Biol Chem 2019; 294:14357-14369. [PMID: 31391254 PMCID: PMC6768635 DOI: 10.1074/jbc.ra119.009616] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/30/2019] [Indexed: 12/11/2022] Open
Abstract
Bacterial pathogens assemble adhesive surface structures termed pili or fimbriae to initiate and sustain infection of host tissues. Uropathogenic Escherichia coli, the primary causative agent of urinary tract infections, expresses type 1 and P pili required for colonization of the bladder and kidney, respectively. These pili are assembled by the conserved chaperone-usher (CU) pathway, in which a periplasmic chaperone works together with an outer membrane (OM) usher protein to build and secrete the pilus fiber. Previously, we found that the small molecule and antiparasitic drug nitazoxanide (NTZ) inhibits CU pathway-mediated pilus biogenesis in E. coli by specifically interfering with proper maturation of the usher protein in the OM. The usher is folded and inserted into the OM by the β-barrel assembly machine (BAM) complex, which in E. coli comprises five proteins, BamA-E. Here, we show that sensitivity of the usher to NTZ is modulated by BAM expression levels and requires the BamB and BamE lipoproteins. Furthermore, a genetic screen for NTZ-resistant bacterial mutants isolated a mutation in the essential BamD lipoprotein. These findings suggest that NTZ selectively interferes with an usher-specific arm of the BAM complex, revealing new details of the usher folding pathway and BAM complex function. Evaluation of a set of NTZ derivatives identified compounds with increased potency and disclosed that NTZ's nitrothiazole ring is critical for usher inhibition. In summary, our findings indicate highly specific effects of NTZ on the usher folding pathway and have uncovered NTZ analogs that specifically decrease usher levels in the OM.
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Affiliation(s)
- John J Psonis
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York 11794
| | - Peter Chahales
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York 11794
| | - Nadine S Henderson
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York 11794
| | - Nathan W Rigel
- Department of Biology, Hofstra University, Hempstead, New York 11549
| | - Paul S Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia 22908
| | - David G Thanassi
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York 11794
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15
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Abstract
The chaperone-usher (CU) pathway is a conserved secretion system dedicated to the assembly of a superfamily of virulence-associated surface structures by a wide range of Gram-negative bacteria. Pilus biogenesis by the CU pathway requires two specialized assembly components: a dedicated periplasmic chaperone and an integral outer membrane assembly and secretion platform termed the usher. The CU pathway assembles a variety of surface fibers, ranging from thin, flexible filaments to rigid, rod-like organelles. Pili typically act as adhesins and function as virulence factors that mediate contact with host cells and colonization of host tissues. Pilus-mediated adhesion is critical for early stages of infection, allowing bacteria to establish a foothold within the host. Pili are also involved in modulation of host cell signaling pathways, bacterial invasion into host cells, and biofilm formation. Pili are critical for initiating and sustaining infection and thus represent attractive targets for the development of antivirulence therapeutics. Such therapeutics offer a promising alternative to broad-spectrum antibiotics and provide a means to combat antibiotic resistance and treat infection while preserving the beneficial microbiota. A number of strategies have been taken to develop antipilus therapeutics, including vaccines against pilus proteins, competitive inhibitors of pilus-mediated adhesion, and small molecules that disrupt pilus biogenesis. Here we provide an overview of the function and assembly of CU pili and describe current efforts aimed at interfering with these critical virulence structures.
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16
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Classical chaperone-usher (CU) adhesive fimbriome: uropathogenic Escherichia coli (UPEC) and urinary tract infections (UTIs). Folia Microbiol (Praha) 2019; 65:45-65. [DOI: 10.1007/s12223-019-00719-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 05/20/2019] [Indexed: 12/17/2022]
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17
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Liu Y, Sun C, Han L, Yu Y, Zhou H, Shao Q, Lou J, Zhao Y, Huang Y. Conformational Dynamics, Intramolecular Domain Conformation Signaling, and Activation of Apo-FimD Revealed by Single-Molecule Fluorescence Resonance Energy Transfer Studies. Biochemistry 2019; 58:1931-1941. [PMID: 30888187 DOI: 10.1021/acs.biochem.9b00080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chaperone-usher secretion pathway is a conserved bacterial protein secretion system dedicated to the biogenesis of adhesive fibers. Usher, a multidomain-containing outer membrane protein, plays a central role in this process by acting as a molecular machine that recruits different chaperone-subunit complexes, catalyzes subunit polymerization, and forms a channel for secretion of the assembled subunits. While recent crystal structural studies have greatly advanced our understanding of the structure and function of ushers, the overall architecture of the full-length apo-usher, the molecular events that dictate conformational changes in usher during pilus biogenesis, and its activation by the specific chaperone-adhesin complex remain largely elusive. Using single-molecule fluorescence resonance energy transfer studies, we found that the substrate-free usher FimD (apo-FimD) adopts a contracted conformation that is distinct from its substrate-bound states; both the N-terminal domain (NTD) and the C-terminal domain (CTD) of apo-FimD are highly dynamic, and FimD coordinates its domain conformational changes via intramolecular domain conformation signaling. By combining these studies with in vitro photo-cross-linking studies, we further show that only the chaperone-bound adhesin (FimC:FimH) can be transferred to the CTD, dislocates the plug domain, and triggers conformational changes in the remaining FimD domains. Taken together, these studies delineate an overall architecture of the full-length apo-FimD, provide detailed mechanic insight into the activation of apo-FimD, and explain why FimD could adjust its conformational states to perform multiple functions in each cycle of pilus subunit addition and ensure that pilus assembly proceeds progressively in a cellular energy-free environment.
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Affiliation(s)
- Yanqing Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Chuanqi Sun
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Long Han
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Yuqi Yu
- Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica , Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
| | - Haizhen Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China
| | - Qiang Shao
- Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica , Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
| | - Jizhong Lou
- University of Chinese Academy of Sciences , Beijing 100101 , China.,Key Laboratory of RNA Biology, Institute of Biophysics , Chinese Academy of Sciences , Beijing 100101 , China
| | - Yongfang Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
| | - Yihua Huang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , 15 Datun Road , Chaoyang District, Beijing 100101 , China.,University of Chinese Academy of Sciences , Beijing 100101 , China
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18
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Peptide-Based Inhibitors of Fimbrial Biogenesis in Porphyromonas gingivalis. Infect Immun 2019; 87:IAI.00750-18. [PMID: 30642895 DOI: 10.1128/iai.00750-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 01/02/2019] [Indexed: 02/06/2023] Open
Abstract
Periodontitis is a progressive inflammatory disease that affects roughly half of American adults. Colonization of the oral cavity by the Gram-negative bacterial pathogen Porphyromonas gingivalis is a key event in the initiation and development of periodontal disease. Adhesive surface structures termed fimbriae (pili) mediate interactions of P. gingivalis with other bacteria and with host cells throughout the course of disease. The P. gingivalis fimbriae are assembled via a novel mechanism that involves proteolytic processing of lipidated precursor subunits and their subsequent polymerization on the bacterial surface. Given their extracellular assembly mechanism and central roles in pathogenesis, the P. gingivalis fimbriae are attractive targets for anti-infective therapeutics to prevent or treat periodontal disease. Here we confirm that conserved sequences in the N and C termini of the Mfa1 fimbrial subunit protein perform critical roles in subunit polymerization. We show that treatment of P. gingivalis with peptides corresponding to the conserved C-terminal region inhibits the extracellular assembly of Mfa fimbriae on the bacterial surface. We also show that peptide treatment interferes with the function of Mfa fimbriae by reducing P. gingivalis adhesion to Streptococcus gordonii in a dual-species biofilm model. Finally, we show that treatment of bacteria with similar peptides inhibits extracellular polymerization of the Fim fimbriae, which are also expressed by P. gingivalis These results support a donor strand-based assembly mechanism for the P. gingivalis fimbriae and demonstrate the feasibility of using extracellular peptides to disrupt the biogenesis and function of these critical periodontal disease virulence factors.
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19
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Schultz LG, Tasic L, Fattori J. Chaperone-Assisted Secretion in Bacteria: Protein and DNA Transport via Cell Membranes. CURR PROTEOMICS 2018. [DOI: 10.2174/1570164615666180820154821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Bacteria use an impressive arsenal of secretion systems (1-7) to infect their host cells by exporting
proteins, DNA and DNA-protein complexes via cell membranes. They use chaperone-usher
pathways for host colonization as well. To be targeted for transportation across one (Gram-positive) or
two membranes (Gram-negative), clients must be selected, guided and unfolded to pass through type 3
(T3SS) or type 4 (T4SS) secretion systems. For these processes, bacteria count on secretory chaperones
that guide macromolecular transport via membranes. Moreover, if we know how these processes
occur, we might be able to stop them and avoid bacterial infections. Thus, structural and functional
characterizations of secretory chaperones become interesting, as these proteins are the perfect targets
for blocking bacteria action. Therefore, this review focuses on a story of known mechanisms of chaperone-
secretion assisted transport with special attention on virulence proteins and DNA transport in
bacteria.
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Affiliation(s)
- Lilian Goulart Schultz
- Chemical Biology Laboratory, Organic Chemistry Department, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, 13083-970, SP, Brazil
| | - Ljubica Tasic
- Chemical Biology Laboratory, Organic Chemistry Department, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, 13083-970, SP, Brazil
| | - Juliana Fattori
- Chemical Biology Laboratory, Organic Chemistry Department, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, 13083-970, SP, Brazil
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20
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Jiang W, Ubhayasekera W, Pearson MM, Knight SD. Structures of two fimbrial adhesins, AtfE and UcaD, from the uropathogenProteus mirabilis. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:1053-1062. [DOI: 10.1107/s2059798318012391] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 09/03/2018] [Indexed: 11/10/2022]
Abstract
The important uropathogenProteus mirabilisencodes a record number of chaperone/usher-pathway adhesive fimbriae. Such fimbriae, which are used for adhesion to cell surfaces/tissues and for biofilm formation, are typically important virulence factors in bacterial pathogenesis. Here, the structures of the receptor-binding domains of the tip-located two-domain adhesins UcaD (1.5 Å resolution) and AtfE (1.58 Å resolution) from twoP. mirabilisfimbriae (UCA/NAF and ATF) are presented. The structures of UcaD and AtfE are both similar to the F17G type of tip-located fimbrial receptor-binding domains, and the structures are very similar despite having only limited sequence similarity. These structures represent an important step towards a molecular-level understanding ofP. mirabilisfimbrial adhesins and their roles in the complex pathogenesis of urinary-tract infections.
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21
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Handover mechanism of the growing pilus by the bacterial outer-membrane usher FimD. Nature 2018; 562:444-447. [PMID: 30283140 PMCID: PMC6309448 DOI: 10.1038/s41586-018-0587-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 08/15/2018] [Indexed: 12/19/2022]
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22
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Mechanical architecture and folding of E. coli type 1 pilus domains. Nat Commun 2018; 9:2758. [PMID: 30013059 PMCID: PMC6048123 DOI: 10.1038/s41467-018-05107-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 05/03/2018] [Indexed: 12/16/2022] Open
Abstract
Uropathogenic Escherichia coli attach to tissues using pili type 1. Each pilus is composed by thousands of coiled FimA domains followed by the domains of the tip fibrillum, FimF-FimG-FimH. The domains are linked by non-covalent β-strands that must resist mechanical forces during attachment. Here, we use single-molecule force spectroscopy to measure the mechanical contribution of each domain to the stability of the pilus and monitor the oxidative folding mechanism of a single Fim domain assisted by periplasmic FimC and the oxidoreductase DsbA. We demonstrate that pilus domains bear high mechanical stability following a hierarchy by which domains close to the tip are weaker than those close to or at the pilus rod. During folding, this remarkable stability is achieved by the intervention of DsbA that not only forms strategic disulfide bonds but also serves as a chaperone assisting the folding of the domains. The pilus type 1 of uropathogenic E. coli must resist mechanical forces to remain attached to the epithelium. Here the authors use single-molecule force spectroscopy to demonstrate a hierarchy of mechanical stability among the pilus domains and show that the oxidoreductase DsbA also acts as a folding chaperone on the domains.
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23
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Schönfelder J, Alonso-Caballero A, De Sancho D, Perez-Jimenez R. The life of proteins under mechanical force. Chem Soc Rev 2018; 47:3558-3573. [PMID: 29473060 DOI: 10.1039/c7cs00820a] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although much of our understanding of protein folding comes from studies of isolated protein domains in bulk, in the cellular environment the intervention of external molecular machines is essential during the protein life cycle. During the past decade single molecule force spectroscopy techniques have been extremely useful to deepen our understanding of these interventional molecular processes, as they allow for monitoring and manipulating mechanochemical events in individual protein molecules. Here, we review some of the critical steps in the protein life cycle, starting with the biosynthesis of the nascent polypeptide chain in the ribosome, continuing with the folding supported by chaperones and the translocation into different cell compartments, and ending with proteolysis in the proteasome. Along these steps, proteins experience molecular forces often combined with chemical transformations, affecting their folding and structure, which are measured or mimicked in the laboratory by the application of force with a single molecule apparatus. These mechanochemical reactions can potentially be used as targets for fighting against diseases. Inspired by these insightful experiments, we devise an outlook on the emerging field of mechanopharmacology, which reflects an alternative paradigm for drug design.
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24
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Hu J, Zhan J, Chen H, He C, Cang H, Wang Q. The Small Regulatory Antisense RNA PilR Affects Pilus Formation and Cell Motility by Negatively Regulating pilA11 in Synechocystis sp. PCC 6803. Front Microbiol 2018; 9:786. [PMID: 29740417 PMCID: PMC5924778 DOI: 10.3389/fmicb.2018.00786] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 04/06/2018] [Indexed: 01/19/2023] Open
Abstract
Pili are found on the surface of many bacteria and play important roles in cell motility, pathogenesis, biofilm formation, and sensing and reacting to environmental changes. Cell motility in the model cyanobacterium Synechocystis sp. PCC 6803 relies on expression of the putative pilA9-pilA10-pilA11-slr2018 operon. In this study, we identified the antisense RNA PilR encoded in the noncoding strand of the prepilin-encoding gene pilA11. Analysis of overexpressor [PilR(+)] and suppressor [PilR(-)] mutant strains revealed that PilR is a direct negative regulator of PilA11 protein. Although overexpression of PilR did not affect cell growth, it greatly reduced levels of pilA11 mRNA and protein and decreased both the thickness and number of pili, resulting in limited cell motility and small, distinct colonies. Suppression of PilR had the opposite effect. A hypothetical model on the regulation of pilA9-pilA10-pilA11-slr2018 operon expression by PilR was proposed. These results add a layer of complexity to the mechanisms controlling pilA11 gene expression and cell motility, and provide novel insights into how sRNA and the intergenic region secondary structures can work together to discoordinatly regulate target gene in an operon in cyanobacterium.
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Affiliation(s)
- Jinlu Hu
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China
| | - Jiao Zhan
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Hui Chen
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Chenliu He
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Huaixing Cang
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China
| | - Qiang Wang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
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Werneburg GT, Thanassi DG. Pili Assembled by the Chaperone/Usher Pathway in Escherichia coli and Salmonella. EcoSal Plus 2018; 8:10.1128/ecosalplus.ESP-0007-2017. [PMID: 29536829 PMCID: PMC5940347 DOI: 10.1128/ecosalplus.esp-0007-2017] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Indexed: 12/12/2022]
Abstract
Gram-negative bacteria assemble a variety of surface structures, including the hair-like organelles known as pili or fimbriae. Pili typically function in adhesion and mediate interactions with various surfaces, with other bacteria, and with other types of cells such as host cells. The chaperone/usher (CU) pathway assembles a widespread class of adhesive and virulence-associated pili. Pilus biogenesis by the CU pathway requires a dedicated periplasmic chaperone and integral outer membrane protein termed the usher, which forms a multifunctional assembly and secretion platform. This review addresses the molecular and biochemical aspects of the CU pathway in detail, focusing on the type 1 and P pili expressed by uropathogenic Escherichia coli as model systems. We provide an overview of representative CU pili expressed by E. coli and Salmonella, and conclude with a discussion of potential approaches to develop antivirulence therapeutics that interfere with pilus assembly or function.
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Affiliation(s)
- Glenn T. Werneburg
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, NY, USA
| | - David G. Thanassi
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, NY, USA
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26
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Bacterial Filamentous Appendages Investigated by Solid-State NMR Spectroscopy. Methods Mol Biol 2017. [PMID: 28667627 DOI: 10.1007/978-1-4939-7033-9_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The assembly of filamentous appendages at the surface of bacteria is essential in many infection mechanisms. The extent of mechanical, dynamical, and functional properties of such appendages is very diverse, ranging from a structural scaffold of the pathogen-host cell interaction to cell motility, surface adhesion, or the export of virulence effectors. In particular, the architectures of several bacterial secretion systems have revealed the presence of filamentous architectures, known as pili, fimbriae, andneedles. At the macroscopic level, filamentous bacterial appendages appear as thin extracellular filaments of several nanometers in diameter and up to several microns in length. The structural characterization of these appendages at atomic-scale resolution represents an extremely challenging task because of their inherent noncrystallinity and very poor solubility. Here, we describe protocols based on recent advances in solid-state NMR spectroscopy to investigate the secondary structure, subunit-subunit protein interactions, symmetry parameters, and atomic architecture of bacterial filaments.
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27
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PG1058 Is a Novel Multidomain Protein Component of the Bacterial Type IX Secretion System. PLoS One 2016; 11:e0164313. [PMID: 27711252 PMCID: PMC5053529 DOI: 10.1371/journal.pone.0164313] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/22/2016] [Indexed: 01/10/2023] Open
Abstract
Porphyromonas gingivalis utilises the Bacteroidetes-specific type IX secretion system (T9SS) to export proteins across the outer membrane (OM), including virulence factors such as the gingipains. The secreted proteins have a conserved carboxy-terminal domain essential for type IX secretion that is cleaved upon export. In P. gingivalis the T9SS substrates undergo glycosylation with anionic lipopolysaccharide (A-LPS) and are attached to the OM. In this study, comparative analyses of 24 Bacteroidetes genomes identified ten putative novel components of the T9SS in P. gingivalis, one of which was PG1058. Computer modelling of the PG1058 structure predicted a novel N- to C-terminal architecture comprising a tetratricopeptide repeat (TPR) domain, a β-propeller domain, a carboxypeptidase regulatory domain-like fold (CRD) and an OmpA_C-like putative peptidoglycan binding domain. Inactivation of pg1058 in P. gingivalis resulted in loss of both colonial pigmentation and surface-associated proteolytic activity; a phenotype common to T9SS mutants. Immunoblot and LC-MS/MS analyses of subcellular fractions revealed T9SS substrates accumulated within the pg1058 mutant periplasm whilst whole-cell ELISA showed the Kgp gingipain was absent from the cell surface, confirming perturbed T9SS function. Immunoblot, TEM and whole-cell ELISA analyses indicated A-LPS was produced and present on the pg1058 mutant cell surface although it was not linked to T9SS substrate proteins. This indicated that PG1058 is crucial for export of T9SS substrates but not for the translocation of A-LPS. PG1058 is a predicted lipoprotein and was localised to the periplasmic side of the OM using whole-cell ELISA, immunoblot and LC-MS/MS analyses of subcellular fractions. The structural prediction and localisation of PG1058 suggests that it may have a role as an essential scaffold linking the periplasmic and OM components of the T9SS.
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28
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Dubreuil JD, Isaacson RE, Schifferli DM. Animal Enterotoxigenic Escherichia coli. EcoSal Plus 2016; 7:10.1128/ecosalplus.ESP-0006-2016. [PMID: 27735786 PMCID: PMC5123703 DOI: 10.1128/ecosalplus.esp-0006-2016] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Indexed: 12/13/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is the most common cause of E. coli diarrhea in farm animals. ETEC are characterized by the ability to produce two types of virulence factors: adhesins that promote binding to specific enterocyte receptors for intestinal colonization and enterotoxins responsible for fluid secretion. The best-characterized adhesins are expressed in the context of fimbriae, such as the F4 (also designated K88), F5 (K99), F6 (987P), F17, and F18 fimbriae. Once established in the animal small intestine, ETEC produce enterotoxin(s) that lead to diarrhea. The enterotoxins belong to two major classes: heat-labile toxins that consist of one active and five binding subunits (LT), and heat-stable toxins that are small polypeptides (STa, STb, and EAST1). This review describes the disease and pathogenesis of animal ETEC, the corresponding virulence genes and protein products of these bacteria, their regulation and targets in animal hosts, as well as mechanisms of action. Furthermore, vaccines, inhibitors, probiotics, and the identification of potential new targets by genomics are presented in the context of animal ETEC.
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Affiliation(s)
- J Daniel Dubreuil
- Faculté de Médecine Vétérinaire, Université de Montréal, Québec J2S 7C6, Canada
| | - Richard E Isaacson
- Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN 55108
| | - Dieter M Schifferli
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104
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29
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The Escherichia coli P and Type 1 Pilus Assembly Chaperones PapD and FimC Are Monomeric in Solution. J Bacteriol 2016; 198:2360-9. [PMID: 27353649 PMCID: PMC4984555 DOI: 10.1128/jb.00366-16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 06/19/2016] [Indexed: 01/07/2023] Open
Abstract
UNLABELLED The chaperone/usher pathway is used by Gram-negative bacteria to assemble adhesive surface structures known as pili or fimbriae. Uropathogenic strains of Escherichia coli use this pathway to assemble P and type 1 pili, which facilitate colonization of the kidney and bladder, respectively. Pilus assembly requires a periplasmic chaperone and outer membrane protein termed the usher. The chaperone allows folding of pilus subunits and escorts the subunits to the usher for polymerization into pili and secretion to the cell surface. Based on previous structures of mutant versions of the P pilus chaperone PapD, it was suggested that the chaperone dimerizes in the periplasm as a self-capping mechanism. Such dimerization is counterintuitive because the chaperone G1 strand, important for chaperone-subunit interaction, is buried at the dimer interface. Here, we show that the wild-type PapD chaperone also forms a dimer in the crystal lattice; however, the dimer interface is different from the previously solved structures. In contrast to the crystal structures, we found that both PapD and the type 1 pilus chaperone, FimC, are monomeric in solution. Our findings indicate that pilus chaperones do not sequester their G1 β-strand by forming a dimer. Instead, the chaperones may expose their G1 strand for facile interaction with pilus subunits. We also found that the type 1 pilus adhesin, FimH, is flexible in solution while in complex with its chaperone, whereas the P pilus adhesin, PapGII, is rigid. Our study clarifies a crucial step in pilus biogenesis and reveals pilus-specific differences that may relate to biological function. IMPORTANCE Pili are critical virulence factors for many bacterial pathogens. Uropathogenic E. coli relies on P and type 1 pili assembled by the chaperone/usher pathway to adhere to the urinary tract and establish infection. Studying pilus assembly is important for understanding mechanisms of protein secretion, as well as for identifying points for therapeutic intervention. Pilus biogenesis is a multistep process. This work investigates the oligomeric state of the pilus chaperone in the periplasm, which is important for understanding early assembly events. Our work unambiguously demonstrates that both PapD and FimC chaperones are monomeric in solution. We further demonstrate that the solution behavior of the FimH and PapGII adhesins differ, which may be related to functional differences between the two pilus systems.
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30
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Rasheed M, Garnett J, Pérez-Dorado I, Muhl D, Filloux A, Matthews S. Crystal structure of the CupB6 adhesive tip from the chaperone-usher family of pili from Pseudomonas aeruginosa. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1500-5. [PMID: 27481165 PMCID: PMC5022761 DOI: 10.1016/j.bbapap.2016.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 07/14/2016] [Accepted: 07/28/2016] [Indexed: 11/26/2022]
Abstract
Pseudomonas aeruginosa is a Gram-negative opportunistic bacterial pathogen that can cause chronic infection of the lungs of cystic fibrosis patients. Chaperone-usher systems in P. aeruginosa are known to translocate and assemble adhesive pili on the bacterial surface and contribute to biofilm formation within the host. Here, we report the crystal structure of the tip adhesion subunit CupB6 from the cupB1–6 gene cluster. The tip domain is connected to the pilus via the N-terminal donor strand from the main pilus subunit CupB1. Although the CupB6 adhesion domain bears structural features similar to other CU adhesins it displays an unusual polyproline helix adjacent to a prominent surface pocket, which are likely the site for receptor recognition. Crystal structure of the tip adhesion subunit CupB6 from the cupB1-6 gene cluster of Pseudomonas aeruginosa CupB6 possesses an atypical adhesion domain connected to a canonical chaperone-usher pilus subunit CupB6 caps the pilus shaft via donor strand complementation with the N-terminus of CupB1 CupB6 possesses unusual polyproline helices adjacent to a prominent surface pocket
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Affiliation(s)
- Masooma Rasheed
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - James Garnett
- Queen Mary University of London, Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Joseph Priestley Building, Mile End Road, London E1 4NS, United Kingdom
| | | | - Daniela Muhl
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Alain Filloux
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Steve Matthews
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom.
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De Geyter J, Tsirigotaki A, Orfanoudaki G, Zorzini V, Economou A, Karamanou S. Protein folding in the cell envelope of Escherichia coli. Nat Microbiol 2016; 1:16107. [PMID: 27573113 DOI: 10.1038/nmicrobiol.2016.107] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 06/02/2016] [Indexed: 11/09/2022]
Abstract
While the entire proteome is synthesized on cytoplasmic ribosomes, almost half associates with, localizes in or crosses the bacterial cell envelope. In Escherichia coli a variety of mechanisms are important for taking these polypeptides into or across the plasma membrane, maintaining them in soluble form, trafficking them to their correct cell envelope locations and then folding them into the right structures. The fidelity of these processes must be maintained under various environmental conditions including during stress; if this fails, proteases are called in to degrade mislocalized or aggregated proteins. Various soluble, diffusible chaperones (acting as holdases, foldases or pilotins) and folding catalysts are also utilized to restore proteostasis. These responses can be general, dealing with multiple polypeptides, with functional overlaps and operating within redundant networks. Other chaperones are specialized factors, dealing only with a few exported proteins. Several complex machineries have evolved to deal with binding to, integration in and crossing of the outer membrane. This complex protein network is responsible for fundamental cellular processes such as cell wall biogenesis; cell division; the export, uptake and degradation of molecules; and resistance against exogenous toxic factors. The underlying processes, contributing to our fundamental understanding of proteostasis, are a treasure trove for the development of novel antibiotics, biopharmaceuticals and vaccines.
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Affiliation(s)
- Jozefien De Geyter
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
| | - Alexandra Tsirigotaki
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
| | - Georgia Orfanoudaki
- Institute of Molecular Biology and Biotechnology, FORTH and Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece
| | - Valentina Zorzini
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
| | - Anastassios Economou
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium.,Institute of Molecular Biology and Biotechnology, FORTH and Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece
| | - Spyridoula Karamanou
- KU Leuven-University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, B-3000 Leuven, Belgium
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32
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Identification of Novel Host Interactors of Effectors Secreted by Salmonella and Citrobacter. mSystems 2016; 1:mSystems00032-15. [PMID: 27822540 PMCID: PMC5069955 DOI: 10.1128/msystems.00032-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/16/2016] [Indexed: 11/24/2022] Open
Abstract
During infection, pathogenic bacteria face an adverse environment of factors driven by both cellular and humoral defense mechanisms. To help evade the immune response and ultimately proliferate inside the host, many bacteria evolved specialized secretion systems to deliver effector proteins directly into host cells. Translocated effector proteins function to subvert host defense mechanisms. Numerous pathogenic bacteria use a specialized secretion system called type III secretion to deliver effectors into the host cell cytosol. Here, we identified 75 new host targets of Salmonella and Citrobacter effectors, which will help elucidate their mechanisms of action. Many pathogenic bacteria of the family Enterobacteriaceae use type III secretion systems to inject virulence proteins, termed “effectors,” into the host cell cytosol. Although host-cellular activities of several effectors have been demonstrated, the function and host-targeted pathways of most of the effectors identified to date are largely undetermined. To gain insight into host proteins targeted by bacterial effectors, we performed coaffinity purification of host proteins from cell lysates using recombinant effectors from the Enterobacteriaceae intracellular pathogens Salmonella enterica serovar Typhimurium and Citrobacter rodentium. We identified 54 high-confidence host interactors for the Salmonella effectors GogA, GtgA, GtgE, SpvC, SrfH, SseL, SspH1, and SssB collectively and 21 interactors for the Citrobacter effectors EspT, NleA, NleG1, and NleK. We biochemically validated the interaction between the SrfH Salmonella protein and the extracellular signal-regulated kinase 2 (ERK2) host protein kinase, which revealed a role for this effector in regulating phosphorylation levels of this enzyme, which plays a central role in signal transduction. IMPORTANCE During infection, pathogenic bacteria face an adverse environment of factors driven by both cellular and humoral defense mechanisms. To help evade the immune response and ultimately proliferate inside the host, many bacteria evolved specialized secretion systems to deliver effector proteins directly into host cells. Translocated effector proteins function to subvert host defense mechanisms. Numerous pathogenic bacteria use a specialized secretion system called type III secretion to deliver effectors into the host cell cytosol. Here, we identified 75 new host targets of Salmonella and Citrobacter effectors, which will help elucidate their mechanisms of action.
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33
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Pham T, Werneburg GT, Henderson NS, Thanassi DG, Delcour AH. Effect of chaperone-adhesin complex on plug release by the PapC usher. FEBS Lett 2016; 590:2172-9. [PMID: 27313078 DOI: 10.1002/1873-3468.12257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 11/06/2022]
Abstract
The P pilus of uropathogenic Escherichia coli is a multisubunit fiber assembled at the outer membrane in a defined sequence by a chaperone/usher secretion system, comprising a periplasmic chaperone and a beta-barrel outer membrane protein, the PapC usher. To gain insight into the pilus biogenesis mechanism, we used patch clamp electrophysiology to investigate the effect of the initiating adhesin subunit, as it is delivered to PapC in a complex with the chaperone. We show that the chaperone-adhesin complex facilitates opening of the PapC pore and appears to engage within the PapC lumen, in agreement with prior biochemical and structural data.
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Affiliation(s)
- Thieng Pham
- Department of Biology and Biochemistry, University of Houston, TX, USA
| | - Glenn T Werneburg
- Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, NY, USA
| | - Nadine S Henderson
- Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, NY, USA
| | - David G Thanassi
- Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, NY, USA
| | - Anne H Delcour
- Department of Biology and Biochemistry, University of Houston, TX, USA
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34
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Pham T, Henderson NS, Werneburg GT, Thanassi DG, Delcour AH. Electrostatic networks control plug stabilization in the PapC usher. Mol Membr Biol 2016; 32:198-207. [PMID: 27181766 DOI: 10.3109/09687688.2016.1160450] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The PapC usher, a β-barrel pore in the outer membrane of uropathogenic Escherichia coli, is used for assembly of the P pilus, a key virulence factor in bacterial colonization of human kidney cells. Each PapC protein is composed of a 24-stranded β-barrel channel, flanked by N- and C-terminal globular domains protruding into the periplasm, and occluded by a plug domain (PD). The PD is displaced from the channel towards the periplasm during pilus biogenesis, but the molecular mechanism for PD displacement remains unclear. Two structural features within the β-barrel, an α-helix and β5-6 hairpin loop, may play roles in controlling plug stabilization. Here we have tested clusters of residues at the interface of the plug, barrel, α-helix and hairpin, which participate in electrostatic networks. To assess the roles of these residues in plug stabilization, we used patch-clamp electrophysiology to compare the activity of wild-type and mutant PapC channels containing alanine substitutions at these sites. Mutations interrupting each of two salt bridge networks were relatively ineffective in disrupting plug stabilization. However, mutation of two pairs of arginines located at the inner and the outer surfaces of the PD resulted in an enhanced propensity for plug displacement. One arginine pair involved in a repulsive interaction between the linkers that tether the plug to the β-barrel was particularly sensitive to mutation. These results suggest that plug displacement, which is necessary for pilus assembly and translocation, may require a weakening of key electrostatic interactions between the plug linkers, and the plug and the α-helix.
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Affiliation(s)
- Thieng Pham
- a Department of Biology and Biochemistry , University of Houston , Houston , TX and
| | - Nadine S Henderson
- b Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University , Stony Brook , NY , USA
| | - Glenn T Werneburg
- b Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University , Stony Brook , NY , USA
| | - David G Thanassi
- b Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University , Stony Brook , NY , USA
| | - Anne H Delcour
- a Department of Biology and Biochemistry , University of Houston , Houston , TX and
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Nitazoxanide Inhibits Pilus Biogenesis by Interfering with Folding of the Usher Protein in the Outer Membrane. Antimicrob Agents Chemother 2016; 60:2028-38. [PMID: 26824945 DOI: 10.1128/aac.02221-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/07/2016] [Indexed: 12/21/2022] Open
Abstract
Many bacterial pathogens assemble surface fibers termed pili or fimbriae that facilitate attachment to host cells and colonization of host tissues. The chaperone/usher (CU) pathway is a conserved secretion system that is responsible for the assembly of virulence-associated pili by many different Gram-negative bacteria. Pilus biogenesis by the CU pathway requires a dedicated periplasmic chaperone and an integral outer membrane (OM) assembly and secretion platform termed the usher. Nitazoxanide (NTZ), an antiparasitic drug, was previously shown to inhibit the function of aggregative adherence fimbriae and type 1 pili assembled by the CU pathway in enteroaggregativeEscherichia coli, an important causative agent of diarrhea. We show here that NTZ also inhibits the function of type 1 and P pili from uropathogenicE. coli(UPEC). UPEC is the primary causative agent of urinary tract infections, and type 1 and P pili mediate colonization of the bladder and kidneys, respectively. By analysis of the different stages of the CU pilus biogenesis pathway, we show that treatment of bacteria with NTZ causes a reduction in the number of usher molecules in the OM, resulting in a loss of pilus assembly on the bacterial surface. In addition, we determine that NTZ specifically prevents proper folding of the usher β-barrel domain in the OM. Our findings demonstrate that NTZ is a pilicide with a novel mechanism of action and activity against diverse CU pathways. This suggests that further development of the NTZ scaffold may lead to new antivirulence agents that target the usher to prevent pilus assembly.
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Wang D, Xu S, Song D, Knight S, Mao X. A gene encoding a potential adenosine 5'-phosphosulphate kinase is necessary for timely development of Myxococcus xanthus. MICROBIOLOGY-SGM 2016; 162:672-683. [PMID: 26860640 DOI: 10.1099/mic.0.000254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A Myxococcus xanthus gene, MXAN3487, was identified by transposon mutagenesis to be required for the expression of mcuABC, an operon coding for part of the chaperone-usher (CU) system in this bacterium. The MXAN3487 protein displays sequence and structural homology to adenosine 5'-phosphosulphate (APS) kinase family members and contains putative motifs for ATP and APS binding. Although the MXAN3487 locus is not linked to other sulphate assimilation genes, its protein product may have APS kinase activity in vivo and the importance of the ATP-binding site for activity was demonstrated. Expression of MXAN3487 was not affected by sulphate availability, suggesting that MXAN3487 may not function in a reductive sulphate assimilation pathway. Deletion of MXAN3487 significantly delayed fruiting body formation and the production of McuA, a spore coat protein secreted by the M. xanthus Mcu CU system. Based on these observations and data from our previous studies, we propose that MXAN3487 may phosphorylate molecules structurally related to APS, generating metabolites necessary for M. xanthus development, and that MXAN3487 exerts a positive effect on the mcuABC operon whose expression is morphogenesis dependent.
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Affiliation(s)
- Daoyong Wang
- Department of Biochemistry, School of Medicine, Key Laboratory of Ministry of Education for Developmental Genes and Human Diseases, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Shihui Xu
- Department of Biochemistry, School of Medicine, Key Laboratory of Ministry of Education for Developmental Genes and Human Diseases, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Dan Song
- Department of Biochemistry, School of Medicine, Key Laboratory of Ministry of Education for Developmental Genes and Human Diseases, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Stefan Knight
- Department of Cell and Molecular Biology, Uppsala University, Uppsala Biomedical Centre, 75124 Uppsala, Sweden
| | - Xiaohua Mao
- Department of Biochemistry, School of Medicine, Key Laboratory of Ministry of Education for Developmental Genes and Human Diseases, Southeast University, Nanjing, Jiangsu 210009, PR China
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Bodelón G, Marín E, Fernández LÁ. Analyzing the Role of Periplasmic Folding Factors in the Biogenesis of OMPs and Members of the Type V Secretion System. Methods Mol Biol 2015; 1329:77-110. [PMID: 26427678 DOI: 10.1007/978-1-4939-2871-2_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The outer membrane (OM) of gram-negative bacteria is highly packed with OM proteins (OMPs) and the trafficking and assembly of OMPs in gram-negative bacteria is a subject of intense research. Structurally, OMPs vary in the number of β-strands and in the size and complexity of extra-membrane domains, with extreme examples being the members of the type V protein secretion system (T5SS), such as the autotransporter (AT) and intimin/invasin families of secreted proteins, in which a large extracellular "passenger" domain is linked to a β-barrel that inserts in the OM. Despite their structural and functional diversity, OMPs interact in the periplasm with a relatively small set of protein chaperones that facilitate their transport from the inner membrane (IM) to the β-barrel assembly machinery (BAM complex), preventing aggregation and assisting their folding in various aspects including disulfide bond formation. This chapter is focused on the periplasmic folding factors involved in the biogenesis of integral OMPs and members of T5SS in E. coli, which are used as a model system in this field. Background information on these periplasmic folding factors is provided along with genetic methods to generate conditional mutants that deplete these factors from E. coli and biochemical methods to analyze the folding, surface display, disulfide formation and oligomerization state of OMPs/T5SS in these mutants.
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Affiliation(s)
- Gustavo Bodelón
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049, Madrid, Spain
| | - Elvira Marín
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049, Madrid, Spain
| | - Luis Ángel Fernández
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049, Madrid, Spain.
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Floyd KA, Meyer AE, Nelson G, Hadjifrangiskou M. The yin-yang driving urinary tract infection and how proteomics can enhance research, diagnostics, and treatment. Proteomics Clin Appl 2015; 9:990-1002. [PMID: 26255866 DOI: 10.1002/prca.201500018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/27/2015] [Accepted: 07/27/2015] [Indexed: 12/30/2022]
Abstract
Bacterial urinary tract infections (UTIs) afflict millions of people worldwide both in the community and the hospital setting. The onset, duration, and severity of infection depend on the characteristics of the invading pathogen (yin), as well as the immune response elicited by the infected individual (yang). Uropathogenic Escherichia coli (UPEC) account for the majority of UTIs, and extensive investigations by many scientific groups have elucidated an elaborate pathogenic UPEC life cycle, involving the occupation of extracellular and intracellular niches and the expression of an arsenal of virulence factors that facilitate niche occupation. This review will summarize the current knowledge on UPEC pathogenesis; the host immune responses elicited to combat infection; and it will describe proteomics approaches used to understand UPEC pathogenesis, as well as drive diagnostics and treatment options. Finally, new strategies are highlighted that could be applied toward furthering our knowledge regarding host-bacterial interactions during UTI.
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Affiliation(s)
- Kyle A Floyd
- Department of Pathology, Microbiology and Immunology, Division of Molecular Pathogenesis, Vanderbilt University School of Medicine, Nashville, TN, USA
| | | | - George Nelson
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Maria Hadjifrangiskou
- Department of Pathology, Microbiology and Immunology, Division of Molecular Pathogenesis, Vanderbilt University School of Medicine, Nashville, TN, USA
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The pilus usher controls protein interactions via domain masking and is functional as an oligomer. Nat Struct Mol Biol 2015; 22:540-6. [PMID: 26052892 PMCID: PMC4496297 DOI: 10.1038/nsmb.3044] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 05/12/2015] [Indexed: 12/21/2022]
Abstract
The chaperone-usher (CU) pathway assembles organelles termed pili or
fimbriae in Gram-negative bacteria. Type 1 pili expressed by uropathogenic
Escherichia coli are prototypical structures assembled by
the CU pathway. Biogenesis of pili by the CU pathway requires a periplasmic
chaperone and an outer membrane protein termed the usher (FimD). We show that
the FimD C-terminal domains provide the high-affinity substrate binding site,
but that these domains are masked in the resting usher. Domain masking requires
the FimD plug domain, which serves as a switch controlling usher activation. We
demonstrate that usher molecules can act in trans for pilus
biogenesis, providing conclusive evidence for a functional usher oligomer. These
results reveal mechanisms by which molecular machines such as the usher regulate
and harness protein-protein interactions, and suggest that ushers may interact
in a cooperative manner during pilus assembly in bacteria.
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Ruer S, Pinotsis N, Steadman D, Waksman G, Remaut H. Virulence-targeted Antibacterials: Concept, Promise, and Susceptibility to Resistance Mechanisms. Chem Biol Drug Des 2015; 86:379-99. [DOI: 10.1111/cbdd.12517] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/23/2014] [Accepted: 01/06/2015] [Indexed: 12/25/2022]
Affiliation(s)
- Ségolène Ruer
- Structural and Molecular Microbiology; Structural Biology Research Center; VIB; Pleinlaan 2 Brussels 1050 Belgium
- Structural Biology Brussels; Vrije Universiteit Brussel; Pleinlaan 2 Brussels 1050 Belgium
| | - Nikos Pinotsis
- Institute of Structural and Molecular Biology (ISMB); UCL and Birkbeck College; London WC1E 7HX UK
| | - David Steadman
- Wolfson Institute for Biomedical Research (WIBR); UCL; London WC1E 6BT UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology (ISMB); UCL and Birkbeck College; London WC1E 7HX UK
| | - Han Remaut
- Structural and Molecular Microbiology; Structural Biology Research Center; VIB; Pleinlaan 2 Brussels 1050 Belgium
- Structural Biology Brussels; Vrije Universiteit Brussel; Pleinlaan 2 Brussels 1050 Belgium
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Abstract
In recent years, chemical biology and chemical genomics have been increasingly applied to the field of microbiology to uncover new potential therapeutics as well as to probe virulence mechanisms in pathogens. The approach offers some clear advantages, as identified compounds (i) can serve as a proof of principle for the applicability of drugs to specific targets; (ii) can serve as conditional effectors to explore the function of their targets in vitro and in vivo; (iii) can be used to modulate gene expression in otherwise genetically intractable organisms; and (iv) can be tailored to a narrow or broad range of bacteria. This review highlights recent examples from the literature to illustrate how the use of small molecules has advanced discovery of novel potential treatments and has been applied to explore biological mechanisms underlying pathogenicity. We also use these examples to discuss practical considerations that are key to establishing a screening or discovery program. Finally, we discuss the advantages and challenges of different approaches and the methods that are emerging to address these challenges.
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Affiliation(s)
- Rebecca Anthouard
- Laboratory of Genetics & Molecular Biology of Intestinal Pathogens, Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Victor J DiRita
- Laboratory of Genetics & Molecular Biology of Intestinal Pathogens, Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Identification of a putative flavin adenine dinucleotide-binding monooxygenase as a regulator for Myxococcus xanthus development. J Bacteriol 2015; 197:1185-96. [PMID: 25605309 DOI: 10.1128/jb.02555-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Gene clusters coding for the chaperone/usher (CU) pathway are widely distributed in many important environmental and pathogenic microbes; however, information about the regulatory machineries controlling CU gene expression during multicellular morphogenesis is missing. The Myxococcus xanthus Mcu system, encoded by the mcuABCD gene cluster, represents a prototype of the archaic CU family that functions in spore coat formation. Using genome-wide transposon mutagenesis, we identified MXAN2872 to be a potential regulator of the mcuABC operon and demonstrated the necessity of MXAN2872 for mcuABC expression and fruiting body morphogenesis in early development. In silico, biochemical, and genetic analyses suggest that MXAN2872 encodes a Baeyer-Villiger monooxygenase (BVMO) of flavoproteins, and the potential cofactor-binding site as well as the BVMO fingerprint sequence is important for the regulatory role of the MXAN2872 protein. The expression profile of mcuA in strains with an MXAN2872 deletion and point mutation agrees well with the timing of cell aggregation of these mutants. Furthermore, McuA could not be detected either in a fruA-null mutant, where starvation-induced aggregation was completely blocked, or in the glycerol-induced spores, where sporulation was uncoupled from cell aggregation. In sum, the present work uncovers a positive role for MXAN2872, a metabolic enzyme-encoding gene, in controlling M. xanthus development. MXAN2872 functions by affecting the onset of cell aggregation, thereby leading to a secondary effect on the timing of mcuABC expression of this model organism. IMPORTANCE Identification of the players that drive Myxococcus xanthus fruiting body formation is necessary for studying the mechanism of multicellular morphogenesis in this model organism. This study identifies MXAN2872, a gene encoding a putative flavin adenine dinucleotide-binding monooxygenase, to be a new interesting regulator regulating the timing of developmental aggregation. In addition, MXAN2872 seems to affect the expression of the chaperone/usher gene cluster mcu in a manner that is aggregation dependent. Thus, in organisms characterized by a developmental cycle, expression of the chaperone/usher pathway can be controlled by morphological checkpoints, demonstrating another layer of complexity in the regulation of this conserved protein secretion pathway.
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Korotkova N, Freire D, Phan TH, Ummels R, Creekmore CC, Evans TJ, Wilmanns M, Bitter W, Parret AHA, Houben ENG, Korotkov KV. Structure of the Mycobacterium tuberculosis type VII secretion system chaperone EspG5 in complex with PE25-PPE41 dimer. Mol Microbiol 2014; 94:367-82. [PMID: 25155747 DOI: 10.1111/mmi.12770] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2014] [Indexed: 11/29/2022]
Abstract
The growth or virulence of Mycobacterium tuberculosis bacilli depends on homologous type VII secretion systems, ESX-1, ESX-3 and ESX-5, which export a number of protein effectors across membranes to the bacterial surface and environment. PE and PPE proteins represent two large families of highly polymorphic proteins that are secreted by these ESX systems. Recently, it was shown that these proteins require system-specific cytoplasmic chaperones for secretion. Here, we report the crystal structure of M. tuberculosis ESX-5-secreted PE25-PPE41 heterodimer in complex with the cytoplasmic chaperone EspG(5). EspG(5) represents a novel fold that is unrelated to previously characterized secretion chaperones. Functional analysis of the EspG(5) -binding region uncovered a hydrophobic patch on PPE41 that promotes dimer aggregation, and the chaperone effectively abolishes this process. We show that PPE41 contains a characteristic chaperone-binding sequence, the hh motif, which is highly conserved among ESX-1-, ESX-3- and ESX-5-specific PPE proteins. Disrupting the interaction between EspG(5) and three different PPE target proteins by introducing different point mutations generally affected protein secretion. We further demonstrate that the EspG(5) chaperone plays an important role in the ESX secretion mechanism by keeping aggregation-prone PE-PPE proteins in their soluble state.
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Affiliation(s)
- Natalia Korotkova
- Department of Molecular & Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA; Center for Structural Biology, University of Kentucky, Lexington, KY, 40536, USA
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Lillington J, Geibel S, Waksman G. Reprint of "Biogenesis and adhesion of type 1 and P pili". Biochim Biophys Acta Gen Subj 2014; 1850:554-64. [PMID: 25063559 DOI: 10.1016/j.bbagen.2014.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 12/20/2022]
Abstract
BACKGROUND Uropathogenic Escherichia coli (UPEC) cause urinary tract infections (UTIs) in approximately 50% of women. These bacteria use type 1 and P pili for host recognition and attachment. These pili are assembled by the chaperone-usher pathway of pilus biogenesis. SCOPE OF REVIEW The review examines the biogenesis and adhesion of the UPEC type 1 and P pili. Particular emphasis is drawn to the role of the outer membrane usher protein. The structural properties of the complete pilus are also examined to highlight the strength and functionality of the final assembly. MAJOR CONCLUSIONS The usher orchestrates the sequential addition of pilus subunits in a defined order. This process follows a subunit-incorporation cycle which consists of four steps: recruitment at the usher N-terminal domain, donor-strand exchange with the previously assembled subunit, transfer to the usher C-terminal domains and translocation of the nascent pilus. Adhesion by the type 1 and P pili is strengthened by the quaternary structure of their rod sections. The rod is endowed with spring-like properties which provide mechanical resistance against urine flow. The distal adhesins operate differently from one another, targeting receptors in a specific manner. The biogenesis and adhesion of type 1 and P pili are being therapeutically targeted, and efforts to prevent pilus growth or adherence are described. GENERAL SIGNIFICANCE The combination of structural and biochemical study has led to the detailed mechanistic understanding of this membrane spanning nano-machine. This can now be exploited to design novel drugs able to inhibit virulence. This is vital in the present era of resurgent antibiotic resistance. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
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Affiliation(s)
- James Lillington
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Sebastian Geibel
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology (ISMB), University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK.
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Steadman D, Lo A, Waksman G, Remaut H. Bacterial surface appendages as targets for novel antibacterial therapeutics. Future Microbiol 2014; 9:887-900. [DOI: 10.2217/fmb.14.46] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The rise of multidrug resistant bacteria is a major worldwide health concern. There is currently an unmet need for the development of new and selective antibacterial drugs. Therapies that target and disarm the crucial virulence factors of pathogenic bacteria, while not actually killing the cells themselves, could prove to be vital for the treatment of numerous diseases. This article discusses the main surface architectures of pathogenic Gram-negative bacteria and the small molecules that have been discovered, which target their specific biogenesis pathways and/or actively block their virulence. The future perspective for the use of antivirulence compounds is also assessed.
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Affiliation(s)
- David Steadman
- Institute of Structural & Molecular Biology, Birkbeck & University College London, Malet Street, London, WC1E 7HX, UK
| | - Alvin Lo
- Structural & Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Gabriel Waksman
- Institute of Structural & Molecular Biology, Birkbeck & University College London, Malet Street, London, WC1E 7HX, UK
| | - Han Remaut
- Structural & Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
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