1
|
Sterzi L, Nodari R, Di Marco F, Ferrando ML, Saluzzo F, Spitaleri A, Allahverdi H, Papaleo S, Panelli S, Rimoldi SG, Batisti Biffignandi G, Corbella M, Cavallero A, Prati P, Farina C, Cirillo DM, Zuccotti G, Bandi C, Comandatore F. Genetic barriers more than environmental associations explain Serratia marcescens population structure. Commun Biol 2024; 7:468. [PMID: 38632370 PMCID: PMC11023947 DOI: 10.1038/s42003-024-06069-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 03/19/2024] [Indexed: 04/19/2024] Open
Abstract
Bacterial species often comprise well-separated lineages, likely emerged and maintained by genetic isolation and/or ecological divergence. How these two evolutionary actors interact in the shaping of bacterial population structure is currently not fully understood. In this study, we investigate the genetic and ecological drivers underlying the evolution of Serratia marcescens, an opportunistic pathogen with high genomic flexibility and able to colonise diverse environments. Comparative genomic analyses reveal a population structure composed of five deeply-demarcated genetic clusters with open pan-genome but limited inter-cluster gene flow, partially explained by Restriction-Modification (R-M) systems incompatibility. Furthermore, a large-scale research on hundred-thousands metagenomic datasets reveals only a partial habitat separation of the clusters. Globally, two clusters only show a separate gene composition coherent with ecological adaptations. These results suggest that genetic isolation has preceded ecological adaptations in the shaping of the species diversity, an evolutionary scenario coherent with the Evolutionary Extended Synthesis.
Collapse
Affiliation(s)
- Lodovico Sterzi
- Department of Biomedical and Clinical Sciences, Pediatric Clinical Research Center "Romeo and Enrica Invernizzi", Università Di Milano, 20157, Milan, Italy
| | - Riccardo Nodari
- Department of Biomedical and Clinical Sciences, Pediatric Clinical Research Center "Romeo and Enrica Invernizzi", Università Di Milano, 20157, Milan, Italy
| | - Federico Di Marco
- Emerging Bacterial Pathogens Unit, Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maria Laura Ferrando
- Emerging Bacterial Pathogens Unit, Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Francesca Saluzzo
- Emerging Bacterial Pathogens Unit, Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Hamed Allahverdi
- Department of Biomedical and Clinical Sciences, Pediatric Clinical Research Center "Romeo and Enrica Invernizzi", Università Di Milano, 20157, Milan, Italy
| | - Stella Papaleo
- Department of Biomedical and Clinical Sciences, Pediatric Clinical Research Center "Romeo and Enrica Invernizzi", Università Di Milano, 20157, Milan, Italy
| | - Simona Panelli
- Department of Biomedical and Clinical Sciences, Pediatric Clinical Research Center "Romeo and Enrica Invernizzi", Università Di Milano, 20157, Milan, Italy
| | - Sara Giordana Rimoldi
- Laboratorio di Microbiologia Clinica, Virologia e Diagnostica delle Bioemergenze, ASST Fatebenefratelli Sacco, Milan, Italy
| | | | - Marta Corbella
- Department of Microbiology & Virology, Fondazione IRCCS Policlinico San Matteo, Viale Camillo Golgi 19, 27100, Pavia, Italy
| | | | - Paola Prati
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER), Pavia, Italy
| | - Claudio Farina
- Laboratory of Microbiology and Virology, Azienda Socio-Sanitaria Territoriale (ASST) Papa Giovanni XXIII, Bergamo, Italy
| | - Daniela Maria Cirillo
- Emerging Bacterial Pathogens Unit, Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Gianvincenzo Zuccotti
- Department of Biomedical and Clinical Sciences, Pediatric Clinical Research Center "Romeo and Enrica Invernizzi", Università Di Milano, 20157, Milan, Italy
- Department of Paediatrics, Children's Hospital "V. Buzzi", Milano, Italy
| | - Claudio Bandi
- Department of Biosciences and Pediatric Clinical Research Center "Romeo Ed Enrica Invernizzi", University of Milan, 20133, Milan, Italy
| | - Francesco Comandatore
- Department of Biomedical and Clinical Sciences, Pediatric Clinical Research Center "Romeo and Enrica Invernizzi", Università Di Milano, 20157, Milan, Italy.
| |
Collapse
|
2
|
Sicoli G, Konijnenberg A, Guérin J, Hessmann S, Del Nero E, Hernandez-Alba O, Lecher S, Rouaut G, Müggenburg L, Vezin H, Cianférani S, Sobott F, Schneider R, Jacob-Dubuisson F. Large-Scale Conformational Changes of FhaC Provide Insights Into the Two-Partner Secretion Mechanism. Front Mol Biosci 2022; 9:950871. [PMID: 35936790 PMCID: PMC9355242 DOI: 10.3389/fmolb.2022.950871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 06/24/2022] [Indexed: 11/30/2022] Open
Abstract
The Two-Partner secretion pathway mediates protein transport across the outer membrane of Gram-negative bacteria. TpsB transporters belong to the Omp85 superfamily, whose members catalyze protein insertion into, or translocation across membranes without external energy sources. They are composed of a transmembrane β barrel preceded by two periplasmic POTRA domains that bind the incoming protein substrate. Here we used an integrative approach combining in vivo assays, mass spectrometry, nuclear magnetic resonance and electron paramagnetic resonance techniques suitable to detect minor states in heterogeneous populations, to explore transient conformers of the TpsB transporter FhaC. This revealed substantial, spontaneous conformational changes on a slow time scale, with parts of the POTRA2 domain approaching the lipid bilayer and the protein’s surface loops. Specifically, our data indicate that an amphipathic POTRA2 β hairpin can insert into the β barrel. We propose that these motions enlarge the channel and initiate substrate secretion. Our data propose a solution to the conundrum how TpsB transporters mediate protein secretion without the need for cofactors, by utilizing intrinsic protein dynamics.
Collapse
Affiliation(s)
- Giuseppe Sicoli
- Laboratoire Avancé de Spectroscopie pour les Interactions, la Réactivité et l’Environnement (LASIRE), UMR CNRS 8516, Université de Lille, Lille, France
| | | | - Jérémy Guérin
- CNRS, INSERM, Institut Pasteur de Lille, Université de Lille, U1019-UMR9017-CIIL-Center for Infection and Immunity of Lille, Lille, France
| | - Steve Hessmann
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI – FR 2048, Strasbourg, France
| | - Elise Del Nero
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI – FR 2048, Strasbourg, France
| | - Oscar Hernandez-Alba
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI – FR 2048, Strasbourg, France
| | - Sophie Lecher
- CNRS, INSERM, Institut Pasteur de Lille, Université de Lille, U1019-UMR9017-CIIL-Center for Infection and Immunity of Lille, Lille, France
| | - Guillaume Rouaut
- CNRS EMR9002 Integrative Structural Biology, Lille, France
- INSERM, CHU Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Linn Müggenburg
- CNRS EMR9002 Integrative Structural Biology, Lille, France
- INSERM, CHU Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Hervé Vezin
- Laboratoire Avancé de Spectroscopie pour les Interactions, la Réactivité et l’Environnement (LASIRE), UMR CNRS 8516, Université de Lille, Lille, France
| | - Sarah Cianférani
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI – FR 2048, Strasbourg, France
| | - Frank Sobott
- BAMS Research Group, University of Antwerp, Antwerp, Belgium
- Astbury Centre for Structural Molecular Biology and the School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Robert Schneider
- CNRS EMR9002 Integrative Structural Biology, Lille, France
- INSERM, CHU Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, Université de Lille, Lille, France
- *Correspondence: Robert Schneider, ; Françoise Jacob-Dubuisson,
| | - Françoise Jacob-Dubuisson
- CNRS, INSERM, Institut Pasteur de Lille, Université de Lille, U1019-UMR9017-CIIL-Center for Infection and Immunity of Lille, Lille, France
- *Correspondence: Robert Schneider, ; Françoise Jacob-Dubuisson,
| |
Collapse
|
3
|
Jarvela TS, Chaplot K, Lindberg I. A protease protection assay for the detection of internalized alpha-synuclein pre-formed fibrils. PLoS One 2021; 16:e0241161. [PMID: 33497415 PMCID: PMC7837481 DOI: 10.1371/journal.pone.0241161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 01/12/2021] [Indexed: 11/19/2022] Open
Abstract
Alpha-synuclein pre-formed fibrils (PFFs) represent a promising model system for the study of cellular processes underlying cell-to-cell transmission of alpha-synuclein proteopathic aggregates. However, the ability to differentiate the fate of internalized PFFs from those which remain in the extracellular environment remains limited due to the propensity for PFFs to adhere to the cell surface. Removal of PFFs requires repeated washing and/or specific quenching of extracellular fluorescent PFF signals. In this paper we present a new method for analyzing the fate of internalized alpha-synuclein. We inserted a tobacco etch virus (TEV) protease cleavage site between alpha-synuclein and green fluorescent protein and subjected cells to brief treatment with TEV protease after incubation with tagged PFFs. As the TEV protease is highly specific, non-toxic, and active under physiological conditions, protection from TEV cleavage can be used to distinguish internalized PFFs from those which remain attached to the cell surface. Using this experimental paradigm, downstream intracellular events can be analyzed via live or fixed cell microscopy as well as by Western blotting. We suggest that this method will be useful for understanding the fate of PFFs after endocytosis under various experimental manipulations.
Collapse
Affiliation(s)
- Timothy S. Jarvela
- Department of Anatomy and Neurobiology, University of Maryland-Baltimore, Baltimore, MD, United States of America
| | - Kriti Chaplot
- Department of Anatomy and Neurobiology, University of Maryland-Baltimore, Baltimore, MD, United States of America
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland-Baltimore, Baltimore, MD, United States of America
- * E-mail:
| |
Collapse
|
4
|
Billerbeck S. Small Functional Peptides and Their Application in Superfunctionalizing Proteins. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Sonja Billerbeck
- Columbia University; Department of Chemistry; 550 West 120th Street New York NY 10027 USA
| |
Collapse
|
5
|
Dastvan R, Brouwer EM, Schuetz D, Mirus O, Schleiff E, Prisner TF. Relative Orientation of POTRA Domains from Cyanobacterial Omp85 Studied by Pulsed EPR Spectroscopy. Biophys J 2017; 110:2195-206. [PMID: 27224485 DOI: 10.1016/j.bpj.2016.04.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/31/2016] [Accepted: 04/20/2016] [Indexed: 12/30/2022] Open
Abstract
Many proteins of the outer membrane of Gram-negative bacteria and of the outer envelope of the endosymbiotically derived organelles mitochondria and plastids have a β-barrel fold. Their insertion is assisted by membrane proteins of the Omp85-TpsB superfamily. These proteins are composed of a C-terminal β-barrel and a different number of N-terminal POTRA domains, three in the case of cyanobacterial Omp85. Based on structural studies of Omp85 proteins, including the five POTRA-domain-containing BamA protein of Escherichia coli, it is predicted that anaP2 and anaP3 bear a fixed orientation, whereas anaP1 and anaP2 are connected via a flexible hinge. We challenged this proposal by investigating the conformational space of the N-terminal POTRA domains of Omp85 from the cyanobacterium Anabaena sp. PCC 7120 using pulsed electron-electron double resonance (PELDOR, or DEER) spectroscopy. The pronounced dipolar oscillations observed for most of the double spin-labeled positions indicate a rather rigid orientation of the POTRA domains in frozen liquid solution. Based on the PELDOR distance data, structure refinement of the POTRA domains was performed taking two different approaches: 1) treating the individual POTRA domains as rigid bodies; and 2) using an all-atom refinement of the structure. Both refinement approaches yielded ensembles of model structures that are more restricted compared to the conformational ensemble obtained by molecular dynamics simulations, with only a slightly different orientation of N-terminal POTRA domains anaP1 and anaP2 compared with the x-ray structure. The results are discussed in the context of the native environment of the POTRA domains in the periplasm.
Collapse
Affiliation(s)
- Reza Dastvan
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Frankfurt am Main, Germany; Cluster of Excellence Macromolecular Complexes, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Eva-Maria Brouwer
- Molecular Cell Biology of Plants, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Denise Schuetz
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Frankfurt am Main, Germany; Cluster of Excellence Macromolecular Complexes, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Oliver Mirus
- Molecular Cell Biology of Plants, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Enrico Schleiff
- Cluster of Excellence Macromolecular Complexes, Goethe University Frankfurt, Frankfurt am Main, Germany; Molecular Cell Biology of Plants, Goethe University Frankfurt, Frankfurt am Main, Germany; Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany.
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Frankfurt am Main, Germany; Cluster of Excellence Macromolecular Complexes, Goethe University Frankfurt, Frankfurt am Main, Germany.
| |
Collapse
|
6
|
Guérin J, Bigot S, Schneider R, Buchanan SK, Jacob-Dubuisson F. Two-Partner Secretion: Combining Efficiency and Simplicity in the Secretion of Large Proteins for Bacteria-Host and Bacteria-Bacteria Interactions. Front Cell Infect Microbiol 2017; 7:148. [PMID: 28536673 PMCID: PMC5422565 DOI: 10.3389/fcimb.2017.00148] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/10/2017] [Indexed: 12/31/2022] Open
Abstract
Initially identified in pathogenic Gram-negative bacteria, the two-partner secretion (TPS) pathway, also known as Type Vb secretion, mediates the translocation across the outer membrane of large effector proteins involved in interactions between these pathogens and their hosts. More recently, distinct TPS systems have been shown to secrete toxic effector domains that participate in inter-bacterial competition or cooperation. The effects of these systems are based on kin vs. non-kin molecular recognition mediated by specific immunity proteins. With these new toxin-antitoxin systems, the range of TPS effector functions has thus been extended from cytolysis, adhesion, and iron acquisition, to genome maintenance, inter-bacterial killing and inter-bacterial signaling. Basically, a TPS system is made up of two proteins, the secreted TpsA effector protein and its TpsB partner transporter, with possible additional factors such as immunity proteins for protection against cognate toxic effectors. Structural studies have indicated that TpsA proteins mainly form elongated β helices that may be followed by specific functional domains. TpsB proteins belong to the Omp85 superfamily. Open questions remain on the mechanism of protein secretion in the absence of ATP or an electrochemical gradient across the outer membrane. The remarkable dynamics of the TpsB transporters and the progressive folding of their TpsA partners at the bacterial surface in the course of translocation are thought to be key elements driving the secretion process.
Collapse
Affiliation(s)
- Jeremy Guérin
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, USA
| | - Sarah Bigot
- Molecular Microbiology and Structural Biochemistry, Centre National de La Recherche Scientifique UMR 5086-Université Lyon 1, Institute of Biology and Chemistry of ProteinsLyon, France
| | - Robert Schneider
- NMR and Molecular Interactions, Université de Lille, Centre National de La Recherche Scientifique, UMR 8576-Unité de Glycobiologie Structurale et FonctionnelleLille, France
| | - Susan K Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, USA
| | - Françoise Jacob-Dubuisson
- Université de Lille, Centre National de La Recherche Scientifique, Institut National de La Santé et de La Recherche Médicale, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-Centre d'Infection et d'Immunité de LilleLille, France
| |
Collapse
|
7
|
Lesne E, Krammer EM, Dupre E, Locht C, Lensink MF, Antoine R, Jacob-Dubuisson F. Balance between Coiled-Coil Stability and Dynamics Regulates Activity of BvgS Sensor Kinase in Bordetella. mBio 2016; 7:e02089. [PMID: 26933056 PMCID: PMC4810494 DOI: 10.1128/mbio.02089-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/28/2016] [Indexed: 11/24/2022] Open
Abstract
UNLABELLED The two-component system BvgAS controls the expression of the virulence regulon of Bordetella pertussis. BvgS is a prototype of bacterial sensor kinases with extracytoplasmic Venus flytrap perception domains. Following its transmembrane segment, BvgS harbors a cytoplasmic Per-Arnt-Sim (PAS) domain and then a predicted 2-helix coiled coil that precede the dimerization-histidine-phosphotransfer domain of the kinase. BvgS homologs have a similar domain organization, or they harbor only a predicted coiled coil between the transmembrane and the dimerization-histidine-phosphotransfer domains. Here, we show that the 2-helix coiled coil of BvgS regulates the enzymatic activity in a mechanical manner. Its marginally stable hydrophobic interface enables a switch between a state of great rotational dynamics in the kinase mode and a more rigid conformation in the phosphatase mode in response to signal perception by the periplasmic domains. We further show that the activity of BvgS is controlled in the same manner if its PAS domain is replaced with the natural α-helical sequences of PAS-less homologs. Clamshell motions of the Venus flytrap domains trigger the shift of the coiled coil's dynamics. Thus, we have uncovered a general mechanism of regulation for the BvgS family of Venus flytrap-containing two-component sensor kinases. IMPORTANCE The two-component system BvgAS of the whooping cough agent Bordetella pertussis regulates the virulence factors necessary for infection in a coordinated manner. BvgS is the prototype of a family of sensor kinase proteins found in major bacterial pathogens. When BvgS functions as a kinase, B. pertussis is virulent, and the bacterium shifts to an avirulent phase after BvgS senses chemicals that make it switch to phosphatase. Our goal is to decipher the signaling mechanisms of BvgS in order to understand virulence regulation in Bordetella, which may lead to new antimicrobial treatments targeting those two-component systems. We discovered that the activity of BvgS is regulated in a mechanical manner. A short region of the protein that precedes the enzymatic domain switches between two states in response to signal perception by other BvgS domains. This switch region is conserved among BvgS homologs, and thus, the regulation uncovered here will likely be relevant for the family.
Collapse
Affiliation(s)
- E Lesne
- Université de Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL, Centre d'Infection et d'Immunité de Lille, Lille, France
| | - E-M Krammer
- Université de Lille, CNRS, UMR 8576-UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, Lille, France
| | - E Dupre
- Université de Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL, Centre d'Infection et d'Immunité de Lille, Lille, France
| | - C Locht
- Université de Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL, Centre d'Infection et d'Immunité de Lille, Lille, France
| | - M F Lensink
- Université de Lille, CNRS, UMR 8576-UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, Lille, France
| | - R Antoine
- Université de Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL, Centre d'Infection et d'Immunité de Lille, Lille, France
| | - F Jacob-Dubuisson
- Université de Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL, Centre d'Infection et d'Immunité de Lille, Lille, France
| |
Collapse
|
8
|
Abstract
The major class of integral proteins found in the outer membrane (OM) of E. coli and Salmonella adopt a β-barrel conformation (OMPs). OMPs are synthesized in the cytoplasm with a typical signal sequence at the amino terminus, which directs them to the secretion machinery (SecYEG) located in the inner membrane for translocation to the periplasm. Chaperones such as SurA, or DegP and Skp, escort these proteins across the aqueous periplasm protecting them from aggregation. The chaperones then deliver OMPs to a highly conserved outer membrane assembly site termed the Bam complex. In E. coli, the Bam complex is composed of an essential OMP, BamA, and four associated OM lipoproteins, BamBCDE, one of which, BamD, is also essential. Here we provide an overview of what we know about the process of OMP assembly and outline the various hypotheses that have been proposed to explain how proteins might be integrated into the asymmetric OM lipid bilayer in an environment that lacks obvious energy sources. In addition, we describe the envelope stress responses that ensure the fidelity of OM biogenesis and how factors, such as phage and certain toxins, have coopted this essential machine to gain entry into the cell.
Collapse
|
9
|
Abstract
The autotransporter and two-partner secretion (TPS) pathways are used by E. coli and many other Gram-negative bacteria to delivervirulence factors into the extracellular milieu.Autotransporters arecomprised of an N-terminal extracellular ("passenger") domain and a C-terminal β barrel domain ("β domain") that anchors the protein to the outer membrane and facilitates passenger domain secretion. In the TPS pathway, a secreted polypeptide ("exoprotein") is coordinately expressed with an outer membrane protein that serves as a dedicated transporter. Bothpathways are often grouped together under the heading "type V secretion" because they have many features in common and are used for the secretion of structurally related polypeptides, but it is likely that theyhave distinct evolutionary origins. Although it was proposed many years ago that autotransporterpassenger domains are transported across the outer membrane through a channel formed by the covalently linked β domain, there is increasing evidence that additional factors are involved in the translocation reaction. Furthermore, details of the mechanism of protein secretion through the TPS pathway are only beginning to emerge. In this chapter I discussour current understanding ofboth early and late steps in the biogenesis of polypeptides secreted through type V pathways and current modelsofthe mechanism of secretion.
Collapse
|
10
|
Abstract
INTRODUCTION Moraxella catarrhalis is a prominent pathogen that causes acute otitis media in children and lower respiratory tract infections in adults, resulting in a significant socioeconomic burden on healthcare systems globally. No vaccine is currently available for M. catarrhalis. Promising M. catarrhalis target antigens have been characterized in animal models and should soon enter human clinical trials. AREAS COVERED This review discusses the detailed features and research status of current candidate target antigens for an M. catarrhalis vaccine. The approaches for assessing M. catarrhalis vaccine efficacy are also discussed. EXPERT OPINION Targeting the key molecules contributing to serum resistance may be a viable strategy to identify effective vaccine targets among M. catarrhalis antigens. Elucidating the role and mechanisms of the serum and mucosal immune responses to M. catarrhalis is significant for vaccine target selection, testing and evaluation. Developing animal models closely simulating M. catarrhalis-caused human respiratory diseases is of great benefit in better understanding pathogenesis and evaluating vaccine efficacy. Carrying out clinical trials will be a landmark in the progress of M. catarrhalis vaccine research. Combined multicomponent vaccines will be a focus of future M. catarrhalis vaccine studies.
Collapse
Affiliation(s)
- Dabin Ren
- a 1 Research Institute, Rochester General Hospital , 1425 Portland Avenue, Rochester, NY, USA +1 585 922 3706 ;
| | - Michael E Pichichero
- b 2 Research Institute, Rochester General Hospital , 1425 Portland Avenue, Rochester, NY, USA
| |
Collapse
|
11
|
Probing the conformation of FhaC with small-angle neutron scattering and molecular modeling. Biophys J 2015; 107:185-96. [PMID: 24988353 DOI: 10.1016/j.bpj.2014.05.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 04/20/2014] [Accepted: 05/05/2014] [Indexed: 11/22/2022] Open
Abstract
Probing the solution structure of membrane proteins represents a formidable challenge, particularly when using small-angle scattering. Detergent molecules often present residual scattering contributions even at their match point in small-angle neutron scattering (SANS) measurements. Here, we studied the conformation of FhaC, the outer-membrane, β-barrel transporter of the Bordetella pertussis filamentous hemagglutinin adhesin. SANS measurements were performed on homogeneous solutions of FhaC solubilized in n-octyl-d17-βD-glucoside and on a variant devoid of the α helix H1, which critically obstructs the FhaC pore, in two solvent conditions corresponding to the match points of the protein and the detergent, respectively. Protein-bound detergent amounted to 142 ± 10 mol/mol as determined by analytical ultracentrifugation. By using molecular modeling and starting from three distinct conformations of FhaC and its variant embedded in lipid bilayers, we generated ensembles of protein-detergent arrangement models with 120-160 detergent molecules. The scattered curves were back-calculated for each model and compared with experimental data. Good fits were obtained for relatively compact, connected detergent belts, which occasionally displayed small detergent-free patches on the outer surface of the β barrel. The combination of SANS and modeling clearly enabled us to infer the solution structure of FhaC, with H1 inside the pore as in the crystal structure. We believe that our strategy of combining explicit atomic detergent modeling with SANS measurements has significant potential for structural studies of other detergent-solubilized membrane proteins.
Collapse
|
12
|
Guérin J, Saint N, Baud C, Meli AC, Etienne E, Locht C, Vezin H, Jacob-Dubuisson F. Dynamic interplay of membrane-proximal POTRA domain and conserved loop L6 in Omp85 transporter FhaC. Mol Microbiol 2015; 98:490-501. [PMID: 26192332 DOI: 10.1111/mmi.13137] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2015] [Indexed: 12/30/2022]
Abstract
Omp85 transporters mediate protein insertion into, or translocation across, membranes. They have a conserved architecture, with POTRA domains that interact with substrate proteins, a 16-stranded transmembrane β barrel, and an extracellular loop, L6, folded back in the barrel pore. Here using electrophysiology, in vivo biochemical approaches and electron paramagnetic resonance, we show that the L6 loop of the Omp85 transporter FhaC changes conformation and modulates channel opening. Those conformational changes involve breaking the conserved interaction between the tip of L6 and the inner β-barrel wall. The membrane-proximal POTRA domain also exchanges between several conformations, and the binding of FHA displaces this equilibrium. We further demonstrate a dynamic, physical communication between the POTRA domains and L6, which must take place via the β barrel. Our findings thus link all three essential components of Omp85 transporters and indicate that they operate in a concerted fashion in the transport cycle.
Collapse
Affiliation(s)
- Jeremy Guérin
- Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.,Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.,CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.,INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France
| | - Nathalie Saint
- PhyMedExp, University of Montpellier, INSERM U1046, CNRS UMR9214, 371 av. G. Giraud, 34295, Montpellier cedex 05, France
| | - Catherine Baud
- Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.,Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.,CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.,INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France
| | - Albano C Meli
- PhyMedExp, University of Montpellier, INSERM U1046, CNRS UMR9214, 371 av. G. Giraud, 34295, Montpellier cedex 05, France
| | - Emilien Etienne
- Aix-Marseille Université, CNRS, BIP (UMR 7281), 31 chemin J. Aiguier, 13402, Marseille cedex 20, France
| | - Camille Locht
- Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.,Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.,CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.,INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France
| | - Hervé Vezin
- Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.,CNRS UMR8516, Bat. C4, 59658, Villeneuve d'Ascq, France
| | - Françoise Jacob-Dubuisson
- Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.,Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.,CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.,INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France
| |
Collapse
|
13
|
Abstract
The outer membranes of gram-negative bacteria contain integral membrane proteins, most of which are of β-barrel structure, and critical for bacterial survival. These β-barrel proteins rely on the β-barrel assembly machinery (BAM) complex for their integration into the outer membrane as folded species. The central and essential subunit of the BAM complex, BamA, is a β-barrel protein conserved in all gram-negative bacteria and also found in eukaryotic organelles derived from bacterial endosymbionts. In Escherichia coli, BamA docks with four peripheral lipoproteins, BamB, BamC, BamD and BamE, partner subunits that add to the function of the BAM complex in outer membrane protein biogenesis. By way of introduction to this volume, we provide an overview of the work that has illuminated the mechanism by which the BAM complex drives β-barrel assembly. The protocols and methodologies associated with these studies as well as the challenges encountered and their elegant solutions are discussed in subsequent chapters.
Collapse
|
14
|
Baud C, Guérin J, Petit E, Lesne E, Dupré E, Locht C, Jacob-Dubuisson F. Translocation path of a substrate protein through its Omp85 transporter. Nat Commun 2014; 5:5271. [PMID: 25327833 DOI: 10.1038/ncomms6271] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 09/16/2014] [Indexed: 11/09/2022] Open
Abstract
TpsB proteins are Omp85 superfamily members that mediate protein translocation across the outer membrane of Gram-negative bacteria. Omp85 transporters are composed of N-terminal POTRA domains and a C-terminal transmembrane β-barrel. In this work, we track the in vivo secretion path of the Bordetella pertussis filamentous haemagglutinin (FHA), the substrate of the model TpsB transporter FhaC, using site-specific crosslinking. The conserved secretion domain of FHA interacts with the POTRA domains, specific extracellular loops and strands of FhaC and the inner β-barrel surface. The interaction map indicates a funnel-like pathway, with conformationally flexible FHA entering the channel in a non-exclusive manner and exiting along a four-stranded β-sheet at the surface of the FhaC barrel. This sheet of FhaC guides the secretion domain of FHA along discrete steps of translocation and folding. This work demonstrates that the Omp85 barrel serves as a channel for translocation of substrate proteins.
Collapse
Affiliation(s)
- Catherine Baud
- 1] Center for Infection and Immunity of Lille, Institut Pasteur de Lille, 1 rue Calmette, Lille 59021, France [2] CNRS UMR8204, Lille 59021, France [3] INSERM U1019, Lille 59045, France [4] University of Lille Nord de France, Lille 59044, France
| | - Jérémy Guérin
- 1] Center for Infection and Immunity of Lille, Institut Pasteur de Lille, 1 rue Calmette, Lille 59021, France [2] CNRS UMR8204, Lille 59021, France [3] INSERM U1019, Lille 59045, France [4] University of Lille Nord de France, Lille 59044, France
| | - Emmanuelle Petit
- 1] Center for Infection and Immunity of Lille, Institut Pasteur de Lille, 1 rue Calmette, Lille 59021, France [2] CNRS UMR8204, Lille 59021, France [3] INSERM U1019, Lille 59045, France [4] University of Lille Nord de France, Lille 59044, France
| | - Elodie Lesne
- 1] Center for Infection and Immunity of Lille, Institut Pasteur de Lille, 1 rue Calmette, Lille 59021, France [2] CNRS UMR8204, Lille 59021, France [3] INSERM U1019, Lille 59045, France [4] University of Lille Nord de France, Lille 59044, France
| | - Elian Dupré
- 1] Center for Infection and Immunity of Lille, Institut Pasteur de Lille, 1 rue Calmette, Lille 59021, France [2] CNRS UMR8204, Lille 59021, France [3] INSERM U1019, Lille 59045, France [4] University of Lille Nord de France, Lille 59044, France
| | - Camille Locht
- 1] Center for Infection and Immunity of Lille, Institut Pasteur de Lille, 1 rue Calmette, Lille 59021, France [2] CNRS UMR8204, Lille 59021, France [3] INSERM U1019, Lille 59045, France [4] University of Lille Nord de France, Lille 59044, France
| | - Françoise Jacob-Dubuisson
- 1] Center for Infection and Immunity of Lille, Institut Pasteur de Lille, 1 rue Calmette, Lille 59021, France [2] CNRS UMR8204, Lille 59021, France [3] INSERM U1019, Lille 59045, France [4] University of Lille Nord de France, Lille 59044, France
| |
Collapse
|
15
|
Höhr AIC, Straub SP, Warscheid B, Becker T, Wiedemann N. Assembly of β-barrel proteins in the mitochondrial outer membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:74-88. [PMID: 25305573 DOI: 10.1016/j.bbamcr.2014.10.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/25/2014] [Accepted: 10/01/2014] [Indexed: 12/15/2022]
Abstract
Mitochondria evolved through endosymbiosis of a Gram-negative progenitor with a host cell to generate eukaryotes. Therefore, the outer membrane of mitochondria and Gram-negative bacteria contain pore proteins with β-barrel topology. After synthesis in the cytosol, β-barrel precursor proteins are first transported into the mitochondrial intermembrane space. Folding and membrane integration of β-barrel proteins depend on the mitochondrial sorting and assembly machinery (SAM) located in the outer membrane, which is related to the β-barrel assembly machinery (BAM) in bacteria. The SAM complex recognizes β-barrel proteins by a β-signal in the C-terminal β-strand that is required to initiate β-barrel protein insertion into the outer membrane. In addition, the SAM complex is crucial to form membrane contacts with the inner mitochondrial membrane by interacting with the mitochondrial contact site and cristae organizing system (MICOS) and shares a subunit with the endoplasmic reticulum-mitochondria encounter structure (ERMES) that links the outer mitochondrial membrane to the endoplasmic reticulum (ER).
Collapse
Affiliation(s)
- Alexandra I C Höhr
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
| | - Sebastian P Straub
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany; Abteilung Biochemie und Funktionelle Proteomik, Institut für Biologie II, Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
| | - Thomas Becker
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany
| | - Nils Wiedemann
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Universität Freiburg, 79104 Freiburg, Germany.
| |
Collapse
|
16
|
Darvish Alipour Astaneh S, Rasooli I, Mousavi Gargari SL. The role of filamentous hemagglutinin adhesin in adherence and biofilm formation in Acinetobacter baumannii ATCC19606(T). Microb Pathog 2014; 74:42-9. [PMID: 25086432 DOI: 10.1016/j.micpath.2014.07.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 06/14/2014] [Accepted: 07/21/2014] [Indexed: 11/17/2022]
Abstract
Filamentous hemagglutinin adhesins (FHA) are key factors for bacterial attachment and subsequent cell accumulation on substrates. Here an FHA-like Outer membrane (OM) adhesin of Acinetobacter baumannii ATCC19606(T) was displayed on Escherichia coli. The candidate autotransporter (AT) genes were identified in A. baumannii ATCC19606(T) genome. The exoprotein (FhaB1) and transporter (FhaC1) were produced independently within the same cell (FhaB1C1). The fhaC1 was mutated. In vitro adherence to epithelial cells of the recombinant FhaB1C1 and the mutant strains were compared with A. baumanni ATCC19606(T). A bivalent chimeric protein (K) composed of immunologically important portions of fhaB1 (B) and fhaC1 (C) was constructed. The mice vaccinated with chimeric protein were challenged with A. baumannii ATCC19606(T) and FhaB1C1 producing recombinant E. coli. Mutations in the fhaC1 resulted in the absence of FhaB1 in the OM. Expression of FhaB1C1 enhanced the adherence of recombinant bacteria to A546 bronchial cell line. The results revealed association of FhaB1 with bacterial adhesion and biofilm formation. Immunization with a combination of recombinant B and K proteins proved protective against A. baumanni ATCC19606(T). The findings may be applied in active and passive immunization strategies against A. baumannii.
Collapse
Affiliation(s)
| | - Iraj Rasooli
- Department of Biology, Shahed University, Opposite Imam Khomeini's Shrine, Tehran-Qom Express Way, Tehran, Iran; Molecular Microbiology Research Center, Shahed University, Tehran, Iran.
| | | |
Collapse
|
17
|
Tang F, Saier MH. Transport proteins promoting Escherichia coli pathogenesis. Microb Pathog 2014; 71-72:41-55. [PMID: 24747185 DOI: 10.1016/j.micpath.2014.03.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/19/2014] [Accepted: 03/20/2014] [Indexed: 12/26/2022]
Abstract
Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies.
Collapse
Affiliation(s)
- Fengyi Tang
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA.
| | - Milton H Saier
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA.
| |
Collapse
|
18
|
Guérin J, Baud C, Touati N, Saint N, Willery E, Locht C, Vezin H, Jacob-Dubuisson F. Conformational dynamics of protein transporter FhaC: large-scale motions of plug helix. Mol Microbiol 2014; 92:1164-76. [DOI: 10.1111/mmi.12585] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Jérémy Guérin
- Institut Pasteur de Lille; Center for Infection and Immunity; Lille France
- CNRS UMR8204; Lille France
- INSERM U1019; Lille France
- Univ Lille Nord de France; Lille France
| | - Catherine Baud
- Institut Pasteur de Lille; Center for Infection and Immunity; Lille France
- CNRS UMR8204; Lille France
- INSERM U1019; Lille France
- Univ Lille Nord de France; Lille France
| | | | - Nathalie Saint
- INSERM U1046; CHU A. de Villeneuve; Montpellier Cedex 05 France
| | - Eve Willery
- Institut Pasteur de Lille; Center for Infection and Immunity; Lille France
- CNRS UMR8204; Lille France
- INSERM U1019; Lille France
- Univ Lille Nord de France; Lille France
| | - Camille Locht
- Institut Pasteur de Lille; Center for Infection and Immunity; Lille France
- CNRS UMR8204; Lille France
- INSERM U1019; Lille France
- Univ Lille Nord de France; Lille France
| | | | - Françoise Jacob-Dubuisson
- Institut Pasteur de Lille; Center for Infection and Immunity; Lille France
- CNRS UMR8204; Lille France
- INSERM U1019; Lille France
- Univ Lille Nord de France; Lille France
| |
Collapse
|
19
|
Mawas F, Ho MM, Corbel MJ. Current progress withMoraxella catarrhalisantigens as vaccine candidates. Expert Rev Vaccines 2014; 8:77-90. [DOI: 10.1586/14760584.8.1.77] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
20
|
The structural basis of autotransporter translocation by TamA. Nat Struct Mol Biol 2013; 20:1318-20. [DOI: 10.1038/nsmb.2689] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 09/11/2013] [Indexed: 01/08/2023]
|
21
|
Predicting functionally informative mutations in Escherichia coli BamA using evolutionary covariance analysis. Genetics 2013; 195:443-55. [PMID: 23934888 DOI: 10.1534/genetics.113.155861] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The essential outer membrane β-barrel protein BamA forms a complex with four lipoprotein partners BamBCDE that assembles β-barrel proteins into the outer membrane of Escherichia coli. Detailed genetic studies have shown that BamA cycles through multiple conformations during substrate assembly, suggesting that a complex network of residues may be involved in coordinating conformational changes and lipoprotein partner function. While genetic analysis of BamA has been informative, it has also been slow in the absence of a straightforward selection for mutants. Here we take a bioinformatic approach to identify candidate residues for mutagenesis using direct coupling analysis. Starting with the BamA paralog FhaC, we show that direct coupling analysis works well for large β-barrel proteins, identifying pairs of residues in close proximity in tertiary structure with a true positive rate of 0.64 over the top 50 predictions. To reduce the effects of noise, we designed and incorporated a novel structured prior into the empirical correlation matrix, dramatically increasing the FhaC true positive rate from 0.64 to 0.88 over the top 50 predictions. Our direct coupling analysis of BamA implicates residues R661 and D740 in a functional interaction. We find that the substitutions R661G and D740G each confer OM permeability defects and destabilize the BamA β-barrel. We also identify synthetic phenotypes and cross-suppressors that suggest R661 and D740 function in a similar process and may interact directly. We expect that the direct coupling analysis approach to informed mutagenesis will be particularly useful in systems lacking adequate selections and for dynamic proteins with multiple conformations.
Collapse
|
22
|
Jacob-Dubuisson F, Guérin J, Baelen S, Clantin B. Two-partner secretion: as simple as it sounds? Res Microbiol 2013; 164:583-95. [PMID: 23542425 DOI: 10.1016/j.resmic.2013.03.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 02/05/2013] [Indexed: 10/27/2022]
Abstract
The two-partner secretion (TPS) pathway is a branch of type V secretion. TPS systems are dedicated to the secretion across the outer membrane of long proteins that form extended β-helices. They are composed of a 'TpsA' cargo protein and a 'TpsB' transporter, which belongs to the Omp85 superfamily. This basic design can be supplemented by additional components in some TPS systems. X-ray structures are available for the conserved TPS domain of several TpsA proteins and for one TpsB transporter. However, the molecular mechanisms of two-partner secretion remain to be deciphered, and in particular, the specific role(s) of the TPS domain and the conformational dynamics of the TpsB transporter. Deciphering the TPS pathway may reveal functional features of other transporters of the Omp85 superfamily.
Collapse
|
23
|
Conformation-specific labeling of BamA and suppressor analysis suggest a cyclic mechanism for β-barrel assembly in Escherichia coli. Proc Natl Acad Sci U S A 2013; 110:5151-6. [PMID: 23479609 DOI: 10.1073/pnas.1302662110] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In gram-negative bacteria, integral outer membrane β-barrel proteins (OMPs) are assembled by the beta-barrel assembly machine (Bam) complex. The essential components of this complex are the OMP BamA [which contains a carboxyl-terminal β-barrel and an amino-terminal periplasmic module composed of five polypeptide transport associated (POTRA) domains] and the lipoprotein BamD. In Escherichia coli, the Bam complex also contains three nonessential lipoproteins (BamBCE), all of which require the barrel-proximal POTRA domain (P5) for stable interactions with BamA. We have previously reported that the BamA β-barrel assumes two different conformations. A method for conformation-specific labeling of BamA described here reveals that these conformers reflect the degree of surface exposure of the conserved sixth extracellular loop (L6). L6 is surface accessible in one conformation but not in the other, likely because it occupies the lumen of the BamA β-barrel in the latter case. A gain-of-function mutation that promotes Bam activity (bamDR197L) and a loss-of-function mutation that decreases the activity of Bam (ΔbamE) both favor surface exposure of BamA L6, suggesting that BamD and BamE normally act to control L6 exposure through opposing functions. These results, along with the synthetic lethality of the bamDR197L ΔbamE double mutant, imply a cyclic mechanism in which the Bam lipoproteins regulate the conformation of BamA during the OMP assembly reaction. Our results further suggest that BamDE controls L6 exposure via conformational signals transmitted through P5 to L6.
Collapse
|
24
|
Schneiker-Bekel S, Wibberg D, Bekel T, Blom J, Linke B, Neuweger H, Stiens M, Vorhölter FJ, Weidner S, Goesmann A, Pühler A, Schlüter A. The complete genome sequence of the dominant Sinorhizobium meliloti field isolate SM11 extends the S. meliloti pan-genome. J Biotechnol 2011; 155:20-33. [DOI: 10.1016/j.jbiotec.2010.12.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 11/25/2010] [Accepted: 12/08/2010] [Indexed: 10/18/2022]
|
25
|
Affiliation(s)
- Christine L. Hagan
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Thomas J. Silhavy
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544;
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115; ,
| |
Collapse
|
26
|
Delattre A, Saint N, Clantin B, Willery E, Lippens G, Locht C, Villeret V, Jacob‐Dubuisson F. Substrate recognition by the POTRA domains of TpsB transporter FhaC. Mol Microbiol 2011; 81:99-112. [DOI: 10.1111/j.1365-2958.2011.07680.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Anne‐Sophie Delattre
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
| | - Nathalie Saint
- INSERM U1046, Université de Montpellier 1 et 2, F‐34090 Montpellier cedex, France
| | - Bernard Clantin
- CNRS USR3078, Institut de Recherche Interdisciplinaire – Université de Lille 1 – Université de Lille 2, F‐59658 Villeneuve d'Ascq, France
| | - Eve Willery
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
| | - Guy Lippens
- CNRS UMR 8576 – Université de Lille I, F‐59655 Villeneuve d'Ascq – France
| | - Camille Locht
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
| | - Vincent Villeret
- CNRS USR3078, Institut de Recherche Interdisciplinaire – Université de Lille 1 – Université de Lille 2, F‐59658 Villeneuve d'Ascq, France
| | - Françoise Jacob‐Dubuisson
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
| |
Collapse
|
27
|
The complex that inserts lipopolysaccharide into the bacterial outer membrane forms a two-protein plug-and-barrel. Proc Natl Acad Sci U S A 2011; 108:2486-91. [PMID: 21257904 DOI: 10.1073/pnas.1015617108] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cell surfaces of Gram-negative bacteria are composed of lipopolysaccharide (LPS). This glycolipid is found exclusively in the outer leaflet of the asymmetric outer membrane (OM), where it forms a barrier to the entry of toxic hydrophobic molecules into the cell. LPS typically contains six fatty acyl chains and up to several hundred sugar residues. It is biosynthesized in the cytosol and must then be transported across two membranes and an aqueous intermembrane space to the cell surface. These processes are required for the viability of most Gram-negative organisms. The integral membrane β-barrel LptD and the lipoprotein LptE form an essential complex in the OM, which is necessary for LPS assembly. It is not known how this complex translocates large, amphipathic LPS molecules across the OM to the outer leaflet. Here, we show that LptE resides within the LptD β-barrel both in vitro and in vivo. LptD/E associate via an extensive interface; in one specific interaction, LptE contacts a predicted extracellular loop of LptD through the lumen of the β-barrel. Disrupting this interaction site compromises the biogenesis of LptD. This unprecedented two-protein plug-and-barrel architecture suggests how LptD/E can insert LPS from the periplasm directly into the outer leaflet of the OM to establish the asymmetry of the bilayer.
Collapse
|
28
|
Delattre AS, Clantin B, Saint N, Locht C, Villeret V, Jacob-Dubuisson F. Functional importance of a conserved sequence motif in FhaC, a prototypic member of the TpsB/Omp85 superfamily. FEBS J 2010; 277:4755-65. [PMID: 20955520 DOI: 10.1111/j.1742-4658.2010.07881.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In Gram-negative bacteria, the two-partner secretion pathway mediates the secretion of TpsA proteins with various functions. TpsB transporters specifically recognize their TpsA partners in the periplasm and mediate their transport through a hydrophilic channel. The filamentous haemagglutinin adhesin (FHA)/FhaC pair represents a model two-partner secretion system, with the structure of the TpsB transporter FhaC providing the bases to decipher the mechanism of action of these proteins. FhaC is composed of a β-barrel preceded by two periplasmic polypeptide-transport-associated (POTRA) domains in tandem. The barrel is occluded by an N-terminal helix and an extracellular loop, L6, folded back into the FhaC channel. In this article, we describe a functionally important motif of FhaC. The VRGY tetrad is highly conserved in the TpsB family and, in FhaC, it is located at the tip of L6 reaching the periplasm. Replacement by Ala of the invariant Arg dramatically affects the secretion efficiency, although the structure of FhaC and its channel properties remain unaffected. This substitution affects the secretion mechanism at a step beyond the initial TpsA-TpsB interaction. Replacement of the conserved Tyr affects the channel properties, but not the secretion activity, suggesting that this residue stabilizes the loop in the resting conformation of FhaC. Thus, the conserved motif at the tip of L6 represents an important piece of two-partner secretion machinery. This motif is conserved in a predicted loop between two β-barrel strands in more distant relatives of FhaC involved in protein transport across or assembly into the outer membranes of bacteria and organelles, suggesting a conserved function in the molecular mechanism of transport.
Collapse
|
29
|
Schielke S, Frosch M, Kurzai O. Virulence determinants involved in differential host niche adaptation of Neisseria meningitidis and Neisseria gonorrhoeae. Med Microbiol Immunol 2010; 199:185-96. [PMID: 20379743 DOI: 10.1007/s00430-010-0150-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Indexed: 11/28/2022]
Abstract
Neisseria meningitidis and Neisseria gonorrhoeae are the only pathogenic species of the genus Neisseria. Although these two species are closely related, they specialized on survival in completely different environments within the human host-the nasopharynx in the case of N. meningitidis versus the urogenital tract in the case of N. gonorrhoeae. The genetic background of these differences has not yet been determined. Here, we present a comparison of all characterized transcriptional regulators in these species, delineating analogous functions and disclosing differential functional developments of these DNA-binding proteins with a special focus on the recently characterized regulator FarR and its contribution to divergent host niche adaptation in the two Neisseria spp. Furthermore, we summarize the present knowledge on two-partner secretion systems in meningococci, highlighting their overall expression among meningococcal strains in contrast to the complete absence in gonococci. Concluding, the decisive role of these two entirely different factors in host niche adaptation of the two human pathogenic Neisseria species is depicted, illuminating another piece of the puzzle to locate the molecular basis of their differences in preferred colonization sites and pathogenicity.
Collapse
Affiliation(s)
- Stephanie Schielke
- Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | | | | |
Collapse
|
30
|
Voegel TM, Warren JG, Matsumoto A, Igo MM, Kirkpatrick BC. Localization and characterization of Xylella fastidiosa haemagglutinin adhesins. MICROBIOLOGY-SGM 2010; 156:2172-2179. [PMID: 20378647 DOI: 10.1099/mic.0.037564-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Xylella fastidiosa is a gram-negative, xylem-inhabiting, plant-pathogenic bacterium responsible for several important diseases including Pierce's disease (PD) of grapevines. The bacteria form biofilms in grapevine xylem that contribute to the occlusion of the xylem vessels. X. fastidiosa haemagglutinin (HA) proteins are large afimbrial adhesins that have been shown to be crucial for biofilm formation. Little is known about the mechanism of X. fastidiosa HA-mediated cell-cell aggregation or the localization of the adhesins on the cell. We generated anti-HA antibodies and show that X. fastidiosa HAs are present in the outer membrane and secreted both as soluble proteins and in membrane vesicles. Furthermore, the HA pre-proteins are processed from the predicted molecular mass of 360 kDa to a mature 220 kDa protein. Based on this information, we are evaluating a novel form of potential resistance against PD by generating HA-expressing transgenic grapevines.
Collapse
Affiliation(s)
- Tanja M Voegel
- Department of Plant Pathology, University of California, Davis, CA 951616, USA
- Center for Applied Biosciences, University of Freiburg, Germany
| | - Jeremy G Warren
- Department of Plant Pathology, University of California, Davis, CA 951616, USA
| | - Ayumi Matsumoto
- Department of Microbiology, University of California, Davis, CA 951616, USA
| | - Michele M Igo
- Department of Microbiology, University of California, Davis, CA 951616, USA
| | - Bruce C Kirkpatrick
- Department of Plant Pathology, University of California, Davis, CA 951616, USA
| |
Collapse
|
31
|
Choi PS, Bernstein HD. Sequential translocation of an Escherchia coli two-partner secretion pathway exoprotein across the inner and outer membranes. Mol Microbiol 2010; 75:440-51. [PMID: 19968793 PMCID: PMC3107007 DOI: 10.1111/j.1365-2958.2009.06993.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In Gram-negative bacteria, a variety of high molecular weight 'exoproteins' are translocated across the outer membrane (OM) via the two-partner secretion (TPS) pathway by interacting with a dedicated transporter. It is unclear, however, whether the translocation of exoproteins across the OM is coupled to their translocation across the inner membrane (IM). To address this question, we separated the production of an Escherichia coli O157:H7 exoprotein (OtpA) and its transporter (OtpB) temporally by placing otpA and otpB under the control of distinct regulatable promoters. We found that when both full-length and truncated forms of OtpA were expressed prior to OtpB, a significant fraction of the exoprotein was secreted. The results indicate that OtpA can be translocated into the periplasm and briefly remain secretion-competent. Furthermore, by engineering cysteine residues into OtpA and using disulphide bond formation as a reporter of periplasmic localization, we obtained additional evidence that the C-terminus of OtpA enters the periplasm before the N-terminus is translocated across the OM even when OtpA and OtpB are expressed simultaneously. Taken together, our results demonstrate that the translocation of a TPS exoprotein across the OM can occur independently from its translocation across the IM.
Collapse
Affiliation(s)
- Peter S. Choi
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0538, USA
| | - Harris D. Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0538, USA
| |
Collapse
|
32
|
Abstract
Bacterial toxins damage the host at the site of bacterial infection or distant from the site. Bacterial toxins can be single proteins or oligomeric protein complexes that are organized with distinct AB structure-function properties. The A domain encodes a catalytic activity. ADP ribosylation of host proteins is the earliest post-translational modification determined to be performed by bacterial toxins; other modifications include glucosylation and proteolysis. Bacterial toxins also catalyze the non-covalent modification of host protein function or can modify host cell properties through direct protein-protein interactions. The B domain includes two functional domains: a receptor-binding domain, which defines the tropism of a toxin for a cell and a translocation domain that delivers the A domain across a lipid bilayer, either on the plasma membrane or the endosome. Bacterial toxins are often characterized based upon the secretion mechanism that delivers the toxin out of the bacterium, termed types I-VII. This review summarizes the major families of bacterial toxins and also describes the specific structure-function properties of the botulinum neurotoxins.
Collapse
Affiliation(s)
- James S Henkel
- Medical College of Wisconsin, Department of Microbiology and Molecular Genetics, Milwaukee, WI 53151, USA.
| | | | | |
Collapse
|
33
|
EtpB is a pore-forming outer membrane protein showing TpsB protein features involved in the two-partner secretion system. J Membr Biol 2009; 230:143-54. [PMID: 19711123 DOI: 10.1007/s00232-009-9195-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
Abstract
Attachment to host tissues is a critical step in the pathogenesis of most bacterial infections. Enterotoxigenic Escherichia coli (ETEC) remains one of the principal causes of infectious diarrhea in humans. The recent identification of additional ETEC surface molecules suggests that new targets may be exploited in vaccine development. The EtpA protein identified in ETEC H10407 is a large glycosylated adhesin secreted via the two-partner secretion system. EtpA requires its putative partner EtpB for translocation across the outer membrane (OM). We investigated the biochemical and electrophysiological properties of purified EtpB. We showed that EtpB is 65-kDa heat-modifiable protein localized to the OM. Electrophysiological experiments indicated that EtpB is able to form pores in planar lipid bilayer membranes with an asymmetric current, suggesting its functional asymmetry. The pore of EtpB frequently assumes an opened conformation and fluctuates between three well-defined conductance states. In silico analysis of the EtpB amino acid sequence and molecular modeling suggest that EtpB is similar to the well-known TpsB protein FhaC from Bordetella pertussis and has a C-terminal transmembrane beta-barrel domain that is occluded by an N-terminal alpha-helix, an extracellular loop, and two periplasmic polypeptide-transport-associated (POTRA) domains. Together, these data confirm that EtpB is a pore-forming protein mainly folded into a beta-barrel conformation and indicate that EtpB presents typical features of the OM TpsB proteins.
Collapse
|
34
|
Baud C, Hodak H, Willery E, Drobecq H, Locht C, Jamin M, Jacob-Dubuisson F. Role of DegP for two-partner secretion in Bordetella. Mol Microbiol 2009; 74:315-29. [PMID: 19703106 DOI: 10.1111/j.1365-2958.2009.06860.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sorting of proteins destined to the surface or the extracellular milieu is mediated by specific machineries, which guide the protein substrates towards the proper route of secretion and determine the compartment in which folding occurs. In gram-negative bacteria, the two-partner secretion (TPS) pathway is dedicated to the secretion of large proteins rich in beta-helical structure. The secretion of the filamentous haemagglutinin (FHA), a 230 kDa adhesin of Bordetella pertussis, represents a model TPS system. FHA is exported by the Sec machinery and transits through the periplasm in an extended conformation. From there it is translocated across the outer membrane by its dedicated transporter FhaC to finally fold into a long beta-helix at the cell surface in a progressive manner. In this work, we show that B. pertussis lacking the periplasmic chaperone/protease DegP has a strong growth defect at 37 degrees C, and the integrity of its outer membrane is compromised. While both phenotypes are significantly aggravated by the presence of FHA, the chaperone activity of DegP markedly alleviates the periplasmic stress. In vitro, DegP binds to non-native FHA with high affinity. We propose that DegP chaperones the extended FHA polypeptide in the periplasm and is thus involved in the TPS pathway.
Collapse
Affiliation(s)
- C Baud
- INSERM U629, Lille, France
| | | | | | | | | | | | | |
Collapse
|
35
|
Jacob-Dubuisson F, Villeret V, Clantin B, Delattre AS, Saint N. First structural insights into the TpsB/Omp85 superfamily. Biol Chem 2009; 390:675-84. [DOI: 10.1515/bc.2009.099] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
Proteins of the TpsB/Omp85 superfamily are involved in protein transport across, or assembly into, the outer membrane of Gram-negative bacteria, and their distant eukaryotic relatives exert similar functions in chloroplasts and mitochondria. The X-ray structure of one TpsB transporter, FhaC, provides the bases to decipher the mechanisms of action of these proteins. With two POTRA domains in the periplasm, a transmembrane β barrel and a large loop harboring a functionally important motif, FhaC epitomizes the conserved features of the super-family.
Collapse
|
36
|
Saier MH, Ma CH, Rodgers L, Tamang DG, Yen MR. Protein secretion and membrane insertion systems in bacteria and eukaryotic organelles. ADVANCES IN APPLIED MICROBIOLOGY 2009; 65:141-97. [PMID: 19026865 DOI: 10.1016/s0065-2164(08)00606-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Milton H Saier
- Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116, USA
| | | | | | | | | |
Collapse
|
37
|
Role of HrpA in biofilm formation of Neisseria meningitidis and regulation of the hrpBAS transcripts. Infect Immun 2009; 77:2285-93. [PMID: 19289515 DOI: 10.1128/iai.01502-08] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Two-partner secretion systems of gram-negative organisms are utilized in adherence, invasion, and biofilm formation. The HrpAB proteins of Neisseria meningitidis are members of a two-partner secretion system, and HrpA is established as being important to adherence and intracellular escape. This study set out to determine the expression pattern of members of the hrpBAS putative operon and to find a functional role for the HrpA protein. The upregulation of these genes was found in situations of anaerobiosis and cell contact. These observations prompted the study of the function of HrpA in biofilms on human bronchial epithelial cells. HrpA mutants in encapsulated and unencapsulated NMB strains demonstrated biofilm growth equivalent to that of the wild-type strain at 6 h but a decreased ability to form biofilms at 48 h. Biofilms formed by hrpA mutants for 48 h on collagen-coated coverslips demonstrated significant reductions compared to those of wild-type strains. Taken together, these observations imply a role for HrpA in the biofilm structure. Further analysis demonstrated the presence of HrpA on the surface of the bacterium.
Collapse
|
38
|
Knowles TJ, Scott-Tucker A, Overduin M, Henderson IR. Membrane protein architects: the role of the BAM complex in outer membrane protein assembly. Nat Rev Microbiol 2009; 7:206-14. [DOI: 10.1038/nrmicro2069] [Citation(s) in RCA: 231] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
39
|
Newman CL, Stathopoulos C. Autotransporter and Two-Partner Secretion: Delivery of Large-Size Virulence Factors by Gram-Negative Bacterial Pathogens. Crit Rev Microbiol 2008; 30:275-86. [PMID: 15646401 DOI: 10.1080/10408410490499872] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A number of protein secretion mechanisms have been identified in gram-negative pathogens. Many of these secretion systems are dependent upon the Sec translocase for protein export from the cytoplasm into the periplasm and then utilize other mechanisms for transport from the periplasm through the outer membrane. In this article, we review secretion similarities between autotransporter and two-partner secretion systems, and we report similarities between the autotransporter secretion mechanism with that of intimin/invasins. Considering that many secreted proteins are virulence factors, a better understanding of their secretion mechanisms will aid in the development of disease treatments and new bacterial vaccines.
Collapse
Affiliation(s)
- Cheryl L Newman
- Department of Biology & Biochemistry, University of Houston, Houston, Texas 77204, USA
| | | |
Collapse
|
40
|
Omp85(Tt) from Thermus thermophilus HB27: an ancestral type of the Omp85 protein family. J Bacteriol 2008; 190:4568-75. [PMID: 18456816 DOI: 10.1128/jb.00369-08] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteins belonging to the Omp85 family are involved in the assembly of beta-barrel outer membrane proteins or in the translocation of proteins across the outer membrane in bacteria, mitochondria, and chloroplasts. The cell envelope of the thermophilic bacterium Thermus thermophilus HB27 is multilayered, including an outer membrane that is not well characterized. Neither the precise lipid composition nor much about integral membrane proteins is known. The genome of HB27 encodes one Omp85-like protein, Omp85(Tt), representing an ancestral type of this family. We overexpressed Omp85(Tt) in T. thermophilus and purified it from the native outer membranes. In the presence of detergent, purified Omp85(Tt) existed mainly as a monomer, composed of two stable protease-resistant modules. Circular dichroism spectroscopy indicated predominantly beta-sheet secondary structure. Electron microscopy of negatively stained lipid-embedded Omp85(Tt) revealed ring-like structures with a central cavity of approximately 1.5 nm in diameter. Single-channel conductance recordings indicated that Omp85(Tt) forms ion channels with two different conducting states, characterized by conductances of approximately 0.4 nS and approximately 0.65 nS, respectively.
Collapse
|
41
|
Link S, Schmitt K, Beier D, Gross R. Identification and regulation of expression of a gene encoding a filamentous hemagglutinin-related protein in Bordetella holmesii. BMC Microbiol 2007; 7:100. [PMID: 17988394 PMCID: PMC2225982 DOI: 10.1186/1471-2180-7-100] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 11/07/2007] [Indexed: 11/11/2022] Open
Abstract
Background Bordetella holmesii is a human pathogen closely related to B. pertussis, the etiological agent of whooping cough. It is able to cause disease in immunocompromised patients, but also whooping cough-like symptoms in otherwise healthy individuals. However, virtually nothing was known so far about the underlying virulence mechanisms and previous attempts to identify virulence factors related to those of B. pertussis were not successful. Results By use of a PCR approach we were able to identify a B. holmesii gene encoding a protein with significant sequence similarities to the filamentous hemagglutinin (FHA) of B. avium and to a lesser extent to the FHA proteins of B. pertussis, B. parapertussis, and B. bronchiseptica. For these human and animal pathogens FHA is a crucial virulence factor required for successful colonization of the host. Interestingly, the B. holmesii protein shows a relatively high overall sequence similarity with the B. avium protein, while sequence conservation with the FHA proteins of the human and mammalian pathogens is quite limited and is most prominent in signal sequences required for their export to the cell surface. In the other Bordetellae expression of the fhaB gene encoding FHA was shown to be regulated by the master regulator of virulence, the BvgAS two-component system. Recently, we identified orthologs of BvgAS in B. holmesii, and here we show that this system also contributes to regulation of fhaB expression in B. holmesii. Accordingly, the purified BvgA response regulator of B. holmesii was shown to bind specifically in the upstream region of the fhaB promoter in vitro in a manner similar to that previously described for the BvgA protein of B. pertussis. Moreover, by deletion analysis of the fhaB promoter region we show that the BvgA binding sites are relevant for in vivo transcription from this promoter in B. holmesii. Conclusion The data reported here show that B. holmesii is endowed with a factor highly related to filamentous hemagglutinin (FHA), a prominent virulence factor of the well characterized pathogenic Bordetellae. We show that like in the other Bordetellae the virulence regulatory BvgAS system is also involved in the regulation of fhaB expression in B. holmesii. Taken together these data indicate that in contrast to previous notions B. holmesii may in fact make use of virulence mechanisms related to those described for the other Bordetellae.
Collapse
Affiliation(s)
- Stefanie Link
- Lehrstuhl für Mikrobiologie, Biozentrum der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
| | | | | | | |
Collapse
|
42
|
Mazar J, Cotter PA. New insight into the molecular mechanisms of two-partner secretion. Trends Microbiol 2007; 15:508-15. [DOI: 10.1016/j.tim.2007.10.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 08/15/2007] [Accepted: 10/25/2007] [Indexed: 12/29/2022]
|
43
|
Clantin B, Delattre AS, Rucktooa P, Saint N, Méli AC, Locht C, Jacob-Dubuisson F, Villeret V. Structure of the Membrane Protein FhaC: A Member of the Omp85-TpsB Transporter Superfamily. Science 2007; 317:957-61. [PMID: 17702945 DOI: 10.1126/science.1143860] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In Gram-negative bacteria and eukaryotic organelles, beta-barrel proteins of the outer membrane protein 85-two-partner secretion B (Omp85-TpsB) superfamily are essential components of protein transport machineries. The TpsB transporter FhaC mediates the secretion of Bordetella pertussis filamentous hemagglutinin (FHA). We report the 3.15 A crystal structure of FhaC. The transporter comprises a 16-stranded beta barrel that is occluded by an N-terminal alpha helix and an extracellular loop and a periplasmic module composed of two aligned polypeptide-transport-associated (POTRA) domains. Functional data reveal that FHA binds to the POTRA 1 domain via its N-terminal domain and likely translocates the adhesin-repeated motifs in an extended hairpin conformation, with folding occurring at the cell surface. General features of the mechanism obtained here are likely to apply throughout the superfamily.
Collapse
MESH Headings
- Adhesins, Bacterial/chemistry
- Adhesins, Bacterial/metabolism
- Amino Acid Motifs
- Amino Acid Sequence
- Bacterial Outer Membrane Proteins/chemistry
- Bacterial Outer Membrane Proteins/genetics
- Bacterial Outer Membrane Proteins/metabolism
- Bordetella pertussis/chemistry
- Bordetella pertussis/metabolism
- Cell Membrane/metabolism
- Crystallography, X-Ray
- Hydrophobic and Hydrophilic Interactions
- Lipid Bilayers/chemistry
- Lipid Bilayers/metabolism
- Membrane Transport Proteins/chemistry
- Membrane Transport Proteins/metabolism
- Models, Biological
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Conformation
- Protein Folding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Protein Transport
- Virulence Factors, Bordetella/chemistry
- Virulence Factors, Bordetella/metabolism
Collapse
Affiliation(s)
- Bernard Clantin
- UMR8161 CNRS, Institut de Biologie de Lille, Université de Lille 1, Université de Lille 2, 1 rue du Prof. Calmette, F-59021 Lille cedex, France
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Affiliation(s)
- Jan Tommassen
- Department of Molecular Microbiology and the Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands.
| |
Collapse
|
45
|
Li H, Grass S, Wang T, Liu T, St Geme JW. Structure of the Haemophilus influenzae HMW1B translocator protein: evidence for a twin pore. J Bacteriol 2007; 189:7497-502. [PMID: 17693509 PMCID: PMC2168432 DOI: 10.1128/jb.00541-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Secretion of the Haemophilus influenzae HMW1 adhesin occurs via the two-partner secretion pathway and requires the HMW1B outer membrane translocator. HMW1B has been subjected to extensive biochemical studies to date. However, direct examination of the structure of HMW1B has been lacking, leaving fundamental questions about the oligomeric state, the membrane-embedded beta-barrel domain, the approximate size of the beta-barrel pore, and the mechanism of translocator activity. In the current study, examination of purified HMW1B by size exclusion chromatography and negative staining electron microscopy revealed that the predominant species was a dimer. In the presence of lipid, purified HMW1B formed two-dimensional crystalline sheets. Examination of these crystals by cryo-electron microscopy allowed determination of a projection structure of HMW1B to 10 A resolution. The native HMW1B structure is a dimer of beta-barrels, with each beta-barrel measuring 40 A by 50 A in the two orthogonal directions and appearing largely occluded, leaving only a narrow pore. These observations suggest that HMW1B undergoes a large conformational change during translocation of the 125-kDa HMW1 adhesin.
Collapse
Affiliation(s)
- Huilin Li
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
| | | | | | | | | |
Collapse
|
46
|
Abstract
The experimental problems associated with in vivo studies of essential proteins or integral membrane proteins have triggered geneticists to generate novel approaches that have often led to insights of general relevance (Shuman and Silhavy, 2003). In order to extend the experimental portfolio, we developed target-directed proteolysis (TDP), an in vivo method allowing structural and functional characterization of target proteins in living cells. TDP is based on the activity of the highly sequence-specific NIa protease from tobacco etch virus. When its recognition site of seven residues is engineered into target proteins and NIa protease is expressed under tight promoter control, substrates can be conditionally processed while other cellular proteins remain unaffected. Applications include conditional inactivation as well as functional characterization of target proteins.
Collapse
Affiliation(s)
- Markus Eser
- School of Biosciences, Cardiff University, Cardiff, Wales, UK
| | | | | | | |
Collapse
|
47
|
Balder R, Hassel J, Lipski S, Lafontaine ER. Moraxella catarrhalis strain O35E expresses two filamentous hemagglutinin-like proteins that mediate adherence to human epithelial cells. Infect Immun 2007; 75:2765-75. [PMID: 17371858 PMCID: PMC1932885 DOI: 10.1128/iai.00079-07] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two-partner secretion (TPS) systems are a family of proteins being rapidly identified and characterized in a growing number of gram-negative bacteria. TPS systems mediate the secretion of proteins, many involved in virulence traits such as hemolysis, adherence to epithelial cells, inhibition of bacterial growth, and immunomodulation of the host. A TPS system typically consists of a transporter located in the bacterial outer membrane (OM) which is responsible for the recognition and secretion of at least one large exoprotein. Two of the better-characterized TPS systems specify the Bordetella pertussis FHA and Haemophilus influenzae HMW1/HMW2 proteins. We identified three gene products of Moraxella catarrhalis strain O35E that resemble TPS proteins and designated them MhaC (transporter), MhaB1 (exoprotein), and MhaB2 (exoprotein). Western blot analysis using anti-MhaC, or antibodies reacting to both MhaB1 and MhaB2 (MhaB-reactive), revealed that these antigens are expressed in the OM of 63% of isolates tested. Mutations in the mhaC gene specifying the putative transporter of the M. catarrhalis wild-type strains O35E, O12E, and McGHS1 resulted in the absence of MhaB1/MhaB2 in the OM of mutants. These results are therefore consistent with the Mha proteins functioning as a TPS system. Furthermore, we discovered that these mhaC mutants exhibit markedly decreased binding to human epithelial cells relevant to pathogenesis by M. catarrhalis (Chang, HEp2, A549, and/or 16HBE14o(-)). Expression of O12E MhaC and MhaB1 in a nonadherent strain of Escherichia coli was found to increase the adherence of recombinant bacteria to HEp2 monolayers by sevenfold, thereby demonstrating that this M. catarrhalis TPS system directly mediates binding to human epithelial cells. The construction of isogenic mutants in the mhaB1 and mhaB2 genes of strain O35E also suggests that the MhaB proteins play distinct roles in M. catarrhalis adherence.
Collapse
Affiliation(s)
- Rachel Balder
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, 220 Riverbend Road, South Building Room 146, Athens, GA 30602, USA
| | | | | | | |
Collapse
|
48
|
Ran L, Huang F, Ekman M, Klint J, Bergman B. Proteomic analyses of the photoauto- and diazotrophically grown cyanobacterium Nostoc sp. PCC 73102. Microbiology (Reading) 2007; 153:608-618. [PMID: 17259633 DOI: 10.1099/mic.0.29198-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The filamentous cyanobacteria of the genus Nostoc are globally distributed, phenotypically complex organisms, capable of cellular differentiation and of forming symbiotic associations with a wide range of plants. To further our understanding of these processes and functions, the proteome of photoautotrophically and diazotrophically grown Nostoc sp. PCC 73102 (N. punctiforme) cells was examined. Extracted proteins were separated into membrane and soluble protein fractions and analysed using two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). The analysis led to the identification of 82 proteins that could be divided into 12 functional categories. Significantly, 65 of these proteins have not been previously documented in the Nostoc proteome. Many of the proteins identified were readily recognized as housekeeping proteins involved in carbon, nitrogen and energy metabolism, but a number of proteins related to stress, motility, secretion and post-translational modifications were also identified. Ten unclassified proteins were also detected, representing potential novel functions. These proteins were highly expressed, suggesting that they play key roles during photoautotrophic and diazotrophic growth. Nineteen of the proteins expressed under the growth conditions examined contained putative thioredoxin (Trx) targets, a motif that functions in redox regulation via redox equivalent mediators and is known to be significant in a wide range of biological processes. These observations contribute to our understanding of the complex Nostoc life cycle.
Collapse
Affiliation(s)
- Liang Ran
- Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Fang Huang
- Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Martin Ekman
- Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Johan Klint
- Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Birgitta Bergman
- Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden
| |
Collapse
|
49
|
Brown E, Maloy S. Facile approach for constructing TEV insertions to probe protein structure in vivo. Biotechniques 2006; 41:721-4. [PMID: 17191617 DOI: 10.2144/000112284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The tobacco etch virus (TEV) protease has been used as a tool to examine protein structure in vivo. TEV cleavage sites (TEVcs) have been introduced via cloning into unique restriction sites or random transposon mutagenesis. We describe a facile, efficient method for introducing TEVcs at precise locations in a gene to test specific predictions about protein structure. The method uses the lamda Red recombination system to construct seamless, in-frame insertions of the TEVcs at any desired location within an open reading frame (ORF). The system was tested using the multifunctional PutA protein Salmonella enterica sv. Typhimurium. The first step involved insertion of a chloramphenicol resistance (Cam(R)) cassette with a transcriptional terminator at the desired location. A second swap then replaces the Cam(R) insertion with the TEVcs. Placing a copy of the lac operon downstream of the putA gene provides a simple counterselection for replacement of the Cam(R) insertion and also provides a reporter gene for monitoring transcription of the mutated gene.
Collapse
Affiliation(s)
- Elysa Brown
- San Diego State University, San Diego, CA 92182-4614, USA
| | | |
Collapse
|
50
|
Stegmeier JF, Andersen C. Characterization of Pores Formed by YaeT (Omp85) from Escherichia coli. ACTA ACUST UNITED AC 2006; 140:275-83. [PMID: 16829683 DOI: 10.1093/jb/mvj147] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Proteins of the Omp85 family play a major role in the biogenesis of the bacterial outer membrane, since they were shown to mediate insertion of outer membrane proteins. The Escherichia coli Omp85 homologue YaeT is essential for viability, but its exact mode of action is not yet elucidated. We could show that YaeT is composed of two distinct domains, an amino-terminal periplasmic and a carboxy-terminal membrane domain. The full length YaeT and the isolated membrane domain induce pores when reconstituted in planar lipid membranes. The pores exhibit a certain variability of conductance indicating a flexible structure, which could be an essential property of a lateral opening channel releasing proteins into the bacterial outer membrane. We could further show that the periplasmic domain proves to be essential for in vivo function of YaeT.
Collapse
Affiliation(s)
- Johannes F Stegmeier
- Universität Würzburg, Lehrstuhl für Biotechnologie, Biozentrum der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | | |
Collapse
|