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SurA-like and Skp-like Proteins as Important Virulence Determinants of the Gram Negative Bacterial Pathogens. Int J Mol Sci 2022; 24:ijms24010295. [PMID: 36613738 PMCID: PMC9820271 DOI: 10.3390/ijms24010295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
In the Gram-negative bacteria, many important virulence factors reach their destination via two-step export systems, and they must traverse the periplasmic space before reaching the outer membrane. Since these proteins must be maintained in a structure competent for transport into or across the membrane, they frequently require the assistance of chaperones. Based on the results obtained for the model bacterium Escherichia coli and related species, it is assumed that in the biogenesis of the outer membrane proteins and the periplasmic transit of secretory proteins, the SurA peptidyl-prolyl isomerase/chaperone plays a leading role, while the Skp chaperone is rather of secondary importance. However, detailed studies carried out on several other Gram-negative pathogens indicate that the importance of individual chaperones in the folding and transport processes depends on the properties of client proteins and is species-specific. Taking into account the importance of SurA functions in bacterial virulence and severity of phenotypes due to surA mutations, this folding factor is considered as a putative therapeutic target to combat microbial infections. In this review, we present recent findings regarding SurA and Skp proteins: their mechanisms of action, involvement in processes related to virulence, and perspectives to use them as therapeutic targets.
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2
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Genome analysis of
Klebsiella oxytoca
complex for antimicrobial resistance and virulence genes. Antimicrob Agents Chemother 2022; 66:e0218321. [PMID: 35007133 DOI: 10.1128/aac.02183-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Klebsiella oxytoca
complex comprises nine closely-related species causing human infections. We curated genomes labeled
Klebsiella
(n=14,256) in GenBank and identified 588 belonging to the complex, which were examined for precise species, sequence types, K- and O-antigen types, virulence and antimicrobial resistance genes. The complex and
Klebsiella pneumoniae
share many K- and O-antigen types. Of the complex,
K. oxytoca
and
Klebsiella michiganensis
appear to carry more virulence genes and be more commonly associated with human infections.
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3
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Budowa i znaczenie II systemu sekrecji białek w ekologii i patogenezie Legionella pneumophila. POSTEP HIG MED DOSW 2021. [DOI: 10.2478/ahem-2021-0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Pałeczki Legionella pneumophila pasożytują w komórkach odległych filogenetycznie gospodarzy, w środowisku wodnym w pierwotniakach, a w organizmie człowieka w makrofagach alweolarnych. Zdolność tych bakterii do wewnątrzkomórkowego namnażania się w komórkach fagocytujących, wyspecjalizowanych do niszczenia mikroorganizmów, ma podstawowe znaczenie dla rozwoju nietypowego zapalenia płuc zwanego chorobą legionistów. Umiejscowione na kilku różnych loci chromosomu bakteryjnego geny II systemu sekrecji L. pneumophila kodują co najmniej 25 białek, w tym enzymy o aktywności lipolitycznej, proteolitycznej, rybonukleazy oraz białka unikalne bakterii Legionella. W środowisku naturalnym T2SS L. pneumophila odgrywa decydującą rolę w ekologii tych drobnoustrojów determinując ich zdolność do przeżycia zarówno w postaci planktonicznej, jak i w strukturach biofilmu w słodkowodnych zbiornikach o niskiej temperaturze. Białka T2SS umożliwiają L. pneumophila zakażenie różnych gatunków pierwotniaków, a substraty tego systemu określają zakres pierwotniaczego gospodarza. Namnażanie się bakterii w różnorodnych pierwotniakach przyczynia się do ich rozsiewania oraz transmisji do antropogenicznych źródeł. Białka wydzielane za pomocą II systemu sekrecji determinują również zdolność L. pneumophila do zakażania mysich makrofagów alweolarnych i szpiku kostnego, ludzkich makrofagów linii U937 i THP-1 oraz komórek nabłonkowych pęcherzyków płucnych. Enzymy wydzielane za pomocą tego systemu, takie jak: proteazy, aminopeptydazy czy fosfolipazy umożliwiają pozyskanie substancji pokarmowych oraz powodują destrukcję tkanki płucnej myszy. W organizmie człowieka białka T2SS przyczyniają się do osłabienia wrodzonej odpowiedzi immunologicznej na zakażenie L. pneumophila przez hamowanie indukcji prozapalnych cytokin (IL-6, TNF-α, IL-1 oraz IL-8).
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4
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Pineau C, Guschinskaya N, Gonçalves IR, Ruaudel F, Robert X, Gouet P, Ballut L, Shevchik VE. Structure-function analysis of pectate lyase Pel3 reveals essential facets of protein recognition by the bacterial type 2 secretion system. J Biol Chem 2021; 296:100305. [PMID: 33465378 PMCID: PMC7949064 DOI: 10.1016/j.jbc.2021.100305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/11/2021] [Accepted: 01/14/2021] [Indexed: 12/02/2022] Open
Abstract
The type II secretion system (T2SS) transports fully folded proteins of various functions and structures through the outer membrane of Gram-negative bacteria. The molecular mechanisms of substrate recruitment by T2SS remain elusive but a prevailing view is that the secretion determinants could be of a structural nature. The phytopathogenic γ-proteobacteria, Pectobacterium carotovorum and Dickeya dadantii, secrete similar sets of homologous plant cell wall degrading enzymes, mainly pectinases, by similar T2SSs, called Out. However, the orthologous pectate lyases Pel3 and PelI from these bacteria, which share 67% of sequence identity, are not secreted by the counterpart T2SS of each bacterium, indicating a fine-tuned control of protein recruitment. To identify the related secretion determinants, we first performed a structural characterization and comparison of Pel3 with PelI using X-ray crystallography. Then, to assess the biological relevance of the observed structural variations, we conducted a loop-substitution analysis of Pel3 combined with secretion assays. We showed that there is not one element with a definite secondary structure but several distant and structurally flexible loop regions that are essential for the secretion of Pel3 and that these loop regions act together as a composite secretion signal. Interestingly, depending on the crystal contacts, one of these key secretion determinants undergoes disorder-to-order transitions that could reflect its transient structuration upon the contact with the appropriate T2SS components. We hypothesize that such T2SS-induced structuration of some intrinsically disordered zones of secretion substrates could be part of the recruitment mechanism used by T2SS.
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Affiliation(s)
- Camille Pineau
- Microbiologie Adaptation et Pathogénie, Univ Lyon, Université de Lyon 1, UMR5240 CNRS, Villeurbanne, France; Microbiologie Adaptation et Pathogénie, Univ Lyon, INSA Lyon, UMR5240, Villeurbanne, France
| | - Natalia Guschinskaya
- Microbiologie Adaptation et Pathogénie, Univ Lyon, Université de Lyon 1, UMR5240 CNRS, Villeurbanne, France; Microbiologie Adaptation et Pathogénie, Univ Lyon, INSA Lyon, UMR5240, Villeurbanne, France
| | - Isabelle R Gonçalves
- Microbiologie Adaptation et Pathogénie, Univ Lyon, Université de Lyon 1, UMR5240 CNRS, Villeurbanne, France
| | - Florence Ruaudel
- Microbiologie Adaptation et Pathogénie, Univ Lyon, Université de Lyon 1, UMR5240 CNRS, Villeurbanne, France
| | - Xavier Robert
- Molecular Microbiology and Structural Biochemistry, Univ Lyon, UMR5086 CNRS, Lyon, France
| | - Patrice Gouet
- Molecular Microbiology and Structural Biochemistry, Univ Lyon, UMR5086 CNRS, Lyon, France
| | - Lionel Ballut
- Molecular Microbiology and Structural Biochemistry, Univ Lyon, UMR5086 CNRS, Lyon, France.
| | - Vladimir E Shevchik
- Microbiologie Adaptation et Pathogénie, Univ Lyon, Université de Lyon 1, UMR5240 CNRS, Villeurbanne, France; Microbiologie Adaptation et Pathogénie, Univ Lyon, INSA Lyon, UMR5240, Villeurbanne, France.
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5
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Pierce JV, Fellows JD, Anderson DE, Bernstein HD. A clostripain-like protease plays a major role in generating the secretome of enterotoxigenic Bacteroides fragilis. Mol Microbiol 2020; 115:290-304. [PMID: 32996200 DOI: 10.1111/mmi.14616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/21/2020] [Accepted: 09/23/2020] [Indexed: 11/27/2022]
Abstract
Bacteroides fragilis toxin (BFT) is a protein secreted by enterotoxigenic (ETBF) strains of B. fragilis. BFT is synthesized as a proprotein (proBFT) that is predicted to be a lipoprotein and that is cleaved into two discrete fragments by a clostripain-like protease called fragipain (Fpn). In this study, we obtained evidence that Fpn cleaves proBFT following its transport across the outer membrane. Remarkably, we also found that the disruption of the fpn gene led to a strong reduction in the level of >100 other proteins, many of which are predicted to be lipoproteins, in the culture medium of an ETBF strain. Experiments performed with purified Fpn provided direct evidence that the protease releases at least some of these proteins from the cell surface. The observation that wild-type cells outcompeted an fpn- strain in co-cultivation assays also supported the notion that Fpn plays an important role in cell physiology and is not simply dedicated to toxin biogenesis. Finally, we found that purified Fpn altered the adhesive properties of HT29 intestinal epithelial cells. Our results suggest that Fpn is a broad-spectrum protease that not only catalyzes the protein secretion on a wide scale but that also potentially cleaves host cell proteins during colonization.
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Affiliation(s)
- Jessica V Pierce
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Justin D Fellows
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - D Eric Anderson
- Advanced Mass Spectrometry Facility, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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6
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Yap PSX, Ahmad Kamar A, Chong CW, Ngoi ST, Teh CSJ. Genomic Insights into Two Colistin-Resistant Klebsiella pneumoniae Strains Isolated from the Stool of Preterm Neonate During the First Week of Life. Microb Drug Resist 2019; 26:190-203. [PMID: 31545116 DOI: 10.1089/mdr.2019.0199] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background: Klebsiella pneumoniae is a major opportunistic pathogen frequently associated with nosocomial infections, and often poses a major threat to immunocompromised patients. In our previous study, two K. pneumoniae (K36 and B13), which displayed resistance to almost all major antibiotics, including colistin, were isolated. Both isolates were not associated with infection and isolated from the stools of two preterm neonates admitted to the neonatal intensive care unit (NICU) during their first week of life. Materials and Methods: In this study, whole genome sequencing was performed on these two clinical multidrug resistant K. pneumoniae. We aimed to determine the genetic factors that underline the antibiotic-resistance phenotypes of these isolates. Results: The strains harbored blaSHV-27, blaSHV-71, and oqxAB genes conferring resistance to cephalosporins, carbapenems, and fluoroquinolones, respectively, but not harboring any known plasmid-borne colistin resistance determinants such as mcr-1. However, genome analysis discovered interruption of mgrB gene by insertion sequences gaining insight into the development of colistin resistance. Conclusion: The observed finding that points to a scenario of potential gut-associated resistance genes to Gram negative (K. pneumoniae) host in the NICU environment warrants attention and further investigation.
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Affiliation(s)
- Polly Soo Xi Yap
- Department of Medical Microbiology and Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Azanna Ahmad Kamar
- Department of Paediatrics, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Chun Wie Chong
- School of Pharmacy, Monash University, Jalan Lagoon Selatan, Selangor, Malaysia
| | - Soo Tein Ngoi
- Department of Medical Microbiology and Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Cindy Shuan Ju Teh
- Department of Medical Microbiology and Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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7
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Bardiaux B, de Amorim GC, Luna Rico A, Zheng W, Guilvout I, Jollivet C, Nilges M, Egelman EH, Izadi-Pruneyre N, Francetic O. Structure and Assembly of the Enterohemorrhagic Escherichia coli Type 4 Pilus. Structure 2019; 27:1082-1093.e5. [PMID: 31056419 PMCID: PMC7003672 DOI: 10.1016/j.str.2019.03.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/18/2019] [Accepted: 03/25/2019] [Indexed: 12/30/2022]
Abstract
Bacterial type 4a pili are dynamic surface filaments that promote bacterial adherence, motility, and macromolecular transport. Their genes are highly conserved among enterobacteria and their expression in enterohemorrhagic Escherichia coli (EHEC) promotes adhesion to intestinal epithelia and pro-inflammatory signaling. To define the molecular basis of EHEC pilus assembly, we determined the structure of the periplasmic domain of its major subunit PpdD (PpdDp), a prototype of an enterobacterial pilin subfamily containing two disulfide bonds. The structure of PpdDp, determined by NMR, was then docked into the density envelope of purified EHEC pili obtained by cryoelectron microscopy (cryo-EM). Cryo-EM reconstruction of EHEC pili at ∼8 Å resolution revealed extremely high pilus flexibility correlating with a large extended region of the pilin stem. Systematic mutagenesis combined with functional and interaction analyses identified charged residues essential for pilus assembly. Structural information on exposed regions and interfaces between EHEC pilins is relevant for vaccine and drug discovery.
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Affiliation(s)
- Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France
| | - Gisele Cardoso de Amorim
- NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Areli Luna Rico
- NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Ingrid Guilvout
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Camille Jollivet
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur, CNRS UMR3528, CNRS USR3756, Paris, France; NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France.
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, Paris, France.
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8
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Chua MD, Liou CH, Bogdan AC, Law HT, Yeh KM, Lin JC, Siu LK, Guttman JA. Klebsiella pneumoniae disassembles host microtubules in lung epithelial cells. Cell Microbiol 2018; 21:e12977. [PMID: 30415487 DOI: 10.1111/cmi.12977] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 01/21/2023]
Abstract
Klebsiella pneumoniae raises significant concerns to the health care industry as these microbes are the source of widespread contamination of medical equipment, cause pneumonia as well as other multiorgan metastatic infections and have gained multidrug resistance. Despite soaring mortality rates, the host cell alterations occurring during these infections remain poorly understood. Here, we show that during in vitro and in vivo K. pneumoniae infections of lung epithelia, microtubules are severed and then eliminated. This destruction does not require direct association of K. pneumoniae with the host cells, as microtubules are disassembled in cells that are distant from the infecting bacteria. This microtubule dismantling is dependent on the K. pneumoniae (Kp) gene ytfL as non-pathogenic Escherichia coli expressing Kp ytfL disassemble microtubules in the absence of K. pneumoniae itself. Our data points to the host katanin catalytic subunit A like 1 protein (KATNAL1) and the katanin regulatory subunit B1 protein (KATNB1) as the gatekeepers to the microtubule severing event as both proteins localise specifically to microtubule cut sites. Infected cells that had either of these proteins knocked out maintained intact microtubules. Taken together, we have identified a novel mechanism that a bacterial pathogen has exploited to cause microtubule destruction within the host epithelia.
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Affiliation(s)
- Michael Dominic Chua
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Ci-Hong Liou
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | | | - Hong T Law
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Kuo-Ming Yeh
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Jung-Chung Lin
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - L Kristopher Siu
- Division of Infection Diseases, National Health Research Institutes, Miaoli, Taiwan
| | - Julian Andrew Guttman
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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9
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Gu S, Shevchik VE, Shaw R, Pickersgill RW, Garnett JA. The role of intrinsic disorder and dynamics in the assembly and function of the type II secretion system. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1255-1266. [PMID: 28733198 DOI: 10.1016/j.bbapap.2017.07.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/02/2017] [Accepted: 07/17/2017] [Indexed: 10/19/2022]
Abstract
Many Gram-negative commensal and pathogenic bacteria use a type II secretion system (T2SS) to transport proteins out of the cell. These exported proteins or substrates play a major role in toxin delivery, maintaining biofilms, replication in the host and subversion of host immune responses to infection. We review the current structural and functional work on this system and argue that intrinsically disordered regions and protein dynamics are central for assembly, exo-protein recognition, and secretion competence of the T2SS. The central role of intrinsic disorder-order transitions in these processes may be a particular feature of type II secretion.
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Affiliation(s)
- Shuang Gu
- Queen Mary University of London, School of Biological and Chemical Sciences, London E1 4NS, United Kingdom
| | - Vladimir E Shevchik
- Université de Lyon, F-69003, Université Lyon 1, Lyon, F-69622, INSA-Lyon, Villeurbanne F-69621, CNRS, UMR5240, Microbiologie Adaptation et Pathogénie, Lyon F-69622, France
| | - Rosie Shaw
- Queen Mary University of London, School of Biological and Chemical Sciences, London E1 4NS, United Kingdom
| | - Richard W Pickersgill
- Queen Mary University of London, School of Biological and Chemical Sciences, London E1 4NS, United Kingdom.
| | - James A Garnett
- Queen Mary University of London, School of Biological and Chemical Sciences, London E1 4NS, United Kingdom.
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10
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Maffei B, Francetic O, Subtil A. Tracking Proteins Secreted by Bacteria: What's in the Toolbox? Front Cell Infect Microbiol 2017; 7:221. [PMID: 28620586 PMCID: PMC5449463 DOI: 10.3389/fcimb.2017.00221] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/15/2017] [Indexed: 01/14/2023] Open
Abstract
Bacteria have acquired multiple systems to expose proteins on their surface, release them in the extracellular environment or even inject them into a neighboring cell. Protein secretion has a high adaptive value and secreted proteins are implicated in many functions, which are often essential for bacterial fitness. Several secreted proteins or secretion machineries have been extensively studied as potential drug targets. It is therefore important to identify the secretion substrates, to understand how they are specifically recognized by the secretion machineries, and how transport through these machineries occurs. The purpose of this review is to provide an overview of the biochemical, genetic and imaging tools that have been developed to evaluate protein secretion in a qualitative or quantitative manner. After a brief overview of the different tools available, we will illustrate their advantages and limitations through a discussion of some of the current open questions related to protein secretion. We will start with the question of the identification of secreted proteins, which for many bacteria remains a critical initial step toward a better understanding of their interactions with the environment. We will then illustrate our toolbox by reporting how these tools have been applied to better understand how substrates are recognized by their cognate machinery, and how secretion proceeds. Finally, we will highlight recent approaches that aim at investigating secretion in real time, and in complex environments such as a tissue or an organism.
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Affiliation(s)
- Benoit Maffei
- Unité de Biologie Cellulaire de l'Infection Microbienne, Institut PasteurParis, France.,Centre National de la Recherche Scientifique UMR3691Paris, France
| | - Olivera Francetic
- Unité de Biochimie des Interactions Macromoléculaires, Institut PasteurParis, France.,Centre National de la Recherche Scientifique ERL6002Paris, France
| | - Agathe Subtil
- Unité de Biologie Cellulaire de l'Infection Microbienne, Institut PasteurParis, France.,Centre National de la Recherche Scientifique UMR3691Paris, France
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11
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Thomassin JL, Santos Moreno J, Guilvout I, Tran Van Nhieu G, Francetic O. The trans-envelope architecture and function of the type 2 secretion system: new insights raising new questions. Mol Microbiol 2017; 105:211-226. [DOI: 10.1111/mmi.13704] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Jenny-Lee Thomassin
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Javier Santos Moreno
- Université Paris Diderot (Paris 7) Sorbonne Paris Cité; Paris France
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Ingrid Guilvout
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Guy Tran Van Nhieu
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Olivera Francetic
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
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12
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Depluverez S, Devos S, Devreese B. The Role of Bacterial Secretion Systems in the Virulence of Gram-Negative Airway Pathogens Associated with Cystic Fibrosis. Front Microbiol 2016; 7:1336. [PMID: 27625638 PMCID: PMC5003817 DOI: 10.3389/fmicb.2016.01336] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 08/12/2016] [Indexed: 11/16/2022] Open
Abstract
Cystic fibrosis (CF) is the most common lethal inherited disorder in Caucasians. It is caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. A defect in the CFTR ion channel causes a dramatic change in the composition of the airway surface fluid, leading to a highly viscous mucus layer. In healthy individuals, the majority of bacteria trapped in the mucus layer are removed and destroyed by mucociliary clearance. However, in the lungs of patients with CF, the mucociliary clearance is impaired due to dehydration of the airway surface fluid. As a consequence, patients with CF are highly susceptible to chronic or intermittent pulmonary infections, often causing extensive lung inflammation and damage, accompanied by a decreased life expectancy. This mini review will focus on the different secretion mechanisms used by the major bacterial CF pathogens to release virulence factors, their role in resistance and discusses the potential for therapeutically targeting secretion systems.
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Affiliation(s)
- Sofie Depluverez
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
| | - Simon Devos
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
| | - Bart Devreese
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
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13
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Abstract
Lipoproteins play a variety of roles in bacterial physiology and virulence. Correct localization is essential for lipoprotein function, yet the mechanisms by which this occurs are not yet fully understood. In this issue of Structure, East et al. (2016) describe the factors that govern secretion of the PulA lipoprotein.
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Affiliation(s)
- Jane R Allison
- Centre for Theoretical Chemistry and Physics, Institute of Natural and Mathematical Sciences, Massey University, Auckland 0632, New Zealand.
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14
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East A, Mechaly A, Huysmans G, Bernarde C, Tello-Manigne D, Nadeau N, Pugsley A, Buschiazzo A, Alzari P, Bond P, Francetic O. Structural Basis of Pullulanase Membrane Binding and Secretion Revealed by X-Ray Crystallography, Molecular Dynamics and Biochemical Analysis. Structure 2016; 24:92-104. [DOI: 10.1016/j.str.2015.10.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/23/2015] [Accepted: 10/26/2015] [Indexed: 10/22/2022]
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15
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Wilson MM, Bernstein HD. Surface-Exposed Lipoproteins: An Emerging Secretion Phenomenon in Gram-Negative Bacteria. Trends Microbiol 2015; 24:198-208. [PMID: 26711681 DOI: 10.1016/j.tim.2015.11.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/17/2015] [Accepted: 11/23/2015] [Indexed: 01/07/2023]
Abstract
Bacterial lipoproteins are hydrophilic proteins that are anchored to a cell membrane by N-terminally linked fatty acids. It is widely believed that nearly all lipoproteins produced by Gram-negative bacteria are either retained in the inner membrane (IM) or transferred to the inner leaflet of the outer membrane (OM). Lipoproteins that are exposed on the cell surface have also been reported but are generally considered to be rare. Results from a variety of recent studies, however, now suggest that the prevalence of surface-exposed lipoproteins has been underestimated. In this review we describe the evidence that the surface exposure of lipoproteins in Gram-negative bacteria is a widespread phenomenon and discuss possible mechanisms by which these proteins might be transported across the OM.
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Affiliation(s)
- Marlena M Wilson
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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16
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Auto-induction-based Rapid Evaluation of Extracellular Enzyme Expression from Lac Operator-involved Recombinant Escherichia coli. Appl Biochem Biotechnol 2014; 174:2516-26. [DOI: 10.1007/s12010-014-1201-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/22/2014] [Indexed: 12/30/2022]
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17
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Pineau C, Guschinskaya N, Robert X, Gouet P, Ballut L, Shevchik VE. Substrate recognition by the bacterial type II secretion system: more than a simple interaction. Mol Microbiol 2014; 94:126-40. [DOI: 10.1111/mmi.12744] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2014] [Indexed: 01/08/2023]
Affiliation(s)
- Camille Pineau
- Université Lyon 1; F-69622 Lyon France
- INSA-Lyon; F-69621 Villeurbanne France
- CNRS; UMR5240; Microbiologie Adaptation et Pathogénie; F-69622 Lyon France
| | - Natalia Guschinskaya
- Université Lyon 1; F-69622 Lyon France
- CNRS; UMR5240; Microbiologie Adaptation et Pathogénie; F-69622 Lyon France
| | - Xavier Robert
- Laboratory for Biocrystallography and Structural Biology of Therapeutic Targets; Molecular and Structural Bases of Infectious Diseases; CNRS; UMR5086; F-69367 Lyon France
| | - Patrice Gouet
- Laboratory for Biocrystallography and Structural Biology of Therapeutic Targets; Molecular and Structural Bases of Infectious Diseases; CNRS; UMR5086; F-69367 Lyon France
| | - Lionel Ballut
- Laboratory for Biocrystallography and Structural Biology of Therapeutic Targets; Molecular and Structural Bases of Infectious Diseases; CNRS; UMR5086; F-69367 Lyon France
| | - Vladimir E. Shevchik
- Université Lyon 1; F-69622 Lyon France
- INSA-Lyon; F-69621 Villeurbanne France
- CNRS; UMR5240; Microbiologie Adaptation et Pathogénie; F-69622 Lyon France
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18
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Secretion of bacterial lipoproteins: through the cytoplasmic membrane, the periplasm and beyond. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1509-16. [PMID: 24780125 DOI: 10.1016/j.bbamcr.2014.04.022] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/16/2014] [Accepted: 04/18/2014] [Indexed: 11/20/2022]
Abstract
Bacterial lipoproteins are peripherally anchored membrane proteins that play a variety of roles in bacterial physiology and virulence in monoderm (single membrane-enveloped, e.g., gram-positive) and diderm (double membrane-enveloped, e.g., gram-negative) bacteria. After export of prolipoproteins through the cytoplasmic membrane, which occurs predominantly but not exclusively via the general secretory or Sec pathway, the proteins are lipid-modified at the cytoplasmic membrane in a multistep process that involves sequential modification of a cysteine residue and cleavage of the signal peptide by the signal II peptidase Lsp. In both monoderms and diderms, signal peptide processing is preceded by acylation with a diacylglycerol through preprolipoprotein diacylglycerol transferase (Lgt). In diderms but also some monoderms, lipoproteins are further modified with a third acyl chain through lipoprotein N-acyl transferase (Lnt). Fully modified lipoproteins that are destined to be anchored in the inner leaflet of the outer membrane (OM) are selected, transported and inserted by the Lol (lipoprotein outer membrane localization) pathway machinery, which consists of the inner-membrane (IM) ABC transporter-like LolCDE complex, the periplasmic LolA chaperone and the OM LolB lipoprotein receptor. Retention of lipoproteins in the cytoplasmic membrane results from Lol avoidance signals that were originally described as the "+2 rule". Surface localization of lipoproteins in diderms is rare in most bacteria, with the exception of several spirochetal species. Type 2 (T2SS) and type 5 (T5SS) secretion systems are involved in secretion of specific surface lipoproteins of γ-proteobacteria. In the model spirochete Borrelia burgdorferi, surface lipoprotein secretion does not follow established sorting rules, but remains dependent on N-terminal peptide sequences. Secretion through the outer membrane requires maintenance of lipoproteins in a translocation-competent unfolded conformation, likely through interaction with a periplasmic holding chaperone, which delivers the proteins to an outer membrane lipoprotein flippase. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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19
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Sané S, Richter K, Rubenwolf S, Matschke NJ, Jolivalt C, Madzak C, Zengerle R, Gescher J, Kerzenmacher S. Using planktonic microorganisms to supply the unpurified multi-copper oxidases laccase and copper efflux oxidases at a biofuel cell cathode. BIORESOURCE TECHNOLOGY 2014; 158:231-238. [PMID: 24607459 DOI: 10.1016/j.biortech.2014.02.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/07/2014] [Accepted: 02/10/2014] [Indexed: 06/03/2023]
Abstract
The feasibility to apply crude culture supernatants that contain the multicopper oxidases laccase or copper efflux oxidase (CueO) as oxygen reducing catalysts in a biofuel cell cathode is shown. As enzyme-secreting recombinant planktonic microorganisms, the yeast Yarrowia lipolytica and the bacterium Escherichia coli were investigated. The cultivation and operation conditions (choice of medium, pH) had distinct effects on the electro-catalytic performance. The highest current density of 119 ± 23 μA cm(-2) at 0.400 V vs. NHE was obtained with the crude culture supernatant of E. coli cells overexpressing CueO and tested at pH 5.0. In comparison, at pH 7.4 the electrode potential at 100 μA cm(-2) is 0.25 V lower. Laccase-containing supernatants of Y. lipolytica yielded a maximum current density of 6.7 ± 0.4 μAcm(-2) at 0.644 V vs. NHE. These results open future possibilities to circumvent elaborate enzyme purification procedures and realize cost effective and easy-to-operate enzymatic biofuel cells.
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Affiliation(s)
- Sabine Sané
- Laboratory for MEMS Applications, IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany.
| | - Katrin Richter
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany.
| | - Stefanie Rubenwolf
- Laboratory for MEMS Applications, IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany
| | - Nina Joan Matschke
- Laboratory for MEMS Applications, IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany
| | - Claude Jolivalt
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7197 Laboratoire de Réactivité de surface, F-75005 Paris, France; CNRS, UMR 7197 Laboratoire de Réactivité de surface, F-75005 Paris, France.
| | - Catherine Madzak
- INRA, UMR 1319 Micalis, Domaine de Vilvert, F-78352 Jouy-en-Josas, France.
| | - Roland Zengerle
- Laboratory for MEMS Applications, IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany; BIOSS - Centre for Biological Signalling Studies, University of Freiburg, 79110 Freiburg, Germany.
| | - Johannes Gescher
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany.
| | - Sven Kerzenmacher
- Laboratory for MEMS Applications, IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany.
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20
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Abstract
Type IV pili (T4P) are multifunctional protein fibers produced on the surfaces of a wide variety of bacteria and archaea. The major subunit of T4P is the type IV pilin, and structurally related proteins are found as components of the type II secretion (T2S) system, where they are called pseudopilins; of DNA uptake/competence systems in both Gram-negative and Gram-positive species; and of flagella, pili, and sugar-binding systems in the archaea. This broad distribution of a single protein family implies both a common evolutionary origin and a highly adaptable functional plan. The type IV pilin is a remarkably versatile architectural module that has been adopted widely for a variety of functions, including motility, attachment to chemically diverse surfaces, electrical conductance, acquisition of DNA, and secretion of a broad range of structurally distinct protein substrates. In this review, we consider recent advances in this research area, from structural revelations to insights into diversity, posttranslational modifications, regulation, and function.
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21
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Yuen ASW, Kolappan S, Ng D, Craig L. Structure and secretion of CofJ, a putative colonization factor of enterotoxigenic Escherichia coli. Mol Microbiol 2013; 90:898-918. [PMID: 24106767 DOI: 10.1111/mmi.12407] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2013] [Indexed: 01/19/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) colonize the human gut, causing severe cholera-like diarrhoea. ETEC utilize a diverse array of pili and fimbriae for host colonization, including the Type IVb pilus CFA/III. The CFA/III pilus machinery is encoded on the cof operon, which is similar in gene sequence and synteny to the tcp operon that encodes another Type IVb pilus, the Vibrio cholerae toxin co-regulated pilus (TCP). Both pilus operons possess a syntenic gene encoding a protein of unknown function. In V. cholerae, this protein, TcpF, is a critical colonization factor secreted by the TCP apparatus. Here we show that the corresponding ETEC protein, CofJ, is a soluble protein secreted via the CFA/III apparatus. We present a 2.6 Å resolution crystal structure of CofJ, revealing a large β-sandwich protein that bears no sequence or structural homology to TcpF. CofJ has a cluster of exposed hydrophobic side-chains at one end and structural homology to the pore-forming proteins perfringolysin O and α-haemolysin. CofJ binds to lipid vesicles and epithelial cells, suggesting a role in membrane attachment during ETEC colonization.
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Affiliation(s)
- Alex S W Yuen
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
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22
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Korotkov KV, Delarosa JR, Hol WGJ. A dodecameric ring-like structure of the N0 domain of the type II secretin from enterotoxigenic Escherichia coli. J Struct Biol 2013; 183:354-362. [PMID: 23820381 DOI: 10.1016/j.jsb.2013.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 06/24/2013] [Accepted: 06/24/2013] [Indexed: 01/06/2023]
Abstract
In many bacteria, secretins from the type II secretion system (T2SS) function as outer membrane gated channels that enable passage of folded proteins from the periplasm into the extracellular milieu. Cryo-electron microscopy of the T2SS secretin GspD revealed previously the dodecameric cylindrical architecture of secretins, and crystal structures of periplasmic secretin domains showed a modular domain organization. However, no high-resolution experimental data has as yet been provided about how the entire T2SS secretin or its domains are organized in a cylindrical fashion. Here we present a crystal structure of the N0 domain of the T2SS secretin GspD from enterotoxigenic Escherichia coli containing a helix with 12 subunits per turn. The helix has an outer diameter of ∼125Å and a pitch of only 24Å which suggests a model of a cylindrical dodecameric N0 ring whose dimensions correspond with the cryo-electron microscopy map of Vibrio cholerae GspD. The N0 domain is known to interact with the HR domain of the inner membrane T2SS protein GspC. When the new N0 ring model is combined with the known N0·HR crystal structure, a dodecameric double-ring of twelve N0-HR heterodimers is obtained. In contrast, the previously observed compact N0-N1 GspD module is not compatible with the N0 ring. Interestingly, a N0-N1 T3SS homolog is compatible with forming a N0-N1 dodecameric ring, due to a different N0-vs-N1 orientation. This suggests that the dodecameric N0 ring is an important feature of T2SS secretins with periplasmic domains undergoing considerable motions during exoprotein translocation.
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Affiliation(s)
- Konstantin V Korotkov
- Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, United States
| | - Jaclyn R Delarosa
- Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, United States
| | - Wim G J Hol
- Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, United States.
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23
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Dunstan RA, Heinz E, Wijeyewickrema LC, Pike RN, Purcell AW, Evans TJ, Praszkier J, Robins-Browne RM, Strugnell RA, Korotkov KV, Lithgow T. Assembly of the type II secretion system such as found in Vibrio cholerae depends on the novel Pilotin AspS. PLoS Pathog 2013; 9:e1003117. [PMID: 23326233 PMCID: PMC3542185 DOI: 10.1371/journal.ppat.1003117] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 11/20/2012] [Indexed: 12/18/2022] Open
Abstract
The Type II Secretion System (T2SS) is a molecular machine that drives the secretion of fully-folded protein substrates across the bacterial outer membrane. A key element in the machinery is the secretin: an integral, multimeric outer membrane protein that forms the secretion pore. We show that three distinct forms of T2SSs can be distinguished based on the sequence characteristics of their secretin pores. Detailed comparative analysis of two of these, the Klebsiella-type and Vibrio-type, showed them to be further distinguished by the pilotin that mediates their transport and assembly into the outer membrane. We have determined the crystal structure of the novel pilotin AspS from Vibrio cholerae, demonstrating convergent evolution wherein AspS is functionally equivalent and yet structurally unrelated to the pilotins found in Klebsiella and other bacteria. AspS binds to a specific targeting sequence in the Vibrio-type secretins, enhances the kinetics of secretin assembly, and homologs of AspS are found in all species of Vibrio as well those few strains of Escherichia and Shigella that have acquired a Vibrio-type T2SS. The type 2 secretion system (T2SS) is a sophisticated, multi-component molecular machine that drives the secretion of fully-folded protein substrates across the bacterial outer membrane. In Vibrio cholerae, for example, the T2SS mediates the secretion of cholera toxin. We find that there are three distinct forms of T2SS, based on the sequence characteristics of the secretin. A targeting paradigm, developed for the Klebsiella-type secretin PulD, could not previously be applied to the T2SS in Vibrio cholerae and many other bacterial species whose genomes encode no homolog of the crucial targeting factor PulS (also called OutS, EtpO or GspS). Using bioinformatics we find, remarkably, that these bacteria have instead evolved a structurally distinct protein to serve in place of PulS. We crystallized and solved the structure of this distinct factor, AspS, measured its activity in novel assays for T2SS assembly, and show that the protein is essential for the function of the Vibrio-type T2SS. A structural homolog of AspS found here in Pseudomonas suggests widespread use of the pilotin-secretin targeting paradigm for T2SS assembly.
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Affiliation(s)
- Rhys A. Dunstan
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Eva Heinz
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
- Victorian Bioinformatics Consortium, Monash University, Melbourne, Australia
| | | | - Robert N. Pike
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Anthony W. Purcell
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Timothy J. Evans
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Judyta Praszkier
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Australia
- Monash Institute of Medical Research, Melbourne, Australia
| | - Roy M. Robins-Browne
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Australia
- Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Richard A. Strugnell
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Australia
| | - Konstantin V. Korotkov
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail: (KVK); (TL)
| | - Trevor Lithgow
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
- * E-mail: (KVK); (TL)
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24
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Bücking C, Piepenbrock A, Kappler A, Gescher J. Outer-membrane cytochrome-independent reduction of extracellular electron acceptors in Shewanella oneidensis. Microbiology (Reading) 2012; 158:2144-2157. [DOI: 10.1099/mic.0.058404-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Clemens Bücking
- Institut für angewandte Biowissenschaften, Angewandte Biologie, Karlsruher Institut für Technologie, Fritz-Haber-Weg 2, D-76131 Karlsruhe, Germany
| | - Annette Piepenbrock
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Sigwartstrasse 10, D-72076 Tübingen, Germany
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Sigwartstrasse 10, D-72076 Tübingen, Germany
| | - Johannes Gescher
- Institut für angewandte Biowissenschaften, Angewandte Biologie, Karlsruher Institut für Technologie, Fritz-Haber-Weg 2, D-76131 Karlsruhe, Germany
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25
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Douzi B, Filloux A, Voulhoux R. On the path to uncover the bacterial type II secretion system. Philos Trans R Soc Lond B Biol Sci 2012; 367:1059-72. [PMID: 22411978 DOI: 10.1098/rstb.2011.0204] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Gram-negative bacteria have evolved several secretory pathways to release enzymes or toxins into the surrounding environment or into the target cells. The type II secretion system (T2SS) is conserved in Gram-negative bacteria and involves a set of 12 to 16 different proteins. Components of the T2SS are located in both the inner and outer membranes where they assemble into a supramolecular complex spanning the bacterial envelope, also called the secreton. The T2SS substrates transiently go through the periplasm before they are translocated across the outer membrane and exposed to the extracellular milieu. The T2SS is unique in its ability to promote secretion of large and sometimes multimeric proteins that are folded in the periplasm. The present review describes recently identified protein-protein interactions together with structural and functional advances in the field that have contributed to improve our understanding on how the type II secretion apparatus assembles and on the role played by individual proteins of this highly sophisticated system.
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Affiliation(s)
- Badreddine Douzi
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (CNRS-LISM-UPR 9027), Aix-Marseille Universités, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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26
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The type II secretion system: biogenesis, molecular architecture and mechanism. Nat Rev Microbiol 2012; 10:336-51. [PMID: 22466878 DOI: 10.1038/nrmicro2762] [Citation(s) in RCA: 347] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many gram-negative bacteria use the sophisticated type II secretion system (T2SS) to translocate a wide range of proteins from the periplasm across the outer membrane. The inner-membrane platform of the T2SS is the nexus of the system and orchestrates the secretion process through its interactions with the periplasmic filamentous pseudopilus, the dodecameric outer-membrane complex and a cytoplasmic secretion ATPase. Here, recent structural and biochemical information is reviewed to describe our current knowledge of the biogenesis and architecture of the T2SS and its mechanism of action.
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27
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Minor pseudopilin self-assembly primes type II secretion pseudopilus elongation. EMBO J 2011; 31:1041-53. [PMID: 22157749 DOI: 10.1038/emboj.2011.454] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 11/11/2011] [Indexed: 12/23/2022] Open
Abstract
In Gram-negative bacteria, type II secretion systems (T2SS) assemble inner membrane proteins of the major pseudopilin PulG (GspG) family into periplasmic filaments, which could drive protein secretion in a piston-like manner. Three minor pseudopilins PulI, PulJ and PulK are essential for protein secretion in the Klebsiella oxytoca T2SS, but their molecular function is unknown. Here, we demonstrate that together these proteins prime pseudopilus assembly, without actively controlling its length or secretin channel opening. Using molecular dynamics, bacterial two-hybrid assays, cysteine crosslinking and functional analysis, we show that PulI and PulJ nucleate filament assembly by forming a staggered complex in the plasma membrane. Binding of PulK to this complex results in its partial extraction from the membrane and in a 1-nm shift between their transmembrane segments, equivalent to the major pseudopilin register in the assembled PulG filament. This promotes fully efficient pseudopilus assembly and protein secretion. Therefore, we propose that PulI, PulJ and PulK self-assembly is thermodynamically coupled to the initiation of pseudopilus assembly, possibly setting the assembly machinery in motion.
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28
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Nickerson NN, Tosi T, Dessen A, Baron B, Raynal B, England P, Pugsley AP. Outer membrane targeting of secretin PulD protein relies on disordered domain recognition by a dedicated chaperone. J Biol Chem 2011; 286:38833-43. [PMID: 21878629 PMCID: PMC3234708 DOI: 10.1074/jbc.m111.279851] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 08/26/2011] [Indexed: 12/29/2022] Open
Abstract
Interaction of bacterial outer membrane secretin PulD with its dedicated lipoprotein chaperone PulS relies on a disorder-to-order transition of the chaperone binding (S) domain near the PulD C terminus. PulS interacts with purified S domain to form a 1:1 complex. Circular dichroism, one-dimensional NMR, and hydrodynamic measurements indicate that the S domain is elongated and intrinsically disordered but gains secondary structure upon binding to PulS. Limited proteolysis and mass spectrometry identified the 28 C-terminal residues of the S domain as a minimal binding site with low nanomolar affinity for PulS in vitro that is sufficient for outer membrane targeting of PulD in vivo. The region upstream of this binding site is not required for targeting or multimerization and does not interact with PulS, but it is required for secretin function in type II secretion. Although other secretin chaperones differ substantially from PulS in sequence and secondary structure, they have all adopted at least superficially similar mechanisms of interaction with their cognate secretins, suggesting that intrinsically disordered regions facilitate rapid interaction between secretins and their chaperones.
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Affiliation(s)
- Nicholas N. Nickerson
- From the Institut Pasteur, Molecular Genetics Unit, Microbiology Department, rue du Dr. Roux, 75015 Paris
- the CNRS URA2172, rue du Dr. Roux, 75015 Paris
| | - Tommaso Tosi
- the Institut de Biologie Structurale, Bacterial Pathogenesis Group, Université de Grenoble I, Rue Jules Horowitz, 38027 Grenoble
- the CNRS UMR 5075, Rue Jules Horowitz, 38027 Grenoble
- the Commissariat à l'Enérgie Atomique, Rue Jules Horowitz, 38027 Grenoble
| | - Andréa Dessen
- the Institut de Biologie Structurale, Bacterial Pathogenesis Group, Université de Grenoble I, Rue Jules Horowitz, 38027 Grenoble
- the CNRS UMR 5075, Rue Jules Horowitz, 38027 Grenoble
- the Commissariat à l'Enérgie Atomique, Rue Jules Horowitz, 38027 Grenoble
| | - Bruno Baron
- the Institut Pasteur, Biophysics of Macromolecules and their Interactions Platform, Proteopole and Structural Biology and Chemistry Department, rue du Dr. Roux, 75015 Paris, and
- the CNRS URA2185, rue du Dr. Roux, 75015 Paris, France
| | - Bertrand Raynal
- the Institut Pasteur, Biophysics of Macromolecules and their Interactions Platform, Proteopole and Structural Biology and Chemistry Department, rue du Dr. Roux, 75015 Paris, and
- the CNRS URA2185, rue du Dr. Roux, 75015 Paris, France
| | - Patrick England
- the Institut Pasteur, Biophysics of Macromolecules and their Interactions Platform, Proteopole and Structural Biology and Chemistry Department, rue du Dr. Roux, 75015 Paris, and
- the CNRS URA2185, rue du Dr. Roux, 75015 Paris, France
| | - Anthony P. Pugsley
- From the Institut Pasteur, Molecular Genetics Unit, Microbiology Department, rue du Dr. Roux, 75015 Paris
- the CNRS URA2172, rue du Dr. Roux, 75015 Paris
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29
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Filloux A. Protein Secretion Systems in Pseudomonas aeruginosa: An Essay on Diversity, Evolution, and Function. Front Microbiol 2011; 2:155. [PMID: 21811488 PMCID: PMC3140646 DOI: 10.3389/fmicb.2011.00155] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 07/01/2011] [Indexed: 12/25/2022] Open
Abstract
Protein secretion systems are molecular nanomachines used by Gram-negative bacteria to thrive within their environment. They are used to release enzymes that hydrolyze complex carbon sources into usable compounds, or to release proteins that capture essential ions such as iron. They are also used to colonize and survive within eukaryotic hosts, causing acute or chronic infections, subverting the host cell response and escaping the immune system. In this article, the opportunistic human pathogen Pseudomonas aeruginosa is used as a model to review the diversity of secretion systems that bacteria have evolved to achieve these goals. This diversity may result from a progressive transformation of cell envelope complexes that initially may not have been dedicated to secretion. The striking similarities between secretion systems and type IV pili, flagella, bacteriophage tail, or efflux pumps is a nice illustration of this evolution. Differences are also needed since various secretion configurations call for diversity. For example, some proteins are released in the extracellular medium while others are directly injected into the cytosol of eukaryotic cells. Some proteins are folded before being released and transit into the periplasm. Other proteins cross the whole cell envelope at once in an unfolded state. However, the secretion system requires conserved basic elements or features. For example, there is a need for an energy source or for an outer membrane channel. The structure of this review is thus quite unconventional. Instead of listing secretion types one after each other, it presents a melting pot of concepts indicating that secretion types are in constant evolution and use basic principles. In other words, emergence of new secretion systems could be predicted the way Mendeleïev had anticipated characteristics of yet unknown elements.
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Affiliation(s)
- Alain Filloux
- Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, Imperial College London London, UK
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Abstract
The dimeric OspC/Vsp family surface lipoproteins of Borrelia spirochetes are crucial to the transmission and persistence of Lyme borreliosis and tick-borne relapsing fever. However, the requirements for their proper surface display remained undefined. In previous studies, we showed that localization of Borrelia burgdorferi monomeric surface lipoprotein OspA was dependent on residues in the N-terminal "tether" peptide. Here, site-directed mutagenesis of the B. burgdorferi OspC tether revealed two distinct regions affecting either release from the inner membrane or translocation through the outer membrane. Determinants of both of these steps appear consolidated within a single region of the Borrelia turicatae Vsp1 tether. Periplasmic OspC mutants still were able to form dimers. Their localization defect could be rescued by the addition of an apparently structure-destabilizing C-terminal epitope tag but not by coexpression with wild-type OspC. Furthermore, disruption of intermolecular Vsp1 salt bridges blocked dimerization but not surface localization of the resulting Vsp1 monomers. Together, these results suggest that Borrelia OspC/Vsp1 surface lipoproteins traverse the periplasm and the outer membrane as unfolded monomeric intermediates and assemble into their functional multimeric folds only upon reaching the spirochetal surface.
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Structure of the cholera toxin secretion channel in its closed state. Nat Struct Mol Biol 2010; 17:1226-32. [PMID: 20852644 PMCID: PMC2950906 DOI: 10.1038/nsmb.1910] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 07/27/2010] [Indexed: 01/26/2023]
Abstract
The type II secretion system (T2SS) is a macromolecular complex spanning the inner and outer membranes of Gram-negative bacteria. Remarkably, the T2SS secretes folded proteins, including multimeric assemblies such as cholera toxin and heat-labile enterotoxin from Vibrio cholerae and enterotoxigenic Escherichia coli, respectively. The major outer membrane T2SS protein is the 'secretin' GspD. Cryo-EM reconstruction of the V. cholerae secretin at 19-Å resolution reveals a dodecameric structure reminiscent of a barrel, with a large channel at its center that contains a closed periplasmic gate. The GspD periplasmic domain forms a vestibule with a conserved constriction, and it binds to a pentameric exoprotein and to the trimeric tip of the T2SS pseudopilus. By combining our results with structures of the cholera toxin and T2SS pseudopilus tip, we provide a structural basis for a possible secretion mechanism of the T2SS.
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Detailed structural and assembly model of the type II secretion pilus from sparse data. Proc Natl Acad Sci U S A 2010; 107:13081-6. [PMID: 20616068 DOI: 10.1073/pnas.1001703107] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many gram-negative bacteria secrete specific proteins via the type II secretion systems (T2SS). These complex machineries share with the related archaeal flagella and type IV pilus (T4P) biogenesis systems the ability to assemble thin, flexible filaments composed of small, initially inner membrane-localized proteins called "pilins." In the T2SS from Klebsiella oxytoca, periplasmic pseudopili that are essential for pullulanase (PulA) secretion extend beyond the bacterial surface and form pili when the major pilin PulG is overproduced. Here, we describe the detailed, experimentally validated structure of the PulG pilus generated from crystallographic and electron microscopy data by a molecular modeling approach. Two intermolecular salt bridges crucial for function were demonstrated using single and complementary charge inversions. Double-cysteine substitutions in the transmembrane segment of PulG led to position-specific cross-linking of protomers in assembled pili. These biochemical data provided information on residue distances in the filament that were used to derive a refined model of the T2SS pilus at pseudoatomic resolution. PulG is organized as a right-handed helix of subunits, consistent with protomer organization in gonococcal T4P. The conserved character of residues involved in key hydrophobic and electrostatic interactions within the major pseudopilin family supports the general relevance of this model for T2SS pseudopilus structure.
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Secretion signal and protein targeting in bacteria: a biological puzzle. J Bacteriol 2010; 192:3847-9. [PMID: 20525826 DOI: 10.1128/jb.00565-10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Schulze RJ, Chen S, Kumru OS, Zückert WR. Translocation of Borrelia burgdorferi surface lipoprotein OspA through the outer membrane requires an unfolded conformation and can initiate at the C-terminus. Mol Microbiol 2010; 76:1266-78. [PMID: 20398211 DOI: 10.1111/j.1365-2958.2010.07172.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: 11/28/2022]
Abstract
Borrelia burgdorferi surface lipoproteins are essential to the pathogenesis of Lyme borreliosis, but the mechanisms responsible for their localization are only beginning to emerge. We have previously demonstrated the critical nature of the amino-terminal 'tether' domain of the mature lipoprotein for sorting a fluorescent reporter to the Borrelia cell surface. Here, we show that individual deletion of four contiguous residues within the tether of major surface lipoprotein OspA results in its inefficient translocation across the Borrelia outer membrane. Intriguingly, C-terminal epitope tags of these N-terminal deletion mutants were selectively surface-exposed. Fold-destabilizing C-terminal point mutations and deletions did not block OspA secretion, but rather restored one of the otherwise periplasmic tether mutants to the bacterial surface. Together, these data indicate that disturbance of a confined tether feature leads to premature folding of OspA in the periplasm and thereby prevents secretion through the outer membrane. Furthermore, they suggest that OspA emerges tail-first on the bacterial surface, yet independent of a specific C-terminal targeting peptide sequence.
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Affiliation(s)
- Ryan J Schulze
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Mail Stop 3029, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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Cianciotto NP. Many substrates and functions of type II secretion: lessons learned from Legionella pneumophila. Future Microbiol 2009; 4:797-805. [PMID: 19722835 DOI: 10.2217/fmb.09.53] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Type II secretion is one of six systems that exist in Gram-negative bacteria for the purpose of secreting proteins into the extracellular milieu and/or into host cells. This article will review the various recent studies of Legionella pneumophila that have increased our appreciation of the numbers, types and novelties of proteins that can be secreted via the type II system, as well as the many ways in which type II secretion can promote bacterial physiology, growth, ecology, intracellular infection and virulence. In this context, type II secretion represents a potentially important target for industrial and biomedical applications.
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Affiliation(s)
- Nicholas P Cianciotto
- Department of Microbiology & Immunology, Northwestern University Medical School, 320 East Superior St., Chicago, IL 60611, USA.
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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
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Genetic mapping of secretion and functional determinants of the Vibrio cholerae TcpF colonization factor. J Bacteriol 2009; 191:3665-76. [PMID: 19304855 DOI: 10.1128/jb.01724-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Colonization of the human small intestine by Vibrio cholerae requires the type IV toxin-coregulated pilus (TCP). TcpF, which is encoded within the tcp operon, is secreted from the bacterial cell by the TCP apparatus and is also essential for colonization. Bacteria lacking tcpF are deficient in colonization, and anti-TcpF antibodies are protective in the infant mouse cholera model. In order to elucidate the regions of the protein that are required for secretion through the TCP apparatus and for its function in colonization, random mutagenesis of tcpF was performed. Analysis of these mutants suggests that multiple regions throughout the protein influence extracellular secretion and that determinants near the C terminus are important for the function of TcpF in colonization. The TcpF proteins of certain environmental V. cholerae isolates with 31% to 66% identity to pathogenic V. cholerae TcpF showed higher similarity in regions identified as secretion determinants but diverged in regions found to be important for colonization. These environmental TcpF proteins are secreted from the pathogenic strain; however, they do not mediate colonization in the infant mouse model. Here we provide genetic evidence pointing toward regions of TcpF that influence secretion, as well as regions that play an important role in in vivo colonization.
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Munera D, Palomino C, Fernández LÁ. Specific residues in the N-terminal domain of FimH stimulate type 1 fimbriae assembly inEscherichia colifollowing the initial binding of the adhesin to FimD usher. Mol Microbiol 2008; 69:911-25. [DOI: 10.1111/j.1365-2958.2008.06325.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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39
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Direct involvement of type II secretion system in extracellular translocation of Shewanella oneidensis outer membrane cytochromes MtrC and OmcA. J Bacteriol 2008; 190:5512-6. [PMID: 18502849 DOI: 10.1128/jb.00514-08] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MtrC and OmcA are cell surface-exposed lipoproteins important for reducing solid metal oxides. Deletions of type II secretion system (T2SS) genes reduced their extracellular release and their accessibility to the proteinase K treatment, demonstrating the direct involvement of T2SS in translocation of MtrC and OmcA to the bacterial cell surface.
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Shi L, Squier TC, Zachara JM, Fredrickson JK. Respiration of metal (hydr)oxides by Shewanella and Geobacter: a key role for multihaem c-type cytochromes. Mol Microbiol 2007; 65:12-20. [PMID: 17581116 PMCID: PMC1974784 DOI: 10.1111/j.1365-2958.2007.05783.x] [Citation(s) in RCA: 425] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobacter sulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer electrons from the inner membrane quinone/quinol pool through the periplasm to the outer membrane. The type II secretion system of S. oneidensis MR-1 has been implicated in the reduction of metal (hydr)oxides, most likely by translocating decahaem c-Cyts MtrC and OmcA across outer membrane to the surface of bacterial cells where they form a protein complex. The extracellular MtrC and OmcA can directly reduce solid metal (hydr)oxides. Likewise, outer membrane multihaem c-Cyts OmcE and OmcS of G. sulfurreducens are suggested to transfer electrons from outer membrane to type IV pili that are hypothesized to relay the electrons to solid metal (hydr)oxides. Thus, multihaem c-Cyts play critical roles in S. oneidensis MR-1- and G. sulfurreducens-mediated dissimilatory reduction of solid metal (hydr)oxides by facilitating ET across the bacterial cell envelope.
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Affiliation(s)
- Liang Shi
- For corresspondence. *E-mail ; Tel. (+1) 509 376 4834; Fax (+1) 509 372 1632
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Saier MH. Protein Secretion and Membrane Insertion Systems in Gram-Negative Bacteria. J Membr Biol 2007; 214:75-90. [PMID: 17546510 DOI: 10.1007/s00232-006-0049-7] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 11/07/2006] [Indexed: 12/30/2022]
Abstract
In contrast to other organisms, gram-negative bacteria have evolved numerous systems for protein export. Eight types are known that mediate export across or insertion into the cytoplasmic membrane, while eight specifically mediate export across or insertion into the outer membrane. Three of the former secretory pathway (SP) systems, type I SP (ISP, ABC), IIISP (Fla/Path) and IVSP (Conj/Vir), can export proteins across both membranes in a single energy-coupled step. A fourth generalized mechanism for exporting proteins across the two-membrane envelope in two distinct steps (which we here refer to as type II secretory pathways [IISP]) utilizes either the general secretory pathway (GSP or Sec) or the twin-arginine targeting translocase for translocation across the inner membrane, and either the main terminal branch or one of several protein-specific export systems for translocation across the outer membrane. We here survey the various well-characterized protein translocation systems found in living organisms and then focus on the systems present in gram-negative bacteria. Comparisons between these systems suggest specific biogenic, mechanistic and evolutionary similarities as well as major differences.
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Affiliation(s)
- Milton H Saier
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA.
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Hodak H, Clantin B, Willery E, Villeret V, Locht C, Jacob-Dubuisson F. Secretion signal of the filamentous haemagglutinin, a model two-partner secretion substrate. Mol Microbiol 2006; 61:368-82. [PMID: 16771844 DOI: 10.1111/j.1365-2958.2006.05242.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The sorting of proteins to their proper subcellular compartment requires specific addressing signals that mediate interactions with ad hoc transport machineries. In Gram-negative bacteria, the widespread two-partner secretion (TPS) pathway is dedicated to the secretion of large, mostly virulence-related proteins. The secreted TpsA proteins carry a characteristic 250-residue-long N-terminal 'TPS domain' essential for secretion, while their TpsB transporters are pore-forming proteins that specifically recognize their respective TpsA partners and mediate their translocation across the outer membrane. However, the nature of the secretion signal has not been elucidated yet. The whooping cough agent Bordetella pertussis secretes its major adhesin filamentous haemagglutinin (FHA) via the TpsB transporter FhaC. In this work, we show specific interactions between an N-terminal fragment of FHA containing the TPS domain and FhaC by using two different techniques, an overlay assay and a pull-down of the complex. FhaC recognizes only non-native conformations of the TPS domain, corroborating the model that in vivo, periplasmic FHA is not yet folded. By generating single amino acid substitutions, we have identified interaction determinants forming the secretion signal. They are found unexpectedly far into the TPS domain and include both conserved and variable residues, which most likely explains the specificity of the TpsA-TpsB interaction. The N-terminal domain of FhaC is involved in the FHA-FhaC interaction, in agreement with its proposed function and periplasmic localization.
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Affiliation(s)
- Hélène Hodak
- INSERM U629, 1 rue Calmette, F-59019 Lille Cedex, France
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Abstract
Borrelia spirochaetes are unique among diderm bacteria in their abundance of surface-displayed lipoproteins, some of which play important roles in the pathogenesis of Lyme disease and relapsing fever. To identify the lipoprotein-sorting signals in Borrelia burgdorferi, we generated chimeras between the outer surface lipoprotein OspA, the periplasmic oligopeptide-binding lipoprotein OppAIV and mRFP1, a monomeric red fluorescent reporter protein. Localization of OspA and OppAIV point mutants showed that Borrelia lipoproteins do not follow the '+2' sorting rule which targets lipoproteins to the cytoplasmic or outer membrane of Gram-negative bacteria via the Lol pathway. Fusions of mRFP1 to short N-terminal lipopeptides of OspA, and surprisingly OppAIV, were targeted to the spirochaetal surface. Mutagenesis of the OspA N-terminus defined less than five N-terminal amino acids as the minimal secretion-facilitating signal. With the exception of negative charges, which can act as partial subsurface retention signals in certain peptide contexts, lipoprotein secretion occurs independent of N-terminal sequence. Together, these data indicate that Borrelia lipoproteins are targeted to the bacterial surface by default, but can be retained in the periplasm by sequence-specific signals.
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Affiliation(s)
- Ryan J Schulze
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Mail Stop 3029, 3901 Rainbow Boulevard, Kansas City, 66160, USA
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