51
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Lasica AM, Ksiazek M, Madej M, Potempa J. The Type IX Secretion System (T9SS): Highlights and Recent Insights into Its Structure and Function. Front Cell Infect Microbiol 2017. [PMID: 28603700 DOI: 10.3389/fcimb.2017.00215.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Protein secretion systems are vital for prokaryotic life, as they enable bacteria to acquire nutrients, communicate with other species, defend against biological and chemical agents, and facilitate disease through the delivery of virulence factors. In this review, we will focus on the recently discovered type IX secretion system (T9SS), a complex translocon found only in some species of the Bacteroidetes phylum. T9SS plays two roles, depending on the lifestyle of the bacteria. It provides either a means of movement (called gliding motility) for peace-loving environmental bacteria or a weapon for pathogens. The best-studied members of these two groups are Flavobacterium johnsoniae, a commensal microorganism often found in water and soil, and Porphyromonas gingivalis, a human oral pathogen that is a major causative agent of periodontitis. In P. gingivalis and some other periodontopathogens, T9SS translocates proteins, especially virulence factors, across the outer membrane (OM). Proteins destined for secretion bear a conserved C-terminal domain (CTD) that directs the cargo to the OM translocon. At least 18 proteins are involved in this still enigmatic process, with some engaged in the post-translational modification of T9SS cargo proteins. Upon translocation across the OM, the CTD is removed by a protease with sortase-like activity and an anionic LPS is attached to the newly formed C-terminus. As a result, a cargo protein could be secreted into the extracellular milieu or covalently attached to the bacterial surface. T9SS is regulated by a two-component system; however, the precise environmental signal that triggers it has not been identified. Exploring unknown systems contributing to bacterial virulence is exciting, as it may eventually lead to new therapeutic strategies. During the past decade, the major components of T9SS were identified, as well as hints suggesting the possible mechanism of action. In addition, the list of characterized cargo proteins is constantly growing. The actual structure of the translocon, situated in the OM of bacteria, remains the least explored area; however, new technical approaches and increasing scientific attention have resulted in a growing body of data. Therefore, we present a compact up-to-date review of this topic.
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Affiliation(s)
- Anna M Lasica
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of DentistryLouisville, KY, United States.,Department of Bacterial Genetics, Faculty of Biology, Institute of Microbiology, University of WarsawWarsaw, Poland
| | - Miroslaw Ksiazek
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of DentistryLouisville, KY, United States.,Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian UniversityKrakow, Poland
| | - Mariusz Madej
- Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian UniversityKrakow, Poland
| | - Jan Potempa
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of DentistryLouisville, KY, United States.,Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian UniversityKrakow, Poland
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52
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Lasica AM, Ksiazek M, Madej M, Potempa J. The Type IX Secretion System (T9SS): Highlights and Recent Insights into Its Structure and Function. Front Cell Infect Microbiol 2017; 7:215. [PMID: 28603700 PMCID: PMC5445135 DOI: 10.3389/fcimb.2017.00215] [Citation(s) in RCA: 174] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/11/2017] [Indexed: 12/11/2022] Open
Abstract
Protein secretion systems are vital for prokaryotic life, as they enable bacteria to acquire nutrients, communicate with other species, defend against biological and chemical agents, and facilitate disease through the delivery of virulence factors. In this review, we will focus on the recently discovered type IX secretion system (T9SS), a complex translocon found only in some species of the Bacteroidetes phylum. T9SS plays two roles, depending on the lifestyle of the bacteria. It provides either a means of movement (called gliding motility) for peace-loving environmental bacteria or a weapon for pathogens. The best-studied members of these two groups are Flavobacterium johnsoniae, a commensal microorganism often found in water and soil, and Porphyromonas gingivalis, a human oral pathogen that is a major causative agent of periodontitis. In P. gingivalis and some other periodontopathogens, T9SS translocates proteins, especially virulence factors, across the outer membrane (OM). Proteins destined for secretion bear a conserved C-terminal domain (CTD) that directs the cargo to the OM translocon. At least 18 proteins are involved in this still enigmatic process, with some engaged in the post-translational modification of T9SS cargo proteins. Upon translocation across the OM, the CTD is removed by a protease with sortase-like activity and an anionic LPS is attached to the newly formed C-terminus. As a result, a cargo protein could be secreted into the extracellular milieu or covalently attached to the bacterial surface. T9SS is regulated by a two-component system; however, the precise environmental signal that triggers it has not been identified. Exploring unknown systems contributing to bacterial virulence is exciting, as it may eventually lead to new therapeutic strategies. During the past decade, the major components of T9SS were identified, as well as hints suggesting the possible mechanism of action. In addition, the list of characterized cargo proteins is constantly growing. The actual structure of the translocon, situated in the OM of bacteria, remains the least explored area; however, new technical approaches and increasing scientific attention have resulted in a growing body of data. Therefore, we present a compact up-to-date review of this topic.
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Affiliation(s)
- Anna M Lasica
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of DentistryLouisville, KY, United States.,Department of Bacterial Genetics, Faculty of Biology, Institute of Microbiology, University of WarsawWarsaw, Poland
| | - Miroslaw Ksiazek
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of DentistryLouisville, KY, United States.,Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian UniversityKrakow, Poland
| | - Mariusz Madej
- Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian UniversityKrakow, Poland
| | - Jan Potempa
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of DentistryLouisville, KY, United States.,Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian UniversityKrakow, Poland
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53
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Hendrickson EL, Beck DAC, Miller DP, Wang Q, Whiteley M, Lamont RJ, Hackett M. Insights into Dynamic Polymicrobial Synergy Revealed by Time-Coursed RNA-Seq. Front Microbiol 2017; 8:261. [PMID: 28293219 PMCID: PMC5329018 DOI: 10.3389/fmicb.2017.00261] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 02/07/2017] [Indexed: 01/31/2023] Open
Abstract
Many bacterial infections involve polymicrobial communities in which constituent organisms are synergistically pathogenic. Periodontitis, a commonly occurring chronic inflammatory disorder, is induced by multispecies bacterial communities. The periodontal keystone pathogen Porphyromonas gingivalis and the accessory pathogen Streptococcus gordonii exhibit polymicrobial synergy in animal models of disease. Mechanisms of co-adhesion and community formation by P. gingivalis and S. gordonii are well-established; however, little is known regarding the basis for increased pathogenicity. In this study we used time-coursed RNA-Seq to comprehensively and quantitatively examine the dynamic transcriptional landscape of P. gingivalis in a model consortium with S. gordonii. Genes encoding a number of potential virulence determinants had higher relative mRNA levels in the context of dual species model communities than P. gingivalis alone, including adhesins, the Type IX secretion apparatus, and tetratricopeptide repeat (TPR) motif proteins. In contrast, genes encoding conjugation systems and many of the stress responses showed lower levels of expression in P. gingivalis. A notable exception to reduced abundance of stress response transcripts was the genes encoding components of the oxidative stress-related OxyR regulon, indicating an adaptation of P. gingivalis to detoxify peroxide produced by the streptococcus. Collectively, the results are consistent with evolutionary adaptation of P. gingivalis to a polymicrobial oral environment, one outcome of which is increased pathogenic potential.
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Affiliation(s)
- Erik L Hendrickson
- Center for Microbial Proteomics and Chemical Engineering, University of Washington Seattle, WA, USA
| | - David A C Beck
- Center for Microbial Proteomics and Chemical Engineering, University of WashingtonSeattle, WA, USA; eScience Institute, University of WashingtonSeattle, WA, USA
| | - Daniel P Miller
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry Louisville, KY, USA
| | - Qian Wang
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry Louisville, KY, USA
| | - Marvin Whiteley
- Department of Molecular Biosciences, University of Texas at Austin Austin, TX, USA
| | - Richard J Lamont
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry Louisville, KY, USA
| | - Murray Hackett
- Center for Microbial Proteomics and Chemical Engineering, University of Washington Seattle, WA, USA
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54
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Pomowski A, Usón I, Nowakowska Z, Veillard F, Sztukowska MN, Guevara T, Goulas T, Mizgalska D, Nowak M, Potempa B, Huntington JA, Potempa J, Gomis-Rüth FX. Structural insights unravel the zymogenic mechanism of the virulence factor gingipain K from Porphyromonas gingivalis, a causative agent of gum disease from the human oral microbiome. J Biol Chem 2017; 292:5724-5735. [PMID: 28196869 DOI: 10.1074/jbc.m117.776724] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 02/06/2017] [Indexed: 01/11/2023] Open
Abstract
Skewing of the human oral microbiome causes dysbiosis and preponderance of bacteria such as Porphyromonas gingivalis, the main etiological agent of periodontitis. P. gingivalis secretes proteolytic gingipains (Kgp and RgpA/B) as zymogens inhibited by a pro-domain that is removed during extracellular activation. Unraveling the molecular mechanism of Kgp zymogenicity is essential to design inhibitors blocking its activity. Here, we found that the isolated 209-residue Kgp pro-domain is a boomerang-shaped all-β protein similar to the RgpB pro-domain. Using composite structural information of Kgp and RgpB, we derived a plausible homology model and mechanism of Kgp-regulating zymogenicity. Accordingly, the pro-domain would laterally attach to the catalytic moiety in Kgp and block the active site through an exposed inhibitory loop. This loop features a lysine (Lys129) likely occupying the S1 specificity pocket and exerting latency. Lys129 mutation to glutamate or arginine led to misfolded protein that was degraded in vivo Mutation to alanine gave milder effects but still strongly diminished proteolytic activity, without affecting the subcellular location of the enzyme. Accordingly, the interactions of Lys129 within the S1 pocket are also essential for correct folding. Uniquely for gingipains, the isolated Kgp pro-domain dimerized through an interface, which partially overlapped with that between the catalytic moiety and the pro-domain within the zymogen, i.e. both complexes are mutually exclusive. Thus, pro-domain dimerization, together with partial rearrangement of the active site upon activation, explains the lack of inhibition of the pro-domain in trans. Our results reveal that the specific latency mechanism of Kgp differs from those of Rgps.
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Affiliation(s)
- Anja Pomowski
- From the Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom
| | - Isabel Usón
- the Proteolysis Lab and Crystallographic Methods Lab, Structural Biology Unit, "María de Maeztu" Unit of Excellence, Molecular Biology Institute of Barcelona, Consejo Superior de Investigaciones Científicas, 08028 Barcelona, Catalonia, Spain.,the Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Catalonia, Spain
| | - Zuzanna Nowakowska
- the Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland, and
| | - Florian Veillard
- the Department of Oral Immunology and Infectious Disease, University of Louisville School of Dentistry, Louisville, Kentucky 40202
| | - Maryta N Sztukowska
- the Department of Oral Immunology and Infectious Disease, University of Louisville School of Dentistry, Louisville, Kentucky 40202
| | - Tibisay Guevara
- the Proteolysis Lab and Crystallographic Methods Lab, Structural Biology Unit, "María de Maeztu" Unit of Excellence, Molecular Biology Institute of Barcelona, Consejo Superior de Investigaciones Científicas, 08028 Barcelona, Catalonia, Spain
| | - Theodoros Goulas
- the Proteolysis Lab and Crystallographic Methods Lab, Structural Biology Unit, "María de Maeztu" Unit of Excellence, Molecular Biology Institute of Barcelona, Consejo Superior de Investigaciones Científicas, 08028 Barcelona, Catalonia, Spain
| | - Danuta Mizgalska
- the Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland, and
| | - Magdalena Nowak
- the Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland, and
| | - Barbara Potempa
- the Department of Oral Immunology and Infectious Disease, University of Louisville School of Dentistry, Louisville, Kentucky 40202
| | - James A Huntington
- From the Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom
| | - Jan Potempa
- the Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland, and .,the Department of Oral Immunology and Infectious Disease, University of Louisville School of Dentistry, Louisville, Kentucky 40202
| | - F Xavier Gomis-Rüth
- the Proteolysis Lab and Crystallographic Methods Lab, Structural Biology Unit, "María de Maeztu" Unit of Excellence, Molecular Biology Institute of Barcelona, Consejo Superior de Investigaciones Científicas, 08028 Barcelona, Catalonia, Spain,
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Vincent MS, Canestrari MJ, Leone P, Stathopulos J, Ize B, Zoued A, Cambillau C, Kellenberger C, Roussel A, Cascales E. Characterization of the Porphyromonas gingivalis Type IX Secretion Trans-envelope PorKLMNP Core Complex. J Biol Chem 2017; 292:3252-3261. [PMID: 28057754 DOI: 10.1074/jbc.m116.765081] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/21/2016] [Indexed: 02/03/2023] Open
Abstract
The transport of proteins at the cell surface of Bacteroidetes depends on a secretory apparatus known as type IX secretion system (T9SS). This machine is responsible for the cell surface exposition of various proteins, such as adhesins, required for gliding motility in Flavobacterium, S-layer components in Tannerella forsythia, and tooth tissue-degrading enzymes in the oral pathogen Porphyromonas gingivalis Although a number of subunits of the T9SS have been identified, we lack details on the architecture of this secretion apparatus. Here we provide evidence that five of the genes encoding the core complex of the T9SS are co-transcribed and that the gene products are distributed in the cell envelope. Protein-protein interaction studies then revealed that these proteins oligomerize and interact through a dense network of contacts.
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Affiliation(s)
- Maxence S Vincent
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Mickaël J Canestrari
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Philippe Leone
- Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France; Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Julien Stathopulos
- Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France; Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Bérengère Ize
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Abdelrahim Zoued
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France; Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Christine Kellenberger
- Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France; Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Alain Roussel
- Architecture et Fonction des Macromolécules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France; Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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56
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Nakayama K. [The type IX secretion system and the type V pilus in the phylum Bacteroidetes]. Nihon Saikingaku Zasshi 2017; 72:219-227. [PMID: 29109335 DOI: 10.3412/jsb.72.219] [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: 06/07/2023]
Abstract
Many bacteria symbiotic and parasitic in humans are included in the genera Bacteroides, Prevotella, Porphyromonas and others, which belong to the phylum Bacteroidetes. We have been studying gingipain, a major secretory protease of Porphyromonas gingivalis which is a periodontopathogenic bacterium belonging to the genus Porphyromonas, and pili which contribute to host colonization in the bacterium. In the process, it was found that gingipain was secreted by a system not reported previously. Furthermore, this secretion system was found to exist widely in the Bacteroidetes phylum bacteria and closely related to the gliding motility of bacteroidete bacteria, and it was named the Por secretion system (later renamed the type IX secretion system). Regarding P. gingivalis pili, it was found that the pilus protein is transported as a lipoprotein to the cell surface, and the pilus formation occurs due to degradation by arginine-gingipain. Pili with this novel formation mechanism was found to be widely present in bacteria belonging to the class Bacteroidia in the phylum Bacteroidetes and was named the type V pili.
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Affiliation(s)
- Koji Nakayama
- Department of Microbiology and Oral Infection, Nagasaki University Graduate School of Biomedical Sciences
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57
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Structural and functional probing of PorZ, an essential bacterial surface component of the type-IX secretion system of human oral-microbiomic Porphyromonas gingivalis. Sci Rep 2016; 6:37708. [PMID: 27883039 PMCID: PMC5121618 DOI: 10.1038/srep37708] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/03/2016] [Indexed: 12/30/2022] Open
Abstract
Porphyromonas gingivalis is a member of the human oral microbiome abundant in dysbiosis and implicated in the pathogenesis of periodontal (gum) disease. It employs a newly described type-IX secretion system (T9SS) for secretion of virulence factors. Cargo proteins destined for secretion through T9SS carry a recognition signal in the conserved C-terminal domain (CTD), which is removed by sortase PorU during translocation. Here, we identified a novel component of T9SS, PorZ, which is essential for surface exposure of PorU and posttranslational modification of T9SS cargo proteins. These include maturation of enzyme precursors, CTD removal and attachment of anionic lipopolysaccharide for anchorage in the outer membrane. The crystal structure of PorZ revealed two β-propeller domains and a C-terminal β-sandwich domain, which conforms to the canonical CTD architecture. We further documented that PorZ is itself transported to the cell surface via T9SS as a full-length protein with its CTD intact, independently of the presence or activity of PorU. Taken together, our results shed light on the architecture and possible function of a novel component of the T9SS. Knowledge of how T9SS operates will contribute to our understanding of protein secretion as part of host-microbiome interactions by dysbiotic members of the human oral cavity.
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PG1058 Is a Novel Multidomain Protein Component of the Bacterial Type IX Secretion System. PLoS One 2016; 11:e0164313. [PMID: 27711252 PMCID: PMC5053529 DOI: 10.1371/journal.pone.0164313] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/22/2016] [Indexed: 01/10/2023] Open
Abstract
Porphyromonas gingivalis utilises the Bacteroidetes-specific type IX secretion system (T9SS) to export proteins across the outer membrane (OM), including virulence factors such as the gingipains. The secreted proteins have a conserved carboxy-terminal domain essential for type IX secretion that is cleaved upon export. In P. gingivalis the T9SS substrates undergo glycosylation with anionic lipopolysaccharide (A-LPS) and are attached to the OM. In this study, comparative analyses of 24 Bacteroidetes genomes identified ten putative novel components of the T9SS in P. gingivalis, one of which was PG1058. Computer modelling of the PG1058 structure predicted a novel N- to C-terminal architecture comprising a tetratricopeptide repeat (TPR) domain, a β-propeller domain, a carboxypeptidase regulatory domain-like fold (CRD) and an OmpA_C-like putative peptidoglycan binding domain. Inactivation of pg1058 in P. gingivalis resulted in loss of both colonial pigmentation and surface-associated proteolytic activity; a phenotype common to T9SS mutants. Immunoblot and LC-MS/MS analyses of subcellular fractions revealed T9SS substrates accumulated within the pg1058 mutant periplasm whilst whole-cell ELISA showed the Kgp gingipain was absent from the cell surface, confirming perturbed T9SS function. Immunoblot, TEM and whole-cell ELISA analyses indicated A-LPS was produced and present on the pg1058 mutant cell surface although it was not linked to T9SS substrate proteins. This indicated that PG1058 is crucial for export of T9SS substrates but not for the translocation of A-LPS. PG1058 is a predicted lipoprotein and was localised to the periplasmic side of the OM using whole-cell ELISA, immunoblot and LC-MS/MS analyses of subcellular fractions. The structural prediction and localisation of PG1058 suggests that it may have a role as an essential scaffold linking the periplasmic and OM components of the T9SS.
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59
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Vincent MS, Durand E, Cascales E. The PorX Response Regulator of the Porphyromonas gingivalis PorXY Two-Component System Does Not Directly Regulate the Type IX Secretion Genes but Binds the PorL Subunit. Front Cell Infect Microbiol 2016; 6:96. [PMID: 27630829 PMCID: PMC5005315 DOI: 10.3389/fcimb.2016.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 08/19/2016] [Indexed: 12/27/2022] Open
Abstract
The Type IX secretion system (T9SS) is a versatile multi-protein complex restricted to bacteria of the Bacteriodetes phylum and responsible for the secretion or cell surface exposition of diverse proteins that participate to S-layer formation, gliding motility or pathogenesis. The T9SS is poorly characterized but a number of proteins involved in the assembly of the secretion apparatus in the oral pathogen Porphyromonas gingivalis have been identified based on genome substractive analyses. Among these proteins, PorY, and PorX encode typical two-component system (TCS) sensor and CheY-like response regulator respectively. Although the porX and porY genes do not localize at the same genetic locus, it has been proposed that PorXY form a bona fide TCS. Deletion of porX in P. gingivalis causes a slight decrease of the expression of a number of other T9SS genes, including sov, porT, porP, porK, porL, porM, porN, and porY. Here, we show that PorX and the soluble cytoplasmic domain of PorY interact. Using electrophoretic mobility shift, DNA-protein co-purification and heterologous host expression assays, we demonstrate that PorX does not bind T9SS gene promoters and does not directly regulate expression of the T9SS genes. Finally, we show that PorX interacts with the cytoplasmic domain of PorL, a component of the T9SS membrane core complex and propose that the CheY-like PorX protein might be involved in the dynamics of the T9SS.
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Affiliation(s)
- Maxence S Vincent
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - Centre National de la Recherche Scientifique (UMR7255) Marseille, France
| | - Eric Durand
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - Centre National de la Recherche Scientifique (UMR7255) Marseille, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - Centre National de la Recherche Scientifique (UMR7255) Marseille, France
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