1
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Mizgalska D, Rodríguez-Banqueri A, Veillard F, Książęk M, Goulas T, Guevara T, Eckhard U, Potempa J, Gomis-Rüth FX. Structural and functional insights into the C-terminal signal domain of the Bacteroidetes type-IX secretion system. Open Biol 2024; 14:230448. [PMID: 38862016 DOI: 10.1098/rsob.230448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 02/20/2024] [Indexed: 06/13/2024] Open
Abstract
Gram-negative bacteria from the Bacteroidota phylum possess a type-IX secretion system (T9SS) for protein secretion, which requires cargoes to have a C-terminal domain (CTD). Structurally analysed CTDs are from Porphyromonas gingivalis proteins RgpB, HBP35, PorU and PorZ, which share a compact immunoglobulin-like antiparallel 3+4 β-sandwich (β1-β7). This architecture is essential as a P. gingivalis strain with a single-point mutant of RgpB disrupting the interaction of the CTD with its preceding domain prevented secretion of the protein. Next, we identified the C-terminus ('motif C-t.') and the loop connecting strands β3 and β4 ('motif Lβ3β4') as conserved. We generated two strains with insertion and replacement mutants of PorU, as well as three strains with ablation and point mutants of RgpB, which revealed both motifs to be relevant for T9SS function. Furthermore, we determined the crystal structure of the CTD of mirolase, a cargo of the Tannerella forsythia T9SS, which shares the same general topology as in Porphyromonas CTDs. However, motif Lβ3β4 was not conserved. Consistently, P. gingivalis could not properly secrete a chimaeric protein with the CTD of peptidylarginine deiminase replaced with this foreign CTD. Thus, the incompatibility of the CTDs between these species prevents potential interference between their T9SSs.
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Affiliation(s)
- Danuta Mizgalska
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Arturo Rodríguez-Banqueri
- Proteolysis Laboratory, Department of Structural Biology, Molecular Biology Institute of Barcelona (CSIC), Barcelona, Catalonia 08028, Spain
| | - Florian Veillard
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Mirosław Książęk
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Theodoros Goulas
- Department of Food Science and Nutrition, School of Agricultural Sciences, University of Thessaly, Karditsa 43100, Greece
| | - Tibisay Guevara
- Proteolysis Laboratory, Department of Structural Biology, Molecular Biology Institute of Barcelona (CSIC), Barcelona, Catalonia 08028, Spain
| | - Ulrich Eckhard
- Synthetic Structural Biology Group, Department of Structural Biology, Molecular Biology Institute of Barcelona (CSIC), Barcelona, Catalonia 08028, Spain
| | - Jan Potempa
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
- Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY 40202, USA
| | - F Xavier Gomis-Rüth
- Proteolysis Laboratory, Department of Structural Biology, Molecular Biology Institute of Barcelona (CSIC), Barcelona, Catalonia 08028, Spain
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Sahoo A, Vivek-Ananth RP, Chivukula N, Rajaram SV, Mohanraj K, Khare D, Acharya C, Samal A. T9GPred: A Comprehensive Computational Tool for the Prediction of Type 9 Secretion System, Gliding Motility, and the Associated Secreted Proteins. ACS OMEGA 2023; 8:34091-34102. [PMID: 37744817 PMCID: PMC10515386 DOI: 10.1021/acsomega.3c05155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 08/24/2023] [Indexed: 09/26/2023]
Abstract
Type 9 secretion system (T9SS) is one of the least characterized secretion systems exclusively found in the Bacteroidetes phylum, which comprises various environmental and economically relevant bacteria. While T9SS plays a central role in bacterial movement termed gliding motility, survival, and pathogenicity, there is an unmet need for a comprehensive tool that predicts T9SS, gliding motility, and proteins secreted via T9SS. In this study, we develop such a computational tool, Type 9 secretion system and Gliding motility Prediction (T9GPred). To build this tool, we manually curated published experimental evidence and identified mandatory components for T9SS and gliding motility prediction. We also compiled experimentally characterized proteins secreted via T9SS and determined the presence of three unique types of C-terminal domain signals, and these insights were leveraged to predict proteins secreted via T9SS. Notably, using recently published experimental evidence, we show that T9GPred has high predictive power. Thus, we used T9GPred to predict the presence of T9SS, gliding motility, and associated secreted proteins across 693 completely sequenced Bacteroidetes strains. T9GPred predicted 402 strains to have T9SS, of which 327 strains are also predicted to exhibit gliding motility. Further, T9GPred also predicted putative secreted proteins for the 402 strains. In a nutshell, T9GPred is a novel computational tool for systems-level prediction of T9SS and streamlining future experimentation. The source code of the computational tool is available in our GitHub repository: https://github.com/asamallab/T9GPred. The tool and its predicted results are compiled in a web server available at: https://cb.imsc.res.in/t9gpred/.
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Affiliation(s)
- Ajaya
Kumar Sahoo
- The
Institute of Mathematical Sciences (IMSc), Chennai 600113, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - R. P. Vivek-Ananth
- The
Institute of Mathematical Sciences (IMSc), Chennai 600113, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Nikhil Chivukula
- The
Institute of Mathematical Sciences (IMSc), Chennai 600113, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Shri Vishalini Rajaram
- The
Institute of Mathematical Sciences (IMSc), Chennai 600113, India
- Centre
for Biotechnology, Anna University, Chennai 600025, India
| | - Karthikeyan Mohanraj
- Institute
for Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, Dresden 01307, Germany
| | - Devanshi Khare
- Molecular
Biology Division, Bhabha Atomic Research
Centre, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Celin Acharya
- Molecular
Biology Division, Bhabha Atomic Research
Centre, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Areejit Samal
- The
Institute of Mathematical Sciences (IMSc), Chennai 600113, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
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3
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Mahmud ASM, Seers CA, Huq NL, Zhang L, Butler CA, Moore C, Cross KJ, Reynolds EC. Production and properties of adhesin-free gingipain proteinase RgpA. Sci Rep 2023; 13:10780. [PMID: 37402780 DOI: 10.1038/s41598-023-37534-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 06/23/2023] [Indexed: 07/06/2023] Open
Abstract
The Arg-specific gingipains of Porphyromonas gingivalis RgpA and RgpB have 97% identical sequences in their catalytic domains yet their propeptides are only 76% identical. RgpA isolates as a proteinase-adhesin complex (HRgpA) which hinders direct kinetic comparison of RgpAcat as a monomer with monomeric RgpB. We tested modifications of rgpA identifying a variant that enabled us to isolate histidine-tagged monomeric RgpA (rRgpAH). Kinetic comparisons between rRgpAH and RgpB used benzoyl-L-Arg-4-nitroanilide with and without cysteine and glycylglycine acceptor molecules. With no glycylglycine, values of Km, Vmax, kcat and kcat/Km for each enzyme were similar, but with glycylglycine Km decreased, Vmax increased and kcat increased ~ twofold for RgpB but ~ sixfold for rRgpAH. The kcat/Km for rRgpAH was unchanged whereas that of RgpB more than halved. Recombinant RgpA propeptide inhibited rRgpAH and RgpB with Ki 13 nM and 15 nM Ki respectively slightly more effectively than RgpB propeptide which inhibited rRgpAH and RgpB with Ki 22 nM and 29 nM respectively (p < 0.0001); a result that may be attributable to the divergent propeptide sequences. Overall, the data for rRgpAH reflected observations previously made by others using HRgpA, indicating rRgpAH fidelity and confirming the first production and isolation of functional affinity tagged RgpA.
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Affiliation(s)
- Abu Sayeed M Mahmud
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Christine A Seers
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - N Laila Huq
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Lianyi Zhang
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Catherine A Butler
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Caroline Moore
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Keith J Cross
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Eric C Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, VIC, 3010, Australia.
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Shen R, Yu Y, Chen Z, Zhu M, Feng Y, Niu P, Yu S. Riemerella anatipestifer Endonuclease I displays enzymatic activity and is associated with bacterial virulence. Vet Microbiol 2023; 280:109700. [PMID: 36807978 DOI: 10.1016/j.vetmic.2023.109700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/24/2022] [Accepted: 02/15/2023] [Indexed: 02/18/2023]
Abstract
Riemerella anatipestifer is an important pathogen of waterfowl, causing septicemic and exudative diseases. We previously reported that the R. anatipestifer AS87_RS02625 is a secretory protein of the type IX secretion system (T9SS). In this study, R. anatipestifer T9SS protein AS87_RS02625 was determined to be a functional Endonuclease I (EndoI), which has DNase and RNase activities. Optimal temperature and pH of the recombinant R. anatipestifer EndoI (rEndoI) to cleave λDNA were determined as 55-60 °C and 7.5 respectively. The DNase activity of the rEndoI was dependent on the presence of divalent metal ions. Presence of Mg2+ at a concentration range of 7.5-15 mM in the rEndoI reaction buffer displayed the highest DNase activity. In addition, the rEndoI displayed RNase activity to cleave MS2-RNA (ssRNA), either in the absence or presence of divalent cations Mg2+, Mn2+, Ca2+, Zn2+ and Cu2+. The DNase activity of the rEndoI was significantly enhanced by Mg2+, Mn2+ and Ca2+ but not Zn2+ and Cu2+. Moreover, we indicated that R. anatipestifer EndoI functioned on the bacterial adherence, invasion, in vivo survival and inducing inflammatory cytokines. These results indicate that the R. anatipestifer T9SS protein AS87_RS02625 is a novel EndoI, displays endonuclease activity and plays an important role in bacterial virulence.
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Affiliation(s)
- Ruyu Shen
- Jiangsu Agri-Animal Husbandry Vocational College, Veterinary Bio-Pharmaceutical, Jiangsu Key Laboratory for High-Tech Research and Development of Veterinary Biopharmaceuticals, Taizhou, Jiangsu, China; Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, China; College of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China
| | - Yang Yu
- Jiangsu Agri-Animal Husbandry Vocational College, Veterinary Bio-Pharmaceutical, Jiangsu Key Laboratory for High-Tech Research and Development of Veterinary Biopharmaceuticals, Taizhou, Jiangsu, China
| | - Zongchao Chen
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, China
| | - Min Zhu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, China
| | - Yating Feng
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, China; College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Pengfei Niu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, China.
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Kondo Y, Ohara K, Fujii R, Nakai Y, Sato C, Naito M, Tsukuba T, Kadowaki T, Sato K. Transposon mutagenesis and genome sequencing identify two novel, tandem genes involved in the colony spreading of Flavobacterium collinsii, isolated from an ayu fish, Plecoglossus altivelis. Front Cell Infect Microbiol 2023; 13:1095919. [PMID: 36844397 PMCID: PMC9950754 DOI: 10.3389/fcimb.2023.1095919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 01/16/2023] [Indexed: 02/12/2023] Open
Abstract
Bacteria of the family Flavobacteriaceae (flavobacteria) primarily comprise nonpathogenic bacteria that inhabit soil and water (both marine and freshwater). However, some bacterial species in the family, including Flavobacterium psychrophilum and Flavobacterium columnare, are known to be pathogenic to fish. Flavobacteria, including the abovementioned pathogenic bacteria, belong to the phylum Bacteroidota and possess two phylum-specific features, gliding motility and a protein secretion system, which are energized by a common motor complex. Herein, we focused on Flavobacterium collinsii (GiFuPREF103) isolated from a diseased fish (Plecoglossus altivelis). Genomic analysis of F. collinsii GiFuPREF103 revealed the presence of a type IX secretion system and additional genes associated with gliding motility and spreading. Using transposon mutagenesis, we isolated two mutants with altered colony morphology and colony spreading ability; these mutants had transposon insertions in pep25 and lbp26. The glycosylation material profiles revealed that these mutants lacked the high-molecular-weight glycosylated materials present in the wild-type strain. In addition, the wild-type strains exhibited fast cell population movement at the edge of the spreading colony, whereas reduced cell population behavior was observed in the pep25- and lbp26-mutant strains. In the aqueous environment, the surface layers of these mutant strains were more hydrophobic, and they formed biofilms with enhanced microcolony growth compared to those with the wild-type. In Flavobacterium johnsoniae, the Fjoh_0352 and Fjoh_0353 mutant strains were generated, which were based on the ortholog genes of pep25 and lbp26. In these F. johnsoniae mutants, as in F. collinsii GiFuPREF103, colonies with diminished spreading capacity were formed. Furthermore, cell population migration was observed at the edge of the colony in wild-type F. johnsoniae, whereas individual cells, and not cell populations, migrated in these mutant strains. The findings of the present study indicate that pep25 and lbp26 contribute to the colony spreading of F. collinsii.
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Affiliation(s)
- Yoshio Kondo
- Department of Pediatric Dentistry, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan,*Correspondence: Yoshio Kondo, ; Keiko Sato,
| | - Kenichi Ohara
- Gifu Prefectural Research Institute for Fisheries and Aquatic Environments, Gifu, Japan
| | - Ryoji Fujii
- Gifu Prefectural Research Institute for Fisheries and Aquatic Environments, Gifu, Japan
| | - Yudai Nakai
- Department of Frontier Oral Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Chikara Sato
- School of Integrative and Global Majors (SIGMA), University of Tsukuba, Ibaraki, Japan,Biological Science Course, Graduate School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan,Division of Immune Homeostasis, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan,Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan
| | - Mariko Naito
- Department of Microbiology and Oral Infection, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Takayuki Tsukuba
- Department of Dental Pharmacology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Tomoko Kadowaki
- Department of Frontier Oral Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Keiko Sato
- Department of Frontier Oral Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan,*Correspondence: Yoshio Kondo, ; Keiko Sato,
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6
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Thunes NC, Mohammed HH, Evenhuis JP, Lipscomb RS, Pérez-Pascual D, Stevick RJ, Birkett C, Conrad RA, Ghigo JM, McBride MJ. Secreted peptidases contribute to virulence of fish pathogen Flavobacterium columnare. Front Cell Infect Microbiol 2023; 13:1093393. [PMID: 36816589 PMCID: PMC9936825 DOI: 10.3389/fcimb.2023.1093393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/18/2023] [Indexed: 02/05/2023] Open
Abstract
Flavobacterium columnare causes columnaris disease in freshwater fish in both natural and aquaculture settings. This disease is often lethal, especially when fish population density is high, and control options such as vaccines are limited. The type IX secretion system (T9SS) is required for F. columnare virulence, but secreted virulence factors have not been fully identified. Many T9SS-secreted proteins are predicted peptidases, and peptidases are common virulence factors of other pathogens. T9SS-deficient mutants, such as ΔgldN and ΔporV, exhibit strong defects in secreted proteolytic activity. The F. columnare genome has many peptidase-encoding genes that may be involved in nutrient acquisition and/or virulence. Mutants lacking individual peptidase-encoding genes, or lacking up to ten peptidase-encoding genes, were constructed and examined for extracellular proteolytic activity, for growth defects, and for virulence in zebrafish and rainbow trout. Most of the mutants retained virulence, but a mutant lacking 10 peptidases, and a mutant lacking the single peptidase TspA exhibited decreased virulence in rainbow trout fry, suggesting that peptidases contribute to F. columnare virulence.
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Affiliation(s)
- Nicole C. Thunes
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Haitham H. Mohammed
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States,Department of Rangeland, Wildlife and Fisheries Management, Texas A&M University, College Station, TX, United States
| | - Jason P. Evenhuis
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | - Ryan S. Lipscomb
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | - David Pérez-Pascual
- Institut Pasteur, Université de Paris-Cité, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 6047, Genetics of Biofilms Laboratory, Paris, France
| | - Rebecca J. Stevick
- Institut Pasteur, Université de Paris-Cité, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 6047, Genetics of Biofilms Laboratory, Paris, France
| | - Clayton Birkett
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | - Rachel A. Conrad
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Jean-Marc Ghigo
- Institut Pasteur, Université de Paris-Cité, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 6047, Genetics of Biofilms Laboratory, Paris, France
| | - Mark J. McBride
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States,*Correspondence: Mark J. McBride,
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Gorasia DG, Veith PD, Reynolds EC. Protein interactome mapping of Porphyromonas gingivalis provides insights into the formation of the PorQ-Z complex of the type IX secretion system. Mol Oral Microbiol 2023; 38:34-40. [PMID: 35862235 PMCID: PMC10947112 DOI: 10.1111/omi.12383] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/14/2022] [Accepted: 07/18/2022] [Indexed: 11/30/2022]
Abstract
Porphyromonas gingivalis is an anaerobic Gram-negative human oral pathogen highly associated with the more severe forms of periodontal disease. Porphyromonas gingivalis utilises the type IX secretion system (T9SS) to transport ∼30 cargo proteins, including multiple virulence factors, to the cell surface. The T9SS is a multiprotein system consisting of at least 20 proteins, and recently, we characterised the protein interactome of these components. Similar to the T9SS, almost all biological processes are mediated through protein-protein interactions (PPIs). Therefore, mapping PPIs is important to understand the biological functions of many proteins in P. gingivalis. Herein, we provide native migration profiles of over 1000 P. gingivalis proteins. Using the T9SS, we demonstrate that our dataset is a useful resource for identifying novel protein interactions. Using this dataset and further analysis of T9SS P. gingivalis mutants, we discover new mechanistic insights into the formation of the PorQ-Z complex of the T9SS. This dataset is a valuable resource for studies of P. gingivalis.
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Affiliation(s)
- Dhana G. Gorasia
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 InstituteThe University of MelbourneParkvilleAustralia
| | - Paul D. Veith
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 InstituteThe University of MelbourneParkvilleAustralia
| | - Eric C. Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 InstituteThe University of MelbourneParkvilleAustralia
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8
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Dorgan B, Liu Y, Wang S, Aduse-Opoku J, Whittaker SBM, Roberts MAJ, Lorenz CD, Curtis MA, Garnett JA. Structural Model of a Porphyromonas gingivalis type IX Secretion System Shuttle Complex. J Mol Biol 2022; 434:167871. [PMID: 36404438 DOI: 10.1016/j.jmb.2022.167871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 10/14/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
Porphyromonas gingivalis is a gram-negative oral anaerobic pathogen and is one of the key causative agents of periodontitis. P. gingivalis utilises a range of virulence factors, including the cysteine protease RgpB, to drive pathogenesis and these are exported and attached to the cell surface via the type IX secretion system (T9SS). All cargo proteins possess a conserved C-terminal signal domain (CTD) which is recognised by the T9SS, and the outer membrane β-barrel protein PorV (PG0027/LptO) can interact with cargo proteins as they are exported to the bacterial surface. Using a combination of solution nuclear magnetic resonance (NMR) spectroscopy, biochemical analyses, machine-learning-based modelling and molecular dynamics (MD) simulations, we present a structural model of a PorV:RgpB-CTD complex from P. gingivalis. This is the first structural insight into CTD recognition by the T9SS and shows how the conserved motifs in the CTD are the primary sites that mediate binding. In PorV, interactions with extracellular surface loops are important for binding the CTD, and together these appear to cradle and lock RgpB-CTD in place. This work provides insight into cargo recognition by PorV but may also have important implications for understanding other aspects of type-IX dependent secretion.
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Affiliation(s)
- Ben Dorgan
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral & Craniofacial Sciences, King's College London, London, UK; School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Yichao Liu
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral & Craniofacial Sciences, King's College London, London, UK
| | - Sunjun Wang
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral & Craniofacial Sciences, King's College London, London, UK
| | - Joseph Aduse-Opoku
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral & Craniofacial Sciences, King's College London, London, UK
| | - Sara B-M Whittaker
- Institute of Cancer & Genomic Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Mark A J Roberts
- Centre for Immunobiology, Blizard Institute, Queen Mary University of London, London, UK
| | - Christian D Lorenz
- Biological Physics & Soft Matter Research Group, Department of Physics, King's College London, London, UK
| | - Michael A Curtis
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral & Craniofacial Sciences, King's College London, London, UK.
| | - James A Garnett
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral & Craniofacial Sciences, King's College London, London, UK.
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Pei D, Dalbey RE. Membrane Translocation of Folded Proteins. J Biol Chem 2022; 298:102107. [PMID: 35671825 PMCID: PMC9251779 DOI: 10.1016/j.jbc.2022.102107] [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: 02/05/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 12/01/2022] Open
Abstract
An ever-increasing number of proteins have been shown to translocate across various membranes of bacterial as well as eukaryotic cells in their folded states as a part of physiological and/or pathophysiological processes. Herein we provide an overview of the systems/processes that are established or likely to involve the membrane translocation of folded proteins, such as protein export by the twin-arginine translocation (TAT) system in bacteria and chloroplasts, unconventional protein secretion (UPS) and protein import into the peroxisome in eukaryotes, and the cytosolic entry of proteins (e.g., bacterial toxins) and viruses into eukaryotes. We also discuss the various mechanistic models that have previously been proposed for the membrane translocation of folded proteins including pore/channel formation, local membrane disruption, membrane thinning, and transport by membrane vesicles. Finally, we introduce a newly discovered vesicular transport mechanism, vesicle budding and collapse (VBC), and present evidence that VBC may represent a unifying mechanism that drives some (and potentially all) of folded protein translocation processes.
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Affiliation(s)
- Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
| | - Ross E Dalbey
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
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Type B CTD Proteins Secreted by the Type IX Secretion System Associate with PorP-like Proteins for Cell Surface Anchorage. Int J Mol Sci 2022; 23:ijms23105681. [PMID: 35628493 PMCID: PMC9143113 DOI: 10.3390/ijms23105681] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 02/07/2023] Open
Abstract
The Bacteroidetes type IX secretion system (T9SS) consists of at least 20 components that translocate proteins with type A or type B C-terminal domain (CTD) signals across the outer membrane (OM). While type A CTD proteins are anchored to the cell surface via covalent linkage to the anionic lipopolysaccharide, it is still unclear how type B CTD proteins are anchored to the cell surface. Moreover, very little is known about the PorE and PorP components of the T9SS. In this study, for the first time, we identified a complex comprising the OM β-barrel protein PorP, the OM-associated periplasmic protein PorE and the type B CTD protein PG1035. Cross-linking studies supported direct interactions between PorE-PorP and PorP-PG1035. Furthermore, we show that the formation of the PorE-PorP-PG1035 complex was independent of PorU and PorV. Additionally, the Flavobacterium johnsoniae PorP-like protein, SprF, was found bound to the major gliding motility adhesin, SprB, which is also a type B CTD protein. Together, these results suggest that type B-CTD proteins may anchor to the cell surface by binding to their respective PorP-like proteins.
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Protein Interactome Analysis of the Type IX Secretion System Identifies PorW as the Missing Link between the PorK/N Ring Complex and the Sov Translocon. Microbiol Spectr 2022; 10:e0160221. [PMID: 35019767 PMCID: PMC8754138 DOI: 10.1128/spectrum.01602-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The type IX secretion system (T9SS) transports cargo proteins through the outer membrane of Bacteroidetes and attaches them to the cell surface for functions including pathogenesis, gliding motility, and degradation of carbon sources. The T9SS comprises at least 20 different proteins and includes several modules: the trans-envelope core module comprising the PorL/M motor and the PorK/N ring, the outer membrane Sov translocon, and the cell attachment complex. However, the spatial organization of these modules is unknown. We have characterized the protein interactome of the Sov translocon in Porphyromonas gingivalis and identified Sov-PorV-PorA as well as Sov-PorW-PorN-PorK to be novel networks. PorW also interacted with PGN_1783 (PorD), which was required for maximum secretion efficiency. The identification of PorW as the missing link completes a continuous interaction network from the PorL/M motor to the Sov translocon, providing a pathway for cargo delivery and energy transduction from the inner membrane to the secretion pore. IMPORTANCE The T9SS is a newly identified protein secretion system of the Fibrobacteres-Chlorobi-Bacteroidetes superphylum used by pathogens associated with diseases of humans, fish, and poultry for the secretion and cell surface attachment of virulence factors. The T9SS comprises three known modules: (i) the trans-envelope core module comprising the PorL/M motor and the PorK/N ring, (ii) the outer membrane Sov translocon, and (iii) the cell surface attachment complex. The spatial organization and interaction of these modules have been a mystery. Here, we describe the protein interactome of the Sov translocon in the human pathogen Porphyromonas gingivalis and have identified PorW as the missing link which bridges PorN with Sov and so completes a continuous interaction network from the PorL/M motor to the Sov translocon, providing, for the first time, a pathway for cargo delivery and energy transduction from the inner membrane to the secretion pore.
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Braun ML, Tomek MB, Grünwald-Gruber C, Nguyen PQ, Bloch S, Potempa JS, Andrukhov O, Schäffer C. Shut-Down of Type IX Protein Secretion Alters the Host Immune Response to Tannerella forsythia and Porphyromonas gingivalis. Front Cell Infect Microbiol 2022; 12:835509. [PMID: 35223555 PMCID: PMC8869499 DOI: 10.3389/fcimb.2022.835509] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/24/2022] [Indexed: 12/26/2022] Open
Abstract
Tannerella forsythia and Porphyromonas gingivalis target distinct virulence factors bearing a structurally conserved C-terminal domain (CTD) to the type IX protein secretion system (T9SS). The T9SS comprises an outer membrane translocation complex which works in concert with a signal peptidase for CTD cleavage. Among prominent T9SS cargo linked to periodontal diseases are the TfsA and TfsB components of T. forsythia’s cell surface (S-) layer, the bacterium’s BspA surface antigen and a set of cysteine proteinases (gingipains) from P. gingivalis. To assess the overall role of the bacterial T9SS in the host response, human macrophages and human gingival fibroblasts were stimulated with T. forsythia and P. gingivalis wild-type bacteria and T9SS signal peptidase-deficient mutants defective in protein secretion, respectively. The immunostimulatory potential of these bacteria was compared by analyzing the mRNA expression levels of the pro-inflammatory mediators IL-6, IL-8, MCP-1 and TNF-α by qPCR and by measuring the production of the corresponding proteins by ELISA. Shot-gun proteomics analysis of T. forsythia and P. gingivalis outer membrane preparations confirmed that several CTD-bearing virulence factors which interact with the human immune system were depleted from the signal peptidase mutants, supportive of effective T9SS shut-down. Three and, more profoundly, 16 hours post stimulation, the T. forsythia T9SS mutant induced significantly less production of cytokines and the chemokine in human cells compared to the corresponding parent strain, while the opposite was observed for the P. gingivalis T9SS mutant. Our data indicate that T9SS shut-down translates into an altered inflammatory response in periodontal pathogens. Thus, the T9SS as a potential novel target for periodontal therapy needs further evaluation.
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Affiliation(s)
- Matthias L. Braun
- Department of NanoBiotechnology, NanoGlycobiology Unit, Universität für Bodenkultur Wien, Vienna, Austria
| | - Markus B. Tomek
- Department of NanoBiotechnology, NanoGlycobiology Unit, Universität für Bodenkultur Wien, Vienna, Austria
| | - Clemens Grünwald-Gruber
- Department of Chemistry, Institute of Biochemistry, Universität für Bodenkultur Wien, Vienna, Austria
| | - Phuong Q. Nguyen
- Competence Center for Periodontal Research, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria
| | - Susanne Bloch
- Department of NanoBiotechnology, NanoGlycobiology Unit, Universität für Bodenkultur Wien, Vienna, Austria
| | - Jan S. Potempa
- Oral Health and Systemic Disease Group, University of Louisville, Louisville, KY, United States
| | - Oleh Andrukhov
- Competence Center for Periodontal Research, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria
- *Correspondence: Christina Schäffer, ; Oleh Andrukhov,
| | - Christina Schäffer
- Department of NanoBiotechnology, NanoGlycobiology Unit, Universität für Bodenkultur Wien, Vienna, Austria
- *Correspondence: Christina Schäffer, ; Oleh Andrukhov,
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Fuchsbauer O, Lunar Silva I, Cascales E, Roussel A, Leone P. Structural and functional analyses of the Porphyromonas gingivalis type IX secretion system PorN protein. J Biol Chem 2022; 298:101618. [PMID: 35065963 PMCID: PMC8861641 DOI: 10.1016/j.jbc.2022.101618] [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: 10/15/2021] [Revised: 01/15/2022] [Accepted: 01/17/2022] [Indexed: 11/13/2022] Open
Abstract
Porphyromonas gingivalis, the major human pathogen bacterium associated with periodontal diseases, secretes virulence factors through the Bacteroidetes-specific type IX secretion system (T9SS). Effector proteins of the T9SS are recognized by the complex via their conserved C-terminal domains (CTDs). Among the 18 proteins essential for T9SS function in P. gingivalis, PorN is a periplasmic protein that forms large ring-shaped structures in association with the PorK outer membrane lipoprotein. PorN also mediates contacts with the PorM subunit of the PorLM energetic module, and with the effector’s CTD. However, no information is available on the PorN structure and on the implication of PorN domains for T9SS assembly and effector recognition. Here we present the crystal structure of PorN at 2.0-Å resolution, which represents a novel fold with no significant similarity to any known structure. In agreement with in silico analyses, we also found that the N- and C-terminal regions of PorN are intrinsically disordered. Our functional studies showed that the N-terminal disordered region is involved in PorN dimerization while the C-terminal disordered region is involved in the interaction with PorK. Finally, we determined that the folded PorN central domain is involved in the interaction with PorM, as well as with the effector’s CTD. Altogether, these results lay the foundations for a more comprehensive model of T9SS architecture and effector transport.
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Affiliation(s)
- Olivier Fuchsbauer
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Marseille, France; Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, Marseille, France
| | - Ignacio Lunar Silva
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Aix-Marseille Université - Centre National de la Recherche Scientifique (UMR7255), Marseille Cedex 20, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Aix-Marseille Université - Centre National de la Recherche Scientifique (UMR7255), Marseille Cedex 20, France
| | - Alain Roussel
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Marseille, France; Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, Marseille, France
| | - Philippe Leone
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, Marseille, France; Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, Marseille, France.
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Intermolecular latency regulates the essential C-terminal signal peptidase and sortase of the Porphyromonas gingivalis type-IX secretion system. Proc Natl Acad Sci U S A 2021; 118:2103573118. [PMID: 34593635 DOI: 10.1073/pnas.2103573118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2021] [Indexed: 02/08/2023] Open
Abstract
Porphyromonas gingivalis is a keystone pathogen of the human dysbiotic oral microbiome that causes severe periodontitis. It employs a type-IX secretion system (T9SS) to shuttle proteins across the outer membrane (OM) for virulence. Uniquely, T9SS cargoes carry a C-terminal domain (CTD) as a secretion signal, which is cleaved and replaced with anionic lipopolysaccharide by transpeptidation for extracellular anchorage to the OM. Both reactions are carried out by PorU, the only known dual-function, C-terminal signal peptidase and sortase. PorU is itself secreted by the T9SS, but its CTD is not removed; instead, intact PorU combines with PorQ, PorV, and PorZ in the OM-inserted "attachment complex." Herein, we revealed that PorU transits between active monomers and latent dimers and solved the crystal structure of the ∼260-kDa dimer. PorU has an elongated shape ∼130 Å in length and consists of seven domains. The first three form an intertwined N-terminal cluster likely engaged in substrate binding. They are followed by a gingipain-type catalytic domain (CD), two immunoglobulin-like domains (IGL), and the CTD. In the first IGL, a long "latency β-hairpin" protrudes ∼30 Å from the surface to form an intermolecular β-barrel with β-strands from the symmetric CD, which is in a latent conformation. Homology modeling of the competent CD followed by in vivo validation through a cohort of mutant strains revealed that PorU is transported and functions as a monomer through a C690/H657 catalytic dyad. Thus, dimerization is an intermolecular mechanism for PorU regulation to prevent untimely activity until joining the attachment complex.
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Okamura H, Hirota K, Yoshida K, Weng Y, He Y, Shiotsu N, Ikegame M, Uchida-Fukuhara Y, Tanai A, Guo J. Outer membrane vesicles of Porphyromonas gingivalis: Novel communication tool and strategy. JAPANESE DENTAL SCIENCE REVIEW 2021; 57:138-146. [PMID: 34484474 PMCID: PMC8399048 DOI: 10.1016/j.jdsr.2021.07.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/09/2021] [Accepted: 07/18/2021] [Indexed: 12/11/2022] Open
Abstract
Extracellular vesicles (EVs) have been recognized as a universal method of cellular communications and are reportedly produced in bacteria, archaea, and eukaryotes. Bacterial EVs are often called “Outer Membrane Vesicles” (OMVs) as they were the result of a controlled blebbing of the outer membrane of gram-negative bacteria such as Porphyromonas gingivalis (P. gingivalis). Bacterial EVs are natural messengers, implicated in intra- and inter-species cell-to-cell communication among microorganism populations present in microbiota. Bacteria can incorporate their pathogens into OMVs; the content of OMVs differs, depending on the type of bacteria. The production of distinct types of OMVs can be mediated by different factors and routes. A recent study highlighted OMVs ability to carry crucial molecules implicated in immune modulation, and, nowadays, they are considered as a way to communicate and transfer messages from the bacteria to the host and vice versa. This review article focuses on the current understanding of OMVs produced from major oral bacteria, P. gingivalis: generation, characteristics, and contents as well as the involvement in signal transduction of host cells and systemic diseases. Our recent study regarding the action of P. gingivalis OMVs in the living body is also summarized.
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Affiliation(s)
- Hirohiko Okamura
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata, Kitaku, Okayama 770-8525, Japan
| | - Katsuhiko Hirota
- Department of Medical Hygiene, Dental Hygiene Course, Kochi Gakuen College, Kochi 780-0955, Japan
| | - Kaya Yoshida
- Department of Oral Healthcare Education, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8504, Japan
| | - Yao Weng
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata, Kitaku, Okayama 770-8525, Japan
| | - Yuhan He
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata, Kitaku, Okayama 770-8525, Japan
| | - Noriko Shiotsu
- Comprehensive Dental Clinic, Okayama University Hospital, Okayama University, Okayama, Japan
| | - Mika Ikegame
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata, Kitaku, Okayama 770-8525, Japan
| | - Yoko Uchida-Fukuhara
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata, Kitaku, Okayama 770-8525, Japan
| | - Airi Tanai
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata, Kitaku, Okayama 770-8525, Japan
| | - Jiajie Guo
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata, Kitaku, Okayama 770-8525, Japan.,Department of Endodontics, School of Stomatology, China Medical University, Nanjing North Street 117, Shenyang 110002, China
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A Riemerella anatipestifer Metallophosphoesterase That Displays Phosphatase Activity and Is Associated with Virulence. Appl Environ Microbiol 2021; 87:AEM.00086-21. [PMID: 33741629 DOI: 10.1128/aem.00086-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/27/2021] [Indexed: 11/20/2022] Open
Abstract
Riemerella anatipestifer is an important pathogen of waterfowl, causing septicemic and exudative diseases. In our previous study, we demonstrated that bacterial virulence and secretion proteins of the type IX secretion system (T9SS) mutant strains Yb2ΔgldK and Yb2ΔgldM were significantly reduced, in comparison to those of wild-type strain Yb2. In this study, the T9SS secretion protein AS87_RS00980, which is absent from the secretion proteins of Yb2ΔgldK and Yb2ΔgldM, was investigated by construction of gene mutation and complementation strains. The virulence assessment showed >1,000-fold attenuated virulence and significantly reduced bacterial loads in the blood of ducks infected with Yb2Δ00980, the AS87_RS00980 gene deletion mutant strain. Bacterial virulence was recovered in complementation strain cYb2Δ00980 Further study indicated that the T9SS secretion protein AS87_RS00980 is a metallophosphoesterase (MPPE), which displayed phosphatase activity and was cytomembrane localized. Moreover, the optimal reactive pH and temperature were determined to be 7.0 and 60°C, respectively, and the Km and V max were determined to be 3.53 mM and 198.1 U/mg. The rMPPE activity was activated by Zn2+ and Cu2+ but inhibited by Fe3+, Fe2+, and EDTA. There are five conserved sites, namely, N267, H268 H351, H389, and H391, in the metallophosphatase domain. Mutant proteins Y267-rMPPE and Y268-rMPPE retained 29.30% and 19.81% relative activity, respectively, and mutant proteins Y351-rMPPE, Y389-rMPPE, and Y391-rMPPE lost almost all MPPE activity. Taken together, these results indicate that the R. anatipestifer AS87_RS00980 gene encodes an MPPE that is a secretion protein of T9SS that plays an important role in bacterial virulence.IMPORTANCE Riemerella anatipestifer T9SS was recently discovered to be associated with bacterial gliding motility and secretion of virulence factors. Several T9SS genes have been identified, but no effector has been reported in R. anatipestifer to date. In this study, we identified the T9SS secretion protein AS87_RS00980 as an MPPE that displays phosphatase activity and is associated with bacterial virulence. The enzymatic activity of the rMPPE was determined, and the Km and V max were 3.53 mM and 198.1 U/mg, respectively. Five conserved sites were also identified. The AS87_RS00980 gene deletion mutant strain was attenuated >1,000-fold, indicating that MPPE is an important virulence factor. In summary, we identified that the R. anatipestifer AS87_RS00980 gene encodes an important T9SS effector, MPPE, which plays an important role in bacterial virulence.
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PorZ, an Essential Component of the Type IX Secretion System of Porphyromonas gingivalis, Delivers Anionic Lipopolysaccharide to the PorU Sortase for Transpeptidase Processing of T9SS Cargo Proteins. mBio 2021; 12:mBio.02262-20. [PMID: 33622730 PMCID: PMC8545088 DOI: 10.1128/mbio.02262-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cargo proteins of the type IX secretion system (T9SS) in human pathogens from the Bacteroidetes phylum invariably possess a conserved C-terminal domain (CTD) that functions as a signal for outer membrane (OM) translocation. In Porphyromonas gingivalis, the CTD of cargos is cleaved off after translocation, and anionic lipopolysaccharide (A-LPS) is attached. This transpeptidase reaction anchors secreted proteins to the OM. PorZ, a cell surface-associated protein, is an essential component of the T9SS whose function was previously unknown. We recently solved the crystal structure of PorZ and found that it consists of two β-propeller moieties, followed by a CTD. In this study, we performed structure-based modeling, suggesting that PorZ is a carbohydrate-binding protein. Indeed, we found that recombinant PorZ specifically binds A-LPS in vitro Binding was blocked by monoclonal antibodies that specifically react with a phosphorylated branched mannan in the anionic polysaccharide (A-PS) component of A-LPS, but not with the core oligosaccharide or the lipid A endotoxin. Examination of A-LPS derived from a cohort of mutants producing various truncations of A-PS confirmed that the phosphorylated branched mannan is indeed the PorZ ligand. Moreover, purified recombinant PorZ interacted with the PorU sortase in an A-LPS-dependent manner. This interaction on the cell surface is crucial for the function of the "attachment complex" composed of PorU, PorZ, and the integral OM β-barrel proteins PorV and PorQ, which is involved in posttranslational modification and retention of T9SS cargos on the bacterial surface.IMPORTANCE Bacteria have evolved multiple systems to transport effector proteins to their surface or into the surrounding milieu. These proteins have a wide range of functions, including attachment, motility, nutrient acquisition, and toxicity in the host. Porphyromonas gingivalis, the human pathogen responsible for severe gum diseases (periodontitis), uses a recently characterized type IX secretion system (T9SS) to translocate and anchor secreted virulence effectors to the cell surface. Anchorage is facilitated by sortase, an enzyme that covalently attaches T9SS cargo proteins to a unique anionic lipopolysaccharide (A-LPS) moiety of P. gingivalis Here, we show that the T9SS component PorZ interacts with sortase and specifically binds A-LPS. Binding is mediated by a phosphorylated branched mannan repeat in A-LPS polysaccharide. A-LPS-bound PorZ interacts with sortase with significantly higher affinity, facilitating modification of cargo proteins by the cell surface attachment complex of the T9SS.
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Lunar Silva I, Cascales E. Molecular Strategies Underlying Porphyromonas gingivalis Virulence. J Mol Biol 2021; 433:166836. [PMID: 33539891 DOI: 10.1016/j.jmb.2021.166836] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/15/2021] [Accepted: 01/15/2021] [Indexed: 02/07/2023]
Abstract
The anaerobic Gram-negative bacterium Porphyromonas gingivalis is considered the keystone of periodontitis diseases, a set of inflammatory conditions that affects the tissues surrounding the teeth. In the recent years, the major virulence factors exploited by P. gingivalis have been identified and characterized, including a cocktail of toxins, mainly proteases called gingipains, which promote gingival tissue invasion. These effectors use the Sec pathway to cross the inner membrane and are then recruited and transported across the outer membrane by the type IX secretion system (T9SS). In P. gingivalis, most secreted effectors are attached to anionic lipopolysaccharides (A-LPS), and hence form a virulence coat at the cell surface. P. gingivalis produces additional virulence factors to evade host immune responses, such as capsular polysaccharide, fimbriae and outer membrane vesicles. In addition to periodontitis, it is proposed that this broad repertoire of virulence factors enable P. gingivalis to be involved in diverse human diseases such as rheumatoid arthritis, and neurodegenerative, Alzheimer, and cardiovascular disorders. Here, we review the major virulence determinants of P. gingivalis and discuss future directions to better understand their mechanisms of action.
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Affiliation(s)
- Ignacio Lunar Silva
- Laboratoire d'Ingénierie des Syst èmes Macromol éculaires (LISM), Institut de Microbiologie, Bioénergies and Biotechnologie (IM2B), Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 Chemin Joseph Aiguier CS7071, 13009 Marseille Cedex 20, France.
| | - Eric Cascales
- Laboratoire d'Ingénierie des Syst èmes Macromol éculaires (LISM), Institut de Microbiologie, Bioénergies and Biotechnologie (IM2B), Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), UMR7255, 31 Chemin Joseph Aiguier CS7071, 13009 Marseille Cedex 20, France.
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Abstract
The type IX secretion system (T9SS) is the most recently discovered secretion system in the gram-negative bacteria and is specific to the Bacteroidetes phylum. It is comprised of at least 19 proteins, which together allows for the secretion and cell surface attachment of a specific group of proteins (T9SS substrates), that harbor a signal sequence at the C-terminus. Here we describe the structural characterization of the PorK, PorN and PorG components of the Porphyromonas gingivalis T9SS using electron microscopy and cross-linking mass spectrometry.
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PorA, a conserved C-terminal domain-containing protein, impacts the PorXY-SigP signaling of the type IX secretion system. Sci Rep 2020; 10:21109. [PMID: 33273542 PMCID: PMC7712824 DOI: 10.1038/s41598-020-77987-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 11/19/2020] [Indexed: 01/07/2023] Open
Abstract
Porphyromonas gingivalis, a periodontal pathogen, translocates many virulence factors including the cysteine proteases referred to as gingipains to the cell surface via the type IX secretion system (T9SS). Expression of the T9SS component proteins is regulated by the tandem signaling of the PorXY two-component system and the ECF sigma factor SigP. However, the details of this regulatory pathway are still unknown. We found that one of the T9SS conserved C-terminal domain-containing proteins, PGN_0123, which we have designated PorA, is involved in regulating expression of genes encoding T9SS structural proteins and that PorA can be translocated onto the cell surface without the T9SS translocation machinery. X-ray crystallography revealed that PorA has a domain similar to the mannose-binding domain of Escherichia coli FimH, the tip protein of Type 1 pilus. Mutations in the cytoplasmic domain of the sensor kinase PorY conferred phenotypic recovery on the ΔporA mutant. The SigP sigma factor, which is activated by the PorXY two-component system, markedly decreased in the ΔporA mutant. These results strongly support a potential role for PorA in relaying a signal from the cell surface to the PorXY-SigP signaling pathway.
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Nemoto TK, Ohara Nemoto Y. Dipeptidyl-peptidases: Key enzymes producing entry forms of extracellular proteins in asaccharolytic periodontopathic bacterium Porphyromonas gingivalis. Mol Oral Microbiol 2020; 36:145-156. [PMID: 33006264 PMCID: PMC8048996 DOI: 10.1111/omi.12317] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/17/2020] [Accepted: 09/24/2020] [Indexed: 02/06/2023]
Abstract
Porphyromonas gingivalis, a pathogen of chronic periodontitis, is an asaccharolytic microorganism that solely utilizes nutritional amino acids as its energy source and cellular constituents. The bacterium is considered to incorporate proteinaceous nutrients mainly as dipeptides, thus exopeptidases that produce dipeptides from polypeptides are critical for survival and proliferation. We present here an overview of dipeptide production by P. gingivalis mediated by dipeptidyl-peptidases (DPPs), e.g., DPP4, DPP5, DPP7, and DPP11, serine exopeptidases localized in periplasm, which release dipeptides from the N-terminus of polypeptides. Additionally, two other exopeptidases, acylpeptidyl-oligopeptidase (AOP) and prolyl tripeptidyl-peptidase A (PTP-A), which liberate N-terminal acylated di-/tri-peptides and tripeptides with Pro at the third position, respectively, provide polypeptides in an acceptable form for DPPs. Hence, a large fraction of dipeptides is produced from nutritional polypeptides by DPPs with differential specificities in combination with AOP and PTP-A. The resultant dipeptides are then incorporated across the inner membrane mainly via a proton-dependent oligopeptide transporter (POT), a member of the major facilitator superfamily. Recent studies also indicate that DPP4 and DPP7 directly link between periodontal and systemic diseases, such as type 2 diabetes mellitus and coagulation abnormality, respectively. Therefore, these dipeptide-producing and incorporation molecules are considered to be potent targets for prevention and treatment of periodontal and related systemic diseases.
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Affiliation(s)
- Takayuki K Nemoto
- Department of Oral Molecular Biology, Course of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yuko Ohara Nemoto
- Department of Oral Molecular Biology, Course of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
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Shahriar ASM, Ono S, Nakayama M, Ohara N, Ohara N. Construction and characterization of the PGN_0296 mutant of Porphyromonas gingivalis. J Oral Biosci 2020; 62:322-326. [PMID: 33038516 DOI: 10.1016/j.job.2020.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/16/2020] [Accepted: 09/09/2020] [Indexed: 10/23/2022]
Abstract
The periodontal pathogen Porphyromonas gingivalis produces gingipains (Kgp, RgpA, and RgpB), cysteine proteases involved in the organism's virulence, and pigmentation. We previously showed that deletion of the PGN_0297 and PGN_0300 genes reduced the proteolytic activity of gingipains. The role of the PGN_0296 gene, consisting of an operon with the PGN_0297 and PGN_0300 genes, is unclear. Herein, we examined the effect of PGN_0296 gene deletion on the proteolytic activity. Although the proteolytic activity of the gingipains did not decrease in the culture supernatant of a PGN_0296 gene deletion mutant (ΔPGN_0296), the growth was delayed.
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Affiliation(s)
- Abu Saleh Muhammad Shahriar
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Shintaro Ono
- Department of Periodontal Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Masaaki Nakayama
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama, Japan
| | - Naoko Ohara
- Department of Operative Dentistry, Okayama University Hospital, Okayama University, Okayama, Japan
| | - Naoya Ohara
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama, Japan.
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Sato K, Okada K, Nakayama K, Imada K. PorM, a core component of bacterial type IX secretion system, forms a dimer with a unique kinked-rod shape. Biochem Biophys Res Commun 2020; 532:114-119. [DOI: 10.1016/j.bbrc.2020.08.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 01/06/2023]
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Abstract
Porphyromonas gingivalis is a key pathogen of periodontitis, a polymicrobial disease characterized by a chronic inflammation that destroys the tissues supporting the teeth. Thus, understanding the virulence potential of P. gingivalis is essential to maintaining a healthy oral microbiome. In nonoral organisms, CRISPR-Cas systems have been shown to modulate a variety of microbial processes, including protection from exogenous nucleic acids, and, more recently, have been implicated in bacterial virulence. Previously, our clinical findings identified activation of the CRISPR-Cas system in patient samples at the transition to disease; however, the mechanism of contribution to disease remained unknown. The importance of the present study resides in that it is becoming increasingly clear that CRISPR-associated proteins have broader functions than initially thought and that those functions now include their role in the virulence of periodontal pathogens. Studying a P. gingivaliscas3 mutant, we demonstrate that at least one of the CRISPR-Cas systems is involved in the regulation of virulence during infection. The CRISPR (clustered regularly interspaced short palindromic repeat)-Cas system is a unique genomic entity that provides prokaryotic cells with adaptive and heritable immunity. Initial studies identified CRISPRs as central elements used by bacteria to protect against foreign nucleic acids; however, emerging evidence points to CRISPR involvement in bacterial virulence. The present study aimed to identify the participation of one CRISPR-Cas protein, Cas3, in the virulence of the oral pathogen Porphyromonas gingivalis, an organism highly associated with periodontitis. Our results show that compared to the wild type, a mutant with a deletion of the Cas3 gene, an essential nuclease part of the class 1 type I CRISPR-Cas system, increased the virulence of P. gingivalis. In vitro infection modeling revealed only mildly enhanced production of proinflammatory cytokines by THP-1 cells when infected with the mutant strain. Dual transcriptome sequencing (RNA-seq) analysis of infected THP-1 cells showed an increase in expression of genes associated with pathogenesis in response to Δcas3 mutant infection, with the target of Cas3 activities in neutrophil chemotaxis and gene silencing. The importance of cas3 in controlling virulence was corroborated in a Galleria mellonella infection model, where the presence of the Δcas3 mutant resulted in a statistically significant increase in mortality of G. mellonella. A time-series analysis of transcription patterning during infection showed that G. mellonella elicited very different immune responses to the wild-type and the Δcas3 mutant strains and revealed a rearrangement of association in coexpression networks. Together, these observations show for the first time that Cas3 plays a significant role in regulating the virulence of P. gingivalis. IMPORTANCEPorphyromonas gingivalis is a key pathogen of periodontitis, a polymicrobial disease characterized by a chronic inflammation that destroys the tissues supporting the teeth. Thus, understanding the virulence potential of P. gingivalis is essential to maintaining a healthy oral microbiome. In nonoral organisms, CRISPR-Cas systems have been shown to modulate a variety of microbial processes, including protection from exogenous nucleic acids, and, more recently, have been implicated in bacterial virulence. Previously, our clinical findings identified activation of the CRISPR-Cas system in patient samples at the transition to disease; however, the mechanism of contribution to disease remained unknown. The importance of the present study resides in that it is becoming increasingly clear that CRISPR-associated proteins have broader functions than initially thought and that those functions now include their role in the virulence of periodontal pathogens. Studying a P. gingivaliscas3 mutant, we demonstrate that at least one of the CRISPR-Cas systems is involved in the regulation of virulence during infection.
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Kin LX, Butler CA, Slakeski N, Hoffmann B, Dashper SG, Reynolds EC. Metabolic cooperativity between Porphyromonas gingivalis and Treponema denticola. J Oral Microbiol 2020; 12:1808750. [PMID: 32944158 PMCID: PMC7482830 DOI: 10.1080/20002297.2020.1808750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Background Porphyromonas gingivalis and Treponema denticola are proteolytic periodontopathogens that co-localize in polymicrobial subgingival plaque biofilms, display in vitro growth symbiosis and synergistic virulence in animal models of disease. These symbioses are underpinned by a range of metabolic interactions including cooperative hydrolysis of glycine-containing peptides to produce free glycine, which T. denticola uses as a major energy and carbon source. Objective To characterize the P. gingivalis gene products essential for these interactions. Methods: The P. gingivalis transcriptome exposed to cell-free T. denticola conditioned medium was determined using RNA-seq. P. gingivalis proteases potentially involved in hydrolysis of glycine-containing peptides were identified using a bioinformatics approach. Results One hundred and thirty-twogenes displayed differential expression, with the pattern of gene expression consistent with succinate cross-feeding from T. denticola to P. gingivalis and metabolic shifts in the P. gingivalis folate-mediated one carbon superpathway. Interestingly, no P. gingivalis proteases were significantly up-regulated. Three P. gingivalis proteases were identified as candidates and inactivated to determine their role in the release of free glycine. P. gingivalis PG0753 and PG1788 but not PG1605 are involved in the hydrolysis of glycine-containing peptides, making free glycine available for T. denticola utilization. Conclusion Collectively these metabolic interactions help to partition resources and engage synergistic interactions between these two species.
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Affiliation(s)
- Lin Xin Kin
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Catherine A Butler
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Nada Slakeski
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Brigitte Hoffmann
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Stuart G Dashper
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Eric C Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
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Gorasia DG, Veith PD, Reynolds EC. The Type IX Secretion System: Advances in Structure, Function and Organisation. Microorganisms 2020; 8:microorganisms8081173. [PMID: 32752268 PMCID: PMC7463736 DOI: 10.3390/microorganisms8081173] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/28/2020] [Accepted: 07/28/2020] [Indexed: 12/24/2022] Open
Abstract
The type IX secretion system (T9SS) is specific to the Bacteroidetes phylum. Porphyromonas gingivalis, a keystone pathogen for periodontitis, utilises the T9SS to transport many proteins—including its gingipain virulence factors—across the outer membrane and attach them to the cell surface. Additionally, the T9SS is also required for gliding motility in motile organisms, such as Flavobacterium johnsoniae. At least nineteen proteins have been identified as components of the T9SS, including the three transcription regulators, PorX, PorY and SigP. Although the components are known, the overall organisation and the molecular mechanism of how the T9SS operates is largely unknown. This review focusses on the recent advances made in the structure, function, and organisation of the T9SS machinery to provide further insight into this highly novel secretion system.
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Outer membrane vesicles derived from Porphyromonas gingivalis induced cell death with disruption of tight junctions in human lung epithelial cells. Arch Oral Biol 2020; 118:104841. [PMID: 32717445 DOI: 10.1016/j.archoralbio.2020.104841] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/13/2020] [Accepted: 07/14/2020] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Porphyromonas gingivalis (P. gingivalis) is a major bacterium responsible for the progression of periodontitis. P. gingivalis produces small vesicles called outer membrane vesicles (OMVs) containing virulence factors. Increasing evidence suggests a close relationship between periodontitis and respiratory system diseases, such as aspiration pneumonia. However, little is known about whether P. gingivalis OMVs give rise to the impediment of lung epithelial cells. We investigated the effect of the OMVs on cell viability and tight junctions of lung epithelial cells. DESIGN Human lung epithelial A549 cells were treated with P. gingivalis OMVs. Cell viability was evaluated, and cell morphology was examined using scanning electron and phase contrast microscopies. To detect apoptosis induced by P. gingivalis OMVs, activation of caspase-3 and poly ADP-ribose polymerase (PARP) cleavage was examined by using Western blotting. Immunocytochemistry was performed to stain tight junction proteins. RESULTS P. gingivalis OMVs decreased cell viability in A549 cells in a dose- and time-dependent manner. Microscopic analysis revealed that the OMVs induced morphological changes leading to irregular cell membrane structures. The OMVs caused cell shrinkage, membrane blebbing, and cytoplasmic expulsion in a dose-dependent manner. Western blot analysis showed the OMVs induced caspase-3 activation and PARP cleavage. Treatment with the OMVs disrupted the intact distributions of tight junction proteins. CONCLUSIONS These results indicate that P. gingivalis OMVs induced cell death by destroying the barrier system in lung epithelial cells. Our present study raises the possibility that P. gingivalis OMVs is an important factor in the engagement of periodontitis with respiratory system diseases.
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Trinh NTT, Tran HQ, Van Dong Q, Cambillau C, Roussel A, Leone P. Crystal structure of Type IX secretion system PorE C-terminal domain from Porphyromonas gingivalis in complex with a peptidoglycan fragment. Sci Rep 2020; 10:7384. [PMID: 32355178 PMCID: PMC7192894 DOI: 10.1038/s41598-020-64115-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 03/31/2020] [Indexed: 02/06/2023] Open
Abstract
Porphyromonas gingivalis, the major human pathogen associated to periodontal diseases, utilizes the Bacteroidetes-specific type IX secretion system (T9SS) to export virulence factors. PorE is a periplasmic multi-domain lipoprotein associated to the outer membrane that was recently identified as essential for T9SS function. Little is known on T9SS at the structural level, and in particular its interaction with peptidoglycan. This prompted us to carry out structural studies on PorE full length as well as on its four isolated domains. Here we report the crystal structure of the C-terminal OmpA_C-like putative peptidoglycan-binding domain at 1.55 Å resolution. An electron density volume was identified in the protein cleft, making it possible to build a naturally-occurring peptidoglycan fragment. This result suggests that PorE interacts with peptidoglycan and that PorE could anchor T9SS to the cell wall.
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Affiliation(s)
- Nhung Thi Trang Trinh
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France.,Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France.,Faculty of Medical Technology, PHENIKAA University, Yen Nghia, Ha Dong, Hanoi 12116, Vietnam.,PHENIKAA Research and Technology Institute (PRATI), A&A Green Phoenix Group JSC, No. 167 Hoang Ngan, Trung Hoa, Cau Giay, Hanoi 11313, Vietnam
| | - Hieu Quang Tran
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France.,Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France
| | - Quyen Van Dong
- Institute of Biotechnology, Vietnam Academy of Science and Technology. 18 Hoang Quoc Viet, Ha Noi, Vietnam.,University of Science and Technology of Hanoi, Vietnam Academy of Science and Technology. 18 Hoang Quoc Viet, Ha Noi, Vietnam
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France.,Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France
| | - Alain Roussel
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France.,Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France
| | - Philippe Leone
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France. .,Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique, UMR 7257, 163 Avenue de Luminy, Case 932, 13009, Marseille, France.
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Abstract
The translocation of proteins across membranes is a fundamental cellular function. Bacteria have evolved a striking array of pathways for delivering proteins into or across cytoplasmic membranes and, when present, outer membranes. Translocated proteins can form part of the membrane landscape, reside in the periplasmic space situated between the inner and outer membranes of Gram-negative bacteria, deposit on the cell surface, or be released to the extracellular milieu or injected directly into target cells. One protein translocation system, the general secretory pathway, is conserved in all domains of life. A second, the twin-arginine translocation pathway, is also phylogenetically distributed among most bacteria and plant chloroplasts. While all cell types have evolved additional systems dedicated to the translocation of protein cargoes, the number of such systems in bacteria is now known to exceed nine. These dedicated protein translocation systems, which include the types 1 through 9 secretion systems (T1SSs-T9SSs), the chaperone-usher pathway, and type IV pilus system, are the subject of this review. Most of these systems were originally identified and have been extensively characterized in Gram-negative or diderm (two-membrane) species. It is now known that several of these systems also have been adapted to function in Gram-positive or monoderm (single-membrane) species, and at least one pathway is found only in monoderms. This review briefly summarizes the distinctive mechanistic and structural features of each dedicated pathway, as well as the shared properties, that together account for the broad biological diversity of protein translocation in bacteria.
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Affiliation(s)
- Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St., Houston, TX, USA.
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30
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Gorasia DG, Glew MD, Veith PD, Reynolds EC. Quantitative proteomic analysis of the type IX secretion system mutants in Porphyromonas gingivalis. Mol Oral Microbiol 2020; 35:78-84. [PMID: 32040252 DOI: 10.1111/omi.12283] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/05/2020] [Accepted: 02/06/2020] [Indexed: 12/25/2022]
Abstract
Porphyromonas gingivalis is an anaerobic, gram-negative human oral pathogen highly associated with chronic periodontitis. P. gingivalis utilizes the type IX secretion system (T9SS) to transport many of its virulence factors including the gingipains to the cell surface. The T9SS is comprised of at least 16 proteins and the involvement of these 16 proteins in the T9SS has been verified by creating gene deletion mutants in P. gingivalis. These T9SS mutants are regularly utilized to understand how these proteins function together to allow the secretion of the T9SS substrates. We performed label-free quantitative proteomic analysis on the T9SS protein mutants in P. gingivalis to understand the relative abundance of each T9SS component in different mutants. The T9SS components were reduced in abundance in the porK, porL, porM, porN, sov and porT mutants, whereas they were increased in the porE, porU, porV, porZ and porQ mutants. Sov and PorW appear to be the lowest in abundance and PorV the highest amongst all the T9SS components in P. gingivalis wild-type strain. These results are consistent with the proposed role of Sov as the translocation pore in the outer membrane and PorV as the shuttle protein that transports the T9SS substrates between sub-complexes. Together, the label-free quantitative proteomics analyses showed that different T9SS mutants have vastly different abundances of the T9SS components. This knowledge will greatly assist in interpreting the phenotype of the T9SS mutants as well as selecting the right mutant for exploring the role of an individual component.
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Affiliation(s)
- Dhana G Gorasia
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Michelle D Glew
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Paul D Veith
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Eric C Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Victoria, Australia
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Sah GP, Cao P, Wall D. MYXO-CTERM sorting tag directs proteins to the cell surface via the type II secretion system. Mol Microbiol 2020; 113:1038-1051. [PMID: 31975447 DOI: 10.1111/mmi.14473] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/16/2020] [Accepted: 01/18/2020] [Indexed: 11/30/2022]
Abstract
Cells interact with their surrounding environment through surface proteins. However, knowledge gaps remain in understanding how these important types of proteins are transported and anchored on the cell surface. In the Gram-negative social bacterium, Myxococcus xanthus, a putative C-terminal sorting tag (MYXO-CTERM) is predicted to help direct 34 different proteins onto the cell surface. Here we investigate the sorting pathway for MYXO-CTERM proteins by using the TraA cell surface receptor as a paradigm. Deleting this motif from TraA abolishes the cell surface anchoring and results in extracellular secretion. Our findings indicate that conserved cysteines within the MYXO-CTERM are posttranslationally modified and are required for TraA cell surface localization and function. A region immediately upstream of these residues is predicted to be disordered and removing this motif caused a secretion defect and blocked cell surface anchoring. We further show that the type II secretion system is required for translocation across the outer membrane and that a cysteine-rich region directs TraA to the T2SS. Similar results were found with another MYXO-CTERM protein indicating our findings can be generalized. Further, we show the universal distribution of MXYO-CTERM motif across the Myxococcales order and provide a working model for sorting of these proteins.
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Affiliation(s)
- Govind Prasad Sah
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
| | - Pengbo Cao
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
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32
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Larsbrink J, McKee LS. Bacteroidetes bacteria in the soil: Glycan acquisition, enzyme secretion, and gliding motility. ADVANCES IN APPLIED MICROBIOLOGY 2020; 110:63-98. [PMID: 32386606 DOI: 10.1016/bs.aambs.2019.11.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The secretion of extracellular enzymes by soil microbes is rate-limiting in the recycling of biomass. Fungi and bacteria compete and collaborate for nutrients in the soil, with wide ranging ecological impacts. Within soil microbiota, the Bacteroidetes tend to be a dominant phylum, just like in human and animal intestines. The Bacteroidetes thrive because of their ability to secrete diverse arrays of carbohydrate-active enzymes (CAZymes) that target the highly varied glycans in the soil. Bacteroidetes use an energy-saving system of genomic organization, whereby most of their CAZymes are grouped into Polysaccharide Utilization Loci (PULs). These loci enable high level production of specific CAZymes only when their substrate glycans are abundant in the local environment. This gives the Bacteroidetes a clear advantage over other species in the competitive soil environment, further enhanced by the phylum-specific Type IX Secretion System (T9SS). The T9SS is highly effective at secreting CAZymes and/or tethering them to the cell surface, and is tightly coupled to the ability to rapidly glide over solid surfaces, a connection that promotes an active hunt for nutrition. Although the soil Bacteroidetes are less well studied than human gut symbionts, research is uncovering important biochemical and physiological phenomena. In this review, we summarize the state of the art on research into the CAZymes secreted by soil Bacteroidetes in the contexts of microbial soil ecology and the discovery of novel CAZymes for use in industrial biotechnology. We hope that this review will stimulate further investigations into the somewhat neglected enzymology of non-gut Bacteroidetes.
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Affiliation(s)
- Johan Larsbrink
- Wallenberg Wood Science Center, Gothenburg and Stockholm, Sweden; Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Lauren Sara McKee
- Wallenberg Wood Science Center, Gothenburg and Stockholm, Sweden; Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden.
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The Carboxy-Terminal Region of Flavobacterium johnsoniae SprB Facilitates Its Secretion by the Type IX Secretion System and Propulsion by the Gliding Motility Machinery. J Bacteriol 2019; 201:JB.00218-19. [PMID: 31262839 DOI: 10.1128/jb.00218-19] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/26/2019] [Indexed: 12/18/2022] Open
Abstract
Flavobacterium johnsoniae SprB moves rapidly along the cell surface, resulting in gliding motility. SprB secretion requires the type IX secretion system (T9SS). Proteins secreted by the T9SS typically have conserved C-terminal domains (CTDs) belonging to the type A CTD or type B CTD family. Attachment of 70- to 100-amino-acid type A CTDs to a foreign protein allows its secretion. Type B CTDs are common but have received little attention. Secretion of the foreign protein superfolder green fluorescent protein (sfGFP) fused to regions spanning the SprB type B CTD (sfGFP-CTDSprB) was analyzed. CTDs of 218 amino acids or longer resulted in secretion of sfGFP, whereas a 149-amino-acid region did not. Some sfGFP was secreted in soluble form, whereas the rest was attached on the cell surface. Surface-attached sfGFP was rapidly propelled along the cell, suggesting productive interaction with the motility machinery. This did not result in rapid cell movement, which apparently requires additional regions of SprB. Secretion of sfGFP-CTDSprB required coexpression with sprF, which lies downstream of sprB SprF is similar in sequence to Porphyromonas gingivalis PorP. Most F. johnsoniae genes encoding proteins with type B CTDs lie immediately upstream of porP/sprF-like genes. sfGFP was fused to the type B CTD from one such protein (Fjoh_3952). This resulted in secretion of sfGFP only when it was coexpressed with its cognate PorP/SprF-like protein. These results highlight the need for extended regions of type B CTDs and for coexpression with the appropriate PorP/SprF-like protein for efficient secretion and cell surface localization of cargo proteins.IMPORTANCE The F. johnsoniae gliding motility adhesin SprB is delivered to the cell surface by the type IX secretion system (T9SS) and is rapidly propelled along the cell by the motility machinery. How this 6,497-amino-acid protein interacts with the secretion and motility machines is not known. Fusion of the C-terminal 218 amino acids of SprB to a foreign cargo protein resulted in its secretion, attachment to the cell surface, and rapid movement by the motility machinery. Efficient secretion of SprB required coexpression with the outer membrane protein SprF. Secreted proteins that have sequence similarity to SprB in their C-terminal regions are common in the phylum Bacteroidetes and may have roles in adhesion, motility, and virulence.
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Saiki K, Urano-Tashiro Y, Konishi K, Takahashi Y. A screening system using minimal media identifies a flavin-competing inhibitor of Porphyromonas gingivalis growth. FEMS Microbiol Lett 2019; 366:5580286. [PMID: 31578552 DOI: 10.1093/femsle/fnz204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/29/2019] [Indexed: 12/14/2022] Open
Abstract
Chronic periodontitis is caused by dysbiosis of human oral commensals and especially by increase in Porphyromonas gingivalis. Inhibitors of P. gingivalis growth are expected to serve as effective drugs for the periodontal therapy. In the present study, we isolated new growth inhibitors of P. gingivalis using minimal media for P. gingivalis. The minimal media included the previously reported Globulin-Albumin (GA) and the newly developed Lactalbumin-Ferric chloride (LF) and Globulin-Calcium chloride (GC); all supported growth of the wild-type strain of P. gingivalis but did not support the growth of a mutant defective for a type IX secretion system. GC contains CaCl2, indicating that P. gingivalis requires a calcium ion for growth. Using LF and GA, we screened about 100 000 compounds and identified 73 that strongly inhibited the growth of P. gingivalis. More than half of these candidates would not have been obtained if these minimal media had not been used in our screen. One of our candidate inhibitors was diphenyleneiodonium chloride (DPIC), which showed strong bactericidal activity against P. gingivalis. Excess amounts of flavin adenine dinucleotide or flavin mononucleotide suppressed the inhibitory activity of DPIC, suggesting that DPIC would be a novel potent growth inhibitor.
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Affiliation(s)
- Keitarou Saiki
- Department of Microbiology, Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan
| | - Yumiko Urano-Tashiro
- Department of Microbiology, Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan
| | - Kiyoshi Konishi
- Department of Microbiology, Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan
| | - Yukihiro Takahashi
- Department of Microbiology, Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan
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Chen Z, Wang X, Ren X, Han W, Malhi KK, Ding C, Yu S. Riemerella anatipestifer GldM is required for bacterial gliding motility, protein secretion, and virulence. Vet Res 2019; 50:43. [PMID: 31164171 PMCID: PMC6549377 DOI: 10.1186/s13567-019-0660-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 04/12/2019] [Indexed: 12/02/2022] Open
Abstract
Riemerella anatipestifer is a major pathogenic agent of duck septicemic and exudative diseases. Genetic analyses suggest that this pathogen has a novel protein secretion system, known as the “type IX secretion system” (T9SS). We previously reported that deletion of the AS87_RS08465 gene significantly reduced the bacterial virulence of the R. anatipestifer strain Yb2, but the mechanism remained unclear. The AS87_RS08465 gene is predicted to encode the gliding motility protein GldM (GldM) protein, a key component of the T9SS complex. In this study, Western blotting analysis demonstrated that R. anatipestifer GldM was localized to the cytomembrane. Further study revealed that the adhesion and invasion capacities of the mutant strain RA2281 (designated Yb2ΔgldM) in Vero cells and the bacterial loads in the blood of infected ducks were significantly reduced. RNA-Seq and PCR analyses showed that six genes were upregulated and five genes were downregulated in the mutant strain Yb2ΔgldM and that these genes were mainly involved in the secretion of proteins. Yb2ΔgldM was also found to be defective in gliding motility and protein secretion. Liquid chromatography–tandem mass spectrometry analysis revealed that nine of the proteins had a conserved T9SS C-terminal domain and were differentially secreted by Yb2ΔgldM compared to Yb2. The complementation strain cYb2ΔgldM recovered the adhesion and invasion capacities in Vero cells and the bacterial loads in the blood of infected ducks as well as the bacterial gliding motility and most protein secretion in the mutant strain Yb2ΔgldM to the levels of the wild-type strain Yb2. Taken together, these results indicate that R. anatipestifer GldM is associated with T9SS and is important in bacterial virulence.
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Affiliation(s)
- Zongchao Chen
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Xiaolan Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Xiaomei Ren
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Wenlong Han
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Kanwar Kumar Malhi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, China. .,Jiangsu Agri-animal Husbandry Vocational College, Veterinary Bio-pharmaceutical, Jiangsu Key Laboratory for High-Tech Research and Development of Veterinary Biopharmaceuticals, Taizhou, Jiangsu, China.
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Abstract
ABSTRACT
Members of the phylum
Bacteroidetes
have many unique features, including gliding motility and the type IX protein secretion system (T9SS).
Bacteroidetes
gliding and T9SSs are common in, but apparently confined to, this phylum. Most, but not all, members of the phylum secrete proteins using the T9SS, and most also exhibit gliding motility. T9SSs secrete cell surface components of the gliding motility machinery and also secrete many extracellular or cell surface enzymes, adhesins, and virulence factors. The components of the T9SS are novel and are unrelated to those of other bacterial secretion systems. Proteins secreted by the T9SS rely on the Sec system to cross the cytoplasmic membrane, and they use the T9SS for delivery across the outer membrane. Secreted proteins typically have conserved C-terminal domains that target them to the T9SS. Some of the T9SS components were initially identified as proteins required for gliding motility. Gliding does not involve flagella or pili and instead relies on the rapid movement of motility adhesins, such as SprB, along the cell surface by the gliding motor. Contact of the adhesins with the substratum provides the traction that results in cell movement. SprB and other motility adhesins are delivered to the cell surface by the T9SS. Gliding and the T9SS appear to be intertwined, and components of the T9SS that span the cytoplasmic membrane may energize both gliding and protein secretion. The functions of the individual proteins in each process are the subject of ongoing investigations.
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Sato K, Kakuda S, Yukitake H, Kondo Y, Shoji M, Takebe K, Narita Y, Naito M, Nakane D, Abiko Y, Hiratsuka K, Suzuki M, Nakayama K. Immunoglobulin‐like domains of the cargo proteins are essential for protein stability during secretion by the type IX secretion system. Mol Microbiol 2018; 110:64-81. [DOI: 10.1111/mmi.14083] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2018] [Indexed: 01/12/2023]
Affiliation(s)
- Keiko Sato
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Shinji Kakuda
- Institute for Protein Research Osaka University Yamadaoka, Suita Osaka 565‐0871Japan
| | - Hideharu Yukitake
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Yoshio Kondo
- Department of Pediatric Dentistry Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Mikio Shoji
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Katsuki Takebe
- Institute for Protein Research Osaka University Yamadaoka, Suita Osaka 565‐0871Japan
| | - Yuka Narita
- Department of Functional Bioscience, Infection Biology Fukuoka Dental College Matsudo, Tamura, Sawara, Fukuoka 814‐0913Japan
| | - Mariko Naito
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Daisuke Nakane
- Department of Physics, Faculty of Science Gakushuin University Toshima‐ku, Tokyo 171‐8588Japan
| | - Yoshimitsu Abiko
- Department of Biochemistry and Molecular Biology Nihon University School of Dentistry at Matsudo Matsudo Chiba 271‐8587Japan
| | - Koichi Hiratsuka
- Department of Biochemistry and Molecular Biology Nihon University School of Dentistry at Matsudo Matsudo Chiba 271‐8587Japan
| | - Mamoru Suzuki
- Institute for Protein Research Osaka University Yamadaoka, Suita Osaka 565‐0871Japan
| | - Koji Nakayama
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
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Dropping anchor: attachment of peptidylarginine deiminase via A-LPS to secreted outer membrane vesicles of Porphyromonas gingivalis. Sci Rep 2018; 8:8949. [PMID: 29895934 PMCID: PMC5997701 DOI: 10.1038/s41598-018-27223-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/21/2018] [Indexed: 12/30/2022] Open
Abstract
The periodontal pathogen Porphyromonas gingivalis has been invoked in the autoimmune disease rheumatoid arthritis (RA). This association relates to the peptidylarginine deiminase of P. gingivalis (PPAD), an enzyme capable of citrullinating human proteins and potentially contributing to loss of tolerance to citrullinated proteins in RA. PPAD is both retained in the outer membrane (OM) of P. gingivalis cells and secreted into the extracellular milieu, where it is detected in a soluble form and in association with outer membrane vesicles (OMVs). Recent studies showed that certain P. gingivalis proteins are retained in the OM through modification with an A-type lipopolysaccharide (A-LPS). Here, we investigated the possible involvement of A-LPS modification in the association of PPAD to the OM and OMVs. The results indicate that the OM- and OMV-associated PPAD is A-LPS-modified. The modified PPAD species is of low abundance in particular clinical isolates of P. gingivalis, which is not due to defects in the overall synthesis of A-LPS-modified proteins but, rather, to particular traits of the respective PPAD proteins. Lastly, we show that OMV association protects the A-LPS-modified PPAD from proteolytic degradation. Altogether, our observations show that A-LPS modification contributes to OM(V) sorting and ‘protective secretion’ of PPAD.
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The Type IX Secretion System Is Required for Virulence of the Fish Pathogen Flavobacterium columnare. Appl Environ Microbiol 2017; 83:AEM.01769-17. [PMID: 28939608 DOI: 10.1128/aem.01769-17] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 09/18/2017] [Indexed: 01/21/2023] Open
Abstract
Flavobacterium columnare, a member of the phylum Bacteroidetes, causes columnaris disease in wild and aquaculture-reared freshwater fish. The mechanisms responsible for columnaris disease are not known. Many members of the phylum Bacteroidetes use type IX secretion systems (T9SSs) to secrete enzymes, adhesins, and proteins involved in gliding motility. The F. columnare genome has all of the genes needed to encode a T9SS. gldN, which encodes a core component of the T9SS, was deleted in wild-type strains of F. columnare The F. columnare ΔgldN mutants were deficient in the secretion of several extracellular proteins and lacked gliding motility. The ΔgldN mutants exhibited reduced virulence in zebrafish, channel catfish, and rainbow trout, and complementation restored virulence. PorV is required for the secretion of a subset of proteins targeted to the T9SS. An F. columnare ΔporV mutant retained gliding motility but exhibited reduced virulence. Cell-free spent media from exponentially growing cultures of wild-type and complemented strains caused rapid mortality, but spent media from ΔgldN and ΔporV mutants did not, suggesting that soluble toxins are secreted by the T9SS.IMPORTANCE Columnaris disease, caused by F. columnare, is a major problem for freshwater aquaculture. Little is known regarding the virulence factors produced by F. columnare, and control measures are limited. Analysis of targeted gene deletion mutants revealed the importance of the type IX protein secretion system (T9SS) and of secreted toxins in F. columnare virulence. T9SSs are common in members of the phylum Bacteroidetes and likely contribute to the virulence of other animal and human pathogens.
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Jinmei Z, Lei Z, Yafei W. [Research progress on the type Ⅸ secretion system of Porphyromonas gingivalis]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2017; 35:538-542. [PMID: 29188653 DOI: 10.7518/hxkq.2017.05.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In recent years, the study found that Porphyromonas gingivalis type Ⅸ secretion system (T9SS) is a novel protein secretion system, also known as Por secretion system (PorSS). Unlike the eight protein secretion systems found in the past, the system is a polyprotein complex found only in Bacteroides. The secreted proteins have both N- and C-terminus, where the former includes Sec-dependent type Ⅰ signals peptide, and the latter contains conserved domains (C-terminal conserved domain, CTD). Porphyromonas gingivalis T9SS includes proteins such as intima, outer membrane, cytoplasm, and cell cycle, including at least 34 proteins containing CTD. Porphyromonas gingivalis T9SS is involved in regulating associated virulence factors including gingivin, fimbriae, lipopolysaccharide, HBP35, CPG70 protein and peptidyl-arginine deiminase. These CTD-containing virulence proteins are localized by T9SS and then released to the extracellular domain, thereby destroying periodontal tissue. Therefore, this review summarizes the research progress on the T9SS of Porphyromonas gingivalis.
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Affiliation(s)
- Zhang Jinmei
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Dept. of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Zhao Lei
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Dept. of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Wu Yafei
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Dept. of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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41
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Glew MD, Veith PD, Chen D, Gorasia DG, Peng B, Reynolds EC. PorV is an Outer Membrane Shuttle Protein for the Type IX Secretion System. Sci Rep 2017; 7:8790. [PMID: 28821836 PMCID: PMC5562754 DOI: 10.1038/s41598-017-09412-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/24/2017] [Indexed: 01/20/2023] Open
Abstract
Porphyromonas gingivalis is a keystone pathogen associated with chronic periodontitis. Major virulence factors named gingipains (cysteine proteinases, RgpA, RgpB and Kgp) are secreted via the Type IX Secretion System (T9SS). These, together with approximately 30 other proteins, are secreted to the cell surface and anchored to the outer membrane by covalent modification to anionic lipopolysaccharide (A-LPS) via the novel Gram negative sortase, PorU. PorU is localised on the cell surface and cleaves the C-terminal domain signal (CTD) of T9SS substrates and conjugates their new C-termini to A-LPS. A 440 kDa-attachment complex was identified in the wild-type (WT) comprising of PorU:PorV:PorQ:PorZ. In mutant strains, sub-complexes comprising PorU:PorV or PorQ:PorZ were also identified at smaller native sizes suggesting that PorU and PorZ are anchored to the cell surface via interaction with the PorV and PorQ outer membrane proteins, respectively. Analysis of porU mutants and a CTD cleavage mutant revealed accumulation of immature T9SS substrates in a PorV-bound form. Quantitative label-free proteomics of WT whole cell lysates estimated that the proportion of secretion channels:attachment complexes:free PorV:T9SS substrates was 1:6:110:2000 supporting a role for PorV as a shuttle protein delivering secreted proteins to the attachment complex for CTD signal cleavage and A-LPS modification.
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Affiliation(s)
- Michelle D Glew
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Paul D Veith
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Dina Chen
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Dhana G Gorasia
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Ben Peng
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Eric C Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia.
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42
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Veith PD, Glew MD, Gorasia DG, Reynolds EC. Type IX secretion: the generation of bacterial cell surface coatings involved in virulence, gliding motility and the degradation of complex biopolymers. Mol Microbiol 2017; 106:35-53. [DOI: 10.1111/mmi.13752] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Paul D. Veith
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute; The University of Melbourne; Melbourne Australia
| | - Michelle D. Glew
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute; The University of Melbourne; Melbourne Australia
| | - Dhana G. Gorasia
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute; The University of Melbourne; Melbourne Australia
| | - Eric C. Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute; The University of Melbourne; Melbourne Australia
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43
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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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44
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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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45
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Diverse C-Terminal Sequences Involved in Flavobacterium johnsoniae Protein Secretion. J Bacteriol 2017; 199:JB.00884-16. [PMID: 28396348 DOI: 10.1128/jb.00884-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 03/24/2017] [Indexed: 12/26/2022] Open
Abstract
Flavobacteriumjohnsoniae and many related bacteria secrete proteins across the outer membrane using the type IX secretion system (T9SS). Proteins secreted by T9SSs have amino-terminal signal peptides for export across the cytoplasmic membrane by the Sec system and carboxy-terminal domains (CTDs) targeting them for secretion across the outer membrane by the T9SS. Most but not all T9SS CTDs belong to the family TIGR04183 (type A CTDs). We functionally characterized diverse CTDs for secretion by the F. johnsoniae T9SS. Attachment of the CTDs from F. johnsoniae RemA, AmyB, and ChiA to the foreign superfolder green fluorescent protein (sfGFP) that had a signal peptide at the amino terminus resulted in secretion across the outer membrane. In each case, approximately 80 to 100 amino acids from the extreme carboxy termini were needed for efficient secretion. Several type A CTDs from distantly related members of the phylum Bacteroidetes functioned in F. johnsoniae, supporting the secretion of sfGFP by the F. johnsoniae T9SS. F. johnsoniae SprB requires the T9SS for secretion but lacks a type A CTD. It has a conserved C-terminal domain belonging to the family TIGR04131, which we refer to as a type B CTD. The CTD of SprB was required for its secretion, but attachment of C-terminal regions of SprB of up to 1,182 amino acids to sfGFP failed to result in secretion. Additional features outside the C-terminal region of SprB may be required for its secretion.IMPORTANCE Type IX protein secretion systems (T9SSs) are common in but limited to members of the phylum Bacteroidetes Most proteins that are secreted by T9SSs have conserved carboxy-terminal domains that belong to the protein domain family TIGR04183 (type A CTDs) or TIGR04131 (type B CTDs). Here, we identify features of T9SS CTDs of F. johnsoniae that are required for protein secretion and demonstrate that type A CTDs from distantly related members of the phylum function with the F. johnsoniae T9SS to secrete the foreign protein sfGFP. In contrast, type B CTDs failed to target sfGFP for secretion, suggesting a more complex association with the T9SS.
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46
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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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47
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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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48
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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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Structural Insights into the PorK and PorN Components of the Porphyromonas gingivalis Type IX Secretion System. PLoS Pathog 2016; 12:e1005820. [PMID: 27509186 PMCID: PMC4980022 DOI: 10.1371/journal.ppat.1005820] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 07/20/2016] [Indexed: 01/19/2023] Open
Abstract
The type IX secretion system (T9SS) has been recently discovered and is specific to Bacteroidetes species. Porphyromonas gingivalis, a keystone pathogen for periodontitis, utilizes the T9SS to transport many proteins including the gingipain virulence factors across the outer membrane and attach them to the cell surface via a sortase-like mechanism. At least 11 proteins have been identified as components of the T9SS including PorK, PorL, PorM, PorN and PorP, however the precise roles of most of these proteins have not been elucidated and the structural organization of these components is unknown. In this study, we purified PorK and PorN complexes from P. gingivalis and using electron microscopy we have shown that PorN and the PorK lipoprotein interact to form a 50 nm diameter ring-shaped structure containing approximately 32-36 subunits of each protein. The formation of these rings was dependent on both PorK and PorN, but was independent of PorL, PorM and PorP. PorL and PorM were found to form a separate stable complex. PorK and PorN were protected from proteinase K cleavage when present in undisrupted cells, but were rapidly degraded when the cells were lysed, which together with bioinformatic analyses suggests that these proteins are exposed in the periplasm and anchored to the outer membrane via the PorK lipid. Chemical cross-linking and mass spectrometry analyses confirmed the interaction between PorK and PorN and further revealed that they interact with the PG0189 outer membrane protein. Furthermore, we established that PorN was required for the stable expression of PorK, PorL and PorM. Collectively, these results suggest that the ring-shaped PorK/N complex may form part of the secretion channel of the T9SS. This is the first report showing the structural organization of any T9SS component.
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Ormerod KL, Wood DLA, Lachner N, Gellatly SL, Daly JN, Parsons JD, Dal'Molin CGO, Palfreyman RW, Nielsen LK, Cooper MA, Morrison M, Hansbro PM, Hugenholtz P. Genomic characterization of the uncultured Bacteroidales family S24-7 inhabiting the guts of homeothermic animals. MICROBIOME 2016; 4:36. [PMID: 27388460 PMCID: PMC4936053 DOI: 10.1186/s40168-016-0181-2] [Citation(s) in RCA: 424] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/23/2016] [Indexed: 05/05/2023]
Abstract
BACKGROUND Our view of host-associated microbiota remains incomplete due to the presence of as yet uncultured constituents. The Bacteroidales family S24-7 is a prominent example of one of these groups. Marker gene surveys indicate that members of this family are highly localized to the gastrointestinal tracts of homeothermic animals and are increasingly being recognized as a numerically predominant member of the gut microbiota; however, little is known about the nature of their interactions with the host. RESULTS Here, we provide the first whole genome exploration of this family, for which we propose the name "Candidatus Homeothermaceae," using 30 population genomes extracted from fecal samples of four different animal hosts: human, mouse, koala, and guinea pig. We infer the core metabolism of "Ca. Homeothermaceae" to be that of fermentative or nanaerobic bacteria, resembling that of related Bacteroidales families. In addition, we describe three trophic guilds within the family, plant glycan (hemicellulose and pectin), host glycan, and α-glucan, each broadly defined by increased abundance of enzymes involved in the degradation of particular carbohydrates. CONCLUSIONS "Ca. Homeothermaceae" representatives constitute a substantial component of the murine gut microbiota, as well as being present within the human gut, and this study provides important first insights into the nature of their residency. The presence of trophic guilds within the family indicates the potential for niche partitioning and specific roles for each guild in gut health and dysbiosis.
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Affiliation(s)
- Kate L Ormerod
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - David L A Wood
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Nancy Lachner
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Shaan L Gellatly
- Priority Research Centre for Healthy Lungs, The University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Joshua N Daly
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Jeremy D Parsons
- QFAB Bioinformatics, The University of Queensland, Brisbane, Australia
| | - Cristiana G O Dal'Molin
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Robin W Palfreyman
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Lars K Nielsen
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Matthew A Cooper
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Mark Morrison
- Microbial Biology and Metagenomics, The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Australia
| | - Philip M Hansbro
- Priority Research Centre for Healthy Lungs, The University of Newcastle and Hunter Medical Research Institute, Newcastle, Australia
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.
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