1
|
Liu H, Xu G, Guo B, Liu F. Old role with new feature: T2SS ATPase as a cyclic-di-GMP receptor to regulate antibiotic production. Appl Environ Microbiol 2024; 90:e0041824. [PMID: 38624198 PMCID: PMC11107153 DOI: 10.1128/aem.00418-24] [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: 03/04/2024] [Accepted: 03/26/2024] [Indexed: 04/17/2024] Open
Abstract
Cyclic di-GMP (c-di-GMP) is a crucial signaling molecule found extensively in bacteria, involved in the regulation of various physiological and biochemical processes such as biofilm formation, motility, and pathogenicity through binding to downstream receptors. However, the structural dissimilarity of c-di-GMP receptor proteins has hindered the discovery of many such proteins. In this study, we identified LspE, a homologous protein of the type II secretion system (T2SS) ATPase GspE in Lysobacter enzymogenes, as a receptor protein for c-di-GMP. We identified the more conservative c-di-GMP binding amino acid residues as K358 and T359, which differ from the previous reports, indicating that GspE proteins may represent a class of c-di-GMP receptor proteins. Additionally, we found that LspE in L. enzymogenes also possesses a novel role in regulating the production of the antifungal antibiotic HSAF. Further investigations revealed the critical involvement of both ATPase activity and c-di-GMP binding in LspE-mediated regulation of HSAF (Heat-Stable Antifungal Factor) production, with c-di-GMP binding having no impact on LspE's ATPase activity. This suggests that the control of HSAF production by LspE encompasses two distinct processes: c-di-GMP binding and the inherent ATPase activity of LspE. Overall, our study unraveled a new function for the conventional protein GspE of the T2SS as a c-di-GMP receptor protein and shed light on its role in regulating antibiotic production.IMPORTANCEThe c-di-GMP signaling pathway in bacteria is highly intricate. The identification and functional characterization of novel receptor proteins have posed a significant challenge in c-di-GMP research. The type II secretion system (T2SS) is a well-studied secretion system in bacteria. In this study, our findings revealed the ATPase GspE protein of the T2SS as a class of c-di-GMP receptor protein. Notably, we discovered its novel function in regulating the production of antifungal antibiotic HSAF in Lysobacter enzymogenes. Given that GspE may be a conserved c-di-GMP receptor protein, it is worthwhile for researchers to reevaluate its functional roles and mechanisms across diverse bacterial species.
Collapse
Affiliation(s)
- Haofei Liu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Gaoge Xu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Nanjing, China
- School of Plant Protection, Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou, China
| | - Baodian Guo
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Nanjing, China
| | - Fengquan Liu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Nanjing, China
- Department of Plant Pathology, College of Agriculture, Guizhou University, Guiyang, China
| |
Collapse
|
2
|
Guilvout I, Samsudin F, Huber RG, Bond PJ, Bardiaux B, Francetic O. Membrane platform protein PulF of the Klebsiella type II secretion system forms a trimeric ion channel essential for endopilus assembly and protein secretion. mBio 2024; 15:e0142323. [PMID: 38063437 PMCID: PMC10790770 DOI: 10.1128/mbio.01423-23] [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: 06/05/2023] [Accepted: 10/24/2023] [Indexed: 01/17/2024] Open
Abstract
IMPORTANCE Type IV pili and type II secretion systems are members of the widespread type IV filament (T4F) superfamily of nanomachines that assemble dynamic and versatile surface fibers in archaea and bacteria. The assembly and retraction of T4 filaments with diverse surface properties and functions require the plasma membrane platform proteins of the GspF/PilC superfamily. Generally considered dimeric, platform proteins are thought to function as passive transmitters of the mechanical energy generated by the ATPase motor, to somehow promote insertion of pilin subunits into the nascent pilus fibers. Here, we generate and experimentally validate structural predictions that support the trimeric state of a platform protein PulF from a type II secretion system. The PulF trimers form selective proton or sodium channels which might energize pilus assembly using the membrane potential. The conservation of the channel sequence and structural features implies a common mechanism for all T4F assembly systems. We propose a model of the oligomeric PulF-PulE ATPase complex that provides an essential framework to investigate and understand the pilus assembly mechanism.
Collapse
Affiliation(s)
- Ingrid Guilvout
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
| | | | | | - Peter J. Bond
- Bioinformatics Institute (A-STAR), Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Benjamin Bardiaux
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Structural Bioinformatics Unit, Paris, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Bacterial Transmembrane Systems Unit, Paris, France
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, Paris, France
| |
Collapse
|
3
|
Li Y, Santos-Moreno J, Francetic O. The periplasmic coiled coil formed by the assembly platform proteins PulL and PulM is critical for function of the Klebsiella type II secretion system. Res Microbiol 2023; 174:104075. [PMID: 37141929 DOI: 10.1016/j.resmic.2023.104075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/06/2023]
Abstract
Bacteria use type II secretion systems (T2SS) to secrete to their surface folded proteins that confer diverse functions, from nutrient acquisition to virulence. In the Klebsiella species, T2SS-mediated secretion of pullulanase (PulA) requires assembly of a dynamic filament called the endopilus. The inner membrane assembly platform (AP) subcomplex is essential for endopilus assembly and PulA secretion. AP components PulL and PulM interact with each other through their C-terminal globular domains and transmembrane segments. Here, we investigated the roles of their periplasmic helices, predicted to form a coiled coil, in assembly and function of the PulL-PulM complex. PulL and PulM variants lacking these periplasmic helices were defective for interaction in the bacterial two-hybrid (BACTH) assay. Their functions in PulA secretion and assembly of PulG subunits into endopilus filaments were strongly reduced. Interestingly, deleting the cytoplasmic peptide of PulM nearly abolished the function of variant PulMΔN and its interaction with PulG, but not with PulL, in the BACTH assay. Nevertheless, PulL was specifically proteolyzed in the presence of the PulMΔN variant, suggesting that PulM N-terminal peptide stabilizes PulL in the cytoplasm. We discuss the implications of these results for the T2S endopilus and type IV pilus assembly mechanisms.
Collapse
Affiliation(s)
- Yuanyuan Li
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
| | - Javier Santos-Moreno
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
| | - Olivera Francetic
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Biochemistry of Macromolecular Interactions Unit, F-75015 Paris, France.
| |
Collapse
|
4
|
Wang Y, Li Z, Li F. Impact of Previous Pulmonary Tuberculosis on Chronic Obstructive Pulmonary Disease: Baseline Results from a Prospective Cohort Study. Comb Chem High Throughput Screen 2023; 26:93-102. [PMID: 35388750 DOI: 10.2174/1386207325666220406111435] [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: 09/19/2021] [Revised: 12/30/2021] [Accepted: 01/05/2022] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Pulmonary tuberculosis (PTB) is a significant risk factor for COPD, and Xinjiang, China, has a high incidence of pulmonary tuberculosis. The effects of tuberculosis history on airflow restriction, clinical symptoms, and acute episodes in COPD patients have not been reported in the local population. Besides, the exact relationship between lung function changes in people with a history of tuberculosis and COPD risk is not clear. METHODS This study is based on the Xinjiang baseline survey data included in the Natural Population Cohort Study in Northwest China from June to December, 2018. Subjects' questionnaires, physical examination, and lung function tests were performed through a face-to-face field survey to analyze the impact of previous pulmonary tuberculosis on local COPD. Furthermore, we clarified the specific relationship between pulmonary function decline and the probability of developing COPD in people with a history of tuberculosis. RESULTS A total of 3249 subjects were eventually enrolled in this study, including 87 with a history of tuberculosis and 3162 non-TB. The prevalence of COPD in the prior TB group was significantly higher than that in the control group (p-value = 0.005). First, previous pulmonary tuberculosis is an essential contributor to airflow limitation in the general population and patients with COPD. In all subjects included, pulmonary function, FEV1% predicted (p-value < 0.001), and FEV1/FVC (%) (p-value < 0.001) were significantly lower in the prior TB group than in the control group. Compared to non-TB group, FEV1% prediction (p-value = 0.019) and FEV1/FVC (%) (p-value = 0.016) were found to be significantly reduced, and airflow restriction (p-value = 0.004) was more severe in prior TB group among COPD patients. Second, COPD patients in the prior TB group had more severe clinical symptoms. Compared with no history of tuberculosis, mMRC (p-value = 0.001) and CAT (p-value = 0.002) scores were higher in the group with a history of tuberculosis among COPD patients. Third, compared with the non-TB group, the number of acute exacerbations per year (p-values=0.008), the duration of each acute exacerbation (p-values=0.004), and hospitalization/ patient/year (p-values<0.001) were higher in the group with a history of tuberculosis among COPD patients. Finally, a dose-response relationship between FEV1/FVC (%) and the probability of developing COPD in people with previous pulmonary TB was observed; when FEV1/FVC (%) was < 80.8, the risk of COPD increased by 13.5% per unit decrease in lung function [0.865(0.805, 0.930)]. CONCLUSION COPD patients with previous pulmonary tuberculosis have more severe airflow limitations and clinical symptoms and are at higher risk for acute exacerbations. Furthermore, lung function changes in people with a history of tuberculosis were associated with a dose-response relationship with the probability of developing COPD.
Collapse
Affiliation(s)
- Yide Wang
- Department of Integrated Pulmonology, The Traditional Chinese Medicine Hospital Affiliated to Xinjiang Medical University, Urumqi, 830000, P.R. China
- National Clinical Research Base of Traditional Chinese Medicine in Xinjiang, Urumqi, 830000, P.R. China
| | - Zheng Li
- Department of Integrated Pulmonology, The Traditional Chinese Medicine Hospital Affiliated to Xinjiang Medical University, Urumqi, 830000, P.R. China
- National Clinical Research Base of Traditional Chinese Medicine in Xinjiang, Urumqi, 830000, P.R. China
| | - Fengsen Li
- Department of Integrated Pulmonology, The Traditional Chinese Medicine Hospital Affiliated to Xinjiang Medical University, Urumqi, 830000, P.R. China
- National Clinical Research Base of Traditional Chinese Medicine in Xinjiang, Urumqi, 830000, P.R. China
| |
Collapse
|
5
|
Dazzoni R, López-Castilla A, Cordier F, Bardiaux B, Nilges M, Francetic O, Izadi-Pruneyre N. 1H, 15 N and 13C resonance assignments of the C-terminal domain of PulL, a component of the Klebsiella oxytoca type II secretion system. BIOMOLECULAR NMR ASSIGNMENTS 2021; 15:455-459. [PMID: 34410621 DOI: 10.1007/s12104-021-10045-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
Type II secretion systems (T2SS) allow Gram-negative bacteria to transport toxins and enzymes from the periplasm to the external milieu, and are thus important for the pathogenicity of bacteria. To drive secretion, T2SS assemble filaments called pseudopili closely related to bacterial type IV pili. These filaments are non-covalent polymers of proteins that are assembled by an inner membrane complex called the assembly platform connected to a cytoplasmic ATPase motor. In the Klebsiella oxytoca T2SS, the PulL protein from the assembly platform is essential for pseudopilus assembly and protein secretion. However, its role in these processes is not well understood. To decipher the molecular basis of PulL function, we used solution NMR to study its structure and interactions with other components of the machinery. Here as a first step, we report the 1H, 15 N and 13C backbone and side-chain chemical shift assignments of the C-terminal periplasmic domain of PulL and its secondary structure based on NMR data.
Collapse
Affiliation(s)
- Régine Dazzoni
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Aracelys López-Castilla
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Florence Cordier
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
- Biological NMR Technological Platform, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, France
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France
| | - Olivera Francetic
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, France
| | - Nadia Izadi-Pruneyre
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France.
| |
Collapse
|
6
|
Li E, Zhang H, Jiang H, Pieterse CMJ, Jousset A, Bakker PAHM, de Jonge R. Experimental-Evolution-Driven Identification of Arabidopsis Rhizosphere Competence Genes in Pseudomonas protegens. mBio 2021; 12:e0092721. [PMID: 34101491 PMCID: PMC8262913 DOI: 10.1128/mbio.00927-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 04/30/2021] [Indexed: 11/20/2022] Open
Abstract
Beneficial plant root-associated microorganisms carry out a range of functions that are essential for plant performance. Establishment of a bacterium on plant roots, however, requires overcoming several challenges, including competition with neighboring microorganisms and host immunity. Forward and reverse genetics have led to the identification of mechanisms that are used by beneficial microorganisms to overcome these challenges, such as the production of iron-chelating compounds, the formation of strong biofilms, or the concealment of characteristic microbial molecular patterns that trigger the host immune system. However, how such mechanisms arose from an evolutionary perspective is much less understood. To study bacterial adaptation in the rhizosphere, we employed experimental evolution to track the physiological and genetic dynamics of root-dwelling Pseudomonas protegens in the Arabidopsis thaliana rhizosphere under axenic conditions. This simplified binary one plant/one bacterium system allows for the amplification of key adaptive mechanisms for bacterial rhizosphere colonization. We identified 35 mutations, including single-nucleotide polymorphisms, insertions, and deletions, distributed over 28 genes. We found that mutations in genes encoding global regulators and in genes for siderophore production, cell surface decoration, attachment, and motility accumulated in parallel, underlining the finding that bacterial adaptation to the rhizosphere follows multiple strategies. Notably, we observed that motility increased in parallel across multiple independent evolutionary lines. All together, these results underscore the strength of experimental evolution in identifying key genes, pathways, and processes for bacterial rhizosphere colonization and a methodology for the development of elite beneficial microorganisms with enhanced root-colonizing capacities that can support sustainable agriculture in the future. IMPORTANCE Beneficial root-associated microorganisms carry out many functions that are essential for plant performance. Establishment of a bacterium on plant roots, however, requires overcoming many challenges. Previously, diverse mechanisms that are used by beneficial microorganisms to overcome these challenges were identified. However, how such mechanisms have developed from an evolutionary perspective is much less understood. Here, we employed experimental evolution to track the evolutionary dynamics of a root-dwelling pseudomonad on the root of Arabidopsis. We found that mutations in global regulators, as well as in genes for siderophore production, cell surface decoration, attachment, and motility, accumulate in parallel, emphasizing these strategies for bacterial adaptation to the rhizosphere. We identified 35 mutations distributed over 28 genes. All together, our results demonstrate the power of experimental evolution in identifying key pathways for rhizosphere colonization and a methodology for the development of elite beneficial microorganisms that can support sustainable agriculture.
Collapse
Affiliation(s)
- Erqin Li
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Hao Zhang
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Henan Jiang
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Corné M. J. Pieterse
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Alexandre Jousset
- Ecology and Biodiversity, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Peter A. H. M. Bakker
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Ronnie de Jonge
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| |
Collapse
|
7
|
Naskar S, Hohl M, Tassinari M, Low HH. The structure and mechanism of the bacterial type II secretion system. Mol Microbiol 2020; 115:412-424. [PMID: 33283907 DOI: 10.1111/mmi.14664] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/03/2020] [Indexed: 12/17/2022]
Abstract
The type II secretion system (T2SS) is a multi-protein complex used by many bacteria to move substrates across their cell membrane. Substrates released into the environment serve as local and long-range effectors that promote nutrient acquisition, biofilm formation, and pathogenicity. In both animals and plants, the T2SS is increasingly recognized as a key driver of virulence. The T2SS spans the bacterial cell envelope and extrudes substrates through an outer membrane secretin channel using a pseudopilus. An inner membrane assembly platform and a cytoplasmic motor controls pseudopilus assembly. This microreview focuses on the structure and mechanism of the T2SS. Advances in cryo-electron microscopy are enabling increasingly elaborate sub-complexes to be resolved. However, key questions remain regarding the mechanism of pseudopilus extension and retraction, and how this is coupled with the choreography of the substrate moving through the secretion system. The T2SS is part of an ancient type IV filament superfamily that may have been present within the last universal common ancestor (LUCA). Overall, mechanistic principles that underlie T2SS function have implication for other closely related systems such as the type IV and tight adherence pilus systems.
Collapse
Affiliation(s)
- Souvik Naskar
- Department of Infectious Disease, Imperial College, London, UK
| | - Michael Hohl
- Department of Infectious Disease, Imperial College, London, UK
| | | | - Harry H Low
- Department of Infectious Disease, Imperial College, London, UK
| |
Collapse
|
8
|
Burghard-Schrod M, Altenburger S, Graumann PL. The Bacillus subtilis dCMP deaminase ComEB acts as a dynamic polar localization factor for ComGA within the competence machinery. Mol Microbiol 2020; 113:906-922. [PMID: 31954084 DOI: 10.1111/mmi.14457] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 01/08/2020] [Accepted: 01/10/2020] [Indexed: 01/15/2023]
Abstract
Bacillus subtilis can import DNA from the environment by an uptake machinery that localizes to a single cell pole. We investigated the roles of ComEB and of the ATPase ComGA during the state of competence. We show that ComEB plays an important role during competence, possibly because it is necessary for the recruitment of GomGA to the cell pole. ComEB localizes to the cell poles even upon expression during exponential phase, indicating that it can serve as polar marker. ComEB is also a deoxycytidylate monophosphate (dCMP) deaminase, for the function of which a conserved cysteine residue is important. However, cysteine-mutant ComEB is still capable of natural transformation, while a comEB deletion strain is highly impaired in competence, indicating that ComEB confers two independent functions. Single-molecule tracking (SMT) reveals that both proteins exchange at the cell poles between bound and unbound in a time scale of a few milliseconds, but turnover of ComGA increases during DNA uptake, whereas the mobility of ComEB is not affected. Our data reveal a highly dynamic role of ComGA during DNA uptake and an unusual role for ComEB as a mediator of polar localization, localizing by diffusion-capture on an extremely rapid time scale and functioning as a moonlighting enzyme.
Collapse
Affiliation(s)
- Marie Burghard-Schrod
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Stephan Altenburger
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Peter L Graumann
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| |
Collapse
|
9
|
Structure and Membrane Topography of the Vibrio-Type Secretin Complex from the Type 2 Secretion System of Enteropathogenic Escherichia coli. J Bacteriol 2018; 200:JB.00521-17. [PMID: 29084860 DOI: 10.1128/jb.00521-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 10/25/2017] [Indexed: 12/11/2022] Open
Abstract
The β-barrel assembly machinery (BAM) complex is the core machinery for the assembly of β-barrel membrane proteins, and inhibition of BAM complex activity is lethal to bacteria. Discovery of integral membrane proteins that are key to pathogenesis and yet do not require assistance from the BAM complex raises the question of how these proteins assemble into bacterial outer membranes. Here, we address this question through a structural analysis of the type 2 secretion system (T2SS) secretin from enteropathogenic Escherichia coli O127:H6 strain E2348/69. Long β-strands assemble into a barrel extending 17 Å through and beyond the outer membrane, adding insight to how these extensive β-strands are assembled into the E. coli outer membrane. The substrate docking chamber of this secretin is shown to be sufficient to accommodate the substrate mucinase SteC.IMPORTANCE In order to cause disease, bacterial pathogens inhibit immune responses and induce pathology that will favor their replication and dissemination. In Gram-negative bacteria, these key attributes of pathogenesis depend on structures assembled into or onto the outer membrane. One of these is the T2SS. The Vibrio-type T2SS mediates cholera toxin secretion in Vibrio cholerae, and in Escherichia coli O127:H6 strain E2348/69, the same machinery mediates secretion of the mucinases that enable the pathogen to penetrate intestinal mucus and thereby establish deadly infections.
Collapse
|
10
|
Thomassin JL, Santos Moreno J, Guilvout I, Tran Van Nhieu G, Francetic O. The trans-envelope architecture and function of the type 2 secretion system: new insights raising new questions. Mol Microbiol 2017; 105:211-226. [DOI: 10.1111/mmi.13704] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Jenny-Lee Thomassin
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Javier Santos Moreno
- Université Paris Diderot (Paris 7) Sorbonne Paris Cité; Paris France
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Ingrid Guilvout
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Guy Tran Van Nhieu
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Olivera Francetic
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| |
Collapse
|
11
|
Rule CS, Patrick M, Camberg JL, Maricic N, Hol WG, Sandkvist M. Zinc coordination is essential for the function and activity of the type II secretion ATPase EpsE. Microbiologyopen 2016; 5:870-882. [PMID: 27168165 PMCID: PMC5061722 DOI: 10.1002/mbo3.376] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/05/2016] [Accepted: 04/11/2016] [Indexed: 11/10/2022] Open
Abstract
The type II secretion system Eps in Vibrio cholerae promotes the extracellular transport of cholera toxin and several hydrolytic enzymes and is a major virulence system in many Gram‐negative pathogens which is structurally related to the type IV pilus system. The cytoplasmic ATPase EpsE provides the energy for exoprotein secretion through ATP hydrolysis. EpsE contains a unique metal‐binding domain that coordinates zinc through a tetracysteine motif (CXXCX29CXXC), which is also present in type IV pilus assembly but not retraction ATPases. Deletion of the entire domain or substitution of any of the cysteine residues that coordinate zinc completely abrogates secretion in an EpsE‐deficient strain and has a dominant negative effect on secretion in the presence of wild‐type EpsE. Consistent with the in vivo data, chemical depletion of zinc from purified EpsE hexamers results in loss of in vitro ATPase activity. In contrast, exchanging the residues between the two dicysteines with those from the homologous ATPase XcpR from Pseudomonas aeruginosa does not have a significant impact on EpsE. These results indicate that, although the individual residues in the metal‐binding domain are generally interchangeable, zinc coordination is essential for the activity and function of EpsE.
Collapse
Affiliation(s)
- Chelsea S Rule
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Marcella Patrick
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Jodi L Camberg
- Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, Rockville, Maryland
| | - Natalie Maricic
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Wim G Hol
- Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle, Washington
| | - Maria Sandkvist
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan.
| |
Collapse
|
12
|
Systematic Identification of Cyclic-di-GMP Binding Proteins in Vibrio cholerae Reveals a Novel Class of Cyclic-di-GMP-Binding ATPases Associated with Type II Secretion Systems. PLoS Pathog 2015; 11:e1005232. [PMID: 26506097 PMCID: PMC4624772 DOI: 10.1371/journal.ppat.1005232] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 09/25/2015] [Indexed: 11/30/2022] Open
Abstract
Cyclic-di-GMP (c-di-GMP) is a ubiquitous bacterial signaling molecule that regulates a variety of complex processes through a diverse set of c-di-GMP receptor proteins. We have utilized a systematic approach to identify c-di-GMP receptors from the pathogen Vibrio cholerae using the Differential Radial Capillary Action of Ligand Assay (DRaCALA). The DRaCALA screen identified a majority of known c-di-GMP binding proteins in V. cholerae and revealed a novel c-di-GMP binding protein, MshE (VC0405), an ATPase associated with the mannose sensitive hemagglutinin (MSHA) type IV pilus. The known c-di-GMP binding proteins identified by DRaCALA include diguanylate cyclases, phosphodiesterases, PilZ domain proteins and transcription factors VpsT and VpsR, indicating that the DRaCALA-based screen of open reading frame libraries is a feasible approach to uncover novel receptors of small molecule ligands. Since MshE lacks the canonical c-di-GMP-binding motifs, a truncation analysis was utilized to locate the c-di-GMP binding activity to the N-terminal T2SSE_N domain. Alignment of MshE homologs revealed candidate conserved residues responsible for c-di-GMP binding. Site-directed mutagenesis of these candidate residues revealed that the Arg9 residue is required for c-di-GMP binding. The ability of c-di-GMP binding to MshE to regulate MSHA dependent processes was evaluated. The R9A allele, in contrast to the wild type MshE, was unable to complement the ΔmshE mutant for the production of extracellular MshA to the cell surface, reduction in flagella swimming motility, attachment to surfaces and formation of biofilms. Testing homologs of MshE for binding to c-di-GMP identified the type II secretion ATPase of Pseudomonas aeruginosa (PA14_29490) as a c-di-GMP receptor, indicating that type II secretion and type IV pili are both regulated by c-di-GMP. Cyclic-di-GMP (c-di-GMP) is a ubiquitous bacterial signaling molecule that regulates important bacterial functions, including virulence, antibiotic resistance, biofilm formation and cell division. The list of known c-di-GMP receptors is clearly incomplete. Here we utilized a systematic and unbiased biochemical approach to identify c-di-GMP receptors from the 3,812 genes of the Vibrio cholerae genome. Results from this analysis identified most known c-di-GMP receptors as well as MshE, a protein not known to interact with c-di-GMP. The c-di-GMP binding site was identified at the N-terminus of MshE and requires a conserved arginine residue in the 9th position. MshE is the ATPase that powers the secretion of the MshA pili onto the surface of the bacteria. We show that c-di-GMP binding to MshE is required for MshA export and the function of the pili in attachment and biofilm formation. ATPases responsible for related processes such as type IV pili and type II secretion were also tested for c-di-GMP binding, which identified the P. aeruginosa ATPase PA14_29490 as another c-di-GMP binding protein. These findings reveal a new class of c-di-GMP receptor and raise the possibility that c-di-GMP regulate membrane complexes through direct interaction with related type II secretion and type IV pili ATPases.
Collapse
|
13
|
Affiliation(s)
- Alain Filloux
- Alain Filloux, MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK; E-mail:
| |
Collapse
|
14
|
Berry JL, Pelicic V. Exceptionally widespread nanomachines composed of type IV pilins: the prokaryotic Swiss Army knives. FEMS Microbiol Rev 2014; 39:134-54. [PMID: 25793961 PMCID: PMC4471445 DOI: 10.1093/femsre/fuu001] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Prokaryotes have engineered sophisticated surface nanomachines that have allowed them to colonize Earth and thrive even in extreme environments. Filamentous machineries composed of type IV pilins, which are associated with an amazing array of properties ranging from motility to electric conductance, are arguably the most widespread since distinctive proteins dedicated to their biogenesis are found in most known species of prokaryotes. Several decades of investigations, starting with type IV pili and then a variety of related systems both in bacteria and archaea, have outlined common molecular and structural bases for these nanomachines. Using type IV pili as a paradigm, we will highlight in this review common aspects and key biological differences of this group of filamentous structures. Using type IV pili as a paradigm, we review common genetic, structural and mechanistic features (many) as well as differences (few) of the exceptionally widespread and functionally versatile prokaryotic nano-machines composed of type IV pilins.
Collapse
Affiliation(s)
- Jamie-Lee Berry
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Vladimir Pelicic
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
15
|
Lu C, Korotkov KV, Hol WGJ. Crystal structure of the full-length ATPase GspE from the Vibrio vulnificus type II secretion system in complex with the cytoplasmic domain of GspL. J Struct Biol 2014; 187:223-235. [PMID: 25092625 DOI: 10.1016/j.jsb.2014.07.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 11/15/2022]
Abstract
The type II secretion system (T2SS) is present in many Gram-negative bacteria and is responsible for secreting a large number of folded proteins, including major virulence factors, across the outer membrane. The T2SS consists of 11-15 different proteins most of which are present in multiple copies in the assembled secretion machinery. The ATPase GspE, essential for the functioning of the T2SS, contains three domains (N1E, N2E and CTE) of which the N1E domain is associated with the cytoplasmic domain of the inner membrane protein GspL. Here we describe and analyze the structure of the GspE•cyto-GspL complex from Vibrio vulnificus in the presence of an ATP analog, AMPPNP. There are three such ∼83 kDa complexes per asymmetric unit with essentially the same structure. The N2E and CTE domains of a single V. vulnificus GspE subunit adopt a mutual orientation that has not been seen before in any of the previous GspE structures, neither in structures of related ATPases from other secretion systems. This underlines the tremendous conformational flexibility of the T2SS secretion ATPase. Cyto-GspL interacts not only with the N1E domain, but also with the CTE domain and is even in contact with AMPPNP. Moreover, the cyto-GspL domains engage in two types of mutual interactions, resulting in two essentially identical, but crystallographically independent, "cyto-GspL rods" that run throughout the crystal. Very similar rods are present in previous crystals of cyto-GspL and of the N1E•cyto-GspL complex. This arrangement, now seen four times in three entirely different crystal forms, involves contacts between highly conserved residues suggesting a role in the biogenesis or the secretion mechanism or both of the T2SS.
Collapse
Affiliation(s)
- Connie Lu
- Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, United States
| | - Konstantin V Korotkov
- Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, United States
| | - Wim G J Hol
- Department of Biochemistry and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, United States.
| |
Collapse
|
16
|
Type II secretion system: A magic beanstalk or a protein escalator. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1568-77. [DOI: 10.1016/j.bbamcr.2013.12.020] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 12/13/2013] [Accepted: 12/23/2013] [Indexed: 12/12/2022]
|
17
|
Distinct docking and stabilization steps of the Pseudopilus conformational transition path suggest rotational assembly of type IV pilus-like fibers. Structure 2014; 22:685-96. [PMID: 24685147 DOI: 10.1016/j.str.2014.03.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 02/28/2014] [Accepted: 03/04/2014] [Indexed: 01/07/2023]
Abstract
The closely related bacterial type II secretion (T2S) and type IV pilus (T4P) systems are sophisticated machines that assemble dynamic fibers promoting protein transport, motility, or adhesion. Despite their essential role in virulence, the molecular mechanisms underlying helical fiber assembly remain unknown. Here, we use electron microscopy and flexible modeling to study conformational changes of PulG pili assembled by the Klebsiella oxytoca T2SS. Neural network analysis of 3,900 pilus models suggested a transition path toward low-energy conformations driven by progressive increase in fiber helical twist. Detailed predictions of interprotomer contacts along this path were tested by site-directed mutagenesis, pilus assembly, and protein secretion analyses. We demonstrate that electrostatic interactions between adjacent protomers (P-P+1) in the membrane drive pseudopilin docking, while P-P+3 and P-P+4 contacts determine downstream fiber stabilization steps. These results support a model of a spool-like assembly mechanism for fibers of the T2SS-T4P superfamily.
Collapse
|
18
|
Lu C, Turley S, Marionni ST, Park YJ, Lee KK, Patrick M, Shah R, Sandkvist M, Bush MF, Hol WGJ. Hexamers of the type II secretion ATPase GspE from Vibrio cholerae with increased ATPase activity. Structure 2013; 21:1707-17. [PMID: 23954505 PMCID: PMC3775503 DOI: 10.1016/j.str.2013.06.027] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 06/17/2013] [Accepted: 06/18/2013] [Indexed: 01/07/2023]
Abstract
The type II secretion system (T2SS), a multiprotein machinery spanning two membranes in Gram-negative bacteria, is responsible for the secretion of folded proteins from the periplasm across the outer membrane. The critical multidomain T2SS assembly ATPase GspE(EpsE) had not been structurally characterized as a hexamer. Here, four hexamers of Vibrio cholerae GspE(EpsE) are obtained when fused to Hcp1 as an assistant hexamer, as shown with native mass spectrometry. The enzymatic activity of the GspE(EpsE)-Hcp1 fusions is ∼20 times higher than that of a GspE(EpsE) monomer, indicating that increasing the local concentration of GspE(EpsE) by the fusion strategy was successful. Crystal structures of GspE(EpsE)-Hcp1 fusions with different linker lengths reveal regular and elongated hexamers of GspE(EpsE) with major differences in domain orientation within subunits, and in subunit assembly. SAXS studies on GspE(EpsE)-Hcp1 fusions suggest that even further variability in GspE(EpsE) hexamer architecture is likely.
Collapse
Affiliation(s)
- Connie Lu
- Department of Biochemistry, School of Medicine, University of Washington, Seattle
| | - Stewart Turley
- Department of Biochemistry, School of Medicine, University of Washington, Seattle
| | | | - Young-Jun Park
- Department of Biochemistry, School of Medicine, University of Washington, Seattle
| | - Kelly K. Lee
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle
| | - Marcella Patrick
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Ripal Shah
- Department of Biochemistry, School of Medicine, University of Washington, Seattle
| | - Maria Sandkvist
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | | | - Wim G. J. Hol
- Department of Biochemistry, School of Medicine, University of Washington, Seattle
| |
Collapse
|
19
|
The type II secretion system – a dynamic fiber assembly nanomachine. Res Microbiol 2013; 164:545-55. [DOI: 10.1016/j.resmic.2013.03.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/28/2013] [Indexed: 11/17/2022]
|
20
|
Douzi B, Filloux A, Voulhoux R. On the path to uncover the bacterial type II secretion system. Philos Trans R Soc Lond B Biol Sci 2012; 367:1059-72. [PMID: 22411978 DOI: 10.1098/rstb.2011.0204] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Gram-negative bacteria have evolved several secretory pathways to release enzymes or toxins into the surrounding environment or into the target cells. The type II secretion system (T2SS) is conserved in Gram-negative bacteria and involves a set of 12 to 16 different proteins. Components of the T2SS are located in both the inner and outer membranes where they assemble into a supramolecular complex spanning the bacterial envelope, also called the secreton. The T2SS substrates transiently go through the periplasm before they are translocated across the outer membrane and exposed to the extracellular milieu. The T2SS is unique in its ability to promote secretion of large and sometimes multimeric proteins that are folded in the periplasm. The present review describes recently identified protein-protein interactions together with structural and functional advances in the field that have contributed to improve our understanding on how the type II secretion apparatus assembles and on the role played by individual proteins of this highly sophisticated system.
Collapse
Affiliation(s)
- Badreddine Douzi
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (CNRS-LISM-UPR 9027), Aix-Marseille Universités, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | | | | |
Collapse
|
21
|
Wang X, Pineau C, Gu S, Guschinskaya N, Pickersgill RW, Shevchik VE. Cysteine scanning mutagenesis and disulfide mapping analysis of arrangement of GspC and GspD protomers within the type 2 secretion system. J Biol Chem 2012; 287:19082-93. [PMID: 22523076 DOI: 10.1074/jbc.m112.346338] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The type II secretion system (T2SS) secretes enzymes and toxins across the outer membrane of Gram-negative bacteria. The precise assembly of T2SS, which consists of at least 12 core-components called Gsp, remains unclear. The outer membrane secretin, GspD, forms the channels, through which folded proteins are secreted, and interacts with the inner membrane component, GspC. The periplasmic regions of GspC and GspD consist of several structural domains, HR(GspC) and PDZ(GspC), and N0(GspD) to N3(GspD), respectively, and recent structural and functional studies have proposed several interaction sites between these domains. We used cysteine mutagenesis and disulfide bonding analysis to investigate the organization of GspC and GspD protomers and to map their interaction sites within the secretion machinery of the plant pathogen Dickeya dadantii. At least three distinct GspC-GspD interactions were detected, and they involve two sites in HR(GspC), two in N0(GspD), and one in N2(GspD). None of these interactions occurs through static interfaces because the same sites are also involved in self-interactions with equivalent neighboring domains. Disulfide self-bonding of critical interaction sites halts secretion, indicating the transient nature of these interactions. The secretion substrate diminishes certain interactions and provokes an important rearrangement of the HR(GspC) structure. The T2SS components OutE/L/M affect various interaction sites differently, reinforcing some but diminishing the others, suggesting a possible switching mechanism of these interactions during secretion. Disulfide mapping shows that the organization of GspD and GspC subunits within the T2SS could be compatible with a hexamer of dimers arrangement rather than an organization with 12-fold rotational symmetry.
Collapse
Affiliation(s)
- Xiaohui Wang
- Université de Lyon, F-69003, Université Lyon 1, INSA-Lyon, Villeurbanne F-69621, CNRS, UMR5240, Microbiologie Adaptation et Pathogénie, Lyon F-69622, France
| | | | | | | | | | | |
Collapse
|
22
|
The type II secretion system: biogenesis, molecular architecture and mechanism. Nat Rev Microbiol 2012; 10:336-51. [PMID: 22466878 DOI: 10.1038/nrmicro2762] [Citation(s) in RCA: 347] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many gram-negative bacteria use the sophisticated type II secretion system (T2SS) to translocate a wide range of proteins from the periplasm across the outer membrane. The inner-membrane platform of the T2SS is the nexus of the system and orchestrates the secretion process through its interactions with the periplasmic filamentous pseudopilus, the dodecameric outer-membrane complex and a cytoplasmic secretion ATPase. Here, recent structural and biochemical information is reviewed to describe our current knowledge of the biogenesis and architecture of the T2SS and its mechanism of action.
Collapse
|
23
|
McLaughlin LS, Haft RJF, Forest KT. Structural insights into the Type II secretion nanomachine. Curr Opin Struct Biol 2012; 22:208-16. [PMID: 22425326 DOI: 10.1016/j.sbi.2012.02.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/16/2012] [Accepted: 02/23/2012] [Indexed: 01/31/2023]
Abstract
The Type II secretion nanomachine transports folded proteins across the outer membrane of Gram-negative bacteria. Recent X-ray crystallography, electron microscopy, and molecular modeling studies provide structural insights into three functionally and spatially connected units of this nanomachine: the cytoplasmic and inner membrane energy-harvesting complex, the periplasmic helical pseudopilus, and the outer membrane secretin. Key advances include cryo-EM reconstruction of the secretin and demonstration that it interacts with both secreted substrates and a crucial transmembrane clamp protein, plus a biochemical and structural explanation of the role of low-abundance pseudopilins in initiating pseudopilus growth. Combining structures and protein interactions, we synthesize a 3D view of the complete complex consistent with a stepwise pathway in which secretin oligomerization defines sites of nanomachine biogenesis.
Collapse
|
24
|
Douzi B, Ball G, Cambillau C, Tegoni M, Voulhoux R. Deciphering the Xcp Pseudomonas aeruginosa type II secretion machinery through multiple interactions with substrates. J Biol Chem 2011; 286:40792-801. [PMID: 21949187 DOI: 10.1074/jbc.m111.294843] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The type II secretion system enables gram-negative bacteria to secrete exoproteins into the extracellular milieu. We performed biophysical and biochemical experiments to identify systematic interactions between Pseudomonas aeruginosa Xcp type II secretion system components and their substrates. We observed that three Xcp components, XcpP(C), the secretin XcpQ(D), and the pseudopilus tip, directly and specifically interact with secreted exoproteins. We established that XcpP(C), in addition to its interaction with the substrate, likely shields the entire periplasmic portion of the secreton. It can therefore be considered as the recruiter of the machinery. Moreover, the direct interaction observed between the substrate and the pseudopilus tip validates the piston model hypothesis, in which the pseudopilus pushes the substrate through the secretin pore during the secretion process. All together, our results allowed us to propose a model of the different consecutive steps followed by the substrate during the type II secretion process.
Collapse
Affiliation(s)
- Badreddine Douzi
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM-UPR9027), Institut de Microbiologie de la Méditerranée, CNRS, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France
| | | | | | | | | |
Collapse
|
25
|
Korotkov KV, Johnson TL, Jobling MG, Pruneda J, Pardon E, Héroux A, Turley S, Steyaert J, Holmes RK, Sandkvist M, Hol WGJ. Structural and functional studies on the interaction of GspC and GspD in the type II secretion system. PLoS Pathog 2011; 7:e1002228. [PMID: 21931548 PMCID: PMC3169554 DOI: 10.1371/journal.ppat.1002228] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 07/21/2011] [Indexed: 12/02/2022] Open
Abstract
Type II secretion systems (T2SSs) are critical for secretion of many proteins from Gram-negative bacteria. In the T2SS, the outer membrane secretin GspD forms a multimeric pore for translocation of secreted proteins. GspD and the inner membrane protein GspC interact with each other via periplasmic domains. Three different crystal structures of the homology region domain of GspC (GspCHR) in complex with either two or three domains of the N-terminal region of GspD from enterotoxigenic Escherichia coli show that GspCHR adopts an all-β topology. N-terminal β-strands of GspC and the N0 domain of GspD are major components of the interface between these inner and outer membrane proteins from the T2SS. The biological relevance of the observed GspC–GspD interface is shown by analysis of variant proteins in two-hybrid studies and by the effect of mutations in homologous genes on extracellular secretion and subcellular distribution of GspC in Vibrio cholerae. Substitutions of interface residues of GspD have a dramatic effect on the focal distribution of GspC in V. cholerae. These studies indicate that the GspCHR–GspDN0 interactions observed in the crystal structure are essential for T2SS function. Possible implications of our structures for the stoichiometry of the T2SS and exoprotein secretion are discussed. Many bacterial pathogens affecting humans, animals and plants export diverse proteins across the cell membranes into the medium surrounding the bacteria. Some of these secreted proteins are involved in pathogenesis. One example is cholera toxin secreted by the bacterium Vibrio cholerae, a causative agent of cholera. The sophisticated type II secretion system is responsible for moving this toxin, and several other proteins, across the outer membrane. Here, we studied the interaction between the outer membrane pore of the type II secretion system, the secretin GspD, and the inner membrane protein GspC. We have solved three crystal structures of complexes between the interacting domains and identified critical contacts in the GspC–GspD interface. We also showed the importance of these contacts for assembly of the secretion system and for secretion of proteins by V. cholerae. Our studies provide a major piece in the puzzle of how the type II secretion system is assembled and how it functions. One day this knowledge might allow us to design compounds which interfere with this secretion process. Such compounds would be useful in the battle against bacteria affecting human health.
Collapse
Affiliation(s)
- Konstantin V. Korotkov
- Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle, Washington, United States of America
| | - Tanya L. Johnson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Michael G. Jobling
- Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Jonathan Pruneda
- Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle, Washington, United States of America
| | - Els Pardon
- Department of Molecular and Cellular Interactions, VIB, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Annie Héroux
- National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York, United States of America
| | - Stewart Turley
- Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle, Washington, United States of America
| | - Jan Steyaert
- Department of Molecular and Cellular Interactions, VIB, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Randall K. Holmes
- Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Maria Sandkvist
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Wim G. J. Hol
- Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| |
Collapse
|
26
|
Archaeal flagellar ATPase motor shows ATP-dependent hexameric assembly and activity stimulation by specific lipid binding. Biochem J 2011; 437:43-52. [PMID: 21506936 DOI: 10.1042/bj20110410] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Microbial motility frequently depends on flagella or type IV pili. Using recently developed archaeal genetic tools, archaeal flagella and its assembly machinery have been identified. Archaeal flagella are functionally similar to bacterial flagella and their assembly systems are homologous with type IV pili assembly systems of Gram-negative bacteria. Therefore elucidating their biochemistry may result in insights in both archaea and bacteria. FlaI, a critical cytoplasmic component of the archaeal flagella assembly system in Sulfolobus acidocaldarius, is a member of the type II/IV secretion system ATPase superfamily, and is proposed to be bi-functional in driving flagella assembly and movement. In the present study we show that purified FlaI is a Mn2+-dependent ATPase that binds MANT-ATP [2'-/3'-O-(N'- methylanthraniloyl)adenosine-5'-O-triphosphate] with a high affinity and hydrolyses ATP in a co-operative manner. FlaI has an optimum pH and temperature of 6.5 and 75 °C for ATP hydrolysis. Remarkably, archaeal, but not bacterial, lipids stimulated the ATPase activity of FlaI 3-4-fold. Analytical gel filtration indicated that FlaI undergoes nucleotide-dependent oligomerization. Furthermore, SAXS (small-angle X-ray scattering) analysis revealed an ATP-dependent hexamerization of FlaI in solution. The results of the present study report the first detailed biochemical analyses of the motor protein of an archaeal flagellum.
Collapse
|