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Saberi E, Qureshi JA, Brown JK. Differential expression of "Candidatus Liberibacter solanacearum" genes and prophage loci in different life stages of potato psyllid. Sci Rep 2024; 14:16248. [PMID: 39009624 PMCID: PMC11251058 DOI: 10.1038/s41598-024-65156-4] [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: 01/29/2024] [Accepted: 06/17/2024] [Indexed: 07/17/2024] Open
Abstract
Psyllid species, including the potato psyllid (PoP) Bactericera cockerelli (Sulc) (Triozidae) serve as host and vector of "Candidatus Liberibacter spp." ("Ca. Liberibacter"), which also infects diverse plant hosts, including citrus and tomato. Psyllid transmission of "Ca. Liberibacter" is circulative and propagative. The time of "Ca. Liberibacter" acquisition and therefore vector life stage most competent for bacterial transmission varies by pathosystems. Here, the potato psyllid-"Ca. Liberibacter solanacearum" (CLso) pathosystem was investigated to dissect CLso-prophage interactions in the tomato plant and PoP-psyllid host by real-time quantitative reverse transcriptase amplification of CLso genes/loci with predicted involvement in host infection and psyllid-CLso transmission. Genes/loci analyzed were associated with (1) CLso-adhesion, -invasion, -pathogenicity, and -motility, (2) prophage-adhesion and pathogenicity, and (3) CLso-lysogenic cycle. Relative gene expression was quantified by qRT-PCR amplification from total RNA isolated from CLso-infected 1st-2nd and 4th-5th nymphs and teneral adults and CLso-infected tomato plants in which CLso infection is thought to occur without SC1-SC2 replication. Gene/loci expression was host-dependent and varied with the psyllid developmental stage. Loci previously associated with repressor-anti-repressor regulation in the "Ca Liberibacter asiaticus"-prophage pathosystem, which maintains the lysogenic cycle in Asian citrus psyllid Diaphorina citri, were expressed in CLso-infected psyllids but not in CLso-infected tomato plants.
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Affiliation(s)
- Esmaeil Saberi
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA
- Department of Entomology and Nematology, IFAS, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, USA
| | - Jawwad A Qureshi
- Department of Entomology and Nematology, IFAS, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, USA
| | - Judith K Brown
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA.
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2
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Hajihassan Z, Yazdi M, Fadaie A, Akbarsemnani N. Comparison of the efficiency of the Sec and Tat secretory pathways in the secretion of recombinant neurturin protein using de novo designed signal peptides. Prep Biochem Biotechnol 2024:1-13. [PMID: 38511632 DOI: 10.1080/10826068.2024.2331203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Since cytoplasmic expression of heterologous proteins with disulfide bonds leads to the formation of inclusion bodies in E. coli, periplasmic production is preferable. The N-terminal signal peptide attached to the secreted protein determines the type of secretory pathway through which the target protein is secreted; Sec, Tat, or SRP. The aim of this study was to design and compare two novel signal peptides for the secretion of recombinant neurturin (as a model) via the Sec and Tat pathways. For this purpose, we aligned the natural signal peptides from E. coli and Bacillus subtilis to identify the conserved amino acids and those with the highest repetition. The SignalP4.1 and TatP1.0 software were used to determine the secretion efficiency of the new signal peptides. The efficiency of new signal peptides was then evaluated and compared experimentally with two naturally used signal peptides. Quantitative analysis of Western blot bands showed that approximately 80% of the expressed neurturin was secreted into the periplasmic space by new signal peptides. Circular dichroism spectroscopy also confirmed the correct secondary structure of the secreted neurturin. In conclusion, these novel signal peptides can be used to secrete any other recombinant proteins to the periplasmic space of E. coli efficiently.
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Affiliation(s)
- Zahra Hajihassan
- Faculty of Life Science Engineering, College of interdisciplinary science and technologies, University of Tehran, Tehran, Iran
| | - Mina Yazdi
- Faculty of Life Science Engineering, College of interdisciplinary science and technologies, University of Tehran, Tehran, Iran
| | - Atiyeh Fadaie
- Faculty of Life Science Engineering, College of interdisciplinary science and technologies, University of Tehran, Tehran, Iran
| | - Nooshin Akbarsemnani
- Faculty of Life Science Engineering, College of interdisciplinary science and technologies, University of Tehran, Tehran, Iran
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3
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Costa TRD, Patkowski JB, Macé K, Christie PJ, Waksman G. Structural and functional diversity of type IV secretion systems. Nat Rev Microbiol 2024; 22:170-185. [PMID: 37814112 PMCID: PMC11290344 DOI: 10.1038/s41579-023-00974-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2023] [Indexed: 10/11/2023]
Abstract
Considerable progress has been made in recent years in the structural and molecular biology of type IV secretion systems in Gram-negative bacteria. The latest advances have substantially improved our understanding of the mechanisms underlying the recruitment and delivery of DNA and protein substrates to the extracellular environment or target cells. In this Review, we aim to summarize these exciting structural and molecular biology findings and to discuss their functional implications for substrate recognition, recruitment and translocation, as well as the biogenesis of extracellular pili. We also describe adaptations necessary for deploying a breadth of processes, such as bacterial survival, host-pathogen interactions and biotic and abiotic adhesion. We highlight the functional and structural diversity that allows this extremely versatile secretion superfamily to function under different environmental conditions and in different bacterial species. Additionally, we emphasize the importance of further understanding the mechanism of type IV secretion, which will support us in combating antimicrobial resistance and treating type IV secretion system-related infections.
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Affiliation(s)
- Tiago R D Costa
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College, London, UK.
| | - Jonasz B Patkowski
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College, London, UK
| | - Kévin Macé
- Institute of Structural and Molecular Biology, Birkbeck and UCL, London, UK
- Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes and CNRS, Rennes, France
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, TX, USA.
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck and UCL, London, UK.
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4
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Meir A, Macé K, Vegunta Y, Williams SM, Waksman G. Substrate recruitment mechanism by gram-negative type III, IV, and VI bacterial injectisomes. Trends Microbiol 2023; 31:916-932. [PMID: 37085348 DOI: 10.1016/j.tim.2023.03.005] [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: 10/28/2022] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 04/23/2023]
Abstract
Bacteria use a wide arsenal of macromolecular substrates (DNA and proteins) to interact with or infect prokaryotic and eukaryotic cells. To do so, they utilize substrate-injecting secretion systems or injectisomes. However, prior to secretion, substrates must be recruited to specialized recruitment platforms and then handed over to the secretion apparatus for secretion. In this review, we provide an update on recent advances in substrate recruitment and delivery by gram-negative bacterial recruitment platforms associated with Type III, IV, and VI secretion systems.
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Affiliation(s)
- Amit Meir
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK; Current address: MRC Centre for Virus Research, School of Infection and Immunity, University of Glasgow, Glasgow, UK.
| | - Kévin Macé
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Yogesh Vegunta
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Sunanda M Williams
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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5
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Calder A, Snyder LAS. Diversity of the type VI secretion systems in the Neisseria spp. Microb Genom 2023; 9. [PMID: 37052605 DOI: 10.1099/mgen.0.000986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Complete Type VI Secretion Systems were identified in the genome sequence data of Neisseria subflava isolates sourced from throat swabs of human volunteers. The previous report was the first to describe two complete Type VI Secretion Systems in these isolates, both of which were distinct in terms of their gene organization and sequence homology. Since publication of the first report, Type VI Secretion System subtypes have been identified in Neisseria spp. The characteristics of each type in N. subflava are further investigated here and in the context of the other Neisseria spp., including identification of the lineages containing the different types and subtypes. Type VI Secretion Systems use VgrG for delivery of toxin effector proteins; several copies of vgrG and associated effector / immunity pairs are present in Neisseria spp. Based on sequence similarity between strains and species, these core Type VI Secretion System genes, vgrG, and effector / immunity genes may diversify via horizontal gene transfer, an instrument for gene acquisition and repair in Neisseria spp.
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Affiliation(s)
- Alan Calder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
| | - Lori A S Snyder
- School of Life Sciences, Pharmacy, and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK
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Wang Y, Zeng M, Xia L, Valerie Olovo C, Su Z, Zhang Y. Bacterial strategies for immune systems - Role of the type VI secretion system. Int Immunopharmacol 2023; 114:109550. [PMID: 36525796 DOI: 10.1016/j.intimp.2022.109550] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/09/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022]
Abstract
The process of host infection by bacteria is complicated. Bacterial infections strongly induce the host immune system, which necessitates a robust clearance of the infection. However, bacteria have over time developed strategies that enable their evasion of attacks by the host immune system. One such strategy is the type VI secretion system (T6SS), a special needle-like secretion system that is widespread in Gram-negative bacteria and is responsible for delivering effector proteins into the external bacterial environment or directly into the host cell cytosol. Bacterial T6SS and its secreted effector proteins play an important role in the interaction between bacteria and host immune system. They also serve as antigens that are employed in the development of vaccines for clinical trials as well as future vaccine candidates. This review focuses mainly on aspects of T6SS effectors that impact the strength of the host immune system, including inflammation, autophagy, and apoptosis (silent programmed cell death). The T6SS-based vaccines are also described.
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Affiliation(s)
- Yurou Wang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Minmin Zeng
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Lin Xia
- Department of Laboratory Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Chinasa Valerie Olovo
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Zhaoliang Su
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Ying Zhang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.
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7
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Lopes JA, Rghei AD, Thompson B, Susta L, Khursigara CM, Wootton SK. Overcoming Barriers to Preventing and Treating P. aeruginosa Infections Using AAV Vectored Immunoprophylaxis. Biomedicines 2022; 10:biomedicines10123162. [PMID: 36551918 PMCID: PMC9775905 DOI: 10.3390/biomedicines10123162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/03/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas aeruginosa is a bacterial pathogen of global concern and is responsible for 10-15% of nosocomial infections worldwide. This opportunistic bacterial pathogen is known to cause serious complications in immunocompromised patients and is notably the leading cause of morbidity and mortality in patients suffering from cystic fibrosis. Currently, the only line of defense against P. aeruginosa infections is antibiotic treatment. Due to the acquired and adaptive resistance mechanisms of this pathogen, the prevalence of multidrug resistant P. aeruginosa strains has increased, presenting a major problem in healthcare settings. To date, there are no approved licensed vaccines to protect against P. aeruginosa infections, prompting the urgent need alternative treatment options. An alternative to traditional vaccines is vectored immunoprophylaxis (VIP), which utilizes a safe and effective adeno-associated virus (AAV) gene therapy vector to produce sustained levels of therapeutic monoclonal antibodies (mAbs) in vivo from a single intramuscular injection. In this review, we will provide an overview of P. aeruginosa biology and key mechanisms of pathogenesis, discuss current and emerging treatment strategies for P. aeruginosa infections and highlight AAV-VIP as a promising novel therapeutic platform.
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Affiliation(s)
- Jordyn A. Lopes
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Amira D. Rghei
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Brad Thompson
- Avamab Pharma Inc., 120, 4838 Richard Road SW, Calgary, AB T3E 6L1, Canada
| | - Leonardo Susta
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Cezar M. Khursigara
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Sarah K. Wootton
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
- Correspondence:
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Jing R, Wen T, Liao C, Xue L, Liu F, Yu L, Luo J. DeepT3 2.0: improving type III secreted effector predictions by an integrative deep learning framework. NAR Genom Bioinform 2021; 3:lqab086. [PMID: 34617013 PMCID: PMC8489581 DOI: 10.1093/nargab/lqab086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 08/12/2021] [Accepted: 09/09/2021] [Indexed: 11/13/2022] Open
Abstract
Type III secretion systems (T3SSs) are bacterial membrane-embedded nanomachines that allow a number of humans, plant and animal pathogens to inject virulence factors directly into the cytoplasm of eukaryotic cells. Export of effectors through T3SSs is critical for motility and virulence of most Gram-negative pathogens. Current computational methods can predict type III secreted effectors (T3SEs) from amino acid sequences, but due to algorithmic constraints, reliable and large-scale prediction of T3SEs in Gram-negative bacteria remains a challenge. Here, we present DeepT3 2.0 (http://advintbioinforlab.com/deept3/), a novel web server that integrates different deep learning models for genome-wide predicting T3SEs from a bacterium of interest. DeepT3 2.0 combines various deep learning architectures including convolutional, recurrent, convolutional-recurrent and multilayer neural networks to learn N-terminal representations of proteins specifically for T3SE prediction. Outcomes from the different models are processed and integrated for discriminating T3SEs and non-T3SEs. Because it leverages diverse models and an integrative deep learning framework, DeepT3 2.0 outperforms existing methods in validation datasets. In addition, the features learned from networks are analyzed and visualized to explain how models make their predictions. We propose DeepT3 2.0 as an integrated and accurate tool for the discovery of T3SEs.
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Affiliation(s)
- Runyu Jing
- School of Cyber Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Tingke Wen
- School of Cyber Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Chengxiang Liao
- School of Cyber Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Li Xue
- School of Public Health, Southwest Medical University, Luzhou 646000, China
| | - Fengjuan Liu
- School of Geography and Resources, Guizhou Education University, Guiyang 550018, China
| | - Lezheng Yu
- School of Chemistry and Materials Science, Guizhou Education University, Guiyang 550018, China
| | - Jiesi Luo
- Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou 646000, China
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Yan X, Yang J, Wang Q, Lin S. Transcriptomic analysis reveals resistance mechanisms of Klebsiella michiganensis to copper toxicity under acidic conditions. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 211:111919. [PMID: 33476853 DOI: 10.1016/j.ecoenv.2021.111919] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
The aim of this study was to elucidate the effect of pH on bacterial resistance mechanisms to copper (Cu) stress by genomic and transcriptomic analysis. Klebsiella michiganensis cells were exposed to 0.5 mM CuCl2 at pH 4 and 5. Lower pH (pH < 4) strongly inhibited K. michiganensis growth, while Cu stress and higher pH (pH > 5) induced Cu precipitation in the medium. Transcriptomic analyses indicated that two groups of genes related to quorum sensing (QS) systems (lsrABCDFGKR) and type II secretion systems (T2SS) (gspCDEFGHIJKLM) were significantly up-regulated at pH 4 only. These results suggest that T2SS may be induced and controlled by QS, thereby contributing to the formation of extracellular polymeric substances (EPS) and the secretion of proteins to prevent Cu ions from entering cells. Six Cu resistance genes (cusABF, copA, cueO, and gene05308) were more significantly up-regulated at pH 4 than at pH 5. In addition, the relative expression (log2|FC=) of the sulfur assimilation genes cysHJIK was relatively higher at pH 4 than at pH 5, while the gene encoding organic sulfur metabolism, tauB, was also significantly up-regulated at only pH 4. These results indicate that the Cu efflux system can remove intracellular Cu ions from cells, and that the sulfur assimilation system is related to the detoxification of Cu ions. Furthermore, increased free Cu ions at lower pH (4) could induce communication signals among cells, thereby stimulating the response of T2SS-related genes in K. michiganensis to tolerate Cu stress. Consequently, the resistance of K. michiganensis to Cu stress is a multisystem collaborative process composed of intracellular and extracellular components.
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Affiliation(s)
- Xiaoxue Yan
- Engineering Laboratory for Water Pollution Control and Resources of National Environmental Protection, School of Environment, Northeast Normal University, No. 2555, Jingyue Street, Changchun 130117, Jilin, PR China
| | - Junlin Yang
- Engineering Laboratory for Water Pollution Control and Resources of National Environmental Protection, School of Environment, Northeast Normal University, No. 2555, Jingyue Street, Changchun 130117, Jilin, PR China
| | - Qi Wang
- Engineering Laboratory for Water Pollution Control and Resources of National Environmental Protection, School of Environment, Northeast Normal University, No. 2555, Jingyue Street, Changchun 130117, Jilin, PR China
| | - Shanshan Lin
- Engineering Laboratory for Water Pollution Control and Resources of National Environmental Protection, School of Environment, Northeast Normal University, No. 2555, Jingyue Street, Changchun 130117, Jilin, PR China.
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Gao L, Tan Y, Zhang W, Qi Q, Lu X. Cytophaga hutchinsonii SprA and SprT Are Essential Components of the Type IX Secretion System Required for Ca 2+ Acquisition, Cellulose Degradation, and Cell Motility. Front Microbiol 2021; 12:628555. [PMID: 33643255 PMCID: PMC7906972 DOI: 10.3389/fmicb.2021.628555] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
The type IX secretion system (T9SS) is a novel protein secretion system, which is found in and confined to the phylum Bacteroidetes. T9SS is involved in the secretion of virulence factors, cell surface adhesins, and complex biopolymer degrading enzymes to the cell surface or extracellular medium. Cytophaga hutchinsonii is a widely distributed bacterium, which is able to efficiently digest cellulose and rapidly glide along the solid surfaces. C. hutchinsonii has a full set of orthologs of T9SS components. However, the functions of most homologous proteins have not been verified. In C. hutchinsonii, CHU_0029 and CHU_2709 are similar in sequence to Flavobacterium johnsoniae T9SS components SprA and SprT, respectively. In this study, the single deletion mutants of chu_0029 (sprA) and chu_2709 (sprT) were obtained using a complex medium with the addition of Ca2+ and Mg2+. Single deletion of sprA or sprT resulted in defects in cellulose utilization and gliding motility. Moreover, the ΔsprA and ΔsprT mutants showed growth defects in Ca2+- and Mg2+-deficient media. The results of ICP-MS test showed that both the whole cell and intracellular concentrations of Ca2+ were dramatically reduced in the ΔsprA and ΔsprT mutants, indicating that SprA and SprT are both important for the assimilation of trace amount of Ca2+. While the assimilation of Mg2+ was not obviously influenced in the ΔsprA and ΔsprT mutants. Through proteomics analysis of the cell surface proteins of the wild type and mutants, we found that the ΔsprA and ΔsprT mutants were defective in secretion of the majority of T9SS substrates. Together, these results indicate that SprA and SprT are both essential components of C. hutchinsonii T9SS, which is required for protein secretion, Ca2+ acquisition, cellulose degradation, and gliding motility in C. hutchinsonii. Our study shed more light on the functions of SprA and SprT in T9SS, and further proved the link between the T9SS and Ca2+ uptake system.
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Affiliation(s)
- Lijuan Gao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yahong Tan
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Weican Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xuemei Lu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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Shin CM. Alternations of Gastric Microbiota with Mucosal Atrophy and Intestinal Metaplasia. THE KOREAN JOURNAL OF HELICOBACTER AND UPPER GASTROINTESTINAL RESEARCH 2020. [DOI: 10.7704/kjhugr.2020.0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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Abstract
Gastric cancer represents one of the leading causes of cancer deaths worldwide. Helicobacter pylori (H. pylori) infection is the strongest risk factor associated with gastric cancer. Due to new molecular techniques allowing greater identification of stomach microbes, investigators are beginning to examine the role that bacteria other than H. pylori play in gastric cancer development. Recently, researchers have investigated how the composition of the gastric microbiota varies among individuals with various stages of gastric disease. Specific microbes residing in the stomach have been preferentially associated with gastric cancer patients compared to individuals with a healthy gastric mucosa. Studies conducted on the insulin-gastrin (INS-GAS) transgenic mouse model have provided additional insight into the association between the gastric microbiota and gastric cancer. The purpose of this article is to review the current state of literature on the relationship between the gastric microbiota and gastric cancer based on clinical studies performed to date.
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Affiliation(s)
| | - Fen Wu
- Department of Population Health, New York University School of Medicine, New York, New York, USA,Department of Environmental Medicine, New York University School of Medicine, New York, New York, USA
| | - Yu Chen
- Department of Population Health, New York University School of Medicine, New York, New York, USA,Department of Environmental Medicine, New York University School of Medicine, New York, New York, USA,CONTACT Yu Chen Departments of Population Health and Environmental Medicine, New York University School of Medicine, 180 Madison Ave., Room 514, New York, NY10016, USA
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Breider S, Sehar S, Berger M, Thomas T, Brinkhoff T, Egan S. Genome sequence of Epibacterium ulvae strain DSM 24752 T, an indigoidine-producing, macroalga-associated member of the marine Roseobacter group. ENVIRONMENTAL MICROBIOME 2019; 14:4. [PMID: 33902719 PMCID: PMC7989816 DOI: 10.1186/s40793-019-0343-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 07/08/2019] [Indexed: 06/12/2023]
Abstract
Strain U95T (= DSM 24752T = LMG 26464T) is the type strain of Epibacterium ulvae, which is the type species of the genus Epibacterium. This genus belongs to the marine Roseobacter group. E. ulvae Strain U95T was isolated from the macroalga Ulva australis, is Gram-negative, rod-shaped and motile. Here we describe the permanent draft genome sequence and annotation of E. ulvae U95T with a focus on secondary metabolite production and interaction with its host. The genome contains 4,092,893 bp, 3977 protein-coding genes and 60 RNA genes. The genome encodes a gene cluster for synthesis of the blue-pigmented secondary metabolite indigoidine and contains several genes for adhesion mechanisms, putative bacteriocin, siderophores, a type VI secretion system, and enzymes that confer oxidative stress resistance. Combined, these features may aid in the successful colonization and persistence of E. ulvae on host surfaces and in competition with the surrounding microbial consortium.
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Affiliation(s)
- Sven Breider
- Department of Biology of Geological Processes - Aquatic Microbial Ecology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Oldenburg, Germany
| | - Shama Sehar
- Centre for Marine Science and Innovation (CMSI), School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Martine Berger
- Department of Biology of Geological Processes - Aquatic Microbial Ecology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Oldenburg, Germany
| | - Torsten Thomas
- Centre for Marine Science and Innovation (CMSI), School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Thorsten Brinkhoff
- Department of Biology of Geological Processes - Aquatic Microbial Ecology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Oldenburg, Germany
| | - Suhelen Egan
- Centre for Marine Science and Innovation (CMSI), School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia.
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Ok CK, Chang JH. Crystal Structure of the Type VI Secretion System Accessory Protein TagF from Pseudomonas Aeruginosa. Protein Pept Lett 2019; 26:204-214. [PMID: 30659530 DOI: 10.2174/0929866526666190119121859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/07/2019] [Accepted: 01/08/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND Type VI Secretion System (T6SS) has been found in approximately onequarter of the gram-negative bacterial species, and its structural characteristics appear to slightly differ from species to species. The genes encoding T6SS are designated as type six secretion A-M (tssA-M). The expression of the tss gene cluster is regulated by various accessory genes, designated as type VI-associated genes A-P (tagA-P). Tag family proteins have been commonly found in bacteria expressing T6SS but not in all bacterial species. For instance, the tag gene cluster is well-conserved in Pseudomonas aeruginosa (Pa). The PaTagF protein has large homology with ImpM in Rhizobium leguminosarum and SciT in Salmonella enterica. The overexpression of PaTagF represses T6SS complex accumulation and suppresses T6SS antibacterial activity. Thus, the functions of TagF are mediated through direct interactions with the forkhead-associated protein Fha, as evident from the results of the yeast-two hybrid assays. Fha is involved in recruiting a membrane-associated complex either in threonine phosphorylation pathway-dependent or - independent manner. However, functional reports of the tag gene cluster are still limited. OBJECTIVE In this article, our motivation is to understand the molecular mechanism underlying the regulation of expression of the type VI secretion system complex. METHODS In this article, we start with obtaining the gene encoding PaTagF protein by polymerase chain reaction (PCR). Subsequently, the cloned gene is applied to overexpress of PaTagF protein in Escherichia coli, then purify the recombinant PaTagF protein. Thereafter, the protein is crystallized in a condition of 2.5 M NaCl, 0.1 M imidazole (pH 8.0), 3.2 M NaCl, 0.1 M BIS-TRIS propane (pH 7.0) and diffraction datasets of the PaTagF crystals are collected at the Pohang Accelerator Laboratory (PAL). The molecular structure of PaTagF protein is determined by molecular replacement using the uncharacterized protein PA0076 (PDB code:2QNU) as an initial search model by PHENIX crystallographic software package. Model building of PaTagF structure is performed using Coot program. Finally, the structural model is validated using phenix.refine program. RESULTS PaTagF exists as a tetramer in the asymmetric unit, and the overall fold of each monomer is composed of continuous beta-sheets wrapped by alpha-helices. Each monomer has variable conformations and lengths of both the N- and C-termini. Twelve residues, including the His6 tag from the N-terminus of a symmetry-related molecule, have been found in two of the tetrameric PaTagF structures. A structural homology search revealed that PaTagF was similar to the α-β-α sandwichlike structure of the longin domain on the differentially expressed in normal and neoplastic (DENN) superfamily, which is commonly found in proteins related to trafficking. CONCLUSION The tetrameric structure of PaTagF comprises varied N- and C-terminal regions in each subunit and may be stabilized by a symmetry-related molecule. This feature was also shown in the TssL structure from V. cholerae. Furthermore, our study showed that the overall fold of PaTagF is homologous to the longin domain of the DENN family. Therefore, further studies are warranted to elucidate the structure-based evolutionary relationship between protein transport systems from the bacteria and eukaryotic cells.
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Affiliation(s)
- Chang-Kyu Ok
- Department of Biology Education, Kyungpook National University, Daegu 41566, South Korea
| | - Jeong Ho Chang
- Department of Biology Education, Kyungpook National University, Daegu 41566, South Korea
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Zhang X, Liu X, Yang F, Chen L. Pan-Genome Analysis Links the Hereditary Variation of Leptospirillum ferriphilum With Its Evolutionary Adaptation. Front Microbiol 2018; 9:577. [PMID: 29636744 PMCID: PMC5880901 DOI: 10.3389/fmicb.2018.00577] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/13/2018] [Indexed: 01/16/2023] Open
Abstract
Niche adaptation has long been recognized to drive intra-species differentiation and speciation, yet knowledge about its relatedness with hereditary variation of microbial genomes is relatively limited. Using Leptospirillum ferriphilum species as a case study, we present a detailed analysis of genomic features of five recognized strains. Genome-to-genome distance calculation preliminarily determined the roles of spatial distance and environmental heterogeneity that potentially contribute to intra-species variation within L. ferriphilum species at the genome level. Mathematical models were further constructed to extrapolate the expansion of L. ferriphilum genomes (an 'open' pan-genome), indicating the emergence of novel genes with new sequenced genomes. The identification of diverse mobile genetic elements (MGEs) (such as transposases, integrases, and phage-associated genes) revealed the prevalence of horizontal gene transfer events, which is an important evolutionary mechanism that provides avenues for the recruitment of novel functionalities and further for the genetic divergence of microbial genomes. Comprehensive analysis also demonstrated that the genome reduction by gene loss in a broad sense might contribute to the observed diversification. We thus inferred a plausible explanation to address this observation: the community-dependent adaptation that potentially economizes the limiting resources of the entire community. Now that the introduction of new genes is accompanied by a parallel abandonment of some other ones, our results provide snapshots on the biological fitness cost of environmental adaptation within the L. ferriphilum genomes. In short, our genome-wide analyses bridge the relation between genetic variation of L. ferriphilum with its evolutionary adaptation.
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Affiliation(s)
- Xian Zhang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China
| | - Xueduan Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Fei Yang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China
| | - Lv Chen
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, China
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The adaptation of Escherichia coli cells grown in simulated microgravity for an extended period is both phenotypic and genomic. NPJ Microgravity 2017. [PMID: 28649637 PMCID: PMC5460176 DOI: 10.1038/s41526-017-0020-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Microorganisms impact spaceflight in a variety of ways. They play a positive role in biological systems, such as waste water treatment but can be problematic through buildups of biofilms that can affect advanced life support. Of special concern is the possibility that during extended missions, the microgravity environment will provide positive selection for undesirable genomic changes. Such changes could affect microbial antibiotic sensitivity and possibly pathogenicity. To evaluate this possibility, Escherichia coli (lac plus) cells were grown for over 1000 generations on Luria Broth medium under low-shear modeled microgravity conditions in a high aspect rotating vessel. This is the first study of its kind to grow bacteria for multiple generations over an extended period under low-shear modeled microgravity. Comparisons were made to a non-adaptive control strain using growth competitions. After 1000 generations, the final low-shear modeled microgravity-adapted strain readily outcompeted the unadapted lac minus strain. A portion of this advantage was maintained when the low-shear modeled microgravity strain was first grown in a shake flask environment for 10, 20, or 30 generations of growth. Genomic sequencing of the 1000 generation strain revealed 16 mutations. Of the five changes affecting codons, none were neutral. It is not clear how significant these mutations are as individual changes or as a group. It is concluded that part of the long-term adaptation to low-shear modeled microgravity is likely genomic. The strain was monitored for acquisition of antibiotic resistance by VITEK analysis throughout the adaptation period. Despite the evidence of genomic adaptation, resistance to a variety of antibiotics was never observed.
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Genome analysis of Campylobacter concisus strains from patients with inflammatory bowel disease and gastroenteritis provides new insights into pathogenicity. Sci Rep 2016; 6:38442. [PMID: 27910936 PMCID: PMC5133609 DOI: 10.1038/srep38442] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/09/2016] [Indexed: 12/14/2022] Open
Abstract
Campylobacter concisus is an oral bacterium that is associated with inflammatory bowel disease. C. concisus has two major genomospecies, which appear to have different enteric pathogenic potential. Currently, no studies have compared the genomes of C. concisus strains from different genomospecies. In this study, a comparative genome analysis of 36 C. concisus strains was conducted including 27 C. concisus strains sequenced in this study and nine publically available C. concisus genomes. The C. concisus core-genome was defined and genomospecies-specific genes were identified. The C. concisus core-genome, housekeeping genes and 23S rRNA gene consistently divided the 36 strains into two genomospecies. Two novel genomic islands, CON_PiiA and CON_PiiB, were identified. CON_PiiA and CON_PiiB islands contained proteins homologous to the type IV secretion system, LepB-like and CagA-like effector proteins. CON_PiiA islands were found in 37.5% of enteric C. concisus strains (3/8) isolated from patients with enteric diseases and none of the oral strains (0/27), which was statistically significant. This study reports the findings of C. concisus genomospecies-specific genes, novel genomic islands that contain type IV secretion system and putative effector proteins, and other new genomic features. These data provide novel insights into understanding of the pathogenicity of this emerging opportunistic pathogen.
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Yao J, Saenkham P, Levy J, Ibanez F, Noroy C, Mendoza A, Huot O, Meyer DF, Tamborindeguy C. Interactions "Candidatus Liberibacter solanacearum"-Bactericera cockerelli: Haplotype Effect on Vector Fitness and Gene Expression Analyses. Front Cell Infect Microbiol 2016; 6:62. [PMID: 27376032 PMCID: PMC4899927 DOI: 10.3389/fcimb.2016.00062] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/25/2016] [Indexed: 01/18/2023] Open
Abstract
"Candidatus Liberibacter solanacearum" (Lso) has emerged as a serious threat world-wide. Five Lso haplotypes have been identified so far. Haplotypes A and B are present in the Americas and/or New Zealand, where they are vectored to solanaceous plants by the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). The fastidious nature of these pathogens has hindered the study of the interactions with their eukaryotic hosts (vector and plant). To understand the strategies used by these pathogens to infect their vector, the effects of each Lso haplotype (A or B) on psyllid fitness was investigated, and genome-wide transcriptomic and RT-qPCR analyses were performed to evaluate Lso gene expression in association with its vector. Results showed that psyllids infected with haplotype B had significantly lower percentage of nymphal survival compared to psyllids infected with haplotype A. Although overall gene expression across Lso genome was similar between the two Lso haplotypes, differences in the expression of key candidate genes were found. Among the 16 putative type IV effector genes tested, four of them were differentially expressed between Lso haplotypes, while no differences in gene expression were measured by qPCR or transcriptomic analysis for the rest of the genes. This study provides new information regarding the pathogenesis of Lso haplotypes in their insect vector.
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Affiliation(s)
- Jianxiu Yao
- Department of Entomology, Texas A&M UniversityCollege Station, TX, USA
| | - Panatda Saenkham
- Department of Entomology, Texas A&M UniversityCollege Station, TX, USA
| | - Julien Levy
- Department of Horticultural Sciences, Texas A&M UniversityCollege Station, TX, USA
| | - Freddy Ibanez
- Department of Entomology, Texas A&M UniversityCollege Station, TX, USA
| | - Christophe Noroy
- CIRAD, UMR CMAEEPetit-Bourg, Guadeloupe, France
- Institut National de la Recherche Agronomique, UMR1309 CMAEEMontpellier, France
- Université des Antilles, Pointe-à-PitreGuadeloupe, France
| | - Azucena Mendoza
- Department of Entomology, Texas A&M UniversityCollege Station, TX, USA
| | - Ordom Huot
- Department of Entomology, Texas A&M UniversityCollege Station, TX, USA
| | - Damien F. Meyer
- CIRAD, UMR CMAEEPetit-Bourg, Guadeloupe, France
- Institut National de la Recherche Agronomique, UMR1309 CMAEEMontpellier, France
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Costa TRD, Felisberto-Rodrigues C, Meir A, Prevost MS, Redzej A, Trokter M, Waksman G. Secretion systems in Gram-negative bacteria: structural and mechanistic insights. Nat Rev Microbiol 2015; 13:343-59. [DOI: 10.1038/nrmicro3456] [Citation(s) in RCA: 655] [Impact Index Per Article: 72.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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20
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Computational and experimental analysis of the secretome of Methylococcus capsulatus (Bath). PLoS One 2014; 9:e114476. [PMID: 25479164 PMCID: PMC4257694 DOI: 10.1371/journal.pone.0114476] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 11/10/2014] [Indexed: 12/23/2022] Open
Abstract
The Gram-negative methanotroph Methylococcus capsulatus (Bath) was recently demonstrated to abrogate inflammation in a murine model of inflammatory bowel disease, suggesting interactions with cells involved in maintaining mucosal homeostasis and emphasizing the importance of understanding the many properties of M. capsulatus. Secreted proteins determine how bacteria may interact with their environment, and a comprehensive knowledge of such proteins is therefore vital to understand bacterial physiology and behavior. The aim of this study was to systematically analyze protein secretion in M. capsulatus (Bath) by identifying the secretion systems present and the respective secreted substrates. Computational analysis revealed that in addition to previously recognized type II secretion systems and a type VII secretion system, a type Vb (two-partner) secretion system and putative type I secretion systems are present in M. capsulatus (Bath). In silico analysis suggests that the diverse secretion systems in M.capsulatus transport proteins likely to be involved in adhesion, colonization, nutrient acquisition and homeostasis maintenance. Results of the computational analysis was verified and extended by an experimental approach showing that in addition an uncharacterized protein and putative moonlighting proteins are released to the medium during exponential growth of M. capsulatus (Bath).
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21
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Gillespie JJ, Kaur SJ, Rahman MS, Rennoll-Bankert K, Sears KT, Beier-Sexton M, Azad AF. Secretome of obligate intracellular Rickettsia. FEMS Microbiol Rev 2014; 39:47-80. [PMID: 25168200 DOI: 10.1111/1574-6976.12084] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The genus Rickettsia (Alphaproteobacteria, Rickettsiales, Rickettsiaceae) is comprised of obligate intracellular parasites, with virulent species of interest both as causes of emerging infectious diseases and for their potential deployment as bioterrorism agents. Currently, there are no effective commercially available vaccines, with treatment limited primarily to tetracycline antibiotics, although others (e.g. josamycin, ciprofloxacin, chloramphenicol, and azithromycin) are also effective. Much of the recent research geared toward understanding mechanisms underlying rickettsial pathogenicity has centered on characterization of secreted proteins that directly engage eukaryotic cells. Herein, we review all aspects of the Rickettsia secretome, including six secretion systems, 19 characterized secretory proteins, and potential moonlighting proteins identified on surfaces of multiple Rickettsia species. Employing bioinformatics and phylogenomics, we present novel structural and functional insight on each secretion system. Unexpectedly, our investigation revealed that the majority of characterized secretory proteins have not been assigned to their cognate secretion pathways. Furthermore, for most secretion pathways, the requisite signal sequences mediating translocation are poorly understood. As a blueprint for all known routes of protein translocation into host cells, this resource will assist research aimed at uniting characterized secreted proteins with their apposite secretion pathways. Furthermore, our work will help in the identification of novel secreted proteins involved in rickettsial 'life on the inside'.
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Affiliation(s)
- Joseph J Gillespie
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Simran J Kaur
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - M Sayeedur Rahman
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kristen Rennoll-Bankert
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Khandra T Sears
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Magda Beier-Sexton
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Abdu F Azad
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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Goessweiner-Mohr N, Eder M, Hofer G, Fercher C, Arends K, Birner-Gruenberger R, Grohmann E, Keller W. Structure of the double-stranded DNA-binding type IV secretion protein TraN from Enterococcus. ACTA ACUST UNITED AC 2014; 70:2376-89. [PMID: 25195751 DOI: 10.1107/s1399004714014187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 06/17/2014] [Indexed: 11/10/2022]
Abstract
Conjugative transfer through type IV secretion multiprotein complexes is the most important means of spreading antimicrobial resistance. Plasmid pIP501, frequently found in clinical Enterococcus faecalis and Enterococcus faecium isolates, is the first Gram-positive (G+) conjugative plasmid for which self-transfer to Gram-negative (G-) bacteria has been demonstrated. The pIP501-encoded type IV secretion system (T4SS) protein TraN localizes to the cytoplasm and shows specific DNA binding. The specific DNA-binding site upstream of the pIP501 origin of transfer (oriT) was identified by a novel footprinting technique based on exonuclease digestion and sequencing, suggesting TraN to be an accessory protein of the pIP501 relaxase TraA. The structure of TraN was determined to 1.35 Å resolution. It revealed an internal dimer fold with antiparallel β-sheets in the centre and a helix-turn-helix (HTH) motif at both ends. Surprisingly, structurally related proteins (excisionases from T4SSs of G+ conjugative transposons and transcriptional regulators of the MerR family) resembling only one half of TraN were found. Thus, TraN may be involved in the early steps of pIP501 transfer, possibly triggering pIP501 TraA relaxase activity by recruiting the relaxosome to the assembled mating pore.
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Affiliation(s)
| | - Markus Eder
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
| | - Gerhard Hofer
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
| | - Christian Fercher
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
| | - Karsten Arends
- Robert Koch Institute Berlin, Nordufer 20, 13353 Berlin, Germany
| | - Ruth Birner-Gruenberger
- Institute for Pathology and Omics Center Graz, Medical University Graz, Stiftingtalstrasse 24, 8010 Graz, Austria
| | - Elisabeth Grohmann
- Division of Infectious Diseases, University Medical Center Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany
| | - Walter Keller
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
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Trokter M, Felisberto-Rodrigues C, Christie PJ, Waksman G. Recent advances in the structural and molecular biology of type IV secretion systems. Curr Opin Struct Biol 2014; 27:16-23. [PMID: 24709394 PMCID: PMC4182333 DOI: 10.1016/j.sbi.2014.02.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 02/28/2014] [Indexed: 11/28/2022]
Abstract
We describe the first structure of a type IV secretion (T4S) system. The previously reported core complex is mostly an outer membrane complex. We describe the newly discovered inner membrane complex and the stalk. We discuss proposed translocation mechanisms of T4S systems. We discuss the regulation of pilus biogenesis and substrate transfer by T4S systems.
Bacteria use type IV secretion (T4S) systems to deliver DNA and protein substrates to a diverse range of prokaryotic and eukaryotic target cells. T4S systems have great impact on human health, as they are a major source of antibiotic resistance spread among bacteria and are central to infection processes of many pathogens. Therefore, deciphering the structure and underlying translocation mechanism of T4S systems is crucial to facilitate development of new drugs. The last five years have witnessed considerable progress in unraveling the structure of T4S system subassemblies, notably that of the T4S system core complex, a large 1 MegaDalton (MDa) structure embedded in the double membrane of Gram-negative bacteria and made of 3 of the 12 T4S system components. However, the recent determination of the structure of ∼3 MDa assembly of 8 of these components has revolutionized our views of T4S system architecture and opened up new avenues of research, which are discussed in this review.
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Affiliation(s)
- Martina Trokter
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Catarina Felisberto-Rodrigues
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, University of Texas Medical School, 6431 Fannin Street, Houston, TX 77030, USA
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
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24
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Goessweiner-Mohr N, Fercher C, Arends K, Birner-Gruenberger R, Laverde-Gomez D, Huebner J, Grohmann E, Keller W. The type IV secretion protein TraK from the Enterococcus conjugative plasmid pIP501 exhibits a novel fold. ACTA ACUST UNITED AC 2014; 70:1124-35. [PMID: 24699656 DOI: 10.1107/s1399004714001606] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 01/22/2014] [Indexed: 11/11/2022]
Abstract
Conjugative plasmid transfer presents a serious threat to human health as the most important means of spreading antibiotic resistance and virulence genes among bacteria. The required direct cell-cell contact is established by a multi-protein complex, the conjugative type IV secretion system (T4SS). The conjugative core complex spans the cellular envelope and serves as a channel for macromolecular secretion. T4SSs of Gram-negative (G-) origin have been studied in great detail. In contrast, T4SSs of Gram-positive (G+) bacteria have only received little attention thus far, despite the medical relevance of numerous G+ pathogens (e.g. enterococci, staphylococci and streptococci). This study provides structural information on the type IV secretion (T4S) protein TraK of the G+ broad host range Enterococcus conjugative plasmid pIP501. The crystal structure of the N-terminally truncated construct TraKΔ was determined to 3.0 Å resolution and exhibits a novel fold. Immunolocalization demonstrated that the protein localizes to the cell wall facing towards the cell exterior, but does not exhibit surface accessibility. Circular dichroism, dynamic light scattering and size-exclusion chromatography confirmed the protein to be a monomer. With the exception of proteins from closely related T4SSs, no significant sequence or structural relatives were found. This observation marks the protein as a very exclusive, specialized member of the pIP501 T4SS.
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Affiliation(s)
- Nikolaus Goessweiner-Mohr
- Institute for Molecular Biosciences, Karl-Franzens-University Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
| | - Christian Fercher
- Institute for Molecular Biosciences, Karl-Franzens-University Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
| | | | - Ruth Birner-Gruenberger
- Institute for Pathology and Center of Medical Research, Medical University Graz, Stiftingtalstrasse 24, 8010 Graz, Austria
| | - Diana Laverde-Gomez
- Division of Infectious Diseases, University Medical Center Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany
| | - Johannes Huebner
- Division of Infectious Diseases, University Medical Center Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany
| | - Elisabeth Grohmann
- Division of Infectious Diseases, University Medical Center Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany
| | - Walter Keller
- Institute for Molecular Biosciences, Karl-Franzens-University Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
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TraG encoded by the pIP501 type IV secretion system is a two-domain peptidoglycan-degrading enzyme essential for conjugative transfer. J Bacteriol 2013; 195:4436-44. [PMID: 23913323 DOI: 10.1128/jb.02263-12] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
pIP501 is a conjugative broad-host-range plasmid frequently present in nosocomial Enterococcus faecalis and Enterococcus faecium isolates. We focus here on the functional analysis of the type IV secretion gene traG, which was found to be essential for pIP501 conjugative transfer between Gram-positive bacteria. The TraG protein, which localizes to the cell envelope of E. faecalis harboring pIP501, was expressed and purified without its N-terminal transmembrane helix (TraGΔTMH) and shown to possess peptidoglycan-degrading activity. TraGΔTMH was inhibited by specific lytic transglycosylase inhibitors hexa-N-acetylchitohexaose and bulgecin A. Analysis of the TraG sequence suggested the presence of two domains which both could contribute to the observed cell wall-degrading activity: an N-terminal soluble lytic transglycosylase domain (SLT) and a C-terminal cysteine-, histidine-dependent amidohydrolases/peptidases (CHAP) domain. The protein domains were expressed separately, and both degraded peptidoglycan. A change of the conserved glutamate residue in the putative catalytic center of the SLT domain (E87) to glycine resulted in almost complete inactivity, which is consistent with this part of TraG being a predicted lytic transglycosylase. Based on our findings, we propose that TraG locally opens the peptidoglycan to facilitate insertion of the Gram-positive bacterial type IV secretion machinery into the cell envelope.
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Goessweiner-Mohr N, Grumet L, Pavkov-Keller T, Birner-Gruenberger R, Grohmann E, Keller W. Crystallization and preliminary structure determination of the transfer protein TraM from the Gram-positive conjugative plasmid pIP501. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:178-83. [PMID: 23385763 PMCID: PMC3564624 DOI: 10.1107/s1744309113000134] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 01/02/2013] [Indexed: 11/07/2023]
Abstract
The major means of horizontal gene spread (e.g. of antibiotic resistance) is conjugative plasmid transfer. It presents a serious threat especially for hospitalized and immuno-suppressed patients, as it can lead to the accelerated spread of bacteria with multiple antibiotic resistances. Detailed information about the process is available only for bacteria of Gram-negative (G-) origin and little is known about the corresponding mechanisms in Gram-positive (G+) bacteria. Here we present the purification, biophysical characterization, crystallization and preliminary structure determination of the TraM C-terminal domain (TraMΔ, comprising residues 190-322 of the full-length protein), a putative transfer protein from the G+ conjugative model plasmid pIP501. The crystals diffracted to 2.5 Å resolution and belonged to space group P1, with unit-cell parameters a = 39.21, b = 54.98, c = 93.47 Å, α = 89.91, β = 86.44, γ = 78.63° and six molecules per asymmetric unit. The preliminary structure was solved by selenomethionine single-wavelength anomalous diffraction.
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Affiliation(s)
- Nikolaus Goessweiner-Mohr
- Institute for Molecular Biosciences, Karl-Franzens-University Graz, Humboldtstrasse 50/III, 8010 Graz, Styria, Austria
| | - Lukas Grumet
- Institute for Molecular Biosciences, Karl-Franzens-University Graz, Humboldtstrasse 50/III, 8010 Graz, Styria, Austria
| | - Tea Pavkov-Keller
- Institute for Molecular Biosciences, Karl-Franzens-University Graz, Humboldtstrasse 50/III, 8010 Graz, Styria, Austria
| | - Ruth Birner-Gruenberger
- Institute of Pathology and Center of Medical Research – Core Facility Mass Spectrometry, Medical University Graz, Stiftingtalstrasse 24, 8010 Graz, Styria, Austria
| | - Elisabeth Grohmann
- Division of Infectious Diseases, University Medical Center Freiburg, Hugstetter Str. 55, Freiburg, 79106, Germany
| | - Walter Keller
- Institute for Molecular Biosciences, Karl-Franzens-University Graz, Humboldtstrasse 50/III, 8010 Graz, Styria, Austria
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Pieretti I, Royer M, Barbe V, Carrere S, Koebnik R, Couloux A, Darrasse A, Gouzy J, Jacques MA, Lauber E, Manceau C, Mangenot S, Poussier S, Segurens B, Szurek B, Verdier V, Arlat M, Gabriel DW, Rott P, Cociancich S. Genomic insights into strategies used by Xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels. BMC Genomics 2012; 13:658. [PMID: 23171051 PMCID: PMC3542200 DOI: 10.1186/1471-2164-13-658] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 11/18/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA gyrase inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa-another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH), genomic features of two strains differing in pathogenicity. RESULTS Comparative genomic analyses showed that most of the known pathogenicity factors from other Xanthomonas species are conserved in X. albilineans, with the notable absence of two major determinants of the "artillery" of other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis gene cluster, and the type III secretion system Hrp (hypersensitive response and pathogenicity). Genomic features specific to X. albilineans that may contribute to specific adaptation of this pathogen to sugarcane xylem vessels were also revealed. SSH experiments led to the identification of 20 genes common to three highly pathogenic strains but missing in a less pathogenic strain. These 20 genes, which include four ABC transporter genes, a methyl-accepting chemotaxis protein gene and an oxidoreductase gene, could play a key role in pathogenicity. With the exception of hypothetical proteins revealed by our comparative genomic analyses and SSH experiments, no genes potentially involved in any offensive or counter-defensive mechanism specific to X. albilineans were identified, supposing that X. albilineans has a reduced artillery compared to other pathogenic Xanthomonas species. Particular attention has therefore been given to genomic features specific to X. albilineans making it more capable of evading sugarcane surveillance systems or resisting sugarcane defense systems. CONCLUSIONS This study confirms that X. albilineans is a highly distinctive species within the genus Xanthomonas, and opens new perpectives towards a greater understanding of the pathogenicity of this destructive sugarcane pathogen.
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Affiliation(s)
| | - Monique Royer
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
| | - Valérie Barbe
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | | | - Ralf Koebnik
- IRD, UMR RPB, F-34394 Montpellier Cedex 5, France
| | - Arnaud Couloux
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | | | - Jérôme Gouzy
- INRA, UMR LIPM, F-31326 Castanet-Tolosan Cedex France
| | | | | | | | - Sophie Mangenot
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | - Stéphane Poussier
- Université de la Réunion, UMR PVBMT, F-97715 Saint-Denis La Réunion, France
| | - Béatrice Segurens
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | - Boris Szurek
- IRD, UMR RPB, F-34394 Montpellier Cedex 5, France
| | | | - Matthieu Arlat
- Université Paul Sabatier, UMR LIPM, F-31326 Castanet-Tolosan Cedex France
| | - Dean W Gabriel
- University of Florida, Plant Pathology Department, Gainesville FL 32605 USA
| | - Philippe Rott
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
| | - Stéphane Cociancich
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
- UMR BGPI, Campus International de Baillarguet, TA A-54/K, F-34398 Montpellier Cedex 5, France
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Gliding motility and Por secretion system genes are widespread among members of the phylum bacteroidetes. J Bacteriol 2012; 195:270-8. [PMID: 23123910 DOI: 10.1128/jb.01962-12] [Citation(s) in RCA: 205] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The phylum Bacteroidetes is large and diverse, with rapid gliding motility and the ability to digest macromolecules associated with many genera and species. Recently, a novel protein secretion system, the Por secretion system (PorSS), was identified in two members of the phylum, the gliding bacterium Flavobacterium johnsoniae and the nonmotile oral pathogen Porphyromonas gingivalis. The components of the PorSS are not similar in sequence to those of other well-studied bacterial secretion systems. The F. johnsoniae PorSS genes are a subset of the gliding motility genes, suggesting a role for the secretion system in motility. The F. johnsoniae PorSS is needed for assembly of the gliding motility apparatus and for secretion of a chitinase, and the P. gingivalis PorSS is involved in secretion of gingipain protease virulence factors. Comparative analysis of 37 genomes of members of the phylum Bacteroidetes revealed the widespread occurrence of gliding motility genes and PorSS genes. Genes associated with other bacterial protein secretion systems were less common. The results suggest that gliding motility is more common than previously reported. Microscopic observations confirmed that organisms previously described as nonmotile, including Croceibacter atlanticus, "Gramella forsetii," Paludibacter propionicigenes, Riemerella anatipestifer, and Robiginitalea biformata, exhibit gliding motility. Three genes (gldA, gldF, and gldG) that encode an apparent ATP-binding cassette transporter required for F. johnsoniae gliding were absent from two related gliding bacteria, suggesting that the transporter may not be central to gliding motility.
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29
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Lossi NS, Manoli E, Simpson P, Jones C, Hui K, Dajani R, Coulthurst SJ, Freemont P, Filloux A. The archetypePseudomonas aeruginosaproteins TssB and TagJ form a novel subcomplex in the bacterial type VI secretion system. Mol Microbiol 2012; 86:437-56. [DOI: 10.1111/j.1365-2958.2012.08204.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2012] [Indexed: 12/25/2022]
Affiliation(s)
- Nadine S. Lossi
- MRC Centre for Molecular Bacteriology and Infection (CMBI); Division of Cell and Molecular Biology; Imperial College London; London; SW7 2AZ; UK
| | - Eleni Manoli
- MRC Centre for Molecular Bacteriology and Infection (CMBI); Division of Cell and Molecular Biology; Imperial College London; London; SW7 2AZ; UK
| | - Pete Simpson
- Division of Molecular Biosciences; Imperial College London; London; SW7 2AZ; UK
| | - Cerith Jones
- MRC Centre for Molecular Bacteriology and Infection (CMBI); Division of Cell and Molecular Biology; Imperial College London; London; SW7 2AZ; UK
| | - Kailyn Hui
- MRC Centre for Molecular Bacteriology and Infection (CMBI); Division of Cell and Molecular Biology; Imperial College London; London; SW7 2AZ; UK
| | - Rana Dajani
- MRC Centre for Molecular Bacteriology and Infection (CMBI); Division of Cell and Molecular Biology; Imperial College London; London; SW7 2AZ; UK
| | - Sarah J. Coulthurst
- Division of Molecular Microbiology; College of Life Sciences; University of Dundee; Dow Street; Dundee; DD1 5EH; UK
| | - Paul Freemont
- Division of Molecular Biosciences; Imperial College London; London; SW7 2AZ; UK
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection (CMBI); Division of Cell and Molecular Biology; Imperial College London; London; SW7 2AZ; UK
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Celik N, Webb CT, Leyton DL, Holt KE, Heinz E, Gorrell R, Kwok T, Naderer T, Strugnell RA, Speed TP, Teasdale RD, Likić VA, Lithgow T. A bioinformatic strategy for the detection, classification and analysis of bacterial autotransporters. PLoS One 2012; 7:e43245. [PMID: 22905239 PMCID: PMC3419190 DOI: 10.1371/journal.pone.0043245] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 07/18/2012] [Indexed: 11/18/2022] Open
Abstract
Autotransporters are secreted proteins that are assembled into the outer membrane of bacterial cells. The passenger domains of autotransporters are crucial for bacterial pathogenesis, with some remaining attached to the bacterial surface while others are released by proteolysis. An enigma remains as to whether autotransporters should be considered a class of secretion system, or simply a class of substrate with peculiar requirements for their secretion. We sought to establish a sensitive search protocol that could identify and characterize diverse autotransporters from bacterial genome sequence data. The new sequence analysis pipeline identified more than 1500 autotransporter sequences from diverse bacteria, including numerous species of Chlamydiales and Fusobacteria as well as all classes of Proteobacteria. Interrogation of the proteins revealed that there are numerous classes of passenger domains beyond the known proteases, adhesins and esterases. In addition the barrel-domain-a characteristic feature of autotransporters-was found to be composed from seven conserved sequence segments that can be arranged in multiple ways in the tertiary structure of the assembled autotransporter. One of these conserved motifs overlays the targeting information required for autotransporters to reach the outer membrane. Another conserved and diagnostic motif maps to the linker region between the passenger domain and barrel-domain, indicating it as an important feature in the assembly of autotransporters.
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Affiliation(s)
- Nermin Celik
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Chaille T. Webb
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Denisse L. Leyton
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Department of Microbiology, Monash University, Clayton, Australia
| | - Kathryn E. Holt
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Australia
| | - Eva Heinz
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Rebecca Gorrell
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Department of Microbiology, Monash University, Clayton, Australia
| | - Terry Kwok
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Department of Microbiology, Monash University, Clayton, Australia
| | - Thomas Naderer
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Richard A. Strugnell
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Australia
| | - Terence P. Speed
- Bioinformatics Division, Walter and Eliza Hall Institute, Parkville, Australia
| | - Rohan D. Teasdale
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
| | - Vladimir A. Likić
- The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Australia
| | - Trevor Lithgow
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
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31
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Morrissey B, Leney AC, Toste Rêgo A, Phan G, Allen WJ, Verger D, Waksman G, Ashcroft AE, Radford SE. The role of chaperone-subunit usher domain interactions in the mechanism of bacterial pilus biogenesis revealed by ESI-MS. Mol Cell Proteomics 2012; 11:M111.015289. [PMID: 22371487 PMCID: PMC3394950 DOI: 10.1074/mcp.m111.015289] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 01/23/2012] [Indexed: 01/12/2023] Open
Abstract
The PapC usher is a β-barrel outer membrane protein essential for assembly and secretion of P pili that are required for adhesion of pathogenic E. coli, which cause the development of pyelonephritis. Multiple protein subunits form the P pilus, the highly specific assembly of which is coordinated by the usher. Despite a wealth of structural knowledge, how the usher catalyzes subunit polymerization and orchestrates a correct and functional order of subunit assembly remain unclear. Here, the ability of the soluble N-terminal (UsherN), C-terminal (UsherC2), and Plug (UsherP) domains of the usher to bind different chaperone-subunit (PapDPapX) complexes is investigated using noncovalent electrospray ionization mass spectrometry. The results reveal that each usher domain is able to bind all six PapDPapX complexes, consistent with an active role of all three usher domains in pilus biogenesis. Using collision induced dissociation, combined with competition binding experiments and dissection of the adhesin subunit, PapG, into separate pilin and adhesin domains, the results reveal why PapG has a uniquely high affinity for the usher, which is consistent with this subunit always being displayed at the pilus tip. In addition, we show how the different soluble usher domains cooperate to coordinate and control efficient pilus assembly at the usher platform. As well as providing new information about the protein-protein interactions that determine pilus biogenesis, the results highlight the power of noncovalent MS to interrogate biological mechanisms, especially in complex mixtures of species.
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MESH Headings
- Adhesins, Escherichia coli/chemistry
- Adhesins, Escherichia coli/genetics
- Adhesins, Escherichia coli/metabolism
- Bacterial Adhesion
- Binding Sites
- Binding, Competitive
- Escherichia coli/pathogenicity
- Escherichia coli/physiology
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Fimbriae Proteins/chemistry
- Fimbriae Proteins/genetics
- Fimbriae Proteins/metabolism
- Fimbriae, Bacterial/chemistry
- Fimbriae, Bacterial/genetics
- Fimbriae, Bacterial/metabolism
- Models, Molecular
- Molecular Chaperones/chemistry
- Molecular Chaperones/genetics
- Molecular Chaperones/metabolism
- Periplasmic Proteins/chemistry
- Periplasmic Proteins/genetics
- Periplasmic Proteins/metabolism
- Porins/chemistry
- Porins/genetics
- Porins/metabolism
- Protein Binding
- Protein Structure, Tertiary
- Protein Subunits/chemistry
- Protein Subunits/genetics
- Protein Subunits/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Spectrometry, Mass, Electrospray Ionization
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Affiliation(s)
- Bethny Morrissey
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
| | - Aneika C. Leney
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
| | - Ana Toste Rêgo
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Gilles Phan
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - William J. Allen
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Denis Verger
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Gabriel Waksman
- §Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, WC1E 7HX, UK
| | - Alison E. Ashcroft
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
| | - Sheena E. Radford
- From the ‡Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, The University of Leeds, Leeds, LS2 9JT, UK
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32
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Abstract
Bacterial secretion systems play essential roles in pathogenesis and also in maintaining lines of communication between bacterial cells in the bacterial microflora or between commensal bacteria and their host. Recent breakthroughs in the field have yielded some novel insights into the mechanisms by which these systems operate. This issue of Philosophical Transactions B seeks to provide a detailed survey of the field, with an emphasis on mechanisms and how their unravelling might provide a new future for antibiotics research.
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Affiliation(s)
- Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK.
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33
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Leo JC, Grin I, Linke D. Type V secretion: mechanism(s) of autotransport through the bacterial outer membrane. Philos Trans R Soc Lond B Biol Sci 2012; 367:1088-101. [PMID: 22411980 PMCID: PMC3297439 DOI: 10.1098/rstb.2011.0208] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Autotransport in Gram-negative bacteria denotes the ability of surface-localized proteins to cross the outer membrane (OM) autonomously. Autotransporters perform this task with the help of a β-barrel transmembrane domain localized in the OM. Different classes of autotransporters have been investigated in detail in recent years; classical monomeric but also trimeric autotransporters comprise many important bacterial virulence factors. So do the two-partner secretion systems, which are a special case as the transported protein resides on a different polypeptide chain than the transporter. Despite the great interest in these proteins, the exact mechanism of the transport process remains elusive. Moreover, different periplasmic and OM factors have been identified that play a role in the translocation, making the term ‘autotransport’ debatable. In this review, we compile the wealth of details known on the mechanism of single autotransporters from different classes and organisms, and put them into a bigger perspective. We also discuss recently discovered or rediscovered classes of autotransporters.
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Affiliation(s)
- Jack C Leo
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
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34
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Kuykendall LD, Shao JY, Hartung JS. 'Ca. Liberibacter asiaticus' proteins orthologous with pSymA-encoded proteins of Sinorhizobium meliloti: hypothetical roles in plant host interaction. PLoS One 2012; 7:e38725. [PMID: 22761700 PMCID: PMC3382624 DOI: 10.1371/journal.pone.0038725] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 05/14/2012] [Indexed: 01/09/2023] Open
Abstract
Sinorhizobium meliloti strain 1021, a nitrogen-fixing, root-nodulating bacterial microsymbiont of alfalfa, has a 3.5 Mbp circular chromosome and two megaplasmids including 1.3 Mbp pSymA carrying nonessential 'accessory' genes for nitrogen fixation (nif), nodulation and host specificity (nod). A related bacterium, psyllid-vectored 'Ca. Liberibacter asiaticus,' is an obligate phytopathogen with a reduced genome that was previously analyzed for genes orthologous to genes on the S. meliloti circular chromosome. In general, proteins encoded by pSymA genes are more similar in sequence alignment to those encoded by S. meliloti chromosomal orthologs than to orthologous proteins encoded by genes carried on the 'Ca. Liberibacter asiaticus' genome. Only two 'Ca. Liberibacter asiaticus' proteins were identified as having orthologous proteins encoded on pSymA but not also encoded on the chromosome of S. meliloti. These two orthologous gene pairs encode a Na(+)/K+ antiporter (shared with intracellular pathogens of the family Bartonellacea) and a Co++, Zn++ and Cd++ cation efflux protein that is shared with the phytopathogen Agrobacterium. Another shared protein, a redox-regulated K+ efflux pump may regulate cytoplasmic pH and homeostasis. The pSymA and 'Ca. Liberibacter asiaticus' orthologs of the latter protein are more highly similar in amino acid alignment compared with the alignment of the pSymA-encoded protein with its S. meliloti chromosomal homolog. About 182 pSymA encoded proteins have sequence similarity (≤ E-10) with 'Ca. Liberibacter asiaticus' proteins, often present as multiple orthologs of single 'Ca. Liberibacter asiaticus' proteins. These proteins are involved with amino acid uptake, cell surface structure, chaperonins, electron transport, export of bioactive molecules, cellular homeostasis, regulation of gene expression, signal transduction and synthesis of amino acids and metabolic cofactors. The presence of multiple orthologs defies mutational analysis and is consistent with the hypothesis that these proteins may be of particular importance in host/microbe interaction and their duplication likely facilitates their ongoing evolution.
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Affiliation(s)
- L. David Kuykendall
- United States Department of Agriculture, Agricultural Research Service, Molecular Plant Pathology Laboratory, Beltsville, Maryland, United States of America
| | - Jonathan Y. Shao
- United States Department of Agriculture, Agricultural Research Service, Molecular Plant Pathology Laboratory, Beltsville, Maryland, United States of America
| | - John S. Hartung
- United States Department of Agriculture, Agricultural Research Service, Molecular Plant Pathology Laboratory, Beltsville, Maryland, United States of America
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35
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Liu H, Bao W, Lin M, Niu H, Rikihisa Y. Ehrlichia type IV secretion effector ECH0825 is translocated to mitochondria and curbs ROS and apoptosis by upregulating host MnSOD. Cell Microbiol 2012; 14:1037-50. [PMID: 22348527 DOI: 10.1111/j.1462-5822.2012.01775.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ehrlichia chaffeensis infects monocytes/macrophages and causes human monocytic ehrlichiosis. To determine the role of type IV secretion (T4S) system in infection, candidates for T4S effectors were identified by bacterial two-hybrid screening of E. chaffeensis hypothetical proteins with positively charged C-terminus using E. chaffeensis VirD4 as bait. Of three potential T4S effectors, ECH0825 was highly upregulated early during exponential growth in a human monocytic cell line. ECH0825 was translocated from the bacterium into the host-cell cytoplasm and localized to mitochondria. Delivery of anti-ECH0825 into infected host cells significantly reduced bacterial infection. Ectopically expressed ECH0825 also localized to mitochondria and inhibited apoptosis of transfected cells in response to etoposide treatment. In double transformed yeast, ECH0825 localized to mitochondria and inhibited human Bax-induced apoptosis. Mitochondrial manganese superoxide dismutase (MnSOD) was increased over ninefold in E. chaffeensis-infected cells, and the amount of reactive oxygen species (ROS) in infected cells was significantly lower than that in uninfected cells. Similarly, MnSOD was upregulated and the ROS level was reduced in ECH0825-transfected cells. These data suggest that, by upregulating MnSOD, ECH0825 prevents ROS-induced cellular damage and apoptosis to allow intracellular infection. This is the first example of host ROS levels linked to a bacterial T4S effector.
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Affiliation(s)
- Hongyan Liu
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
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36
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Hébert L, Moumen B, Pons N, Duquesne F, Breuil MF, Goux D, Batto JM, Laugier C, Renault P, Petry S. Genomic characterization of the Taylorella genus. PLoS One 2012; 7:e29953. [PMID: 22235352 PMCID: PMC3250509 DOI: 10.1371/journal.pone.0029953] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 12/07/2011] [Indexed: 01/21/2023] Open
Abstract
The Taylorella genus comprises two species: Taylorella equigenitalis, which causes contagious equine metritis, and Taylorella asinigenitalis, a closely-related species mainly found in donkeys. We herein report on the first genome sequence of T. asinigenitalis, analyzing and comparing it with the recently-sequenced T. equigenitalis genome. The T. asinigenitalis genome contains a single circular chromosome of 1,638,559 bp with a 38.3% GC content and 1,534 coding sequences (CDS). While 212 CDSs were T. asinigenitalis-specific, 1,322 had orthologs in T. equigenitalis. Two hundred and thirty-four T. equigenitalis CDSs had no orthologs in T. asinigenitalis. Analysis of the basic nutrition metabolism of both Taylorella species showed that malate, glutamate and alpha-ketoglutarate may be their main carbon and energy sources. For both species, we identified four different secretion systems and several proteins potentially involved in binding and colonization of host cells, suggesting a strong potential for interaction with their host. T. equigenitalis seems better-equipped than T. asinigenitalis in terms of virulence since we identified numerous proteins potentially involved in pathogenicity, including hemagluttinin-related proteins, a type IV secretion system, TonB-dependent lactoferrin and transferrin receptors, and YadA and Hep_Hag domains containing proteins. This is the first molecular characterization of Taylorella genus members, and the first molecular identification of factors potentially involved in T. asinigenitalis and T. equigenitalis pathogenicity and host colonization. This study facilitates a genetic understanding of growth phenotypes, animal host preference and pathogenic capacity, paving the way for future functional investigations into this largely unknown genus.
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Affiliation(s)
- Laurent Hébert
- ANSES, Dozulé Laboratory for Equine Diseases, Dozulé, France
- * E-mail: (LH); (SP)
| | - Bouziane Moumen
- Institut National de la Recherche Agronomique, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
| | - Nicolas Pons
- Institut National de la Recherche Agronomique, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
| | - Fabien Duquesne
- ANSES, Dozulé Laboratory for Equine Diseases, Dozulé, France
| | | | - Didier Goux
- Centre de Microscopie Appliquée à la Biologie, Université de Caen Basse-Normandie et IFR146 ICORE, Caen, France
| | - Jean-Michel Batto
- Institut National de la Recherche Agronomique, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
| | - Claire Laugier
- ANSES, Dozulé Laboratory for Equine Diseases, Dozulé, France
| | - Pierre Renault
- Institut National de la Recherche Agronomique, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
| | - Sandrine Petry
- ANSES, Dozulé Laboratory for Equine Diseases, Dozulé, France
- * E-mail: (LH); (SP)
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37
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Green fluorescent protein-labeled monitoring tool to quantify conjugative plasmid transfer between Gram-positive and Gram-negative bacteria. Appl Environ Microbiol 2011; 78:895-9. [PMID: 22138997 DOI: 10.1128/aem.05578-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
On the basis of pIP501, a green fluorescent protein (GFP)-tagged monitoring tool was constructed for quantifying plasmid mobilization among Gram-positive bacteria and between Gram-positive Enterococcus faecalis and Gram-negative Escherichia coli. Furthermore, retromobilization of the GFP-tagged monitoring tool was shown from E. faecalis OG1X into the clinical isolate E. faecalis T9.
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38
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Hwang W, Lee NY, Kim J, Lee MA, Kim KS, Lee KH, Park SJ. Functional characterization of EpsC, a component of the type II secretion system, in the pathogenicity of Vibrio vulnificus. Infect Immun 2011; 79:4068-80. [PMID: 21788383 PMCID: PMC3187239 DOI: 10.1128/iai.05351-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 07/16/2011] [Indexed: 01/22/2023] Open
Abstract
EpsC, one of the components comprising the type II secretion system (T2SS), was isolated from a human-pathogenic bacterium, Vibrio vulnificus, to evaluate its role in eliciting virulence. An espC-deleted mutant of V. vulnificus displayed a reduced cytotoxicity to the human cell line HEp-2 and an attenuated virulence in a mouse model. This mutant exhibited dramatic defects in the secretion of diverse extracellular proteins, such as outer membrane proteins, transporters, and the known secreted factors, notably, a hemolysin (VvhA) and an elastase (VvpE). A defect in its secretion of proteins was restored by in trans complementation of the intact epsC gene. Analyses of cellular fractions revealed that VvhA and VvpE of the ΔepsC mutant were not excreted outside the cell but were present mainly in the periplasmic space. Examination of a V. vulnificus mutant deficient in TolC, a component of the T1SS, showed that it is not involved in the secretion of VvhA and VvpE but that it is necessary for the secretion of another major toxin of V. vulnificus, RtxA. Therefore, the T2SS is required for V. vulnificus pathogenicity, which is mediated by at least two secreted factors, VvhA and VvpE, via facilitating the secretion and exposure of these factors to host cells.
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Affiliation(s)
- Won Hwang
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Post Brain Korea 21 Program, Yonsei University College of Medicine, Seoul 120-752
- Department of Life Science, Sogang University, Seoul 121-741
| | - Na Yeon Lee
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Post Brain Korea 21 Program, Yonsei University College of Medicine, Seoul 120-752
| | - Juri Kim
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Post Brain Korea 21 Program, Yonsei University College of Medicine, Seoul 120-752
| | - Mi-Ae Lee
- Department of Environmental Sciences, Hankuk University of Foreign Studies, Yongin 449-741, Republic of Korea
| | - Kun-Soo Kim
- Department of Life Science, Sogang University, Seoul 121-741
| | - Kyu-Ho Lee
- Department of Environmental Sciences, Hankuk University of Foreign Studies, Yongin 449-741, Republic of Korea
| | - Soon-Jung Park
- Department of Environmental Medical Biology, Institute of Tropical Medicine, Post Brain Korea 21 Program, Yonsei University College of Medicine, Seoul 120-752
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The fimbrial usher FimD follows the SurA-BamB pathway for its assembly in the outer membrane of Escherichia coli. J Bacteriol 2011; 193:5222-30. [PMID: 21784935 DOI: 10.1128/jb.05585-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fimbrial ushers are the largest β-barrel outer membrane proteins (OMPs) known to date, which function in the polymerization of fimbriae and their translocation to the bacterial surface. Folding and assembly of these complex OMPs are not characterized. Here, we investigate the role of periplasmic chaperones (SurA, Skp, DegP, and FkpA) and individual components of the β-barrel assembly machinery (BAM) complex (BamA, BamB, BamC, and BamE) in the folding of the Escherichia coli FimD usher. The FimD level is dramatically reduced (∼30-fold) in a surA null mutant, but a strong cell envelope stress is constitutively activated with upregulation of DegP (∼10-fold). To demonstrate a direct role of SurA, FimD folding was analyzed in a conditional surA mutant in which SurA expression was controlled. In this strain, FimD is depleted from bacteria in parallel to SurA without significant upregulation of DegP. Interestingly, the dependency on SurA is higher for FimD than for other OMPs. We also demonstrate that a functional BAM complex is needed for folding of FimD. In addition, FimD levels were strongly reduced (∼5-fold) in a mutant lacking the accessory lipoprotein BamB. The critical role of BamB for FimD folding was confirmed by complementation and BamB depletion experiments. Similar to SurA dependency, FimD showed a stronger dependency on BamB than OMPs. On the other hand, folding of FimD was only marginally affected in bamC and bamE mutants. Collectively, our results indicate that FimD usher follows the SurA-BamB pathway for its assembly. The preferential use of this pathway for the folding of OMPs with large β-barrels is discussed.
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Durand E, Waksman G, Receveur-Brechot V. Structural insights into the membrane-extracted dimeric form of the ATPase TraB from the Escherichia coli pKM101 conjugation system. BMC STRUCTURAL BIOLOGY 2011; 11:4. [PMID: 21266026 PMCID: PMC3032639 DOI: 10.1186/1472-6807-11-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 01/25/2011] [Indexed: 11/26/2022]
Abstract
BACKGROUND Type IV secretion (T4S) systems are involved in secretion of virulence factors such as toxins or transforming molecules, or bacterial conjugation. T4S systems are composed of 12 proteins named VirB1-B11 and VirD4. Among them, three ATPases are involved in the assembly of the T4S system and/or provide energy for substrate transfer, VirB4, VirB11 and VirD4. The X-ray crystal structures of VirB11 and VirD4 have already been solved but VirB4 has proven to be reluctant to any structural investigation so far. RESULTS Here, we have used small-angle X-ray scattering to obtain the first structural models for the membrane-extracted, dimeric form of the TraB protein, the VirB4 homolog encoded by the E. coli pKM101 plasmid, and for the monomeric soluble form of the LvhB4 protein, the VirB4 homolog of the T4S system encoded by the Legionella pneumophila lvh operon. We have obtained the low resolution structures of the full-length TraB and of its N- and C-terminal halves. From these SAXS models, we derive the internal organisation of TraB. We also show that the two TraB N- and C-terminal domains are independently involved in the dimerisation of the full-length protein. CONCLUSIONS These models provide the first structural insights into the architecture of VirB4 proteins. In particular, our results highlight the modular arrangement and functional relevance of the dimeric-membrane-bound form of TraB.
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Affiliation(s)
- Eric Durand
- Institute of Structural and Molecular Biology, UCL/Birkbeck, Malet Street, London WC1E 7HX, UK
- LISM-CNRS - UPR9027, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, UCL/Birkbeck, Malet Street, London WC1E 7HX, UK
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Abstract
Bacteria have developed remarkable systems that sense neighboring target cells upon contact and initiate a series of events that enhance their survival and growth at the expense of the target cells. Four main classes of bacterial cell surface structures have been identified that interact with prokaryotic or eukaryotic target cells to deliver DNA or protein effectors. Type III secretion systems (T3SS) use a flagellum-like tube to deliver protein effectors into eukaryotic host cells, whereas Type IV systems use a pilus-based system to mediate DNA or protein transfer into recipient cells. The contact-dependent growth inhibition system (CDI) is a Type V system, using a long β-helical cell surface protein to contact receptors in target cells and deliver a growth inhibitory signal. Type VI systems utilize a phage-like tube and cell puncturing device to secrete effector proteins into both eukaryotic and prokaryotic target cells.
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Affiliation(s)
- Christopher S Hayes
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106, USA
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Van Gerven N, Waksman G, Remaut H. Pili and flagella biology, structure, and biotechnological applications. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 103:21-72. [PMID: 21999994 DOI: 10.1016/b978-0-12-415906-8.00005-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bacteria and Archaea expose on their outer surfaces a variety of thread-like proteinaceous organelles with which they interact with their environments. These structures are repetitive assemblies of covalently or non-covalently linked protein subunits, organized into filamentous polymers known as pili ("hair"), flagella ("whips") or injectisomes ("needles"). They serve different roles in cell motility, adhesion and host invasion, protein and DNA secretion and uptake, conductance, or cellular encapsulation. Here we describe the functional, morphological and genetic diversity of these bacterial filamentous protein structures. The organized, multi-copy build-up and/or the natural function of pili and flagella have lead to their biotechnological application as display and secretion tools, as therapeutic targets or as molecular motors. We review the documented and potential technological exploitation of bacterial surface filaments in light of their structural and functional traits.
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Affiliation(s)
- Nani Van Gerven
- Structural & Molecular Microbiology, VIB/Vrije Universiteit Brussel, Brussels, Belgium
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Disulfide bond-mediated passenger domain stalling as a structural probe of autotransporter outer membrane secretion in vivo. Methods Enzymol 2011; 492:233-51. [PMID: 21333794 DOI: 10.1016/b978-0-12-381268-1.00030-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Autotransporters (ATs) are the largest class of extracellular virulence proteins secreted by Gram-negative pathogenic bacteria, but the details of their outer membrane (OM) secretion mechanism remain unclear. Recently, a novel strategy has been developed to study OM secretion of AT proteins by introducing pairs of cysteine (Cys) residues into the central passenger domain sequence. Upon oxidation in the periplasm, these Cys residues form a long loop that stalls AT OM secretion. This Cys-loop stalling technique has been used to investigate such questions as the directionality of AT OM secretion and the extent of AT passenger domain folding during secretion. Here, we will describe how to use the Cys-loop approach to produce disulfide-bonded, stalled AT OM secretion intermediates, and how these stalled "snapshots" can be used to investigate structural aspects of the AT OM secretion mechanism.
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Outer membrane translocons: structural insights into channel formation. Trends Microbiol 2010; 19:40-8. [PMID: 21130656 DOI: 10.1016/j.tim.2010.10.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/18/2010] [Accepted: 10/29/2010] [Indexed: 01/26/2023]
Abstract
Gram-negative bacteria need to maintain the integrity of their outer membrane while also regulating the secretion of toxins and other macromolecules. A variety of dedicated outer membrane proteins (OMPs) facilitate this process. Recent structural work has shown that some of these proteins adopt classical β-barrel transmembrane structures and rely on structural changes within the barrel lumen to allow passage of substrate proteins. Other secretion systems have OMP components which use transmembrane α-helices and appear to function in a different way. Here we review a selection of recent structural studies which have major ramifications for our understanding of the passage of macromolecules across the outer membrane.
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Jong WSP, Saurí A, Luirink J. Extracellular production of recombinant proteins using bacterial autotransporters. Curr Opin Biotechnol 2010; 21:646-52. [DOI: 10.1016/j.copbio.2010.07.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 07/15/2010] [Indexed: 01/29/2023]
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Abstract
Type IV secretion systems (T4SSs) are large protein complexes which traverse the cell envelope of many bacteria. They contain a channel through which proteins or protein–DNA complexes can be translocated. This translocation is driven by a number of cytoplasmic ATPases which might energize large conformational changes in the translocation complex. The family of T4SSs is very versatile, shown by the great variety of functions among family members. Some T4SSs are used by pathogenic Gram-negative bacteria to translocate a wide variety of virulence factors into the host cell. Other T4SSs are utilized to mediate horizontal gene transfer, an event that greatly facilitates the adaptation to environmental changes and is the basis for the spread of antibiotic resistance among bacteria. Here we review the recent advances in the characterization of the architecture and mechanism of substrate transfer in a few representative T4SSs with a particular focus on their diversity of structure and function.
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Affiliation(s)
- Karin Wallden
- Institute of Structural and Molecular Biology, UCL and Birkbeck, London WC1E 7HX, UK
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