51
|
Weiler AJ, Spitz O, Gudzuhn M, Schott-Verdugo SN, Kamel M, Thiele B, Streit WR, Kedrov A, Schmitt L, Gohlke H, Kovacic F. A phospholipase B from Pseudomonas aeruginosa with activity towards endogenous phospholipids affects biofilm assembly. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159101. [DOI: 10.1016/j.bbalip.2021.159101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 12/09/2021] [Accepted: 12/15/2021] [Indexed: 11/29/2022]
|
52
|
Kreitmeier M, Ardern Z, Abele M, Ludwig C, Scherer S, Neuhaus K. Spotlight on alternative frame coding: Two long overlapping genes in Pseudomonas aeruginosa are translated and under purifying selection. iScience 2022; 25:103844. [PMID: 35198897 PMCID: PMC8850804 DOI: 10.1016/j.isci.2022.103844] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/14/2021] [Accepted: 01/27/2022] [Indexed: 12/13/2022] Open
Abstract
The existence of overlapping genes (OLGs) with significant coding overlaps revolutionizes our understanding of genomic complexity. We report two exceptionally long (957 nt and 1536 nt), evolutionarily novel, translated antisense open reading frames (ORFs) embedded within annotated genes in the pathogenic Gram-negative bacterium Pseudomonas aeruginosa. Both OLG pairs show sequence features consistent with being genes and transcriptional signals in RNA sequencing. Translation of both OLGs was confirmed by ribosome profiling and mass spectrometry. Quantitative proteomics of samples taken during different phases of growth revealed regulation of protein abundances, implying biological functionality. Both OLGs are taxonomically restricted, and likely arose by overprinting within the genus. Evidence for purifying selection further supports functionality. The OLGs reported here, designated olg1 and olg2, are the longest yet proposed in prokaryotes and are among the best attested in terms of translation and evolutionary constraint. These results highlight a potentially large unexplored dimension of prokaryotic genomes. Two novel, very long, overlapping genes were found in Pseudomonas aeruginosa Both overlapping genes, olg1 and olg2, are transcribed, translated, and regulated Mass spectrometry verifies translation of the overlapping and their mother genes Both overlapping genes are taxonomically restricted, but under purifying selection
Collapse
Affiliation(s)
- Michaela Kreitmeier
- Chair for Microbial Ecology, TUM School of Life Sciences, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Zachary Ardern
- Chair for Microbial Ecology, TUM School of Life Sciences, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany.,Wellcome Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Miriam Abele
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), TUM School of Life Sciences, Technische Universität München, Gregor-Mendel-Strasse 4, 85354 Freising, Germany
| | - Christina Ludwig
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), TUM School of Life Sciences, Technische Universität München, Gregor-Mendel-Strasse 4, 85354 Freising, Germany
| | - Siegfried Scherer
- Chair for Microbial Ecology, TUM School of Life Sciences, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Klaus Neuhaus
- Core Facility Microbiome, ZIEL - Institute for Food & Health, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| |
Collapse
|
53
|
Amaya FA, Blondel CJ, Barros-Infante MF, Rivera D, Moreno-Switt AI, Santiviago CA, Pezoa D. Identification of Type VI Secretion Systems Effector Proteins That Contribute to Interbacterial Competition in Salmonella Dublin. Front Microbiol 2022; 13:811932. [PMID: 35222335 PMCID: PMC8867033 DOI: 10.3389/fmicb.2022.811932] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/04/2022] [Indexed: 12/12/2022] Open
Abstract
The Type VI Secretion System (T6SS) is a multiprotein device that has emerged as an important fitness and virulence factor for many Gram-negative bacteria through the injection of effector proteins into prokaryotic or eukaryotic cells via a contractile mechanism. While some effector proteins specifically target bacterial or eukaryotic cells, others can target both types of cells (trans-kingdom effectors). In Salmonella, five T6SS gene clusters have been identified within pathogenicity islands SPI-6, SPI-19, SPI-20, SPI-21, and SPI-22, which are differentially distributed among serotypes. Salmonella enterica serotype Dublin (S. Dublin) is a cattle-adapted pathogen that harbors both T6SSSPI-6 and T6SSSPI-19. Interestingly, while both systems have been linked to virulence and host colonization in S. Dublin, an antibacterial activity has not been detected for T6SSSPI-6 in this serotype. In addition, there is limited information regarding the repertoire of effector proteins encoded within T6SSSPI-6 and T6SSSPI-19 gene clusters in S. Dublin. In the present study, we demonstrate that T6SSSPI-6 and T6SSSPI-19 of S. Dublin CT_02021853 contribute to interbacterial competition. Bioinformatic and comparative genomic analyses allowed us to identify genes encoding three candidate antibacterial effectors located within SPI-6 and two candidate effectors located within SPI-19. Each antibacterial effector gene is located upstream of a gene encoding a hypothetic immunity protein, thus conforming an effector/immunity (E/I) module. Of note, the genes encoding these effectors and immunity proteins are widely distributed in Salmonella genomes, suggesting a relevant role in interbacterial competition and virulence. Finally, we demonstrate that E/I modules SED_RS01930/SED_RS01935 (encoded in SPI-6), SED_RS06235/SED_RS06230, and SED_RS06335/SED_RS06340 (both encoded in SPI-19) contribute to interbacterial competition in S. Dublin CT_02021853.
Collapse
Affiliation(s)
- Fernando A. Amaya
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos J. Blondel
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | | | - Dácil Rivera
- Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Andrea I. Moreno-Switt
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millennium Initiative on Collaborative Research on Bacterial Resistance (MICROB-R), Santiago, Chile
| | - Carlos A. Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
| | - David Pezoa
- Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
| |
Collapse
|
54
|
Jee S, Kang IJ, Bak G, Kang S, Lee J, Heu S, Hwang I. Comparative Genomic Analysis of Pathogenic Factors of Pectobacterium Species Isolated in South Korea Using Whole-Genome Sequencing. THE PLANT PATHOLOGY JOURNAL 2022; 38:12-24. [PMID: 35144358 PMCID: PMC8831359 DOI: 10.5423/ppj.ft.09.2021.0147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/15/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
In this study, we conducted whole-genome sequencing with six species of Pectobacterium composed of seven strains, JR1.1, BP201601.1, JK2.1, HNP201719, MYP201603, PZ1, and HC, for the analysis of pathogenic factors associated with the genome of Pectobacterium. The genome sizes ranged from 4,724,337 bp to 5,208,618 bp, with the GC content ranging from 50.4% to 52.3%. The average nucleotide identity was 98% among the two Pectobacterium species and ranged from 88% to 96% among the remaining six species. A similar distribution was observed in the carbohydrate-active enzymes (CAZymes) class and extracellular plant cell wall degrading enzymes (PCWDEs). HC showed the highest number of enzymes in CAZymes and the lowest number in the extracellular PCWDEs. Six strains showed four subsets, and HC demonstrated three subsets, except hasDEF, in type I secretion system, while the type II secretion system of the seven strains was conserved. Components of human pathogens, such as Salmonella pathogenicity island 1 type type III secretion system (T3SS) and effectors, were identified in PZ1; T3SSa was not identified in HC. Two putative effectors, including hrpK, were identified in seven strains along with dspEF. We also identified 13 structural genes, six regulator genes, and five accessory genes in the type VI secretion system (T6SS) gene cluster of six Pectobacterium species, along with the loss of T6SS in PZ1. HC had two subsets, and JK2.1 had three subsets of T6SS. With the GxSxG motif, the phospholipase A gene did locate among tssID and duf4123 genes in the T6SSa cluster of all strains. Important domains were identified in the vgrG/paar islands, including duf4123, duf2235, vrr-nuc, and duf3396.
Collapse
Affiliation(s)
- Samnyu Jee
- Highland Agriculture Research Institute, National Institute of Crop Science, Rural Development Administration, Pyeongchang 25342,
Korea
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826,
Korea
| | - In-Jeong Kang
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826,
Korea
- Division of Crop Cultivation and Environment Research, National Institute of Crop Science, Suwon 16613,
Korea
| | - Gyeryeong Bak
- Highland Agriculture Research Institute, National Institute of Crop Science, Rural Development Administration, Pyeongchang 25342,
Korea
| | - Sera Kang
- Highland Agriculture Research Institute, National Institute of Crop Science, Rural Development Administration, Pyeongchang 25342,
Korea
| | - Jeongtae Lee
- Highland Agriculture Research Institute, National Institute of Crop Science, Rural Development Administration, Pyeongchang 25342,
Korea
| | - Sunggi Heu
- Department of Plant Science, College of Agriculture and Life Science, Seoul National University, Seoul 08826,
Korea
| | - Ingyu Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826,
Korea
| |
Collapse
|
55
|
Antimicrobial Weapons of Pseudomonas aeruginosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:223-256. [DOI: 10.1007/978-3-031-08491-1_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
56
|
Ting SY, LaCourse KD, Ledvina HE, Zhang R, Radey MC, Kulasekara HD, Somavanshi R, Bertolli SK, Gallagher LA, Kim J, Penewit KM, Salipante SJ, Xu L, Peterson SB, Mougous JD. Discovery of coordinately regulated pathways that provide innate protection against interbacterial antagonism. eLife 2022; 11:74658. [PMID: 35175195 PMCID: PMC8926400 DOI: 10.7554/elife.74658] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/16/2022] [Indexed: 11/13/2022] Open
Abstract
Bacterial survival is fraught with antagonism, including that deriving from viruses and competing bacterial cells. It is now appreciated that bacteria mount complex antiviral responses; however, whether a coordinated defense against bacterial threats is undertaken is not well understood. Previously, we showed that Pseudomonas aeruginosa possess a danger-sensing pathway that is a critical fitness determinant during competition against other bacteria. Here, we conducted genome-wide screens in P. aeruginosa that reveal three conserved and widespread interbacterial antagonism resistance clusters (arc1-3). We find that although arc1-3 are coordinately activated by the Gac/Rsm danger-sensing system, they function independently and provide idiosyncratic defense capabilities, distinguishing them from general stress response pathways. Our findings demonstrate that Arc3 family proteins provide specific protection against phospholipase toxins by preventing the accumulation of lysophospholipids in a manner distinct from previously characterized membrane repair systems. These findings liken the response of P. aeruginosa to bacterial threats to that of eukaryotic innate immunity, wherein threat detection leads to the activation of specialized defense systems.
Collapse
Affiliation(s)
- See-Yeun Ting
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Kaitlyn D LaCourse
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Hannah E Ledvina
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington School of PharmacySeattleUnited States
| | - Matthew C Radey
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Hemantha D Kulasekara
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Rahul Somavanshi
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Savannah K Bertolli
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Larry A Gallagher
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Jennifer Kim
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Kelsi M Penewit
- Department of Laboratory Medicine and Pathology, University of Washington School of MedicineSeattleUnited States
| | - Stephen J Salipante
- Department of Laboratory Medicine and Pathology, University of Washington School of MedicineSeattleUnited States
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington School of PharmacySeattleUnited States
| | - S Brook Peterson
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States
| | - Joseph D Mougous
- Department of Microbiology, University of Washington School of MedicineSeattleUnited States,Department of Biochemistry, University of Washington School of MedicineSeattleUnited States,Howard Hughes Medical Institute, University of WashingtonSeattleUnited States
| |
Collapse
|
57
|
Allsopp LP, Collins ACZ, Hawkins E, Wood TE, Filloux A. RpoN/Sfa2-dependent activation of the Pseudomonas aeruginosa H2-T6SS and its cognate arsenal of antibacterial toxins. Nucleic Acids Res 2021; 50:227-243. [PMID: 34928327 PMCID: PMC8855297 DOI: 10.1093/nar/gkab1254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/26/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa uses three type six secretion systems
(H1-, H2- and H3-T6SS) to manipulate its environment, subvert host cells and for
microbial competition. These T6SS machines are loaded with a variety of
effectors/toxins, many being associated with a specific VgrG. How P.
aeruginosa transcriptionally coordinates the main T6SS clusters and
the multiple vgrG islands spread through the genome is unknown.
Here we show an unprecedented level of control with RsmA repressing most known
T6SS-related genes. Moreover, each of the H2- and H3-T6SS clusters encodes a
sigma factor activator (SFA) protein
called, Sfa2 and Sfa3, respectively. SFA proteins are enhancer binding proteins
necessary for the sigma factor RpoN. Using a combination of RNA-seq, ChIP-seq
and molecular biology approaches, we demonstrate that RpoN coordinates the T6SSs
of P. aeruginosa by activating the H2-T6SS but repressing the
H1- and H3-T6SS. Furthermore, RpoN and Sfa2 control the expression of the
H2-T6SS-linked VgrGs and their effector arsenal to enable very effective
interbacterial killing. Sfa2 is specific as Sfa3 from the H3-T6SS cannot
complement loss of Sfa2. Our study further delineates the regulatory mechanisms
that modulate the deployment of an arsenal of T6SS effectors likely enabling
P. aeruginosa to adapt to a range of environmental
conditions.
Collapse
Affiliation(s)
- Luke P Allsopp
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Alice C Z Collins
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Eleanor Hawkins
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - Thomas E Wood
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| |
Collapse
|
58
|
Zwe YH, Yadav M, Zhen Ten MM, Srinivasan M, Jobichen C, Sivaraman J, Li D. Bacterial Antagonism of Chromobacterium haemolyticum and Characterization of its Putative Type VI Secretion System. Res Microbiol 2021; 173:103918. [PMID: 34906677 DOI: 10.1016/j.resmic.2021.103918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/08/2021] [Accepted: 12/08/2021] [Indexed: 10/19/2022]
Abstract
This study reports the isolation of a new Chromobacterium haemolyticum strain named WI5 from a hydroponic farming facility. WI5 exhibited remarkable bacterial antagonistic properties, eliminating Salmonella, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus (initial inoculum load ∼105 CFU/ml) in dual-species co-culture biofilms. Antagonism was strictly contact-dependent and highly influenced by nutrient availability. Next, we identified a complete suite of putative Type VI secretion system (T6SS) genes in the WI5 genome, annotated the gene locus architecture, and determined the crystal structure of hallmark T6SS tube protein Hcp1, which revealed a hexameric ring structure with an outer and inner diameter of 77 and 45Å, respectively. Structural comparison with homologs showed differences in the key loops connecting the β-strands in which the conserved residues are located, suggesting a role of these residues in the protein function. The T6SS is well-known to facilitate interbacterial competition, and the putative T6SS characterized herein might be responsible for the remarkable antagonism by C. haemolyticum WI5. Collectively, these findings shed light on the nature of bacterial antagonism and a putative key virulence determinant of C. haemolyticum, which might aid in further understanding its potential ecological role in natural habitats.
Collapse
Affiliation(s)
- Ye Htut Zwe
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Manisha Yadav
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Michelle Mei Zhen Ten
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Mahalashmi Srinivasan
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Chacko Jobichen
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - J Sivaraman
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Dan Li
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543.
| |
Collapse
|
59
|
Major tail proteins of bacteriophages of the order Caudovirales. J Biol Chem 2021; 298:101472. [PMID: 34890646 PMCID: PMC8718954 DOI: 10.1016/j.jbc.2021.101472] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/18/2022] Open
Abstract
Technological advances in cryo-EM in recent years have given rise to detailed atomic structures of bacteriophage tail tubes-a class of filamentous protein assemblies that could previously only be studied on the atomic scale in either their monomeric form or when packed within a crystal lattice. These hollow elongated protein structures, present in most bacteriophages of the order Caudovirales, connect the DNA-containing capsid with a receptor function at the distal end of the tail and consist of helical and polymerized major tail proteins. However, the resolution of cryo-EM data for these systems differs enormously between different tail tube types, partly inhibiting the building of high-fidelity models and barring a combination with further structural biology methods. Here, we review the structural biology efforts within this field and highlight the role of integrative structural biology approaches that have proved successful for some of these systems. Finally, we summarize the structural elements of major tail proteins and conceptualize how different amounts of tail tube flexibility confer heterogeneity within cryo-EM maps and, thus, limit high-resolution reconstructions.
Collapse
|
60
|
Liang X, Pei TT, Li H, Zheng HY, Luo H, Cui Y, Tang MX, Zhao YJ, Xu P, Dong T. VgrG-dependent effectors and chaperones modulate the assembly of the type VI secretion system. PLoS Pathog 2021; 17:e1010116. [PMID: 34852023 PMCID: PMC8668125 DOI: 10.1371/journal.ppat.1010116] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 12/13/2021] [Accepted: 11/15/2021] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) is a spear-like nanomachine found in gram-negative pathogens for delivery of toxic effectors to neighboring bacterial and host cells. Its assembly requires a tip spike complex consisting of a VgrG-trimer, a PAAR protein, and the interacting effectors. However, how the spike controls T6SS assembly remains elusive. Here we investigated the role of three VgrG-effector pairs in Aeromonas dhakensis strain SSU, a clinical isolate with a constitutively active T6SS. By swapping VgrG tail sequences, we demonstrate that the C-terminal ~30 amino-acid tail dictates effector specificity. Double deletion of vgrG1&2 genes (VgrG3+) abolished T6SS secretion, which can be rescued by ectopically expressing chimeric VgrG3 with a VgrG1/2-tail but not the wild type VgrG3. In addition, deletion of effector-specific chaperones also severely impaired T6SS secretion, despite the presence of intact VgrG and effector proteins, in both SSU and Vibrio cholerae V52. We further show that SSU could deliver a V. cholerae effector VasX when expressing a plasmid-borne chimeric VgrG with VasX-specific VgrG tail and chaperone sequences. Pull-down analyses show that two SSU effectors, TseP and TseC, could interact with their cognate VgrGs, the baseplate protein TssK, and the key assembly chaperone TssA. Effectors TseL and VasX could interact with TssF, TssK and TssA in V. cholerae. Collectively, we demonstrate that chimeric VgrG-effector pairs could bypass the requirement of heterologous VgrG complex and propose that effector-stuffing inside the baseplate complex, facilitated by chaperones and the interaction with structural proteins, serves as a crucial structural determinant for T6SS assembly. Effectors of bacterial secretion systems are generally considered as secreted proteins for interspecies interactions rather than components of the secretion apparatus. Our results reveal the complex interactions of effectors, chaperones, and structural proteins are crucial for T6SS assembly, suggesting an integral role of effectors as parts of the apparatus and distinctive from other secretion systems.
Collapse
Affiliation(s)
- Xiaoye Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Tong-Tong Pei
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hao Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hao-Yu Zheng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Han Luo
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yang Cui
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ming-Xuan Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ya-Jie Zhao
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Tao Dong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- * E-mail:
| |
Collapse
|
61
|
Lin J, Xu L, Yang J, Wang Z, Shen X. Beyond dueling: roles of the type VI secretion system in microbiome modulation, pathogenesis and stress resistance. STRESS BIOLOGY 2021; 1:11. [PMID: 37676535 PMCID: PMC10441901 DOI: 10.1007/s44154-021-00008-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 08/09/2021] [Indexed: 09/08/2023]
Abstract
Bacteria inhabit diverse and dynamic environments, where nutrients may be limited and toxic chemicals can be prevalent. To adapt to these stressful conditions, bacteria have evolved specialized protein secretion systems, such as the type VI secretion system (T6SS) to facilitate their survival. As a molecular syringe, the T6SS expels various effectors into neighboring bacterial cells, eukaryotic cells, or the extracellular environment. These effectors improve the competitive fitness and environmental adaption of bacterial cells. Although primarily recognized as antibacterial weapons, recent studies have demonstrated that T6SSs have functions beyond interspecies competition. Here, we summarize recent research on the role of T6SSs in microbiome modulation, pathogenesis, and stress resistance.
Collapse
Affiliation(s)
- Jinshui Lin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Lei Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Jianshe Yang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Zhuo Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China.
| |
Collapse
|
62
|
The two-component system FleS/FleR represses H1-T6SS via c-di-GMP signaling in Pseudomonas aeruginosa. Appl Environ Microbiol 2021; 88:e0165521. [PMID: 34731046 DOI: 10.1128/aem.01655-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type VI secretion system (T6SS) is an important translocation apparatus that is widely employed by Gram-negative bacteria to deliver toxic effectors into eukaryotic and prokaryotic target cells, causing host damage and providing competitive advantages in polymicrobial environments. The genome of P. aeruginosa harbors three T6SS clusters (H1-T6SS, H2-T6SS, H3-T6SS). Activities of these systems are tightly regulated by a complicated signaling network which remains largely elusive. In this study, we focused on a previously characterized two-component system FleS/FleR and performed comparative transcriptome analysis between the PAO1 wild-type strain and its isogenic ΔfleR mutant, which revealed the important role of FleS/FleR in regulating multiple physiological pathways including T6SS. Gene expression and bacterial killing assays showed that the expression and activity of H1-T6SS are repressed in the wild-type strain owing to the high intracellular c-di-GMP content. Further explorations demonstrated that c-di-GMP relies on the transcription factor FleQ to repress H1-T6SS and its synthesis is controlled by a global regulator AmrZ which is induced by the active FleS/FleR. Interestingly, FleS/FleR regulates H1-T6SS in PAO1 is independent of RetS which is known to regulate H1-T6SS by controlling the central post-transcriptional factor RsmA. Together, our results identified a novel regulator of H1-T6SS and provided detailed mechanisms of this signaling pathway in PAO1. IMPORTANCE P. aeruginosa is an opportunistic human pathogen distributed widely in the environment. The genome of this pathogen contains three T6SS clusters which contribute significantly to its virulence. Understanding the complex regulatory network that controls the activity of T6SS is essential for the development of effective therapeutic treatments for P. aeruginosa infections. In this study, transcriptome analysis led to the identification of a novel regulator FleS/FleR which inversely regulates H1-T6SS and H2-T6SS in P. aeruginosa PAO1. We further revealed a detailed FleS/FleR-mediated regulatory pathway of H1-T6SS in PAO1 which involves two additional transcriptional regulators AmrZ and FleQ and the second messenger c-di-GMP, providing important implications to develop novel anti-infective strategies and antimicrobial drugs.
Collapse
|
63
|
Basile LA, Lepek VC. Legume-rhizobium dance: an agricultural tool that could be improved? Microb Biotechnol 2021; 14:1897-1917. [PMID: 34318611 PMCID: PMC8449669 DOI: 10.1111/1751-7915.13906] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 07/15/2021] [Accepted: 07/19/2021] [Indexed: 12/29/2022] Open
Abstract
The specific interaction between rhizobia and legume roots leads to the development of a highly regulated process called nodulation, by which the atmospheric nitrogen is converted into an assimilable plant nutrient. This capacity is the basis for the use of bacterial inoculants for field crop cultivation. Legume plants have acquired tools that allow the entry of compatible bacteria. Likewise, plants can impose sanctions against the maintenance of nodules occupied by rhizobia with low nitrogen-fixing capacity. At the same time, bacteria must overcome different obstacles posed first by the environment and then by the legume. The present review describes the mechanisms involved in the regulation of the entire legume-rhizobium symbiotic process and the strategies and tools of bacteria for reaching the nitrogen-fixing state inside the nodule. Also, we revised different approaches to improve the nodulation process for a better crop yield.
Collapse
Affiliation(s)
- Laura A. Basile
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde”Universidad Nacional de San Martín (IIB‐UNSAM‐CONICET)Av. 25 de Mayo y Francia, Gral. San Martín, Provincia de Buenos AiresBuenos AiresB1650HMPArgentina
| | - Viviana C. Lepek
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde”Universidad Nacional de San Martín (IIB‐UNSAM‐CONICET)Av. 25 de Mayo y Francia, Gral. San Martín, Provincia de Buenos AiresBuenos AiresB1650HMPArgentina
| |
Collapse
|
64
|
Crisan CV, Chandrashekar H, Everly C, Steinbach G, Hill SE, Yunker PJ, Lieberman RR, Hammer BK. A New Contact Killing Toxin Permeabilizes Cells and Belongs to a Broadly Distributed Protein Family. mSphere 2021; 6:e0031821. [PMID: 34287011 PMCID: PMC8386463 DOI: 10.1128/msphere.00318-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/21/2021] [Indexed: 01/12/2023] Open
Abstract
Vibrio cholerae is an aquatic Gram-negative bacterium that causes severe diarrheal cholera disease when ingested by humans. To eliminate competitor cells in both the external environment and inside hosts, V. cholerae uses the type VI secretion system (T6SS). The T6SS is a macromolecular contact-dependent weapon employed by many Gram-negative bacteria to deliver cytotoxic proteins into adjacent cells. In addition to canonical T6SS gene clusters encoded by all sequenced V. cholerae isolates, strain BGT49 encodes another locus, which we named auxiliary (Aux) cluster 4. The Aux 4 cluster is located on a mobile genetic element and can be used by killer cells to eliminate both V. cholerae and Escherichia coli cells in a T6SS-dependent manner. A putative toxin encoded in the cluster, which we name TpeV (type VI permeabilizing effector Vibrio), shares no homology to known proteins and does not contain motifs or domains indicative of function. Ectopic expression of TpeV in the periplasm of E. coli permeabilizes cells and disrupts the membrane potential. Using confocal microscopy, we confirm that susceptible target cells become permeabilized when competed with killer cells harboring the Aux 4 cluster. We also determine that tpiV, the gene located immediately downstream of tpeV, encodes an immunity protein that neutralizes the toxicity of TpeV. Finally, we show that TpeV homologs are broadly distributed across important human, animal, and plant pathogens and are localized in proximity to other T6SS genes. Our results suggest that TpeV is a toxin that belongs to a large family of T6SS proteins. IMPORTANCE Bacteria live in polymicrobial communities where competition for resources and space is essential for survival. Proteobacteria use the T6SS to eliminate neighboring cells and cause disease. However, the mechanisms by which many T6SS toxins kill or inhibit susceptible target cells are poorly understood. The sequence of the TpeV toxin that we describe here is unlike any previously described protein. We demonstrate that it has antimicrobial activity by permeabilizing cells, eliminating membrane potentials, and causing severe cytotoxicity. TpeV homologs are found near known T6SS genes in human, animal, and plant bacterial pathogens, indicating that the toxin is a representative member of a broadly distributed protein family. We propose that TpeV-like toxins contribute to the fitness of many bacteria. Finally, since antibiotic resistance is a critical global health threat, the discovery of new antimicrobial mechanisms could lead to the development of new treatments against resistant strains.
Collapse
Affiliation(s)
- Cristian V. Crisan
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Harshini Chandrashekar
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Catherine Everly
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Gabi Steinbach
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Shannon E. Hill
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Peter J. Yunker
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Raquel R. Lieberman
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Brian K. Hammer
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| |
Collapse
|
65
|
Peterson SB, Bertolli SK, Mougous JD. The Central Role of Interbacterial Antagonism in Bacterial Life. Curr Biol 2021; 30:R1203-R1214. [PMID: 33022265 DOI: 10.1016/j.cub.2020.06.103] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The study of bacteria interacting with their environment has historically centered on strategies for obtaining nutrients and resisting abiotic stresses. We argue this focus has deemphasized a third facet of bacterial life that is equally central to their existence: namely, the threat to survival posed by antagonizing bacteria. The diversity and ubiquity of interbacterial antagonism pathways is becoming increasingly apparent, and the insidious manner by which interbacterial toxins disarm their targets emphasizes the highly evolved nature of these processes. Studies examining the role of antagonism in natural communities reveal it can serve many functions, from facilitating colonization of naïve habitats to maintaining bacterial community stability. The pervasiveness of antagonistic pathways is necessarily matched by an equally extensive array of defense strategies. These overlap with well characterized, central stress response pathways, highlighting the contribution of bacterial interactions to shaping cell physiology. In this review, we build the case for the ubiquity and importance of interbacterial antagonism.
Collapse
Affiliation(s)
- S Brook Peterson
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Savannah K Bertolli
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Joseph D Mougous
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA; Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195, USA.
| |
Collapse
|
66
|
Wen H, Liu G, Geng Z, Zhang H, Li Y, She Z, Dong Y. Structure and SAXS studies unveiled a novel inhibition mechanism of the Pseudomonas aeruginosa T6SS TseT-TsiT complex. Int J Biol Macromol 2021; 188:450-459. [PMID: 34371041 DOI: 10.1016/j.ijbiomac.2021.08.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/20/2021] [Accepted: 08/04/2021] [Indexed: 02/05/2023]
Abstract
The bacterial type VI secretion system (T6SS) is a powerful arsenal that fires many toxic effectors into neighboring cells to gain advantage over inter-bacterial competition and eukaryotic host infection. Meanwhile, the cognate immunity proteins of these effectors are employed to protect themselves from the virulence. TseT-TsiT is a newly discovered effector-immunity (E-I) protein pair secreted by T6SS of Pseudomonas aeruginosa. Our group had reported the crystal structure of TsiT before. Here, we report the crystal structure of P. aeruginosa TseT-TsiT complex at 3.1 Å resolution. The interface of TseT-TsiT is characterized in this work. Through structure and small angle X-ray scattering (SAXS) studies, we discover that the long C-terminal helix of TseT may be flexible. Combining the homolog comparison results, we propose that TseT may form an oligomer in favor of its putative nuclease activity. Although TsiT doesn't directly block the putative active-site of TseT, it may hinder the TseT's oligomerization process to neutralize its virulence.
Collapse
Affiliation(s)
- Haiying Wen
- Key Laboratory of Structural Biology, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Guangfeng Liu
- National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Zhi Geng
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Heng Zhang
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Yanhua Li
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Zhun She
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
| | - Yuhui Dong
- Multidiscipline Research Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, China.
| |
Collapse
|
67
|
Shen X, Wang B, Yang N, Zhang L, Shen D, Wu H, Dong Y, Niu B, Chou SH, Puopolo G, Fan J, Qian G. Lysobacter enzymogenes antagonizes soilborne bacteria using the type IV secretion system. Environ Microbiol 2021; 23:4673-4688. [PMID: 34227200 DOI: 10.1111/1462-2920.15662] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 07/03/2021] [Indexed: 12/23/2022]
Abstract
Soil microbiome comprises numerous microbial species that continuously interact with each other. Among the modes of diverse interactions, cell-cell killing may play a key role in shaping the microbiome composition. Bacteria deploy various secretion systems to fend off other microorganisms and Type IV Secretion System (T4SS) in pathogenic bacteria was shown to function as a contact-dependent, inter-bacterial killing system only recently. The present study investigated the role played by T4SS in the killing behaviour of the soilborne biocontrol bacterium Lysobacter enzymogenes OH11. Results showed that L. enzymogenes OH11 genome encompasses genes encoding all the components of T4SS and effectors potentially involved in inter-bacterial killing system. Generation of knock-out mutants revealed that L. enzymogenes OH11 uses T4SS as the main contact-dependent weapon against other soilborne bacteria. The T4SS-mediated killing behaviour of L. enzymogenes OH11 decreased the antibacterial and antifungal activity of two Pseudomonas spp. but at the same time, protected carrot from infection by Pectobacterium carotovorum. Overall, this study showed for the first time the involvement of T4SS in the killing behaviour of L. enzymogenes and its impact on the multiple interactions occurring in the soil microbiome.
Collapse
Affiliation(s)
- Xi Shen
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| | - Bingxin Wang
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| | - Nianda Yang
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| | - Lulu Zhang
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| | - Danyu Shen
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| | - Huijun Wu
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| | - Ying Dong
- College of Life Science, Northeast Forestry University, Harbin, 150040, China
| | - Ben Niu
- College of Life Science, Northeast Forestry University, Harbin, 150040, China
| | - Shan-Ho Chou
- Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Gerardo Puopolo
- Department of Sustainable Agro-ecosystems and Bioresources, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all'Adige, 38098, Italy.,Center Agriculture Food Environment (C3A), University of Trento, Via E. Mach 1, San Michele all'Adige, 38098, Italy
| | - Jiaqin Fan
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| | - Guoliang Qian
- College of Plant Protection (Laboratory of Plant Immunity; Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, 210095, China
| |
Collapse
|
68
|
Custodio R, Ford RM, Ellison CJ, Liu G, Mickute G, Tang CM, Exley RM. Type VI secretion system killing by commensal Neisseria is influenced by expression of type four pili. eLife 2021; 10:63755. [PMID: 34232858 PMCID: PMC8263058 DOI: 10.7554/elife.63755] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 06/27/2021] [Indexed: 12/14/2022] Open
Abstract
Type VI Secretion Systems (T6SSs) are widespread in bacteria and can dictate the development and organisation of polymicrobial ecosystems by mediating contact dependent killing. In Neisseria species, including Neisseria cinerea a commensal of the human respiratory tract, interbacterial contacts are mediated by Type four pili (Tfp) which promote formation of aggregates and govern the spatial dynamics of growing Neisseria microcolonies. Here, we show that N. cinerea expresses a plasmid-encoded T6SS that is active and can limit growth of related pathogens. We explored the impact of Tfp on N. cinerea T6SS-dependent killing within a colony and show that pilus expression by a prey strain enhances susceptibility to T6SS compared to a non-piliated prey, by preventing segregation from a T6SS-wielding attacker. Our findings have important implications for understanding how spatial constraints during contact-dependent antagonism can shape the evolution of microbial communities.
Collapse
Affiliation(s)
- Rafael Custodio
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Rhian M Ford
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Cara J Ellison
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Guangyu Liu
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Gerda Mickute
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Christoph M Tang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Rachel M Exley
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
69
|
Tayyrov A, Wei C, Fetz C, Goryachkin A, Schächle P, Nyström L, Künzler M. Cytoplasmic Lipases-A Novel Class of Fungal Defense Proteins Against Nematodes. FRONTIERS IN FUNGAL BIOLOGY 2021; 2:696972. [PMID: 37744157 PMCID: PMC10512399 DOI: 10.3389/ffunb.2021.696972] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 05/31/2021] [Indexed: 09/26/2023]
Abstract
Fungi are an attractive food source for predators such as fungivorous nematodes. Several fungal defense proteins and their protective mechanisms against nematodes have been described. Many of these proteins are lectins which are stored in the cytoplasm of the fungal cells and bind to specific glycan epitopes in the digestive tract of the nematode upon ingestion. Here, we studied two novel nematotoxic proteins with lipase domains from the model mushroom Coprinopsis cinerea. These cytoplasmically localized proteins were found to be induced in the vegetative mycelium of C. cinerea upon challenge with fungivorous nematode Aphelenchus avenae. The proteins showed nematotoxicity when heterologously expressed in E. coli and fed to several bacterivorous nematodes. Site-specific mutagenesis of predicted catalytic residues eliminated the in-vitro lipase activity of the proteins and significantly reduced their nematotoxicity, indicating the importance of the lipase activity for the nematotoxicity of these proteins. Our results suggest that cytoplasmic lipases constitute a novel class of fungal defense proteins against predatory nematodes. These findings improve our understanding of fungal defense mechanisms against predators and may find applications in the control of parasitic nematodes in agriculture and medicine.
Collapse
Affiliation(s)
- Annageldi Tayyrov
- Department of Biology, Institute of Microbiology, ETH Zürich, Zurich, Switzerland
| | - Chunyue Wei
- Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zürich, Zurich, Switzerland
| | - Céline Fetz
- Department of Biology, Institute of Microbiology, ETH Zürich, Zurich, Switzerland
| | - Aleksandr Goryachkin
- Department of Biology, Institute of Microbiology, ETH Zürich, Zurich, Switzerland
| | - Philipp Schächle
- Department of Biology, Institute of Microbiology, ETH Zürich, Zurich, Switzerland
| | - Laura Nyström
- Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zürich, Zurich, Switzerland
| | - Markus Künzler
- Department of Biology, Institute of Microbiology, ETH Zürich, Zurich, Switzerland
| |
Collapse
|
70
|
Robinson L, Liaw J, Omole Z, Xia D, van Vliet AHM, Corcionivoschi N, Hachani A, Gundogdu O. Bioinformatic Analysis of the Campylobacter jejuni Type VI Secretion System and Effector Prediction. Front Microbiol 2021; 12:694824. [PMID: 34276628 PMCID: PMC8285248 DOI: 10.3389/fmicb.2021.694824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/07/2021] [Indexed: 12/30/2022] Open
Abstract
The Type VI Secretion System (T6SS) has important roles relating to bacterial antagonism, subversion of host cells, and niche colonisation. Campylobacter jejuni is one of the leading bacterial causes of human gastroenteritis worldwide and is a commensal coloniser of birds. Although recently discovered, the T6SS biological functions and identities of its effectors are still poorly defined in C. jejuni. Here, we perform a comprehensive bioinformatic analysis of the C. jejuni T6SS by investigating the prevalence and genetic architecture of the T6SS in 513 publicly available genomes using C. jejuni 488 strain as reference. A unique and conserved T6SS cluster associated with the Campylobacter jejuni Integrated Element 3 (CJIE3) was identified in the genomes of 117 strains. Analyses of the T6SS-positive 488 strain against the T6SS-negative C. jejuni RM1221 strain and the T6SS-positive plasmid pCJDM202 carried by C. jejuni WP2-202 strain defined the “T6SS-containing CJIE3” as a pathogenicity island, thus renamed as Campylobacter jejuni Pathogenicity Island-1 (CJPI-1). Analysis of CJPI-1 revealed two canonical VgrG homologues, CJ488_0978 and CJ488_0998, harbouring distinct C-termini in a genetically variable region downstream of the T6SS operon. CJPI-1 was also found to carry a putative DinJ-YafQ Type II toxin-antitoxin (TA) module, conserved across pCJDM202 and the genomic island CJIE3, as well as several open reading frames functionally predicted to encode for nucleases, lipases, and peptidoglycan hydrolases. This comprehensive in silico study provides a framework for experimental characterisation of T6SS-related effectors and TA modules in C. jejuni.
Collapse
Affiliation(s)
- Luca Robinson
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Janie Liaw
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Zahra Omole
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Dong Xia
- Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Arnoud H M van Vliet
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Nicolae Corcionivoschi
- Bacteriology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, United Kingdom.,Bioengineering of Animal Science Resources, Banat University of Agricultural Sciences and Veterinary Medicine - King Michael the I of Romania, Timisoara, Romania
| | - Abderrahman Hachani
- The Peter Doherty Institute for Infection and Immunity, Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC, Australia
| | - Ozan Gundogdu
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| |
Collapse
|
71
|
Morin CD, Déziel E, Gauthier J, Levesque RC, Lau GW. An Organ System-Based Synopsis of Pseudomonas aeruginosa Virulence. Virulence 2021; 12:1469-1507. [PMID: 34180343 PMCID: PMC8237970 DOI: 10.1080/21505594.2021.1926408] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Driven in part by its metabolic versatility, high intrinsic antibiotic resistance, and a large repertoire of virulence factors, Pseudomonas aeruginosa is expertly adapted to thrive in a wide variety of environments, and in the process, making it a notorious opportunistic pathogen. Apart from the extensively studied chronic infection in the lungs of people with cystic fibrosis (CF), P. aeruginosa also causes multiple serious infections encompassing essentially all organs of the human body, among others, lung infection in patients with chronic obstructive pulmonary disease, primary ciliary dyskinesia and ventilator-associated pneumonia; bacteremia and sepsis; soft tissue infection in burns, open wounds and postsurgery patients; urinary tract infection; diabetic foot ulcers; chronic suppurative otitis media and otitis externa; and keratitis associated with extended contact lens use. Although well characterized in the context of CF, pathogenic processes mediated by various P. aeruginosa virulence factors in other organ systems remain poorly understood. In this review, we use an organ system-based approach to provide a synopsis of disease mechanisms exerted by P. aeruginosa virulence determinants that contribute to its success as a versatile pathogen.
Collapse
Affiliation(s)
- Charles D Morin
- Centre Armand-Frappier Santé Biotechnologie, Institut National De La Recherche Scientifique (INRS), Laval, Quebec, Canada
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National De La Recherche Scientifique (INRS), Laval, Quebec, Canada
| | - Jeff Gauthier
- Département De Microbiologie-infectiologie Et Immunologie, Institut De Biologie Intégrative Et Des Systèmes (IBIS), Université Laval, Québec City, Quebec, Canada
| | - Roger C Levesque
- Département De Microbiologie-infectiologie Et Immunologie, Institut De Biologie Intégrative Et Des Systèmes (IBIS), Université Laval, Québec City, Quebec, Canada
| | - Gee W Lau
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, US
| |
Collapse
|
72
|
Swietnicki W. Secretory System Components as Potential Prophylactic Targets for Bacterial Pathogens. Biomolecules 2021; 11:892. [PMID: 34203937 PMCID: PMC8232601 DOI: 10.3390/biom11060892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/13/2021] [Accepted: 06/14/2021] [Indexed: 01/18/2023] Open
Abstract
Bacterial secretory systems are essential for virulence in human pathogens. The systems have become a target of alternative antibacterial strategies based on small molecules and antibodies. Strategies to use components of the systems to design prophylactics have been less publicized despite vaccines being the preferred solution to dealing with bacterial infections. In the current review, strategies to design vaccines against selected pathogens are presented and connected to the biology of the system. The examples are given for Y. pestis, S. enterica, B. anthracis, S. flexneri, and other human pathogens, and discussed in terms of effectiveness and long-term protection.
Collapse
Affiliation(s)
- Wieslaw Swietnicki
- Department of Immunology of Infectious Diseases, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. R. Weigla 12, 53-114 Wroclaw, Poland
| |
Collapse
|
73
|
Yadav SK, Magotra A, Ghosh S, Krishnan A, Pradhan A, Kumar R, Das J, Sharma M, Jha G. Immunity proteins of dual nuclease T6SS effectors function as transcriptional repressors. EMBO Rep 2021; 22:e51857. [PMID: 33786997 PMCID: PMC8183406 DOI: 10.15252/embr.202051857] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/26/2021] [Accepted: 03/08/2021] [Indexed: 12/31/2022] Open
Abstract
Bacteria utilize type VI secretion system (T6SS) to deliver antibacterial toxins to target co-habiting bacteria. Here, we report that Burkholderia gladioli strain NGJ1 deploys certain T6SS effectors (TseTBg), having both DNase and RNase activities to kill target bacteria. RNase activity is prominent on NGJ1 as well as other bacterial RNA while DNase activity is pertinent to only other bacteria. The associated immunity (TsiTBg) proteins harbor non-canonical helix-turn-helix motifs and demonstrate transcriptional repression activity, similar to the antitoxins of type II toxin-antitoxin (TA) systems. Genome analysis reveals that homologs of TseTBg are either encoded as TA or T6SS effectors in diverse bacteria. Our results indicate that a new ORF (encoding a hypothetical protein) has evolved as a result of operonic fusion of TA type TseTBg homolog with certain T6SS-related genes by the action of IS3 transposable elements. This has potentially led to the conversion of a TA into T6SS effector in Burkholderia. Our study exemplifies that bacteria can recruit toxins of TA systems as T6SS weapons to diversify its arsenal to dominate during inter-bacterial competitions.
Collapse
Affiliation(s)
- Sunil Kumar Yadav
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Ankita Magotra
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Srayan Ghosh
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Aiswarya Krishnan
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Amrita Pradhan
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Rahul Kumar
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Joyati Das
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Mamta Sharma
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| | - Gopaljee Jha
- Plant Microbe Interactions LaboratoryNational Institute of Plant Genome ResearchAruna Asaf Ali MargIndia
| |
Collapse
|
74
|
Differential Cellular Response to Translocated Toxic Effectors and Physical Penetration by the Type VI Secretion System. Cell Rep 2021; 31:107766. [PMID: 32553162 DOI: 10.1016/j.celrep.2020.107766] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 04/28/2020] [Accepted: 05/21/2020] [Indexed: 01/06/2023] Open
Abstract
The type VI secretion system (T6SS) is a lethal microbial weapon that injects a large needle-like structure carrying toxic effectors into recipient cells through physical penetration. How recipients respond to physical force and effectors remains elusive. Here, we use a series of effector mutants of Vibrio cholerae to determine how T6SS elicits response in Pseudomonas aeruginosa and Escherichia coli. We show that TseL, but no other effectors or physical puncture, triggers the tit-for-tat response of P. aeruginosa H1-T6SS. Although E. coli is sensitive to all periplasmically expressed effectors, P. aeruginosa is most sensitive to TseL alone. We identify a number of stress response pathways that confer protection against TseL. Physical puncture of T6SS has a moderate inhibitory effect only on envelope-impaired tolB and rseA mutants. Our data reveal that recipient cells primarily respond to effector toxicity but not to physical contact, and they rely on the stress response for immunity-independent protection.
Collapse
|
75
|
Characterization of Lysozyme-Like Effector TseP Reveals the Dependence of Type VI Secretion System (T6SS) Secretion on Effectors in Aeromonas dhakensis Strain SSU. Appl Environ Microbiol 2021; 87:e0043521. [PMID: 33837015 DOI: 10.1128/aem.00435-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread weapon employed by Gram-negative bacteria for interspecies interaction in complex communities. Analogous to a contractile phage tail, the double-tubular T6SS injects toxic effectors into prokaryotic and eukaryotic neighboring cells. Although effectors dictate T6SS functions, their identities remain elusive in many pathogens. Here, we report the lysozyme-like effector TseP in Aeromonas dhakensis, a waterborne pathogen that can cause severe gastroenteritis and systemic infection. Using secretion, competition, and enzymatic assays, we demonstrate that TseP is a T6SS-dependent effector with cell wall-lysing activities, and TsiP is its cognate immunity protein. Triple deletion of tseP and two known effector genes, tseI and tseC, abolished T6SS-mediated secretion, while complementation with any single effector gene partially restored bacterial killing and Hcp secretion. In contrast to whole-gene deletions, the triple-effector inactivation in the 3effc mutant abolished antibacterial killing but not T6SS secretion. We further demonstrate that the 3effc mutation abolished T6SS-mediated toxicity of SSU to Dictyostelium discoideum amoebae, suggesting that the T6SS physical puncture is nontoxic to eukaryotic cells. These data highlight not only the necessity of possessing functionally diverse effectors for survival in multispecies communities but also that effector inactivation would be an efficient strategy to detoxify the T6SS while preserving its delivery efficiency, converting the T6SS to a platform for protein delivery to a variety of recipient cells. IMPORTANCE Delivery of cargo proteins via protein secretion systems has been shown to be a promising tool in various applications. However, secretion systems are often used by pathogens to cause disease. Thus, strategies are needed to detoxify secretion systems while preserving their efficiency. The T6SS can translocate proteins through physical puncture of target cells without specific surface receptors and can target a broad range of recipients. In this study, we identified a cell wall-lysing effector, and by inactivating it and the other two known effectors, we have built a detoxified T6SS-active strain that may be used for protein delivery to prokaryotic and eukaryotic recipient cells.
Collapse
|
76
|
Myint SL, Zlatkov N, Aung KM, Toh E, Sjöström A, Nadeem A, Duperthuy M, Uhlin BE, Wai SN. Ecotin and LamB in Escherichia coli influence the susceptibility to Type VI secretion-mediated interbacterial competition and killing by Vibrio cholerae. Biochim Biophys Acta Gen Subj 2021; 1865:129912. [PMID: 33892013 DOI: 10.1016/j.bbagen.2021.129912] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND A prevailing action of the Type VI secretion system (T6SS) in several Gram-negative bacterial species is inter-bacterial competition. In the past several years, many effectors of T6SS were identified in different bacterial species and their involvement in inter-bacterial interactions were described. However, possible defence mechanisms against T6SS attack among prey bacteria were not well clarified yet. METHODS Escherichia coli was assessed for susceptibility to T6SS-mediated killing by Vibrio cholerae. TheT6SS-mediated bacterial killing assays were performed in absence or presence of different protease inhibitors and with different mutant E. coli strains. Expression levels of selected proteins were monitored using SDS-PAGE and immunoblot analyses. RESULTS The T6SS-mediated killing of E. coli by V. cholerae was partly blocked when the serine protease inhibitor Pefabloc was present. E. coli lacking the periplasmic protease inhibitor Ecotin showed enhanced susceptibility to killing by V. cholerae. Mutations affecting E. coli membrane stability also caused increased susceptibility to killing by V. cholerae. E. coli lacking the maltodextrin porin protein LamB showed reduced susceptibility to killing by V. cholerae whereas E. coli with induced high levels of LamB showed reduced survival in inter-bacterial competition. CONCLUSIONS Our study identified two proteins in E. coli, the intrinsic protease inhibitor Ecotin and the outer membrane porin LamB, that influenced E. coli susceptibility to T6SS-mediated killing by V. cholerae. GENERAL SIGNIFICANCE We envision that it is feasible to explore these findings to target and modulate their expression to obtain desired changes in inter-bacterial competition in vivo, e.g. in the gastrointestinal microbiome.
Collapse
Affiliation(s)
- Si Lhyam Myint
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Nikola Zlatkov
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Kyaw Min Aung
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Eric Toh
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Annika Sjöström
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Aftab Nadeem
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Marylise Duperthuy
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden; Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada.
| | - Bernt Eric Uhlin
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
| | - Sun Nyunt Wai
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
| |
Collapse
|
77
|
Li J, Xie L, Qian S, Tang Y, Shen M, Li S, Wang J, Xiong L, Lu J, Zhong W. A Type VI Secretion System Facilitates Fitness, Homeostasis, and Competitive Advantages for Environmental Adaptability and Efficient Nicotine Biodegradation. Appl Environ Microbiol 2021; 87:e03113-20. [PMID: 33608299 PMCID: PMC8091027 DOI: 10.1128/aem.03113-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/15/2021] [Indexed: 12/29/2022] Open
Abstract
Gram-negative bacteria employ secretion systems to translocate proteinaceous effectors from the cytoplasm to the extracellular milieu, thus interacting with the surrounding environment or microniche. It is known that bacteria can benefit from the type VI secretion system (T6SS) by transporting ions to combat reactive oxygen species (ROS). Here, we report that T6SS activities conferred tolerance to nicotine-induced oxidative stress in Pseudomonas sp. strain JY-Q, a highly active nicotine degradation strain isolated from tobacco waste extract. AA098_13375 was identified to encode a dual-functional effector with antimicrobial and anti-ROS activities. Wild-type strain JY-Q grew better than the AA098_13375 deletion mutant in nicotine-containing medium by antagonizing increased intracellular ROS levels. It was, therefore, tentatively designated TseN (type VI secretion system effector for nicotine tolerance), homologs of which were observed to be broadly ubiquitous in Pseudomonas species. TseN was identified as a Tse6-like bacteriostatic toxin via monitoring intracellular NAD+ TseN presented potential antagonism against ROS to fine tune the heavy traffic of nicotine metabolism in strain JY-Q. It is feasible that the dynamic tuning of NAD+ driven by TseN could satisfy demands from nicotine degradation with less cytotoxicity. In this scenario, T6SS involves a fascinating accommodation cascade that prompts constitutive biotransformation of N-heterocyclic aromatics by improving bacterial robustness/growth. In summary, the T6SS in JY-Q mediated resistance to oxidative stress and promoted bacterial fitness via a contact-independent growth competitive advantage, in addition to the well-studied T6SS-dependent antimicrobial activities.IMPORTANCE Mixtures of various pollutants and the coexistence of numerous species of organisms are usually found in adverse environments. Concerning biodegradation of nitrogen-heterocyclic contaminants, the scientific community has commonly focused on screening functional enzymes that transform pollutants into intermediates of attenuated toxicity or for primary metabolism. Here, we identified dual roles of the T6SS effector TseN in Pseudomonas sp. strain JY-Q, which is capable of degrading nicotine. The T6SS in strain JY-Q is able to deliver TseN to kill competitors and provide a growth advantage by a contact-independent pattern. TseN could monitor the intracellular NAD+ level by its hydrolase activity, causing cytotoxicity in competitive rivals but metabolic homeostasis on JY-Q. Moreover, JY-Q could be protected from TseN toxicity by the immunity protein TsiN. In conclusion, we found that TseN with cytotoxicity to bacterial competitors facilitated the nicotine tolerance of JY-Q. We therefore reveal a working model between T6SS and nicotine metabolism. This finding indicates that multiple diversified weapons have been evolved by bacteria for their growth and robustness.
Collapse
Affiliation(s)
- Jun Li
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Linlin Xie
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Shulan Qian
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yuhang Tang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Mingjie Shen
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Shanshan Li
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Jie Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Lie Xiong
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Jie Lu
- Department of Infectious Diseases, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Weihong Zhong
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| |
Collapse
|
78
|
Wang S, Geng Z, Zhang H, She Z, Dong Y. The Pseudomonas aeruginosa PAAR2 cluster encodes a putative VRR-NUC domain-containing effector. FEBS J 2021; 288:5755-5767. [PMID: 33838074 DOI: 10.1111/febs.15870] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/29/2021] [Accepted: 04/08/2021] [Indexed: 01/10/2023]
Abstract
The bacterial type VI secretion system (T6SS) secretes many toxic effectors to gain advantage in inter-bacterial competition and for eukaryotic host infection. The cognate immunity proteins of these effectors protect bacteria from the virulence of their own effectors. The T6SS injects its inner-needle Hcp tube, the sharpening tip complex -consisting of VgrG and proline-alanine-alanine-arginine repeats (PAAR) proteins- and toxic effectors into neighboring cells. Its functions are largely determined by the activities of its delivered effectors. Five PAAR proteins were found in the Pseudomonas aeruginosa PAO1 genome with three of them shown to facilitate the delivery of various effectors. Here, we report a putative virus-type replication-repair nuclease domain-containing effector TseV encoded by the least investigated P. aeruginosa PAAR2 cluster. The crystal structure of its putative cognate effector TsiV is presented at 1.6 Å resolution. Through structure and sequence comparisons, we propose TseV-TsiV to be a putative novel effector-immunity (E-I) pair and we discuss the roles of other PAAR2 cluster encoded proteins.
Collapse
Affiliation(s)
- Shuangyue Wang
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, China
| | - Zhi Geng
- Multidiscipline Research Center, Institte of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Heng Zhang
- Multidiscipline Research Center, Institte of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Zhun She
- Multidiscipline Research Center, Institte of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Yuhui Dong
- Multidiscipline Research Center, Institte of High Energy Physics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
79
|
Perczyk P, Broniatowski M. Simultaneous action of microbial phospholipase C and lipase on model bacterial membranes - Modeling the processes crucial for bioaugmentation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183620. [PMID: 33831405 DOI: 10.1016/j.bbamem.2021.183620] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/17/2021] [Accepted: 03/26/2021] [Indexed: 12/27/2022]
Abstract
Bioaugmentation is a promising method of the remediation of soils polluted by persistent organic pollutants (POP). Unfortunately, it happens frequently that the microorganisms inoculated into the soil die out due to the presence of enzymes secreted by autochthonous microorganisms. Especially destructive are here phospholipases C (PLC) and lipases which destruct the microorganism's cellular membrane. The composition of bacterial membranes differs between species, so it is highly possible that depending on the membrane constitution some bacteria are more resistant to PLCs and lipases than other. To shed light on these problems we applied phospholipid Langmuir monolayers as model microbial membranes and studied their interactions with α-toxin (model bacterial PLC) and the lipase isolated from soil fungus Candida rugosa. Membrane phospholipids differing in their headgroup (phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols and cardiolipins) and in their tail structure were applied. The monolayers were characterized by the Langmuir technique, visualized by Brewster angle microscopy, and the packing mode of the phospholipid molecules was verified by the application of the diffraction of synchrotron radiation. We also studied the mutual miscibility of diacylglycerols and the native phospholipids as their interaction is crucial for the understanding of the PLC and lipase activity. It turned out that all the investigated phospholipid classes can be hydrolyzed by PLC; however, they differ profoundly in the hydrolysis degree. Depending on the effects of the initial PLC action and the mutual organization of the diacylglycerol and phospholipid molecules the lipase can ruin the model membranes or can be completely neutral to them.
Collapse
Affiliation(s)
- Paulina Perczyk
- Department of Environmental Chemistry, Faculty of Chemistry, Jagiellonian University in Krakow, Gronostajowa 2, 30-387 Kraków, Poland
| | - Marcin Broniatowski
- Department of Environmental Chemistry, Faculty of Chemistry, Jagiellonian University in Krakow, Gronostajowa 2, 30-387 Kraków, Poland.
| |
Collapse
|
80
|
Wang T, Du X, Ji L, Han Y, Dang J, Wen J, Wang Y, Pu Q, Wu M, Liang H. Pseudomonas aeruginosa T6SS-mediated molybdate transport contributes to bacterial competition during anaerobiosis. Cell Rep 2021; 35:108957. [PMID: 33852869 DOI: 10.1016/j.celrep.2021.108957] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 01/06/2021] [Accepted: 03/16/2021] [Indexed: 12/20/2022] Open
Abstract
Type VI secretion system (T6SS) is widely distributed in Gram-negative bacteria and functions as a versatile protein export machinery that translocates effectors into eukaryotic or prokaryotic target cells. Growing evidence indicates that T6SS can deliver several effectors to promote bacterial survival in harmful environments through metal ion acquisition. Here, we report that the Pseudomonas aeruginosa H2-T6SS mediates molybdate (MoO42-) acquisition by secretion of a molybdate-binding protein, ModA. The expression of H2-T6SS genes is activated by the master regulator Anr and anaerobiosis. We also identified a ModA-binding protein, IcmP, an insulin-cleaving metalloproteinase outer membrane protein. The T6SS-ModA-IcmP system provides P. aeruginosa with a growth advantage in bacterial competition under anaerobic conditions and plays an important role in bacterial virulence. Overall, this study clarifies the role of T6SS in secretion of an anion-binding protein, emphasizing the fundamental importance of this bacterium using T6SS-mediated molybdate uptake to adapt to complex environmental conditions.
Collapse
Affiliation(s)
- Tietao Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China
| | - Xiao Du
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China
| | - Linxuan Ji
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China
| | - Yuying Han
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China
| | - Jing Dang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China
| | - Jing Wen
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China
| | - Yarong Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China
| | - Qinqin Pu
- Department of Basic Science, School of Medicine and Health Science, University of North Dakota, Grand Forks, ND 58203, USA
| | - Min Wu
- Department of Basic Science, School of Medicine and Health Science, University of North Dakota, Grand Forks, ND 58203, USA
| | - Haihua Liang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, ShaanXi 710069, China.
| |
Collapse
|
81
|
Wang T, Sun W, Fan L, Hua C, Wu N, Fan S, Zhang J, Deng X, Yan J. An atlas of the binding specificities of transcription factors in Pseudomonas aeruginosa directs prediction of novel regulators in virulence. eLife 2021; 10:61885. [PMID: 33779544 PMCID: PMC8041468 DOI: 10.7554/elife.61885] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 03/26/2021] [Indexed: 12/14/2022] Open
Abstract
A high-throughput systematic evolution of ligands by exponential enrichment assay was applied to 371 putative TFs in Pseudomonas aeruginosa, which resulted in the robust enrichment of 199 unique sequence motifs describing the binding specificities of 182 TFs. By scanning the genome, we predicted in total 33,709 significant interactions between TFs and their target loci, which were more than 11-fold enriched in the intergenic regions but depleted in the gene body regions. To further explore and delineate the physiological and pathogenic roles of TFs in P. aeruginosa, we constructed regulatory networks for nine major virulence-associated pathways and found that 51 TFs were potentially significantly associated with these virulence pathways, 32 of which had not been characterized before, and some were even involved in multiple pathways. These results will significantly facilitate future studies on transcriptional regulation in P. aeruginosa and other relevant pathogens, and accelerate to discover effective treatment and prevention strategies for the associated infectious diseases.
Collapse
Affiliation(s)
- Tingting Wang
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Wenju Sun
- School of Medicine, Northwest University, Xi'an, China
| | - Ligang Fan
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,School of Medicine, Northwest University, Xi'an, China
| | - Canfeng Hua
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Nan Wu
- School of Medicine, Northwest University, Xi'an, China
| | - Shaorong Fan
- School of Medicine, Northwest University, Xi'an, China
| | - Jilin Zhang
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
| | - Xin Deng
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Jian Yan
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,School of Medicine, Northwest University, Xi'an, China
| |
Collapse
|
82
|
Computational prediction of secreted proteins in gram-negative bacteria. Comput Struct Biotechnol J 2021; 19:1806-1828. [PMID: 33897982 PMCID: PMC8047123 DOI: 10.1016/j.csbj.2021.03.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 03/18/2021] [Accepted: 03/18/2021] [Indexed: 12/29/2022] Open
Abstract
Gram-negative bacteria harness multiple protein secretion systems and secrete a large proportion of the proteome. Proteins can be exported to periplasmic space, integrated into membrane, transported into extracellular milieu, or translocated into cytoplasm of contacting cells. It is important for accurate, genome-wide annotation of the secreted proteins and their secretion pathways. In this review, we systematically classified the secreted proteins according to the types of secretion systems in Gram-negative bacteria, summarized the known features of these proteins, and reviewed the algorithms and tools for their prediction.
Collapse
|
83
|
Crisan CV, Nichols HL, Wiesenfeld S, Steinbach G, Yunker PJ, Hammer BK. Glucose confers protection to Escherichia coli against contact killing by Vibrio cholerae. Sci Rep 2021; 11:2935. [PMID: 33536444 PMCID: PMC7858629 DOI: 10.1038/s41598-021-81813-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 12/18/2020] [Indexed: 01/30/2023] Open
Abstract
Evolutionary arms races are broadly prevalent among organisms including bacteria, which have evolved defensive strategies against various attackers. A common microbial aggression mechanism is the type VI secretion system (T6SS), a contact-dependent bacterial weapon used to deliver toxic effector proteins into adjacent target cells. Sibling cells constitutively express immunity proteins that neutralize effectors. However, less is known about factors that protect non-sibling bacteria from T6SS attacks independently of cognate immunity proteins. In this study, we observe that human Escherichia coli commensal strains sensitive to T6SS attacks from Vibrio cholerae are protected when co-cultured with glucose. We confirm that glucose does not impair V. cholerae T6SS activity. Instead, we find that cells lacking the cAMP receptor protein (CRP), which regulates expression of hundreds of genes in response to glucose, survive significantly better against V. cholerae T6SS attacks even in the absence of glucose. Finally, we show that the glucose-mediated T6SS protection varies with different targets and killers. Our findings highlight the first example of an extracellular small molecule modulating a genetically controlled response for protection against T6SS attacks. This discovery may have major implications for microbial interactions during pathogen-host colonization and survival of bacteria in environmental communities.
Collapse
Affiliation(s)
- Cristian V Crisan
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
| | - Holly L Nichols
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
| | - Sophia Wiesenfeld
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
| | - Gabi Steinbach
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Peter J Yunker
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Brian K Hammer
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
- Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA.
| |
Collapse
|
84
|
A High-Throughput Method for Identifying Novel Genes That Influence Metabolic Pathways Reveals New Iron and Heme Regulation in Pseudomonas aeruginosa. mSystems 2021; 6:6/1/e00933-20. [PMID: 33531406 PMCID: PMC7857532 DOI: 10.1128/msystems.00933-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The ability to simultaneously and more directly correlate genes with metabolite levels on a global level would provide novel information for many biological platforms yet has thus far been challenging. Here, we describe a method to help address this problem, which we dub “Met-Seq” (metabolite-coupled Tn sequencing). Heme is an essential metabolite for most life on earth. Bacterial pathogens almost universally require iron to infect a host, often acquiring this nutrient in the form of heme. The Gram-negative pathogen Pseudomonas aeruginosa is no exception, where heme acquisition and metabolism are known to be crucial for both chronic and acute infections. To unveil unknown genes and pathways that could play a role with heme metabolic flux in this pathogen, we devised an omic-based approach we dubbed “Met-Seq,” for metabolite-coupled transposon sequencing. Met-Seq couples a biosensor with fluorescence-activated cell sorting (FACS) and massively parallel sequencing, allowing for direct identification of genes associated with metabolic changes. In this work, we first construct and validate a heme biosensor for use with P. aeruginosa and exploit Met-Seq to identify 188 genes that potentially influence intracellular heme levels. Identified genes largely consisted of metabolic pathways not previously associated with heme, including many secreted virulence effectors, as well as 11 predicted small RNAs (sRNAs) and riboswitches whose functions are not currently understood. We verify that five Met-Seq hits affect intracellular heme levels; a predicted extracytoplasmic function (ECF) factor, a phospholipid acquisition system, heme biosynthesis regulator Dnr, and two predicted antibiotic monooxygenase (ABM) domains of unknown function (PA0709 and PA3390). Finally, we demonstrate that PA0709 and PA3390 are novel heme-binding proteins. Our data suggest that Met-Seq could be extrapolated to other biological systems and metabolites for which there is an available biosensor, and provides a new template for further exploration of iron/heme regulation and metabolism in P. aeruginosa and other pathogens. IMPORTANCE The ability to simultaneously and more directly correlate genes with metabolite levels on a global level would provide novel information for many biological platforms yet has thus far been challenging. Here, we describe a method to help address this problem, which we dub “Met-Seq” (metabolite-coupled Tn sequencing). Met-Seq uses the powerful combination of fluorescent biosensors, fluorescence-activated cell sorting (FACS), and next-generation sequencing (NGS) to rapidly identify genes that influence the levels of specific intracellular metabolites. For proof of concept, we create and test a heme biosensor and then exploit Met-Seq to identify novel genes involved in the regulation of heme in the pathogen Pseudomonas aeruginosa. Met-Seq-generated data were largely comprised of genes which have not previously been reported to influence heme levels in this pathogen, two of which we verify as novel heme-binding proteins. As heme is a required metabolite for host infection in P. aeruginosa and most other pathogens, our studies provide a new list of targets for potential antimicrobial therapies and shed additional light on the balance between infection, heme uptake, and heme biosynthesis.
Collapse
|
85
|
Abstract
Rhizobia are a phylogenetically diverse group of soil bacteria that engage in mutualistic interactions with legume plants. Although specifics of the symbioses differ between strains and plants, all symbioses ultimately result in the formation of specialized root nodule organs which host the nitrogen-fixing microsymbionts called bacteroids. Inside nodules, bacteroids encounter unique conditions that necessitate global reprogramming of physiological processes and rerouting of their metabolism. Decades of research have addressed these questions using genetics, omics approaches, and more recently computational modelling. Here we discuss the common adaptations of rhizobia to the nodule environment that define the core principles of bacteroid functioning. All bacteroids are growth-arrested and perform energy-intensive nitrogen fixation fueled by plant-provided C4-dicarboxylates at nanomolar oxygen levels. At the same time, bacteroids are subject to host control and sanctioning that ultimately determine their fitness and have fundamental importance for the evolution of a stable mutualistic relationship.
Collapse
|
86
|
Stolle AS, Meader BT, Toska J, Mekalanos JJ. Endogenous membrane stress induces T6SS activity in Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2021; 118:e2018365118. [PMID: 33443205 PMCID: PMC7817224 DOI: 10.1073/pnas.2018365118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The type 6 secretion system (T6SS) is a dynamic organelle encoded by many gram-negative bacteria that can be used to kill competing bacterial prey species in densely occupied niches. Some predatory species, such as Vibrio cholerae, use their T6SS in an untargeted fashion while in contrast, Pseudomonas aeruginosa assembles and fires its T6SS apparatus only after detecting initial attacks by other bacterial prey cells; this targeted attack strategy has been termed the T6SS tit-for-tat response. Molecules that interact with the P. aeruginosa outer membrane such as polymyxin B can also trigger assembly of T6SS organelles via a signal transduction pathway that involves protein phosphorylation. Recent work suggests that a phospholipase T6SS effector (TseL) of V. cholerae can induce T6SS dynamic activity in P. aeruginosa when delivered to or expressed in the periplasmic space of this organism. Here, we report that inhibiting expression of essential genes involved in outer membrane biogenesis can also trigger T6SS activation in P. aeruginosa Specifically, we developed a CRISPR interference (CRISPRi) system to knock down expression of bamA, tolB, and lptD and found that these knockdowns activated T6SS activity. This increase in T6SS activity was dependent on the same signal transduction pathway that was previously shown to be required for the tit-for-tat response. We conclude that outer membrane perturbation can be sensed by P. aeruginosa to activate the T6SS even when the disruption is generated by aberrant cell envelope biogenesis.
Collapse
Affiliation(s)
- Anne-Sophie Stolle
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
- Institute of Infectiology, Center for Molecular Biology of Inflammation, University of Münster, 48149 Münster, Germany
| | | | - Jonida Toska
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
| | - John J Mekalanos
- Department of Microbiology, Harvard Medical School, Boston, MA 02115;
| |
Collapse
|
87
|
Secrete or perish: The role of secretion systems in Xanthomonas biology. Comput Struct Biotechnol J 2020; 19:279-302. [PMID: 33425257 PMCID: PMC7777525 DOI: 10.1016/j.csbj.2020.12.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/13/2020] [Accepted: 12/13/2020] [Indexed: 12/22/2022] Open
Abstract
Bacteria of the Xanthomonas genus are mainly phytopathogens of a large variety of crops of economic importance worldwide. Xanthomonas spp. rely on an arsenal of protein effectors, toxins and adhesins to adapt to the environment, compete with other microorganisms and colonize plant hosts, often causing disease. These protein effectors are mainly delivered to their targets by the action of bacterial secretion systems, dedicated multiprotein complexes that translocate proteins to the extracellular environment or directly into eukaryotic and prokaryotic cells. Type I to type VI secretion systems have been identified in Xanthomonas genomes. Recent studies have unravelled the diverse roles played by the distinct types of secretion systems in adaptation and virulence in xanthomonads, unveiling new aspects of their biology. In addition, genome sequence information from a wide range of Xanthomonas species and pathovars have become available recently, uncovering a heterogeneous distribution of the distinct families of secretion systems within the genus. In this review, we describe the architecture and mode of action of bacterial type I to type VI secretion systems and the distribution and functions associated with these important nanoweapons within the Xanthomonas genus.
Collapse
|
88
|
The β-encapsulation cage of rearrangement hotspot (Rhs) effectors is required for type VI secretion. Proc Natl Acad Sci U S A 2020; 117:33540-33548. [PMID: 33323487 DOI: 10.1073/pnas.1919350117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria deploy rearrangement hotspot (Rhs) proteins as toxic effectors against both prokaryotic and eukaryotic target cells. Rhs proteins are characterized by YD-peptide repeats, which fold into a large β-cage structure that encapsulates the C-terminal toxin domain. Here, we show that Rhs effectors are essential for type VI secretion system (T6SS) activity in Enterobacter cloacae (ECL). ECL rhs - mutants do not kill Escherichia coli target bacteria and are defective for T6SS-dependent export of hemolysin-coregulated protein (Hcp). The RhsA and RhsB effectors of ECL both contain Pro-Ala-Ala-Arg (PAAR) repeat domains, which bind the β-spike of trimeric valine-glycine repeat protein G (VgrG) and are important for T6SS activity in other bacteria. Truncated RhsA that retains the PAAR domain is capable of forming higher-order, thermostable complexes with VgrG, yet these assemblies fail to restore secretion activity to ∆rhsA ∆rhsB mutants. Full T6SS-1 activity requires Rhs that contains N-terminal transmembrane helices, the PAAR domain, and an intact β-cage. Although ∆rhsA ∆rhsB mutants do not kill target bacteria, time-lapse microscopy reveals that they assemble and fire T6SS contractile sheaths at ∼6% of the frequency of rhs + cells. Therefore, Rhs proteins are not strictly required for T6SS assembly, although they greatly increase secretion efficiency. We propose that PAAR and the β-cage provide distinct structures that promote secretion. PAAR is clearly sufficient to stabilize trimeric VgrG, but efficient assembly of T6SS-1 also depends on an intact β-cage. Together, these domains enforce a quality control checkpoint to ensure that VgrG is loaded with toxic cargo before assembling the secretion apparatus.
Collapse
|
89
|
Jurėnas D, Journet L. Activity, delivery, and diversity of Type VI secretion effectors. Mol Microbiol 2020; 115:383-394. [PMID: 33217073 DOI: 10.1111/mmi.14648] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 12/28/2022]
Abstract
The bacterial type VI secretion system (T6SS) system is a contractile secretion apparatus that delivers proteins to neighboring bacterial or eukaryotic cells. Antibacterial effectors are mostly toxins that inhibit the growth of other species and help to dominate the niche. A broad variety of these toxins cause cell lysis of the prey cell by disrupting the cell envelope. Other effectors are delivered into the cytoplasm where they affect DNA integrity, cell division or exhaust energy resources. The modular nature of T6SS machinery allows different means of recruitment of toxic effectors to secreted inner tube and spike components that act as carriers. Toxic effectors can be translationally fused to the secreted components or interact with them through specialized structural domains. These interactions can also be assisted by dedicated chaperone proteins. Moreover, conserved sequence motifs in effector-associated domains are subject to genetic rearrangements and therefore engage in the diversification of the arsenal of toxic effectors. This review discusses the diversity of T6SS secreted toxins and presents current knowledge about their loading on the T6SS machinery.
Collapse
Affiliation(s)
- Dukas Jurėnas
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université-CNRS, UMR 7255, Marseille, France
| |
Collapse
|
90
|
Steinbach G, Crisan C, Ng SL, Hammer BK, Yunker PJ. Accumulation of dead cells from contact killing facilitates coexistence in bacterial biofilms. J R Soc Interface 2020; 17:20200486. [PMID: 33292099 PMCID: PMC7811593 DOI: 10.1098/rsif.2020.0486] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/12/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial communities are governed by a wide variety of social interactions, some of which are antagonistic with potential significance for bacterial warfare. Several antagonistic mechanisms, such as killing via the type VI secretion system (T6SS), require killer cells to directly contact target cells. The T6SS is hypothesized to be a highly potent weapon, capable of facilitating the invasion and defence of bacterial populations. However, we find that the efficacy of contact killing is severely limited by the material consequences of cell death. Through experiments with Vibrio cholerae strains that kill via the T6SS, we show that dead cell debris quickly accumulates at the interface that forms between competing strains, preventing physical contact and thus preventing killing. While previous experiments have shown that T6SS killing can reduce a population of target cells by as much as 106-fold, we find that, as a result of the formation of dead cell debris barriers, the impact of contact killing depends sensitively on the initial concentration of killer cells. Killer cells are incapable of invading or eliminating competitors on a community level. Instead, bacterial warfare itself can facilitate coexistence between nominally antagonistic strains. While a variety of defensive strategies against microbial warfare exist, the material consequences of cell death provide target cells with their first line of defence.
Collapse
Affiliation(s)
- Gabi Steinbach
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
| | - Cristian Crisan
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Siu Lung Ng
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Brian K. Hammer
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Peter J. Yunker
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, USA
| |
Collapse
|
91
|
Static Growth Promotes PrrF and 2-Alkyl-4(1 H)-Quinolone Regulation of Type VI Secretion Protein Expression in Pseudomonas aeruginosa. J Bacteriol 2020; 202:JB.00416-20. [PMID: 33020221 DOI: 10.1128/jb.00416-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/29/2020] [Indexed: 12/21/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that is frequently associated with both acute and chronic infections. P. aeruginosa possesses a complex regulatory network that modulates nutrient acquisition and virulence, but our knowledge of these networks is largely based on studies with shaking cultures, which are not likely representative of conditions during infection. Here, we provide proteomic, metabolic, and genetic evidence that regulation by iron, a critical metallonutrient, is altered in static P. aeruginosa cultures. Specifically, we observed a loss of iron-induced expression of proteins for oxidative phosphorylation, tricarboxylic acid (TCA) cycle metabolism under static conditions. Moreover, we identified type VI secretion as a target of iron regulation in P. aeruginosa cells under static but not shaking conditions, and we present evidence that this regulation occurs via PrrF small regulatory RNA (sRNA)-dependent production of 2-alkyl-4(1H)-quinolone metabolites. These results yield new iron regulation paradigms in an important opportunistic pathogen and highlight the need to redefine iron homeostasis in static microbial communities.IMPORTANCE Host-mediated iron starvation is a broadly conserved signal for microbial pathogens to upregulate expression of virulence traits required for successful infection. Historically, global iron regulatory studies in microorganisms have been conducted in shaking cultures to ensure culture homogeneity, yet these conditions are likely not reflective of growth during infection. Pseudomonas aeruginosa is a well-studied opportunistic pathogen and model organism for iron regulatory studies. Iron homeostasis is maintained through the Fur protein and PrrF small regulatory sRNAs, the functions of which are highly conserved in many other bacterial species. In the current study, we examined how static growth affects the known iron and PrrF regulons of P. aeruginosa, leading to the discovery of novel PrrF-regulated virulence processes. This study demonstrates how the utilization of distinct growth models can enhance our understanding of basic physiological processes that may also affect pathogenesis.
Collapse
|
92
|
Qin Z, Yang X, Chen G, Park C, Liu Z. Crosstalks Between Gut Microbiota and Vibrio Cholerae. Front Cell Infect Microbiol 2020; 10:582554. [PMID: 33194819 PMCID: PMC7644805 DOI: 10.3389/fcimb.2020.582554] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 09/17/2020] [Indexed: 12/11/2022] Open
Abstract
Vibrio cholerae, the causative agent of cholera, could proliferate in aquatic environment and infect humans through contaminated food and water. Enormous microorganisms residing in human gastrointestinal tract establish a special microecological system, which immediately responds to the invasion of V. cholerae, through “colonization resistance” mechanisms, such as antimicrobial peptide production, nutrients competition, and intestinal barrier maintenances. Meanwhile, V. cholerae could quickly sense those signals and modulate the expression of relevant genes to circumvent those stresses during infection, leading to successful colonization on the surface of small intestinal epithelial cells. In this review, we summarized the crosstalks profiles between gut microbiota and V. cholerae in the terms of Type VI Secretion System (T6SS), Quorum Sensing (QS), Reactive Oxygen Species (ROS)/pH stress, and Bioactive metabolites. These mechanisms can also be applied to molecular bacterial pathogenesis of other pathogens in host.
Collapse
Affiliation(s)
- Zixin Qin
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoman Yang
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Guozhong Chen
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Chaiwoo Park
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Zhi Liu
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| |
Collapse
|
93
|
Vibrio cholerae-Symbiont Interactions Inhibit Intestinal Repair in Drosophila. Cell Rep 2020; 30:1088-1100.e5. [PMID: 31995751 DOI: 10.1016/j.celrep.2019.12.094] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/28/2019] [Accepted: 12/27/2019] [Indexed: 11/20/2022] Open
Abstract
Pathogen-mediated damage to the intestinal epithelium activates compensatory growth and differentiation repair programs in progenitor cells. Accelerated progenitor growth replenishes damaged tissue and maintains barrier integrity. Despite the importance of epithelial renewal to intestinal homeostasis, we know little about the effects of pathogen-commensal interactions on progenitor growth. We find that the enteric pathogen Vibrio cholerae blocks critical growth and differentiation pathways in Drosophila progenitors, despite extensive damage to epithelial tissue. We show that the inhibition of epithelial repair requires interactions between the Vibrio cholerae type six secretion system and a community of common symbiotic bacteria, as elimination of the gut microbiome is sufficient to restore homeostatic growth in infected intestines. This work highlights the importance of pathogen-symbiont interactions for intestinal immune responses and outlines the impact of the type six secretion system on pathogenesis.
Collapse
|
94
|
Monjarás Feria J, Valvano MA. An Overview of Anti-Eukaryotic T6SS Effectors. Front Cell Infect Microbiol 2020; 10:584751. [PMID: 33194822 PMCID: PMC7641602 DOI: 10.3389/fcimb.2020.584751] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 09/22/2020] [Indexed: 12/24/2022] Open
Abstract
The type VI secretion system (T6SS) is a transmembrane multiprotein nanomachine employed by many Gram-negative bacterial species to translocate, in a contact-dependent manner, effector proteins into adjacent prokaryotic or eukaryotic cells. Typically, the T6SS gene cluster encodes at least 13 conserved core components for the apparatus assembly and other less conserved accessory proteins and effectors. It functions as a contractile tail machine comprising a TssB/C sheath and an expelled puncturing device consisting of an Hcp tube topped by a spike complex of VgrG and PAAR proteins. Contraction of the sheath propels the tube out of the bacterial cell into a target cell and leads to the injection of toxic proteins. Different bacteria use the T6SS for specific roles according to the niche and versatility of the organism. Effectors are present both as cargo (by non-covalent interactions with one of the core components) or specialized domains (fused to structural components). Although several anti-prokaryotic effectors T6SSs have been studied, recent studies have led to a substantial increase in the number of characterized anti-eukaryotic effectors. Against eukaryotic cells, the T6SS is involved in modifying and manipulating diverse cellular processes that allows bacteria to colonize, survive and disseminate, including adhesion modification, stimulating internalization, cytoskeletal rearrangements and evasion of host innate immune responses.
Collapse
Affiliation(s)
| | - Miguel A. Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| |
Collapse
|
95
|
Perault AI, Chandler CE, Rasko DA, Ernst RK, Wolfgang MC, Cotter PA. Host Adaptation Predisposes Pseudomonas aeruginosa to Type VI Secretion System-Mediated Predation by the Burkholderia cepacia Complex. Cell Host Microbe 2020; 28:534-547.e3. [PMID: 32755549 PMCID: PMC7554260 DOI: 10.1016/j.chom.2020.06.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 06/05/2020] [Accepted: 06/24/2020] [Indexed: 12/14/2022]
Abstract
Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc) species are opportunistic lung pathogens of cystic fibrosis (CF) patients. While P. aeruginosa can initiate long-term infections in younger CF patients, Bcc infections only arise in teenagers and adults. Both P. aeruginosa and Bcc use type VI secretion systems (T6SSs) to mediate interbacterial competition. Here, we show P. aeruginosa isolates from teenage and adult CF patients, but not those from young CF patients, are outcompeted by the epidemic Bcc isolate Burkholderia cenocepacia strain AU1054 in a T6SS-dependent manner. The genomes of susceptible P. aeruginosa isolates harbor T6SS-abrogating mutations, the repair of which, in some cases, rendered the isolates resistant. Moreover, seven of eight Bcc strains outcompeted P. aeruginosa strains isolated from the same patients. Our findings suggest certain mutations that arise as P. aeruginosa adapts to the CF lung abrogate T6SS activity, making P. aeruginosa and its human host susceptible to potentially fatal Bcc superinfection.
Collapse
Affiliation(s)
- Andrew I Perault
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Courtney E Chandler
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - David A Rasko
- Institute for Genome Sciences, University of Maryland, Baltimore, Baltimore, MD 21201, USA; Department of Microbiology and Immunology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Matthew C Wolfgang
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Marsio Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Peggy A Cotter
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| |
Collapse
|
96
|
Drebes Dörr NC, Blokesch M. Interbacterial competition and anti-predatory behaviour of environmental Vibrio cholerae strains. Environ Microbiol 2020; 22:4485-4504. [PMID: 32885535 PMCID: PMC7702109 DOI: 10.1111/1462-2920.15224] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 12/21/2022]
Abstract
Vibrio cholerae isolates responsible for cholera pandemics represent only a small portion of the diverse strains belonging to this species. Indeed, most V. cholerae are encountered in aquatic environments. To better understand the emergence of pandemic lineages, it is crucial to discern what differentiates pandemic strains from their environmental relatives. Here, we studied the interaction of environmental V. cholerae with eukaryotic predators or competing bacteria and tested the contributions of the haemolysin and the type VI secretion system (T6SS) to those interactions. Both of these molecular weapons are constitutively active in environmental isolates but subject to tight regulation in the pandemic clade. We showed that several environmental isolates resist amoebal grazing and that this anti‐grazing defense relies on the strains' T6SS and its actincross‐linking domain (ACD)‐containing tip protein. Strains lacking the ACD were unable to defend themselves against grazing amoebae but maintained high levels of T6SS‐dependent interbacterial killing. We explored the latter phenotype through whole‐genome sequencing of 14 isolates, which unveiled a wide array of novel T6SS effector and (orphan) immunity proteins. By combining these in silico predictions with experimental validations, we showed that highly similar but non‐identical immunity proteins were insufficient to provide cross‐immunity among those wild strains.
Collapse
Affiliation(s)
- Natália C Drebes Dörr
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| |
Collapse
|
97
|
Wood TE, Howard SA, Förster A, Nolan LM, Manoli E, Bullen NP, Yau HCL, Hachani A, Hayward RD, Whitney JC, Vollmer W, Freemont PS, Filloux A. The Pseudomonas aeruginosa T6SS Delivers a Periplasmic Toxin that Disrupts Bacterial Cell Morphology. Cell Rep 2020; 29:187-201.e7. [PMID: 31577948 PMCID: PMC6899460 DOI: 10.1016/j.celrep.2019.08.094] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 07/02/2019] [Accepted: 08/27/2019] [Indexed: 01/10/2023] Open
Abstract
The type VI secretion system (T6SS) is crucial in interbacterial competition and is a virulence determinant of many Gram-negative bacteria. Several T6SS effectors are covalently fused to secreted T6SS structural components such as the VgrG spike for delivery into target cells. In Pseudomonas aeruginosa, the VgrG2b effector was previously proposed to mediate bacterial internalization into eukaryotic cells. In this work, we find that the VgrG2b C-terminal domain (VgrG2bC-ter) elicits toxicity in the bacterial periplasm, counteracted by a cognate immunity protein. We resolve the structure of VgrG2bC-ter and confirm it is a member of the zinc-metallopeptidase family of enzymes. We show that this effector causes membrane blebbing at midcell, which suggests a distinct type of T6SS-mediated growth inhibition through interference with cell division, mimicking the impact of β-lactam antibiotics. Our study introduces a further effector family to the T6SS arsenal and demonstrates that VgrG2b can target both prokaryotic and eukaryotic cells. The structure of the VgrG2b C-terminal domain presents a metallopeptidase fold VgrG2b exerts antibacterial activity in the periplasmic space Toxicity of VgrG2b is counteracted by a cognate periplasmic immunity protein VgrG2bC-ter-intoxicated prey cells bleb at the midcell and lyse
Collapse
Affiliation(s)
- Thomas E Wood
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Sophie A Howard
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Andreas Förster
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Laura M Nolan
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Eleni Manoli
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Nathan P Bullen
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Hamish C L Yau
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Abderrahman Hachani
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Richard D Hayward
- Division of Microbiology and Parasitology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Paul S Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
| |
Collapse
|
98
|
Liu J, Hou JS, Li YB, Miao ZY, Sun PH, Lin J, Chen WM. Novel 2-Substituted 3-Hydroxy-1,6-dimethylpyridin-4(1H)-ones as Dual-Acting Biofilm Inhibitors of Pseudomonas aeruginosa. J Med Chem 2020; 63:10921-10945. [DOI: 10.1021/acs.jmedchem.0c00763] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jun Liu
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jin-Song Hou
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Yi-Bin Li
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Zhi-Ying Miao
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Ping-Hua Sun
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Jing Lin
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| | - Wei-Min Chen
- College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
| |
Collapse
|
99
|
Ting SY, Martínez-García E, Huang S, Bertolli SK, Kelly KA, Cutler KJ, Su ED, Zhi H, Tang Q, Radey MC, Raffatellu M, Peterson SB, de Lorenzo V, Mougous JD. Targeted Depletion of Bacteria from Mixed Populations by Programmable Adhesion with Antagonistic Competitor Cells. Cell Host Microbe 2020; 28:313-321.e6. [PMID: 32470328 PMCID: PMC7725374 DOI: 10.1016/j.chom.2020.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/21/2020] [Accepted: 05/06/2020] [Indexed: 01/15/2023]
Abstract
Selective and targeted removal of individual species or strains of bacteria from complex communities can be desirable over traditional, broadly acting antibacterials in several contexts. However, generalizable strategies that accomplish this with high specificity have been slow to emerge. Here we develop programmed inhibitor cells (PICs) that direct the potent antibacterial activity of the type VI secretion system (T6SS) against specified target cells. The PICs express surface-displayed nanobodies that mediate antigen-specific cell-cell adhesion to effectively overcome the barrier to T6SS activity in fluid conditions. We demonstrate the capacity of PICs to efficiently deplete low-abundance target bacteria without significant collateral damage to complex microbial communities. The only known requirements for PIC targeting are a Gram-negative cell envelope and a unique cell surface antigen; therefore, this approach should be generalizable to a wide array of bacteria and find application in medical, research, and environmental settings.
Collapse
Affiliation(s)
- See-Yeun Ting
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | | | - Shuo Huang
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Savannah K Bertolli
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Katherine A Kelly
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Kevin J Cutler
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - Elizabeth D Su
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Hui Zhi
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA
| | - Qing Tang
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Matthew C Radey
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Manuela Raffatellu
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA; Center for Microbiome Innovation, University of California San Diego, La Jolla, CA 92093, USA; Chiba University-UC San Diego Center for Mucosal Immunology, Allergy, and Vaccines (CU-UCSD cMAV), La Jolla, CA 92093, USA
| | - S Brook Peterson
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Víctor de Lorenzo
- System Biology Program, National Center of Biotechnology CSIC, 28049 Madrid, Spain
| | - Joseph D Mougous
- Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, USA; Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
100
|
Kim N, Kim JJ, Kim I, Mannaa M, Park J, Kim J, Lee H, Lee S, Park D, Sul WJ, Seo Y. Type VI secretion systems of plant-pathogenic Burkholderia glumae BGR1 play a functionally distinct role in interspecies interactions and virulence. MOLECULAR PLANT PATHOLOGY 2020; 21:1055-1069. [PMID: 32643866 PMCID: PMC7368126 DOI: 10.1111/mpp.12966] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/28/2020] [Accepted: 05/31/2020] [Indexed: 05/02/2023]
Abstract
In the environment, bacteria show close association, such as interspecies interaction, with other bacteria as well as host organisms. The type VI secretion system (T6SS) in gram-negative bacteria is involved in bacterial competition or virulence. The plant pathogen Burkholderia glumae BGR1, causing bacterial panicle blight in rice, has four T6SS gene clusters. The presence of at least one T6SS gene cluster in an organism indicates its distinct role, like in the bacterial and eukaryotic cell targeting system. In this study, deletion mutants targeting four tssD genes, which encode the main component of T6SS needle formation, were constructed to functionally dissect the four T6SSs in B. glumae BGR1. We found that both T6SS group_4 and group_5, belonging to the eukaryotic targeting system, act independently as bacterial virulence factors toward host plants. In contrast, T6SS group_1 is involved in bacterial competition by exerting antibacterial effects. The ΔtssD1 mutant lost the antibacterial effect of T6SS group_1. The ΔtssD1 mutant showed similar virulence as the wild-type BGR1 in rice because the ΔtssD1 mutant, like the wild-type BGR1, still has key virulence factors such as toxin production towards rice. However, metagenomic analysis showed different bacterial communities in rice infected with the ΔtssD1 mutant compared to wild-type BGR1. In particular, the T6SS group_1 controls endophytic plant-associated bacteria such as Luteibacter and Dyella in rice plants and may have an advantage in competing with endophytic plant-associated bacteria for settlement inside rice plants in the environment. Thus, B. glumae BGR1 causes disease using T6SSs with functionally distinct roles.
Collapse
Affiliation(s)
- Namgyu Kim
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Jin Ju Kim
- Department of Systems BiotechnologyChung‐Ang UniversityAnseongKorea
| | - Inyoung Kim
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Mohamed Mannaa
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Jungwook Park
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Juyun Kim
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | - Hyun‐Hee Lee
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| | | | | | - Woo Jun Sul
- Department of Systems BiotechnologyChung‐Ang UniversityAnseongKorea
| | - Young‐Su Seo
- Department of Integrated Biological SciencePusan National UniversityBusanKorea
| |
Collapse
|