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Nasser F, Gaudreau A, Lubega S, Zaker A, Xia X, Mer AS, D'Costa VM. Characterization of the diversity of type IV secretion system-encoding plasmids in Acinetobacter. Emerg Microbes Infect 2024; 13:2320929. [PMID: 38530969 DOI: 10.1080/22221751.2024.2320929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 02/14/2024] [Indexed: 03/28/2024]
Abstract
The multi-drug resistant pathogen Acinetobacter baumannii has gained global attention as an important clinical challenge. Owing to its ability to survive on surfaces, its capacity for horizontal gene transfer, and its resistance to front-line antibiotics, A. baumannii has established itself as a successful pathogen. Bacterial conjugation is a central mechanism for pathogen evolution. The epidemic multidrug-resistant A. baumannii ACICU harbours a plasmid encoding a Type IV Secretion System (T4SS) with homology to the E. coli F-plasmid, and plasmids with homologous gene clusters have been identified in several A. baumannii sequence types. However the genetic and host strain diversity, global distribution, and functional ability of this group of plasmids is not fully understood. Using systematic analysis, we show that pACICU2 belongs to a group of almost 120 T4SS-encoding plasmids within four different species of Acinetobacter and one strain of Klebsiella pneumoniae from human and environmental origin, and globally distributed across 20 countries spanning 4 continents. Genetic diversity was observed both outside and within the T4SS-encoding cluster, and 47% of plasmids harboured resistance determinants, with two plasmids harbouring eleven. Conjugation studies with an extensively drug-resistant (XDR) strain showed that the XDR plasmid could be successfully transferred to a more divergent A. baumanii, and transconjugants exhibited the resistance phenotype of the plasmid. Collectively, this demonstrates that these T4SS-encoding plasmids are globally distributed and more widespread among Acinetobacter than previously thought, and that they represent an important potential reservoir for future clinical concern.
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Affiliation(s)
- Farah Nasser
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
| | - Avery Gaudreau
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
| | - Shareefah Lubega
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
| | - Arvin Zaker
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Xuhua Xia
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
- Department of Biology, University of Ottawa, Ottawa, Canada
| | - Arvind S Mer
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Vanessa M D'Costa
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
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2
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Pan H, Shim A, Lubin MB, Belin BJ. Hopanoid lipids promote soybean -Bradyrhizobium symbiosis. mBio 2024; 15:e0247823. [PMID: 38445860 PMCID: PMC11005386 DOI: 10.1128/mbio.02478-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 01/04/2024] [Indexed: 03/07/2024] Open
Abstract
The symbioses between leguminous plants and nitrogen-fixing bacteria known as rhizobia are well known for promoting plant growth and sustainably increasing soil nitrogen. Recent evidence indicates that hopanoids, a family of steroid-like lipids, promote Bradyrhizobium symbioses with tropical legumes. To characterize hopanoids in Bradyrhizobium symbiosis with soybean, we validated a recently published cumate-inducible hopanoid mutant of Bradyrhizobium diazoefficiens USDA110, Pcu-shc::∆shc. GC-MS analysis showed that this strain does not produce hopanoids without cumate induction, and under this condition, is impaired in growth in rich medium and under osmotic, temperature, and pH stress. In planta, Pcu-shc::∆shc is an inefficient soybean symbiont with significantly lower rates of nitrogen fixation and low survival within the host tissue. RNA-seq revealed that hopanoid loss reduces the expression of flagellar motility and chemotaxis-related genes, further confirmed by swim plate assays, and enhances the expression of genes related to nitrogen metabolism and protein secretion. These results suggest that hopanoids provide a significant fitness advantage to B. diazoefficiens in legume hosts and provide a foundation for future mechanistic studies of hopanoid function in protein secretion and motility. A major problem for global sustainability is feeding our exponentially growing human population while available arable land decreases. Harnessing the power of plant-beneficial microbes is a potential solution, including increasing our reliance on the symbioses of leguminous plants and nitrogen-fixing rhizobia. This study examines the role of hopanoid lipids in the symbiosis between Bradyrhizobium diazoefficiens USDA110, an important commercial inoculant strain, and its economically significant host soybean. Our research extends our knowledge of the functions of bacterial lipids in symbiosis to an agricultural context, which may one day help improve the practical applications of plant-beneficial microbes in agriculture.
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Affiliation(s)
- Huiqiao Pan
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, USA
| | - Ashley Shim
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, USA
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Matthew B. Lubin
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, USA
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Brittany J. Belin
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, USA
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
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3
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Carsten A, Wolters M, Aepfelbacher M. Super-resolution fluorescence microscopy for investigating bacterial cell biology. Mol Microbiol 2024; 121:646-658. [PMID: 38041391 DOI: 10.1111/mmi.15203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/13/2023] [Accepted: 11/16/2023] [Indexed: 12/03/2023]
Abstract
Super-resolution fluorescence microscopy technologies developed over the past two decades have pushed the resolution limit for fluorescently labeled molecules into the nanometer range. These technologies have the potential to study bacterial structures, for example, macromolecular assemblies such as secretion systems, with single-molecule resolution on a millisecond time scale. Here we review recent applications of super-resolution fluorescence microscopy with a focus on bacterial secretion systems. We also describe MINFLUX fluorescence nanoscopy, a relatively new technique that promises to one day produce molecular movies of molecular machines in action.
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Affiliation(s)
- Alexander Carsten
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Manuel Wolters
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Martin Aepfelbacher
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg Eppendorf, Hamburg, Germany
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Ramamoorthy S, Pena M, Ghosh P, Liao YY, Paret M, Jones JB, Potnis N. Transcriptome profiling of type VI secretion system core gene tssM mutant of Xanthomonas perforans highlights regulators controlling diverse functions ranging from virulence to metabolism. Microbiol Spectr 2024; 12:e0285223. [PMID: 38018859 PMCID: PMC10782981 DOI: 10.1128/spectrum.02852-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 10/20/2023] [Indexed: 11/30/2023] Open
Abstract
IMPORTANCE T6SS has received attention due to its significance in mediating interorganismal competition through contact-dependent release of effector molecules into prokaryotic and eukaryotic cells. Reverse-genetic studies have indicated the role of T6SS in virulence in a variety of plant pathogenic bacteria, including the one studied here, Xanthomonas. However, it is not clear whether such effect on virulence is merely due to a shift in the microbiome-mediated protection or if T6SS is involved in a complex virulence regulatory network. In this study, we conducted in vitro transcriptome profiling in minimal medium to decipher the signaling pathways regulated by tssM-i3* in X. perforans AL65. We show that TssM-i3* regulates the expression of a suite of genes associated with virulence and metabolism either directly or indirectly by altering the transcription of several regulators. These findings further expand our knowledge on the intricate molecular circuits regulated by T6SS in phytopathogenic bacteria.
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Affiliation(s)
- Sivakumar Ramamoorthy
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Michelle Pena
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Palash Ghosh
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Ying-Yu Liao
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Mathews Paret
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Jeffrey B. Jones
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
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Taillefer B, Giraud JF, Cascales E. No fitness cost entailed by type VI secretion system synthesis, assembly, contraction, or disassembly in enteroaggregative Escherichia coli. J Bacteriol 2023; 205:e0035723. [PMID: 37971272 PMCID: PMC10729742 DOI: 10.1128/jb.00357-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 11/19/2023] Open
Abstract
IMPORTANCE Bacteria use weapons to deliver effectors into target cells. One of these weapons, the type VI secretion system (T6SS), assembles a contractile tail acting as a spring to propel a toxin-loaded needle. Due to its size and mechanism of action, the T6SS was intuitively thought to be energetically costly. Here, using a combination of mutants and growth measurements in liquid medium, on plates, and in competition experiments, we show that the T6SS does not entail a growth cost to enteroaggregative Escherichia coli.
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Affiliation(s)
- Boris Taillefer
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM, UMR 7255), Institut de Microbiologie de la Méditerranée (IMM), Aix Marseille Univ, CNRS, Marseille, France
| | - Julien F. Giraud
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM, UMR 7255), Institut de Microbiologie de la Méditerranée (IMM), Aix Marseille Univ, CNRS, Marseille, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM, UMR 7255), Institut de Microbiologie de la Méditerranée (IMM), Aix Marseille Univ, CNRS, Marseille, France
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Meir A, Macé K, Vegunta Y, Williams SM, Waksman G. Substrate recruitment mechanism by gram-negative type III, IV, and VI bacterial injectisomes. Trends Microbiol 2023; 31:916-932. [PMID: 37085348 DOI: 10.1016/j.tim.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 04/23/2023]
Abstract
Bacteria use a wide arsenal of macromolecular substrates (DNA and proteins) to interact with or infect prokaryotic and eukaryotic cells. To do so, they utilize substrate-injecting secretion systems or injectisomes. However, prior to secretion, substrates must be recruited to specialized recruitment platforms and then handed over to the secretion apparatus for secretion. In this review, we provide an update on recent advances in substrate recruitment and delivery by gram-negative bacterial recruitment platforms associated with Type III, IV, and VI secretion systems.
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Affiliation(s)
- Amit Meir
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK; Current address: MRC Centre for Virus Research, School of Infection and Immunity, University of Glasgow, Glasgow, UK.
| | - Kévin Macé
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Yogesh Vegunta
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Sunanda M Williams
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck and UCL, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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Han K, Li Y, Zhang Z, Sun L, Wang ET, Li Y. Comparative genome analysis of Sesbania cannabina-nodulating Rhizobium spp. revealing the symbiotic and transferrable characteristics of symbiosis plasmids. Microb Genom 2023; 9. [PMID: 37133904 DOI: 10.1099/mgen.0.001004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023] Open
Abstract
Symbiotic nitrogen fixation between legumes and rhizobia makes a great contribution to the terrestrial ecosystem. The successful symbiosis between the partners mainly depends on the nod and nif genes in rhizobia, while the specific symbiosis is mainly determined by the structure of Nod factors and the corresponding secretion systems (type III secretion system; T3SS), etc. These symbiosis genes are usually located on symbiotic plasmids or a chromosomal symbiotic island, both could be transferred interspecies. In our previous studies, Sesbania cannabina-nodulating rhizobia across the world were classified into 16 species of four genera and all the strains, especially those of Rhizobium spp., harboured extraordinarily highly conserved symbiosis genes, suggesting that horizontal transfer of symbiosis genes might have happened among them. In order to learn the genomic basis of diversification of rhizobia under the selection of host specificity, we performed this study to compare the complete genome sequences of four Rhizobium strains associated with S. cannabina, YTUBH007, YTUZZ027, YTUHZ044 and YTUHZ045. Their complete genomes were sequenced and assembled at the replicon level. Each strain represents a different species according to the average nucleotide identity (ANI) values calculated using the whole-genome sequences; furthermore, except for YTUBH007, which was classified as Rhizobium binae, the remaining three strains were identified as new candidate species. A single symbiotic plasmid sized 345-402 kb containing complete nod, nif, fix, T3SS and conjugal transfer genes was detected in each strain. The high ANI and amino acid identity (AAI) values, as well as the close phylogenetic relationships among the entire symbiotic plasmid sequences, indicate that they have the same origin and the entire plasmid has been transferred among different Rhizobium species. These results indicate that S. cannabina stringently selects a certain symbiosis gene background of the rhizobia for nodulation, which might have forced the symbiosis genes to transfer from some introduced rhizobia to the related native or local-condition-adapted bacteria. The existence of almost complete conjugal transfer related elements, but not the gene virD, indicated that the self-transfer of the symbiotic plasmid in these rhizobial strains may be realized via a virD-independent pathway or through another unidentified gene. This study provides insight for the better understanding of high-frequency symbiotic plasmid transfer, host-specific nodulation and the host shift for rhizobia.
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Affiliation(s)
- Kunming Han
- Yantai Key Laboratory of Characteristic Agricultural Bioresource Conservation & Germplasm Innovative Utilization, College of Life Sciences, Yantai University, Yantai, Shandong 264005, PR China
| | - Yan Li
- Yantai Key Laboratory of Characteristic Agricultural Bioresource Conservation & Germplasm Innovative Utilization, College of Life Sciences, Yantai University, Yantai, Shandong 264005, PR China
| | - Zhenpeng Zhang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, PR China
| | - Liqin Sun
- Yantai Key Laboratory of Characteristic Agricultural Bioresource Conservation & Germplasm Innovative Utilization, College of Life Sciences, Yantai University, Yantai, Shandong 264005, PR China
| | - En Tao Wang
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City 11340, Mexico
| | - Yan Li
- Yantai Key Laboratory of Characteristic Agricultural Bioresource Conservation & Germplasm Innovative Utilization, College of Life Sciences, Yantai University, Yantai, Shandong 264005, PR China
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Liang X, Zheng HY, Zhao YJ, Zhang YQ, Pei TT, Cui Y, Tang MX, Xu P, Dong T. VgrG Spike Dictates PAAR Requirement for the Assembly of the Type VI Secretion System. J Bacteriol 2023; 205:e0035622. [PMID: 36655996 DOI: 10.1128/jb.00356-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Widely employed by Gram-negative pathogens for competition and pathogenesis, the type six protein secretion system (T6SS) can inject toxic effectors into neighboring cells through the penetration of a spear-like structure comprising a long Hcp tube and a VgrG-PAAR spike complex. The cone-shaped PAAR is believed to sharpen the T6SS spear for penetration but it remains unclear why PAAR is required for T6SS functions in some bacteria but dispensable in others. Here, we report the conditional requirement of PAAR for T6SS functions in Aeromonas dhakensis, an emerging human pathogen that may cause severe bacteremia. By deleting the two PAAR paralogs, we show that PAAR is not required for T6SS secretion, bacterial killing, or specific effector delivery in A. dhakensis. By constructing combinatorial PAAR and vgrG deletions, we demonstrate that deletion of individual PAAR moderately reduced T6SS functions but double or triple deletions of PAAR in the vgrG deletion mutants severely impaired T6SS functions. Notably, the auxiliary-cluster-encoded PAAR2 and VgrG3 are less critical than the main-cluster-encoded PAAR1 and VgrG1&2 proteins to T6SS functions. In addition, PAAR1 but not PAAR2 contributes to antieukaryotic virulence in amoeba. Our data suggest that, for a multi-PAAR T6SS, the variable role of PAAR paralogs correlates with the VgrG-spike composition that collectively dictates T6SS assembly. IMPORTANCE Gram-negative bacteria often encode multiple paralogs of the cone-shaped PAAR that sits atop the VgrG-spike and is thought to sharpen the spear-like T6SS puncturing device. However, it is unclear why PAAR is required for the assembly of some but not all T6SSs and why there are multiple PAARs if they are not required. Our data delineate a VgrG-mediated conditional requirement for PAAR and suggest a core-auxiliary relationship among different PAAR-VgrG modules that may have been acquired sequentially by the T6SS during evolution.
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Shao Y, Tang G, Huang Y, Ke W, Wang S, Zheng D, Ruan L. Transcriptional regulator Sar regulates the multiple secretion systems in Xanthomonas oryzae. Mol Plant Pathol 2023; 24:16-27. [PMID: 36177860 PMCID: PMC9742495 DOI: 10.1111/mpp.13272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 08/24/2022] [Accepted: 08/24/2022] [Indexed: 06/16/2023]
Abstract
Xanthomonas oryzae pv. oryzae (Xoo) is a notorious plant pathogen that causes leaf blight of rice cultivars. The pathogenic bacteria possess numerous transcriptional regulators to regulate various biological processes, such as pathogenicity in the host plant. Our previous study identified a new master regulator PXO_RS20790 that is involved in pathogenicity for Xoo against the host rice. However, the molecular functions of PXO_RS20790 are still unclear. Here, we demonstrate that transcriptional regulator Sar (PXO_RS20790) regulates multiple secretion systems. The RNA-sequencing analysis, bacterial one-hybrid assay, and electrophoretic mobility shift assay revealed that Sar enables binding of the promoters of the T1SS-related genes, the avirulence gene, raxX, and positively regulates these genes' expression. Meanwhile, we found that Sar positively regulated the T6SS-1 clusters but did not regulate the T6SS-2 clusters. Furthermore, we revealed that only T6SS-2 is involved in interbacterial competition. We also indicated that Sar could bind the promoters of the T3SS regulators, hrpG and hrpX, to activate these two genes' transcription. Our findings revealed that Sar is a crucial regulator of multiple secretion systems and virulence.
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Affiliation(s)
- Yanan Shao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Guiyu Tang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Yuanyuan Huang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Wenli Ke
- State Key Laboratory of Agricultural Microbiology, College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Shasha Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Dehong Zheng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Demonstration Center for Experimental Plant Science Education, College of AgricultureGuangxi UniversityNanningChina
| | - Lifang Ruan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- College of Resources and EnvironmentTibet Agriculture & Animal Husbandry UniversityLinzhiChina
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Cui Y, Pei TT, Liang X, Li H, Zheng HY, Dong T. Heterologous Assembly of the Type VI Secretion System Empowers Laboratory Escherichia coli with Antimicrobial and Cell Penetration Capabilities. Appl Environ Microbiol 2022;:e0130522. [PMID: 36154120 DOI: 10.1128/aem.01305-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The synthetic biology toolbox has amassed a vast number of diverse functional modules, but protein translocation modules for cell penetration and cytosol-to-cytosol delivery remain relatively scarce. The type VI secretion system (T6SS), commonly found in many Gram-negative pathogens, functions as a contractile device to translocate protein toxins to prokaryotic and eukaryotic cells. Here, we have assembled the T6SS of Aeromonas dhakensis, an opportunistic waterborne pathogen, in the common laboratory strain Escherichia coli BL21(DE3). We constructed a series of plasmids (pT6S) carrying the T6SS structural and effector genes under native or tetracycline-inducible promoters, the latter for controlled expression. Using fluorescence microscopy and biochemical analyses, we demonstrate a functional T6SS in E. coli capable of secreting proteins directly into the cytosol of neighboring bacteria and outcompeting a number of drug-resistant pathogens. The heterologous assembly of T6SS not only confers the lab workhorse E. coli with the cytosol-to-cytosol protein delivery capability but also demonstrates the potential for harnessing the T6SS of various pathogens for general protein delivery and antibacterial applications. IMPORTANCE The T6SS is a powerful and versatile protein delivery system. However, the complexity of its macromolecular structure and gene regulation makes it not a trivial task to reconstitute the T6SSs of pathogens in a nonpathogenic host. In this study, we have assembled an inducible T6SS in E. coli BL21(DE3) and demonstrated its functions in protein delivery and antimicrobial activities. The engineered T6SS empowers E. coli to deliver protein cargos into a wide range of prokaryotic and eukaryotic cells.
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Dhital S, Deo P, Bharathwaj M, Horan K, Nickson J, Azad M, Stuart I, Chow SH, Gunasinghe SD, Bamert R, Li J, Lithgow T, Howden BP, Naderer T. Neisseria gonorrhoeae-derived outer membrane vesicles package β-lactamases to promote antibiotic resistance. Microlife 2022; 3:uqac013. [PMID: 37223348 PMCID: PMC10117772 DOI: 10.1093/femsml/uqac013] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 07/11/2022] [Accepted: 07/27/2022] [Indexed: 05/25/2023]
Abstract
Neisseria gonorrhoeae causes the sexually transmitted disease gonorrhoea. The treatment of gonorrhoea is becoming increasingly challenging, as N. gonorrhoeae has developed resistance to antimicrobial agents routinely used in the clinic. Resistance to penicillin is wide-spread partly due to the acquisition of β-lactamase genes. How N. gonorrhoeae survives an initial exposure to β-lactams before acquiring resistance genes remains to be understood. Here, using a panel of clinical isolates of N. gonorrhoeae we show that the β-lactamase enzyme is packaged into outer membrane vesicles (OMVs) by strains expressing blaTEM-1B or blaTEM-106, which protects otherwise susceptible clinical isolates from the β-lactam drug amoxycillin. We characterized the phenotypes of these clinical isolates of N. gonorrhoeae and the time courses over which the cross-protection of the strains is effective. Imaging and biochemical assays suggest that OMVs promote the transfer of proteins and lipids between bacteria. Thus, N. gonorrhoeae strains secret antibiotic degrading enzymes via OMVs enabling survival of otherwise susceptible bacteria.
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Affiliation(s)
| | | | - Manasa Bharathwaj
- Centre to Impact AMR, Monash University, Clayton, Australia
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Kristy Horan
- Microbiological Diagnostic Unit Public Health Laboratory, Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Joshua Nickson
- Infection Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Centre to Impact AMR, Monash University, Clayton, Australia
| | - Mohammad Azad
- Centre to Impact AMR, Monash University, Clayton, Australia
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Isabella Stuart
- Infection Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Centre to Impact AMR, Monash University, Clayton, Australia
| | - Seong H Chow
- Infection Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Centre to Impact AMR, Monash University, Clayton, Australia
| | - Sachith D Gunasinghe
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
- European Molecular Biology Laboratory (EMBL) Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Rebecca Bamert
- Centre to Impact AMR, Monash University, Clayton, Australia
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Jian Li
- Centre to Impact AMR, Monash University, Clayton, Australia
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Trevor Lithgow
- Centre to Impact AMR, Monash University, Clayton, Australia
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Benjamin P Howden
- Microbiological Diagnostic Unit Public Health Laboratory, Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Thomas Naderer
- Corresponding author: Monash Biomedicine Discovery Institute, Dept of Biochemistry and Molecular Biology, Monash University, 19 Innovation Walk, Clayton, Victoria, 3800, Australia; E-mail:
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Nisa A, Counoupas C, Pinto R, Britton WJ, Triccas JA. Characterization of the Protective Immune Responses Conferred by Recombinant BCG Overexpressing Components of Mycobacterium tuberculosis Sec Protein Export System. Vaccines (Basel) 2022; 10:945. [PMID: 35746553 DOI: 10.3390/vaccines10060945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/08/2022] [Accepted: 06/12/2022] [Indexed: 11/29/2022] Open
Abstract
Mycobacterium bovis Bacillus Calmette-Guérin (BCG) is the only approved vaccine against tuberculosis (TB). However, its efficacy in preventing pulmonary TB in adults is limited. Despite its variable efficacy, BCG offers a number of unique and beneficial characteristics, which make it suitable as a vaccine vehicle to express recombinant molecules. In Mycobacterium tuberculosis, the general Sec pathway is an essential cellular process, and it is responsible for exporting the majority of proteins across the cytoplasmic membrane, including potent immune-protective antigens, such as members of the antigen 85 (Ag85) complex. We engineered BCG to overexpress the M. tuberculosis SecDFG proteins in order to improve the efficiency of the Sec-dependent export system and, thus, enhance the secretion of immunogenic proteins. BCGSecDFG displayed increased intracellular survival within macrophages in vitro and greater persistence in the lymphoid organs of vaccinated mice than parental BCG. In addition, vaccination with BCGSecDFG generated higher numbers of IFN-γ-secreting T cells in response to secreted mycobacterial antigens compared to BCG, particularly members of the Ag85 complex. Furthermore, vaccination with BCGSecDFG significantly reduced the bacterial load in the lungs and spleens of M. tuberculosis-infected mice, which was comparable to the protection afforded by parental BCG. Therefore, the modification of protein secretion in BCG can improve antigen-specific immunogenicity.
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13
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Veetilvalappil VV, Manuel A, Aranjani JM, Tawale R, Koteshwara A. Pathogenic arsenal of Pseudomonas aeruginosa: an update on virulence factors. Future Microbiol 2022; 17:465-481. [PMID: 35289684 DOI: 10.2217/fmb-2021-0158] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The emergence of Pseudomonas aeruginosa as a potential threat in persistent infections can be attributed to the plethora of virulence factors expressed by it. This review discusses the various virulence factors that help this pathogen to establish an infection and regulatory systems controlling these virulence factors. Cell-associated virulence factors such as flagella, type IV pili and non-pilus adhesins have been reviewed. Extracellular virulence factors have also been explained. Quorum-sensing systems present in P. aeruginosa play a cardinal role in regulating the expression of virulence factors. The identification of novel virulence factors in hypervirulent strains indicate that the expression of virulence is dynamic and constantly evolving. An understanding of this is critical for the better clinical management of infections.
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Affiliation(s)
- Vimal V Veetilvalappil
- Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, India
| | - Atulya Manuel
- Central Frozen Semen Production and Training Institute, Bengaluru, Karnataka, 560088, India
| | - Jesil M Aranjani
- Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, India
| | - Roshan Tawale
- Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, India
| | - Ananthamurthy Koteshwara
- Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, 576104, India
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14
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Abstract
Bacterial fish pathogens are one of the key challenges in the aquaculture industry, one of the fast-growing industries worldwide. These pathogens rely on arsenal of virulence factors such as toxins, adhesins, effectors and enzymes to promote colonization and infection. Translocation of virulence factors across the membrane to either the extracellular environment or directly into the host cells is performed by single or multiple dedicated secretion systems. These secretion systems are often key to the infection process. They can range from simple single-protein systems to complex injection needles made from dozens of subunits. Here, we review the different types of secretion systems in Gram-negative bacterial fish pathogens and describe their putative roles in pathogenicity. We find that the available information is fragmented and often descriptive, and hope that our overview will help researchers to more systematically learn from the similarities and differences between the virulence factors and secretion systems of the fish-pathogenic species described here.
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Affiliation(s)
- Sophanit Mekasha
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
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15
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Ge T, Jiang H, Tan EH, Johnson SB, Larkin RP, Charkowski AO, Secor G, Hao J. Pangenomic Analysis of Dickeya dianthicola Strains Related to the Outbreak of Blackleg and Soft Rot of Potato in the United States. Plant Dis 2021; 105:3946-3955. [PMID: 34213964 DOI: 10.1094/pdis-03-21-0587-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Dickeya dianthicola has caused an outbreak of blackleg and soft rot of potato in the eastern half of the United States since 2015. To investigate genetic diversity of the pathogen, a comparative analysis was conducted on genomes of D. dianthicola strains. Whole genomes of 16 strains from the United States outbreak were assembled and compared with 16 previously sequenced genomes of D. dianthicola isolated from potato or carnation. Among the 32 strains, eight distinct clades were distinguished based on phylogenomic analysis. The outbreak strains were grouped into three clades, with the majority of the strains in clade I. Clade I strains were unique and homogeneous, suggesting a recent incursion of this strain into potato production from alternative hosts or environmental sources. The pangenome of the 32 strains contained 6,693 genes, 3,377 of which were core genes. By screening primary protein subunits associated with virulence from all U.S. strains, we found that many virulence-related gene clusters, such as plant cell wall degrading enzyme genes, flagellar and chemotaxis related genes, two-component regulatory genes, and type I/II/III secretion system genes, were highly conserved but that type IV and type VI secretion system genes varied. The clade I strains encoded two clusters of type IV secretion systems, whereas the clade II and III strains encoded only one cluster. Clade I and II strains encoded one more VgrG/PAAR spike protein than did clade III. Thus, we predicted that the presence of additional virulence-related genes may have enabled the unique clade I strain to become predominant in the U.S. outbreak.
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Affiliation(s)
- Tongling Ge
- School of Food and Agriculture, University of Maine, Orono, ME 04469
| | - He Jiang
- School of Food and Agriculture, University of Maine, Orono, ME 04469
| | - Ek Han Tan
- School of Biology and Ecology, University of Maine, Orono, ME 04469
| | | | - Robert P Larkin
- USDA-ARS, New England Plant, Soil, and Water Laboratory, University of Maine, Orono, ME 04469
| | - Amy O Charkowski
- Department of Agricultural Biology, Colorado State University, Fort Collins, CO 80523
| | - Gary Secor
- Department of Plant Pathology, North Dakota State University, Fargo, ND58108
| | - Jianjun Hao
- School of Food and Agriculture, University of Maine, Orono, ME 04469
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16
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Jana B, Keppel K, Salomon D. Engineering a customizable antibacterial T6SS-based platform in Vibrio natriegens. EMBO Rep 2021; 22:e53681. [PMID: 34494702 PMCID: PMC8567230 DOI: 10.15252/embr.202153681] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/19/2021] [Accepted: 08/20/2021] [Indexed: 01/22/2023] Open
Abstract
Bacterial pathogens are a major risk to human, animal, and plant health. To counteract the spread of antibiotic resistance, alternative antibacterial strategies are urgently needed. Here, we construct a proof‐of‐concept customizable, modular, and inducible antibacterial toxin delivery platform. By engineering a type VI secretion system (T6SS) that is controlled by an externally induced on/off switch, we transform the safe bacterium, Vibrio natriegens, into an effective antibacterial weapon. Furthermore, we demonstrate that the delivered effector repertoire, and thus the toxicity range of this platform, can be easily manipulated and tested. We believe that this platform can serve as a foundation for novel antibacterial bio‐treatments, as well as a unique tool to study antibacterial toxins.
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Affiliation(s)
- Biswanath Jana
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kinga Keppel
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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17
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Yadav M, Srinivasan M, Tulsian NK, Liu YX, Lin Q, Rosenshine I, Sivaraman J. Binding specificity of type three secretion system effector NleH2 to multi-cargo chaperone CesT and their phosphorylation. Protein Sci 2021; 30:2433-2444. [PMID: 34662450 DOI: 10.1002/pro.4210] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/08/2021] [Accepted: 10/15/2021] [Indexed: 11/06/2022]
Abstract
Gram-negative pathogens like Enteropathogenic Escherichia coli (EPEC) utilize the type three secretion system (T3SS) to translocate various effector proteins that are needed to "hijack" the host system for pathogenic survival. Specialized T3SS chaperones inside bacterial cells stabilize these effector proteins and facilitate their translocation. CesT is a unique multi-cargo chaperone that interacts with and translocates ~10 different effector proteins. Here, we report the specific interaction between CesT and its key effector, NleH2, and explore the potential role of NleH2 as a kinase for CesT phosphorylation. First, we identified the chaperone-binding domain (CBD; 19-97aa) of NleH2, and mapped the specific interaction sites for both CesT and NleH2. The N- and C-terminal residues of the CBD interact with the dimeric interface of CesT. Further, we compared the CesT binding to NleH2, to that of another key effector Tir and with the global carbon regulator CsrA. Notably, the effectors have the binding regions at the β-sheet core and dimer interface of CesT, whereas the CsrA regulator interacts predominantly through the C-terminal region, which is found ~17 Å away from the effectors-binding sites. Next, we showed that NleH2 remains an active kinase even as a complex with CesT and is responsible for its autophosphorylation as well as phosphorylation of CesT at Tyr153. Collectively, our findings enhance the understanding of the role of multi-cargo chaperone CesT in orchestrating effector translocation through T3SS.
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Affiliation(s)
- Manisha Yadav
- Department of Biological Sciences, National University of Singapore, Singapore
| | | | - Nikhil K Tulsian
- Department of Biological Sciences, National University of Singapore, Singapore.,Department of Biochemistry, National University of Singapore, Singapore
| | - Yu Xuan Liu
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Qingsong Lin
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Ilan Rosenshine
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - J Sivaraman
- Department of Biological Sciences, National University of Singapore, Singapore
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18
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Li H, Zhang J, Wang Z, Yin Y, Gao H, Wang R, Jin L, Wang Q, Zhao C, Wang Z, Wang H. Evolution of Acinetobacter baumannii in Clinical Bacteremia Patients. Infect Drug Resist 2021; 14:3553-3562. [PMID: 34511946 PMCID: PMC8418358 DOI: 10.2147/idr.s320645] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/20/2021] [Indexed: 12/27/2022] Open
Abstract
Introduction Colonization of the respiratory tract by Acinetobacter baumannii has been established as an independent risk factor for bacteremia. However, within-host evolution of A. baumannii in bacteremia has not been extensively investigated. Methods We performed whole-genome sequencing to discover the evolutionary characteristics that accompany the transition from respiratory tract carriage to bloodstream infection in three patients with A. baumannii bacteremia. Results Within-host genetic diversity was identified. A total of 21 single nucleotide variants (SNVs) were detected. Genic and intergenic evolution occurred particularly in secretion system, DNA recombination, and cell motility genes. Intergenic SNVs occurred more frequently compared to synonymous and non-synonymous SNVs, which indicated potential transcription or translation regulation. Non-synonymous mutations mostly occurred during the transition from respiratory tract carriage to bloodstream infection. Isolates of clonal complex 208 (CC208) had lower substitution rate with approximately 10−6 nucleotide substitutions per site year−1, compared with non-CC208 isolates (approximately 10−5). We found evidence for the occurrence of recombination in one patient. A total of 259 genes were found to be gained or lost during the within-host evolution, and 231 genes were only detected in one patient. Gene function annotation results suggested that most genes (71/259) were related to replication, recombination, and repair. Universal bloodstream specific genes were not found in all three patients, and only one putative membrane protein related gene was lost in two patients. Conclusion Our results indicated that within-host evolution of A. baumannii bacteremia was driven by mutations, gene content changes, and limited effect of recombination. Gene content diversity between different patients was identified, which suggested interplay of both host and pathogen factors in within-host genetic diversity. Secretion system-related genes showed higher frequency of genomic variations during the within-host evolution. Our findings enhanced our understanding of within-host evolution of A. baumannii bacteremia and provided a framework for discovering novel genomic changes and pathogenicity genes important for bacteremia, which will be validated in future studies.
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Affiliation(s)
- Henan Li
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Jiangang Zhang
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Zhiren Wang
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Yuyao Yin
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Hua Gao
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Ruobing Wang
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Longyang Jin
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Qi Wang
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Chunjiang Zhao
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Zhanwei Wang
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
| | - Hui Wang
- Department of Clinical Laboratory, Peking University People's Hospital, Beijing, People's Republic of China
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19
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Aharon E, Mookherjee A, Pérez-Montaño F, Mateus da Silva G, Sathyamoorthy R, Burdman S, Jurkevitch E. Secretion systems play a critical role in resistance to predation by Bdellovibrio bacteriovorus. Res Microbiol 2021; 172:103878. [PMID: 34492337 DOI: 10.1016/j.resmic.2021.103878] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 08/02/2021] [Accepted: 08/07/2021] [Indexed: 11/28/2022]
Abstract
Bdellovibrio bacteriovorus, a Gram-negative predatory bacterium belonging to the Bdellovibrio and like organisms (BALOs), predate on Gram-negative bacteria. BALO strains differ in prey range but so far, the genetic basis of resistance against BALO predation is hardly understood. We developed a loss-of-function approach to screen for sensitive mutants in a library of strain M6, a predation-resistant strain of the plant pathogen Acidovorax citrulli. The screen is based on tracking the growth of a B. bacteriovorus strain expressing the fluorescent reporter Tdtomato in mutant pools to reveal predation-sensitive variants. Two independent loci were identified in mutant strains exhibiting significant levels of susceptibility to the predator. Genes in the two loci were analysed using both protein sequence homology and protein structure modeling. Both were secretion-related proteins and thus associated to the bacterial cell wall. Successful complementation of gspK, a gene encoding for a minor pseudopilin protein confirmed the involvement of the type II secretion system in A. citrulli M6 resistance. This proof of concept study shows that our approach can identify key elements of the BALO-prey interaction, and it validates the hypothesis that mutational changes in a single gene can drastically impact prey resistance to BALO predation.
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Affiliation(s)
- Einav Aharon
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
| | - Abhirup Mookherjee
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
| | - Francisco Pérez-Montaño
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel; Department of Microbiology, University of Seville, Seville, Spain.
| | - Gustavo Mateus da Silva
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
| | - Rajesh Sathyamoorthy
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
| | - Saul Burdman
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
| | - Edouard Jurkevitch
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
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20
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Willcocks SJ, Denman C, Cia F, McCarthy E, Cuccui J, Wren BW. Virulence of the emerging pathogen, Burkholderia pseudomallei, depends upon the O-linked oligosaccharyltransferase, PglL. Future Microbiol 2021; 15:241-257. [PMID: 32271107 PMCID: PMC7611010 DOI: 10.2217/fmb-2019-0165] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Aim We sought to characterize the contribution of the O-OTase, PglL, to virulence in two Burkholderia spp. by comparing isogenic mutants in Burkholderia pseudomallei with the related species, Burkholderia thailandensis. Materials & methods We utilized an array of in vitro assays in addition to Galleria mellonella and murine in vivo models to assess virulence of the mutant and wild-type strains in each Burkholderia species. Results We found that pglL contributes to biofilm and twitching motility in both species. PglL uniquely affected morphology; cell invasion; intracellular motility; plaque formation and intergenus competition in B. pseudomallei. This mutant was attenuated in the murine model, and extended survival in a vaccine-challenge experiment. Conclusion Our data support a broad role for pglL in bacterial fitness and virulence, particularly in B. pseudomallei.
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Affiliation(s)
| | - Carmen Denman
- The London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Felipe Cia
- The London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | | | - Jon Cuccui
- The London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Brendan W Wren
- The London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
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21
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Faass L, Stein SC, Hauke M, Gapp M, Albanese M, Josenhans C. Contribution of Heptose Metabolites and the cag Pathogenicity Island to the Activation of Monocytes/Macrophages by Helicobacter pylori. Front Immunol 2021; 12:632154. [PMID: 34093525 PMCID: PMC8174060 DOI: 10.3389/fimmu.2021.632154] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 04/12/2021] [Indexed: 12/11/2022] Open
Abstract
The human gastric pathogen Helicobacter pylori activates human epithelial cells by a particular combination of mechanisms, including NOD1 and ALPK1-TIFA activation. These mechanisms are characterized by a strong participation of the bacterial cag pathogenicity island, which forms a type IV secretion system (CagT4SS) that enables the bacteria to transport proteins and diverse bacterial metabolites, including DNA, glycans, and cell wall components, into human host cells. Building on previous findings, we sought to determine the contribution of lipopolysaccharide inner core heptose metabolites (ADP-heptose) in the activation of human phagocytic cells by H. pylori. Using human monocyte/macrophage-like Thp-1 cells and human primary monocytes and macrophages, we were able to determine that a substantial part of early phagocytic cell activation, including NF-κB activation and IL-8 production, by live H. pylori is triggered by bacterial heptose metabolites. This effect was very pronounced in Thp-1 cells exposed to bacterial purified lysates or pure ADP-heptose, in the absence of other bacterial MAMPs, and was significantly reduced upon TIFA knock-down. Pure ADP-heptose on its own was able to strongly activate Thp-1 cells and human primary monocytes/macrophages. Comprehensive transcriptome analysis of Thp-1 cells co-incubated with live H. pylori or pure ADP-heptose confirmed a signature of ADP-heptose-dependent transcript activation in monocyte/macrophages. Bacterial enzyme-treated lysates (ETL) and pure ADP-heptose–dependent activation differentiated monocytes into macrophages of predominantly M1 type. In Thp-1 cells, the active CagT4SS was less required for the heptose-induced proinflammatory response than in epithelial cells, while active heptose biosynthesis or pure ADP-heptose was required and sufficient for their early innate response and NF-κB activation. The present data suggest that early activation and maturation of incoming and resident phagocytic cells (monocytes, macrophages) in the H. pylori–colonized stomach strongly depend on bacterial LPS inner core heptose metabolites, also with a significant contribution of an active CagT4SS.
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Affiliation(s)
- Larissa Faass
- Max von Pettenkofer Institute, Chair for Medical Microbiology and Hygiene, Ludwig Maximilians University Munich, Munich, Germany
| | - Saskia C Stein
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | - Martina Hauke
- Max von Pettenkofer Institute, Chair for Medical Microbiology and Hygiene, Ludwig Maximilians University Munich, Munich, Germany
| | - Madeleine Gapp
- Max von Pettenkofer Institute, Chair for Virology, Ludwig Maximilians University, Munich, Germany.,Gene Center and Department of Biochemistry, LMU Munich, Munich, Germany
| | - Manuel Albanese
- Max von Pettenkofer Institute, Chair for Virology, Ludwig Maximilians University, Munich, Germany.,Gene Center and Department of Biochemistry, LMU Munich, Munich, Germany
| | - Christine Josenhans
- Max von Pettenkofer Institute, Chair for Medical Microbiology and Hygiene, Ludwig Maximilians University Munich, Munich, Germany.,Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany.,German Center of Infection Research (DZIF), Partner site Munich, Munich, Germany.,DZIF, Partner site Hannover-Braunschweig, Hannover, Germany
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22
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Yanatori I, Miura K, Chen YS, Valdivia RH, Kishi F. Application of a C. trachomatis expression system to identify C. pneumoniae proteins translocated into host cells. J Bacteriol 2021; 203:JB. [PMID: 33685970 DOI: 10.1128/JB.00511-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chlamydia pneumoniae is a Gram-negative, obligate intracellular pathogen that causes community-acquired respiratory infections. C. pneumoniae uses a cell contact-dependent type-III secretion (T3S) system to translocate pathogen effector proteins that manipulate host cellular functions. While several C. pneumoniae T3S effectors have been proposed, few have been experimentally confirmed in Chlamydia In this study, we expressed 382 C. pneumoniae genes in C. trachomatis as fusion proteins to an epitope tag derived from glycogen synthase kinase 3β (GSK3β) which is the target of phosphorylation by mammalian kinases. Based on the detection of the tagged C. pneumoniae protein with anti-phospho GSK3β antibodies, we identified 49 novel C. pneumoniae-specific proteins that are translocated by C. trachomatis into the host cytoplasm and thus likely play a role as modifiers of host cellular functions. In this manner, we identified and characterized a new C. pneumoniae effector CPj0678 that recruits the host cell protein PACSIN2 to the plasma membrane. These findings indicate that C. trachomatis provides a powerful screening system to detect candidate effector proteins encoded by other pathogenic and endosymbiotic Chlamydia species.Importance Chlamydia injects numerous effector proteins into host cells to manipulate cellular functions important for bacterial survival. Based on findings in C. trachomatis, it has been proposed that between 5-10% of the C. pneumoniae genome, a related respiratory pathogen, encodes secreted effectors. However only a few C. pneumoniae effectors have been identified and experimentally validated. With the development of methods for the stable genetic transformation of C. trachomatis, it is now possible to use C. trachomatis shuttle plasmids to express and explore the function of proteins from other Chlamydia in a more relevant bacterial system. In this study, we experimentally determined that 49 C. pneumoniae-specific proteins are translocated into the host cytoplasm by Chlamydia secretion systems, and identify a novel effector required to recruit the host factor PACSIN2 to the plasma membrane during infection.
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23
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Le LHM, Ying L, Ferrero RL. Nuclear trafficking of bacterial effector proteins. Cell Microbiol 2021; 23:e13320. [PMID: 33600054 DOI: 10.1111/cmi.13320] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 02/06/2023]
Abstract
Bacterial pathogens can subvert host responses by producing effector proteins that directly target the nucleus of eukaryotic cells in animals and plants. Nuclear-targeting proteins are categorised as either: "nucleomodulins," which have epigenetic-modulating activities; or "cyclomodulins," which specifically interfere with the host cell cycle. Bacteria can deliver these effector proteins to eukaryotic cells via a range of strategies. Despite an increasing number of reports describing the effects of bacterial effector proteins on nuclear processes in host cells, the intracellular pathways used by these proteins to traffic to the nucleus have yet to be fully elucidated. This review will describe current knowledge about how nucleomodulins and cyclomodulins enter eukaryotic cells, exploit endocytic pathways and translocate to the nucleus. We will also discuss the secretion of nuclear-targeting proteins or their release in bacterial membrane vesicles and the trafficking pathways employed by each of these forms. Besides their importance for bacterial pathogenesis, some nuclear-targeting proteins have been implicated in the development of chronic diseases and even cancer. A greater understanding of nuclear-targeting proteins and their actions will provide new insights into the pathogenesis of infectious diseases, as well as contribute to advances in the development of novel therapies against bacterial infections and possibly cancer.
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Affiliation(s)
- Lena Hoang My Le
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Biomedicine Discovery Institute, Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Le Ying
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Richard L Ferrero
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Biomedicine Discovery Institute, Department of Microbiology, Monash University, Melbourne, Victoria, Australia.,Department of Molecular and Translational Science, Monash University, Melbourne, Victoria, Australia
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24
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Sun M, Gao X, Zhao K, Ma J, Yao H, Pan Z. Insight Into the Virulence Related Secretion Systems, Fimbriae, and Toxins in O2:K1 Escherichia coli Isolated From Bovine Mastitis. Front Vet Sci 2021; 8:622725. [PMID: 33644149 PMCID: PMC7904677 DOI: 10.3389/fvets.2021.622725] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/05/2021] [Indexed: 11/13/2022] Open
Abstract
Mastitis remains a major infection of dairy cows and an important issue for the dairy farmers, and Escherichia coli (E. coli) bovine mastitis is a disease of significant economic importance in the dairy industry. Our study identified six isolates belong to phylogroup B2 from 69 bovine mastitis E. coli strains. Except for one serotype O1 strain, all group B2 isolates were identified into serotype O2 and showed significantly higher mortality in the mouse infection than other phylogroups' strains. Genomic analyses and further tests were performed to examine the role of secretion systems, fimbriae, and toxins during the systemic infection of O2:K1 strain BCE049. Two integral T6SS loci and three predicted effectors clusters were found to assemble the functional T6SS complex and deliver diverse toxic effectors to modulate bacterial virulence in the mouse infection model. A total of four T4SS loci were harbored in the BCE049 genome, three of them are encoded in different plasmids, respectively, whereas the last one locates within the bacterial chromosome at FQU84_16715 to FQU84_16760, and was significantly involved in the bacterial pathogenicity. Numerous predicted pilus biosynthesis gene loci were found in the BCE049 genome, whereas most of them lost long fragments encoding key genes for the pili assembly. Unexpectedly, a type IV pilus gene locus locating at FQU84_01405 to FQU84_01335 in the plasmid 2, was found to be required for the full virulence of mastitis strain BCE049. It should be noted that a genetic neighborhood inserted with diverse genes is encoded by the plasmid 1, which harbors three prominent toxins including β-hemolysin, cytotoxic necrotizing factor 2 and cytolethal distending toxin type III. Consequent studies verified that these toxins significantly contributed to the bacterial pathogenicity. These findings provide a molecular blueprint for understanding the underlying mechanisms employed by the bovine mastitis E. coli to colonize in host and cause systemic infection.
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Affiliation(s)
- Min Sun
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xing Gao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China
| | - Kejie Zhao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China
| | - Jiale Ma
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China
| | - Huochun Yao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China
| | - Zihao Pan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing, China
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25
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Liu F, Chen S, Luu LDW, Lee SA, Tay ACY, Wu R, Riordan SM, Lan R, Liu L, Zhang L. Analysis of complete Campylobacter concisus genomes identifies genomospecies features, secretion systems and novel plasmids and their association with severe ulcerative colitis. Microb Genom 2020; 6:mgen000457. [PMID: 33111662 PMCID: PMC7725323 DOI: 10.1099/mgen.0.000457] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 10/01/2020] [Indexed: 12/12/2022] Open
Abstract
Campylobacter concisus is an emerging enteric pathogen that is associated with several gastrointestinal diseases, such as inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC). Currently, only three complete C. concisus genomes are available and more complete C. concisus genomes are needed in order to better understand the genomic features and pathogenicity of this emerging pathogen. DNA extracted from 22 C. concisus strains were subjected to Oxford Nanopore genome sequencing. Complete genome assembly was performed using Nanopore genome data in combination with previously reported short-read Illumina data. Genome features of complete C. concisus genomes were analysed using bioinformatic tools. The enteric disease associations of C. concisus plasmids were examined using 239 C. concisus strains and confirmed using PCRs. Proteomic analysis was used to examine T6SS secreted proteins. We successfully obtained 13 complete C. concisus genomes in this study. Analysis of 16 complete C. concisus genomes (3 from public databases) identified multiple novel plasmids. pSma1 plasmid was found to be associated with severe UC. Sec-SRP, Tat and T6SS were found to be the main secretion systems in C. concisus and proteomic data showed a functional T6SS despite the lack of ClpV. T4SS was found in 25% of complete C. concisus genomes. This study also found that GS2 strains had larger genomes and higher GC content than GS1 strains and more often had plasmids. In conclusion, this study provides fundamental genomic data for understanding C. concisus plasmids, genomospecies features, evolution, secretion systems and pathogenicity.
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Affiliation(s)
- Fang Liu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Siying Chen
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Laurence Don Wai Luu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Seul A. Lee
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Alfred Chin Yen Tay
- Helicobacter Research Laboratory, Marshall Centre for Infectious Diseases Research and Training, School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Australia
| | - Ruochen Wu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Stephen M. Riordan
- Gastrointestinal and Liver Unit, Prince of Wales Hospital, University of New South Wales, Sydney, Australia
| | - Ruiting Lan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Lu Liu
- School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Li Zhang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
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26
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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.
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Affiliation(s)
| | - Miguel A. Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
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27
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Rocchi I, Ericson CF, Malter KE, Zargar S, Eisenstein F, Pilhofer M, Beyhan S, Shikuma NJ. A Bacterial Phage Tail-like Structure Kills Eukaryotic Cells by Injecting a Nuclease Effector. Cell Rep 2020; 28:295-301.e4. [PMID: 31291567 DOI: 10.1016/j.celrep.2019.06.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/09/2019] [Accepted: 06/05/2019] [Indexed: 11/28/2022] Open
Abstract
Many bacteria interact with target organisms using syringe-like structures called contractile injection systems (CISs). CISs structurally resemble headless bacteriophages and share evolutionarily related proteins such as the tail tube, sheath, and baseplate complex. In many cases, CISs mediate trans-kingdom interactions between bacteria and eukaryotes by delivering effectors to target cells. However, the specific effectors and their modes of action are often unknown. Here, we establish an ex vivo model to study an extracellular CIS (eCIS) called metamorphosis-associated contractile structures (MACs) that target eukaryotic cells. MACs kill two eukaryotic cell lines, fall armyworm Sf9 cells and J774A.1 murine macrophage cells, by translocating an effector termed Pne1. Before the identification of Pne1, no CIS effector exhibiting nuclease activity against eukaryotic cells had been described. Our results define a new mechanism of CIS-mediated bacteria-eukaryote interaction and are a step toward developing CISs as novel delivery systems for eukaryotic hosts.
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Affiliation(s)
- Iara Rocchi
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA; Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA
| | - Charles F Ericson
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA; Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
| | - Kyle E Malter
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Sahar Zargar
- Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA
| | - Fabian Eisenstein
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
| | - Martin Pilhofer
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich, Switzerland
| | - Sinem Beyhan
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA.
| | - Nicholas J Shikuma
- Department of Biology, San Diego State University, San Diego, CA 92182, USA; Viral Information Institute, San Diego State University, San Diego, CA 92182, USA; Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, CA 92037, USA.
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28
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Rojas MI, Cavalcanti GS, McNair K, Benler S, Alker AT, Cobián-Güemes AG, Giluso M, Levi K, Rohwer F, Bailey BA, Beyhan S, Edwards RA, Shikuma NJ. A Distinct Contractile Injection System Gene Cluster Found in a Majority of Healthy Adult Human Microbiomes. mSystems 2020; 5:e00648-20. [PMID: 32723799 PMCID: PMC7394362 DOI: 10.1128/msystems.00648-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/26/2022] Open
Abstract
Many commensal bacteria antagonize each other or their host by producing syringe-like secretion systems called contractile injection systems (CIS). Members of the Bacteroidales family have been shown to produce only one type of CIS-a contact-dependent type 6 secretion system that mediates bacterium-bacterium interactions. Here, we show that a second distinct cluster of genes from Bacteroidales bacteria from the human microbiome may encode yet-uncharacterized injection systems that we term Bacteroidales injection systems (BIS). We found that BIS genes are present in the gut microbiomes of 99% of individuals from the United States and Europe and that BIS genes are more prevalent in the gut microbiomes of healthy individuals than in those individuals suffering from inflammatory bowel disease. Gene clusters similar to that of the BIS mediate interactions between bacteria and diverse eukaryotes, like amoeba, insects, and tubeworms. Our findings highlight the ubiquity of the BIS gene cluster in the human gut and emphasize the relevance of the gut microbiome to the human host. These results warrant investigations into the structure and function of the BIS and how they might mediate interactions between Bacteroidales bacteria and the human host or microbiome.IMPORTANCE To engage with host cells, diverse pathogenic bacteria produce syringe-like structures called contractile injection systems (CIS). CIS are evolutionarily related to the contractile tails of bacteriophages and are specialized to puncture membranes, often delivering effectors to target cells. Although CIS are key for pathogens to cause disease, paradoxically, similar injection systems have been identified within healthy human microbiome bacteria. Here, we show that gene clusters encoding a predicted CIS, which we term Bacteroidales injection systems (BIS), are present in the microbiomes of nearly all adult humans tested from Western countries. BIS genes are enriched within human gut microbiomes and are expressed both in vitro and in vivo Further, a greater abundance of BIS genes is present within healthy gut microbiomes than in those humans with with inflammatory bowel disease (IBD). Our discovery provides a potentially distinct means by which our microbiome interacts with the human host or its microbiome.
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Affiliation(s)
- Maria I Rojas
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Giselle S Cavalcanti
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Katelyn McNair
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Computational Science Research Center, San Diego State University, San Diego, California, USA
| | - Sean Benler
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Amanda T Alker
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Ana G Cobián-Güemes
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Melissa Giluso
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Computational Science Research Center, San Diego State University, San Diego, California, USA
| | - Kyle Levi
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Computational Science Research Center, San Diego State University, San Diego, California, USA
| | - Forest Rohwer
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
- Computational Science Research Center, San Diego State University, San Diego, California, USA
| | - Barbara A Bailey
- Department of Mathematics and Statistics, San Diego State University, San Diego, California, USA
| | - Sinem Beyhan
- Department of Biology, San Diego State University, San Diego, California, USA
- Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, California, USA
| | - Robert A Edwards
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
- Computational Science Research Center, San Diego State University, San Diego, California, USA
| | - Nicholas J Shikuma
- Viral Information Institute, San Diego State University, San Diego, California, USA
- Department of Biology, San Diego State University, San Diego, California, USA
- Computational Science Research Center, San Diego State University, San Diego, California, USA
- Department of Infectious Diseases, J. Craig Venter Institute, La Jolla, California, USA
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29
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Banerjee G, Basak S, Roy T, Chattopadhyay P. Intrinsic role of bacterial secretion systems in phylogenetic niche conservation of Bradyrhizobium spp. FEMS Microbiol Ecol 2020; 95:5586991. [PMID: 31609448 DOI: 10.1093/femsec/fiz165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 10/13/2019] [Indexed: 11/12/2022] Open
Abstract
Bradyrhizobium is a biologically important bacterial genus. Different Bradyrhizobium strains exhibit distinct niche selection like free living, root nodular and stem nodular. The present in-silico study was undertaken to identify the role of bacterial secretome in the phylogenetic niche conservation (PNC) of Bradyrhizobium sp. Analysis was carried out with the publicly available 19 complete genome assembly and annotation reports. A protocol was developed to screen the secretome related genes using three different database, viz. genome, proteome and gene ortholog. This resulted into 139 orthologs that include type secretion systems (T1SS-T6SS) along with flagella (Flg), type IV pili (T4P) and tight adherence (Tad) systems. Multivariate analysis using bacterial secretome was undertaken to find out the role of these secretion systems in PNC. In free living strains, T3SS, T4SS and T6SS were completely absent. Whereas, in the stem nodulating strains, T3SS and T6SS were absent, but T4SS was found to be present. On the other hand, the T3SS was found to be present only in the root-nodulating strains. The present investigation clearly demonstrated a pattern of PNC based on the distribution of secretion system components. To the best of our knowledge, this is the first report on PNC of Bradyrhizobium using the multivariate analysis of secretome.
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Affiliation(s)
- Goutam Banerjee
- Department of Biochemistry, University of Calcutta, West Bengal 700019, India
| | - Swarnendu Basak
- Department of Medical Zoology, Kyung Hee University, School of Medicine, Seoul 02447, Republic of Korea
| | - Tathagato Roy
- Member of Jeevak Herb Welfare Society (registration number S/1L/78148 OF 2010-2011), Santiniketan, 731235, India.,Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, U.S
| | - Pritam Chattopadhyay
- Department of Biotechnology, Gauhati University, Guwahati, Assam 781014, India.,Department of Botany, M.U.C. Women's College, University of Bardhaman, Bardhaman, West Bengal 713104, India
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30
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Chatterjee P, Sass G, Swietnicki W, Stevens DA. Review of Potential Pseudomonas Weaponry, Relevant to the Pseudomonas-Aspergillus Interplay, for the Mycology Community. J Fungi (Basel) 2020; 6:jof6020081. [PMID: 32517271 PMCID: PMC7345761 DOI: 10.3390/jof6020081] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/03/2020] [Accepted: 06/03/2020] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is one of the most prominent opportunistic bacteria in airways of cystic fibrosis patients and in immunocompromised patients. These bacteria share the same polymicrobial niche with other microbes, such as the opportunistic fungus Aspergillus fumigatus. Their inter-kingdom interactions and diverse exchange of secreted metabolites are responsible for how they both fare in competition for ecological niches. The outcomes of their contests likely determine persistent damage and degeneration of lung function. With a myriad of virulence factors and metabolites of promising antifungal activity, P. aeruginosa products or their derivatives may prove useful in prophylaxis and therapy against A. fumigatus. Quorum sensing underlies the primary virulence strategy of P. aeruginosa, which serves as cell–cell communication and ultimately leads to the production of multiple virulence factors. Understanding the quorum-sensing-related pathogenic mechanisms of P. aeruginosa is a first step for understanding intermicrobial competition. In this review, we provide a basic overview of some of the central virulence factors of P. aeruginosa that are regulated by quorum-sensing response pathways and briefly discuss the hitherto known antifungal properties of these virulence factors. This review also addresses the role of the bacterial secretion machinery regarding virulence factor secretion and maintenance of cell–cell communication.
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Affiliation(s)
- Paulami Chatterjee
- California Institute for Medical Research, San Jose, CA 95128, USA; (P.C.); (G.S.)
| | - Gabriele Sass
- California Institute for Medical Research, San Jose, CA 95128, USA; (P.C.); (G.S.)
| | - Wieslaw Swietnicki
- Department of Immunology of Infectious Diseases, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 50-114 Wroclaw, Poland;
| | - David A. Stevens
- California Institute for Medical Research, San Jose, CA 95128, USA; (P.C.); (G.S.)
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Correspondence: ; Tel.: +1-408-998-4554
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31
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Li Y, Chen L, Zhang P, Bhagirath AY, Duan K. ClpV3 of the H3-Type VI Secretion System (H3-T6SS) Affects Multiple Virulence Factors in Pseudomonas aeruginosa. Front Microbiol 2020; 11:1096. [PMID: 32547522 PMCID: PMC7273116 DOI: 10.3389/fmicb.2020.01096] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 05/01/2020] [Indexed: 11/13/2022] Open
Abstract
The type VI secretion system (T6SS) is a toxic effector delivery apparatus widely distributed in Gram-negative bacteria. The opportunistic pathogen Pseudomonas aeruginosa encodes three T6SSs, namely H1-, H2-, and H3-T6SS. Each T6SS possesses its own effectors and their roles are not yet fully understood. Here, we report that an H3-T6SS deletion mutant PAO1(ΔclpV3) significantly affected the virulence-related phenotypes including pyocyanin production, biofilm formation, proteolytic activity, and motilities. Most interestingly, the expression of T3SS genes was markedly affected, indicating a link between H3-T6SS and T3SS. RNA-Sequencing was performed to globally identify the genes differentially expressed when H3-T6SS was inactivated and the results obtained correlated well with the observed phenotypes. Interestingly, the expressions of T2SS, T3SS, H2-T6SS, and H3-T6SS were all significantly decreased, while H1-T6SS was increased in the PAO1(ΔclpV3) strain. We also observed that the intracellular concentration of secondary messenger cAMP was reduced in PAO1(ΔclpV3), and the c-di-GMP level was also decreased as indicated by the decreased cdrA reporter activity. Finally, by using a Galleria mellonella infection model, we show that H3-T6SS plays a key role in the pathogenicity of P. aeruginosa in vivo. Overall, our study highlights the unique connection of H3-T6SS in P. aeruginosa with T3SS, pyocyanin production, biofilm formation and in vivo pathogenicity.
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Affiliation(s)
- Yanqi Li
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Lin Chen
- College of Life Sciences, Northwest University, Xi'an, China
| | - Pansong Zhang
- College of Life Sciences, Northwest University, Xi'an, China
| | - Anjali Y Bhagirath
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Kangmin Duan
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,Department of Medical Microbiology & Infectious Diseases, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
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32
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Lam WWL, Sun K, Zhang H, Au SWN. Crystal Structure of Flagellar Export Chaperone FliS in Complex With Flagellin and HP1076 of Helicobacter pylori. Front Microbiol 2020; 11:787. [PMID: 32508757 PMCID: PMC7248283 DOI: 10.3389/fmicb.2020.00787] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/02/2020] [Indexed: 12/13/2022] Open
Abstract
Functional flagella formation is a widespread virulence factor that plays a critical role in survival and host colonization. Flagellar synthesis is a complex and highly coordinated process. The assembly of the axial structure beyond the cell membrane is mediated by export chaperone proteins that transport their cognate substrates to the export gate complex. The export chaperone FliS interacts with flagellin, the basic component used to construct the filament. Unlike enterobacteria, the gastric pathogen Helicobacter pylori produces two different flagellins, FlaA and FlaB, which exhibit distinct spatial localization patterns in the filament. Previously, we demonstrated a molecular interaction between FliS and an uncharacterized protein, HP1076, in H. pylori. Here, we present the crystal structure of FliS in complex with both the C-terminal D0 domain of FlaB and HP1076. Although this ternary complex reveals that FliS interacts with flagellin using a conserved binding mode demonstrated previously in Aquifex aeolicus, Bacillus subtilis, and Salmonella enterica serovar Typhimurium, the helical conformation of FlaB in this complex was different. Moreover, HP1076 and the D1 domain of flagellin share structural similarity and interact with the same binding interface on FliS. This observation was further validated through competitive pull-down assays and kinetic binding analyses. Interestingly, we did not observe any detrimental flagellation or motility phenotypes in an hp1076-null strain. Our localization studies suggest that HP1076 is a membrane-associated protein with a cellular localization independent of FliS. As HP1076 is uniquely expressed in H. pylori and related species, we propose that this protein may contribute to the divergence of the flagellar system, although its relationship with FliS remains incompletely elucidated.
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Affiliation(s)
- Wendy Wai-Ling Lam
- Center for Protein Science and Crystallography, School of Life Sciences, Faculty of Science, Chinese University of Hong Kong, Shatin, Hong Kong
| | - Kailei Sun
- Center for Protein Science and Crystallography, School of Life Sciences, Faculty of Science, Chinese University of Hong Kong, Shatin, Hong Kong
| | - Huawei Zhang
- Center for Protein Science and Crystallography, School of Life Sciences, Faculty of Science, Chinese University of Hong Kong, Shatin, Hong Kong
| | - Shannon Wing-Ngor Au
- Center for Protein Science and Crystallography, School of Life Sciences, Faculty of Science, Chinese University of Hong Kong, Shatin, Hong Kong
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33
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Park D, Chetrit D, Hu B, Roy CR, Liu J. Analysis of Dot/Icm Type IVB Secretion System Subassemblies by Cryoelectron Tomography Reveals Conformational Changes Induced by DotB Binding. mBio 2020; 11:e03328-19. [PMID: 32071271 PMCID: PMC7029142 DOI: 10.1128/mbio.03328-19] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 01/03/2020] [Indexed: 12/23/2022] Open
Abstract
Type IV secretion systems (T4SSs) are sophisticated nanomachines used by many bacterial pathogens to translocate protein and DNA substrates across a host cell membrane. Although T4SSs have important roles in promoting bacterial infections, little is known about the biogenesis of the apparatus and the mechanism of substrate transfer. Here, high-throughput cryoelectron tomography (cryo-ET) was used to visualize Legionella pneumophila T4SSs (also known as Dot/Icm secretion machines) in both the whole-cell context and at the cell pole. These data revealed the distribution patterns of individual Dot/Icm machines in the bacterial cell and identified five distinct subassembled intermediates. High-resolution in situ structures of the Dot/Icm machine derived from subtomogram averaging revealed that docking of the cytoplasmic DotB (VirB11-related) ATPase complex onto the DotO (VirB4-related) ATPase complex promotes a conformational change in the secretion system that results in the opening of a channel in the bacterial inner membrane. A model is presented for how the Dot/Icm apparatus is assembled and for how this machine may initiate the transport of cytoplasmic substrates across the inner membrane.IMPORTANCE Many bacteria use type IV secretion systems (T4SSs) to translocate proteins and nucleic acids into target cells, which promotes DNA transfer and host infection. The Dot/Icm T4SS in Legionella pneumophila is a multiprotein nanomachine that is known to translocate over 300 different protein effectors into eukaryotic host cells. Here, advanced cryoelectron tomography and subtomogram analysis were used to visualize the Dot/Icm machine assembly and distribution in a single L. pneumophila cell. Extensive classification and averaging revealed five distinct intermediates of the Dot/Icm machine at high resolution. Comparative analysis of the Dot/Icm machine and subassemblies derived from wild-type cells and several mutants provided a structural basis for understanding mechanisms that underlie the assembly and activation of the Dot/Icm machine.
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Affiliation(s)
- Donghyun Park
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, USA
| | - David Chetrit
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Bo Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Craig R Roy
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, USA
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Ono S, Nakayama M, Tachibana M, Shahriar ASM, Heling W, Takashiba S, Ohara N. Construction and Characterization of a PGN_0297 Mutant of Porphyromonas gingivalis: Evidence of the Contribution of PGN_0297 to Gingipain Activity. Acta Med Okayama 2020; 73:315-323. [PMID: 31439954 DOI: 10.18926/amo/56933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The periodontal pathogen Porphyromonas gingivalis shows colonial pigmentation on blood agar and produces gingipains (Kgp, RgpA, and RgpB), cysteine proteases involved in an organism's virulence and pigmentation. We showed previously that deletion of the PGN_0300 gene abolished the pigmentation activity and reduced the proteolytic activity of gingipains. The role of the PGN_0297 gene, which consists of an operon with the PGN_0300 gene, is unclear. Herein we examined the effect of PGN_0297 gene deletion on the pigmentation and proteolytic activities and transcriptional levels of gingipains. A PGN_0297 gene deletion mutant (ΔPGN_0297) did not exhibit the pigmentation. The proteolytic activity of the gingipains was decreased in the culture supernatant and on the cell surface of ΔPGN_0297. The mutant ΔPGN_0297 failed to attenuate Akt phosphorylation at Thr308 and Ser473, but both phosphorylations were attenuated in the wild-type and its complementation strain. The deletion of PGN_0297 gene did not substantially affect the transcriptional levels of the gingipain genes kgp, rgpA, and rgpB. Taken together, these results indicate that PGN_0297 is closely involved in the secretion and maturation of gingipains.
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Affiliation(s)
- Shintaro Ono
- Department of Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Masaaki Nakayama
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.,Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama 700-8558, Japan
| | - Masato Tachibana
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Abu Saleh Muhammad Shahriar
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Wang Heling
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Shogo Takashiba
- Department of Periodontal Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Naoya Ohara
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.,Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University Okayama 700-8558, Japan
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35
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Poweleit N, Czudnochowski N, Nakagawa R, Trinidad DD, Murphy KC, Sassetti CM, Rosenberg OS. The structure of the endogenous ESX-3 secretion system. eLife 2019; 8:52983. [PMID: 31886769 PMCID: PMC6986878 DOI: 10.7554/elife.52983] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/30/2019] [Indexed: 12/15/2022] Open
Abstract
The ESX (or Type VII) secretion systems are protein export systems in mycobacteria and many Gram-positive bacteria that mediate a broad range of functions including virulence, conjugation, and metabolic regulation. These systems translocate folded dimers of WXG100-superfamily protein substrates across the cytoplasmic membrane. We report the cryo-electron microscopy structure of an ESX-3 system, purified using an epitope tag inserted with recombineering into the chromosome of the model organism Mycobacterium smegmatis. The structure reveals a stacked architecture that extends above and below the inner membrane of the bacterium. The ESX-3 protomer complex is assembled from a single copy of the EccB3, EccC3, and EccE3 and two copies of the EccD3 protein. In the structure, the protomers form a stable dimer that is consistent with assembly into a larger oligomer. The ESX-3 structure provides a framework for further study of these important bacterial transporters.
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Affiliation(s)
- Nicole Poweleit
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
| | - Nadine Czudnochowski
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
| | - Rachel Nakagawa
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States
| | - Donovan D Trinidad
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
| | - Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Christopher M Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Oren S Rosenberg
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
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36
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Hernández-Robles MF, Álvarez-Contreras AK, Juárez-García P, Natividad-Bonifacio I, Curiel-Quesada E, Vázquez-Salinas C, Quiñones-Ramírez EI. Virulence factors and antimicrobial resistance in environmental strains of Vibrio alginolyticus. Int Microbiol 2018; 19:191-198. [PMID: 28504816 DOI: 10.2436/20.1501.01.277] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 11/15/2016] [Indexed: 11/15/2022]
Abstract
Vibrio alginolyticus has acquired increasing importance because this microorganism may be pathogenic to aquatic animals and humans. It has been reported that some V. alginolyticus strains carry virulence genes derived from pathogenic V. cholerae and V. parahaemolyticus strains. In this work V. alginolyticus was isolated from oyster samples acquired from a food-market in Mexico City. Thirty isolates were identified as V. alginolitycus. Strains showed β-haemolysis and proteolytic activity and produced a capsule. Strains displayed swimming and swarming motility and 93.3% of them produced siderophores. Several genes encoding virulence factors were detected using PCR amplification. These included proA, wza, vopD, vopB, hcp, vasH and vgrG genes, which were present in all strains. Other genes had a variable representation: tdh (86.6%), lafA (96.6%), pvsA (62%) and pvuA (16%). The trh gene could not be amplified from any of the strains. The antimicrobial resistance profile revealed that more than 90% of the strains were resistant to beta-lactams antibiotics, 60% to cephalotin, 45% to amikacin, 16% to cephotaxime, and 10% to pefloxacin, while 100% were susceptible to ceftriaxone. The V. alginolyticus strains isolated from oysters showed multiple resistance to antibiotics and several virulence factors described in well-characterized pathogenic vibrios. [Int Microbiol 19(4):191-198 (2016)].
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Affiliation(s)
- Marcos F Hernández-Robles
- Department of Microbiology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Ana K Álvarez-Contreras
- Department of Microbiology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Patricia Juárez-García
- Department of Microbiology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Iván Natividad-Bonifacio
- Department of Microbiology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Everardo Curiel-Quesada
- Department of Biochemistry, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Carlos Vázquez-Salinas
- Department of Biotechnology, Division of Biological Sciences and of the Health, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, Mexico
| | - Elsa I Quiñones-Ramírez
- Department of Microbiology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
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Hepp C, Maier B. Bacterial Translocation Ratchets: Shared Physical Principles with Different Molecular Implementations: How bacterial secretion systems bias Brownian motion for efficient translocation of macromolecules. Bioessays 2017; 39. [PMID: 28895164 DOI: 10.1002/bies.201700099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/02/2017] [Indexed: 12/20/2022]
Abstract
Secretion systems enable bacteria to import and secrete large macromolecules including DNA and proteins. While most components of these systems have been identified, the molecular mechanisms of macromolecular transport remain poorly understood. Recent findings suggest that various bacterial secretion systems make use of the translocation ratchet mechanism for transporting polymers across the cell envelope. Translocation ratchets are powered by chemical potential differences generated by concentration gradients of ions or molecules that are specific to the respective secretion systems. Bacteria employ these potential differences for biasing Brownian motion of the macromolecules within the conduits of the secretion systems. Candidates for this mechanism include DNA import by the type II secretion/type IV pilus system, DNA export by the type IV secretion system, and protein export by the type I secretion system. Here, we propose that these three secretion systems employ different molecular implementations of the translocation ratchet mechanism.
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Affiliation(s)
- Christof Hepp
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
| | - Berenike Maier
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
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38
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Muangsombut V, Withatanung P, Srinon V, Chantratita N, Stevens MP, Blackwell JM, Korbsrisate S. Burkholderia pseudomallei Evades Nramp1 (Slc11a1)- and NADPH Oxidase-Mediated Killing in Macrophages and Exhibits Nramp1-Dependent Virulence Gene Expression. Front Cell Infect Microbiol 2017; 7:350. [PMID: 28848712 PMCID: PMC5550678 DOI: 10.3389/fcimb.2017.00350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 07/21/2017] [Indexed: 02/02/2023] Open
Abstract
Bacterial survival in macrophages can be affected by the natural resistance-associated macrophage protein 1 (Nramp1; also known as solute carrier family 11 member a1 or Slc11a1) which localizes to phagosome membranes and transports divalent cations, including iron. Little is known about the role of Nramp1 in Burkholderia infection, in particular whether this differs for pathogenic species like Burkholderia pseudomallei causing melioidosis or non-pathogenic species like Burkholderia thailandensis. Here we show that transfected macrophages stably expressing wild-type Nramp1 (Nramp1+) control the net replication of B. thailandensis, but not B. pseudomallei. Control of B. thailandensis was associated with increased cytokine responses, and could be abrogated by blocking NADPH oxidase-mediated production of reactive oxygen species but not by blocking generation of reactive nitrogen species. The inability of Nramp1+ macrophages to control B. pseudomallei was associated with rapid escape of bacteria from phagosomes, as indicated by decreased co-localization with LAMP1 compared to B. thailandensis. A B. pseudomallei bipB mutant impaired in escape from phagosomes was controlled to a greater extent than the parent strain in Nramp1+ macrophages, but was also attenuated in Nramp1− cells. Consistent with reduced escape from phagosomes, B. thailandensis formed fewer multinucleated giant cells in Nramp1+ macrophages at later time points compared to B. pseudomallei. B. pseudomallei exhibited elevated transcription of virulence-associated genes of Type VI Secretion System cluster 1 (T6SS-1), the Bsa Type III Secretion System (T3SS-3) and the bimA gene required for actin-based motility in Nramp1+ macrophages. Nramp1+ macrophages were found to contain decreased iron levels that may impact on expression of such genes. Our data show that B. pseudomallei is able to evade Nramp1- and NADPH oxidase-mediated killing in macrophages and that expression of virulence-associated genes by pathogenic B pseudomallei is enhanced in macrophages expressing wild-type compared to non-functional Nramp1. B. thailandensis has been proposed as surrogate for B. pseudomallei in the study of melioidosis however our study highlights important differences in the interaction of these bacteria with macrophages.
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Affiliation(s)
- Veerachat Muangsombut
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol UniversityBangkok, Thailand
| | - Patoo Withatanung
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol UniversityBangkok, Thailand
| | - Varintip Srinon
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol UniversityBangkok, Thailand.,Microbiology Laboratory, Veterinary Diagnostic Center, Faculty of Veterinary Science, Mahidol UniversityNakhon Pathom, Thailand
| | - Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol UniversityBangkok, Thailand
| | - Mark P Stevens
- Division of Infection and Immunity, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of EdinburghMidlothian, United Kingdom
| | - Jenefer M Blackwell
- Telethon Kids Institute, The University of Western AustraliaSubiaco, WA, Australia.,Department of Pathology, University of CambridgeCambridge, United Kingdom
| | - Sunee Korbsrisate
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol UniversityBangkok, Thailand
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39
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Zeytuni N, Hong C, Flanagan KA, Worrall LJ, Theiltges KA, Vuckovic M, Huang RK, Massoni SC, Camp AH, Yu Z, Strynadka NC. Near-atomic resolution cryoelectron microscopy structure of the 30-fold homooligomeric SpoIIIAG channel essential to spore formation in Bacillus subtilis. Proc Natl Acad Sci U S A 2017; 114:E7073-81. [PMID: 28784753 DOI: 10.1073/pnas.1704310114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Bacterial sporulation allows starving cells to differentiate into metabolically dormant spores that can survive extreme conditions. Following asymmetric division, the mother cell engulfs the forespore, surrounding it with two bilayer membranes. During the engulfment process, an essential channel, the so-called feeding tube apparatus, is thought to cross both membranes to create a direct conduit between the mother cell and the forespore. At least nine proteins are required to create this channel, including SpoIIQ and SpoIIIAA-AH. Here, we present the near-atomic resolution structure of one of these proteins, SpoIIIAG, determined by single-particle cryo-EM. A 3D reconstruction revealed that SpoIIIAG assembles into a large and stable 30-fold symmetric complex with a unique mushroom-like architecture. The complex is collectively composed of three distinctive circular structures: a 60-stranded vertical β-barrel that forms a large inner channel encircled by two concentric rings, one β-mediated and the other formed by repeats of a ring-building motif (RBM) common to the architecture of various dual membrane secretion systems of distinct function. Our near-atomic resolution structure clearly shows that SpoIIIAG exhibits a unique and dramatic adaptation of the RBM fold with a unique β-triangle insertion that assembles into the prominent channel, the dimensions of which suggest the potential passage of large macromolecules between the mother cell and forespore during the feeding process. Indeed, mutation of residues located at key interfaces between monomers of this RBM resulted in severe defects both in vivo and in vitro, providing additional support for this unprecedented structure.
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40
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Abstract
The lytic transglycosylases (LTs) are bacterial enzymes that catalyze the non-hydrolytic cleavage of the peptidoglycan structures of the bacterial cell wall. They are not catalysts of glycan synthesis as might be surmised from their name. Notwithstanding the seemingly mundane reaction catalyzed by the LTs, their lytic reactions serve bacteria for a series of astonishingly diverse purposes. These purposes include cell-wall synthesis, remodeling, and degradation; for the detection of cell-wall-acting antibiotics; for the expression of the mechanism of cell-wall-acting antibiotics; for the insertion of secretion systems and flagellar assemblies into the cell wall; as a virulence mechanism during infection by certain Gram-negative bacteria; and in the sporulation and germination of Gram-positive spores. Significant advances in the mechanistic understanding of each of these processes have coincided with the successive discovery of new LTs structures. In this review, we provide a systematic perspective on what is known on the structure-function correlations for the LTs, while simultaneously identifying numerous opportunities for the future study of these enigmatic enzymes.
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Affiliation(s)
- David A Dik
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
| | - Daniel R Marous
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
| | - Jed F Fisher
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
| | - Shahriar Mobashery
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
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41
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Santin YG, Cascales E. Domestication of a housekeeping transglycosylase for assembly of a Type VI secretion system. EMBO Rep 2016; 18:138-149. [PMID: 27920034 DOI: 10.15252/embr.201643206] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 10/27/2016] [Accepted: 10/28/2016] [Indexed: 01/06/2023] Open
Abstract
The type VI secretion system (T6SS) is an anti-bacterial weapon comprising a contractile tail anchored to the cell envelope by a membrane complex. The TssJ, TssL, and TssM proteins assemble a 1.7-MDa channel complex that spans the cell envelope, including the peptidoglycan layer. The electron microscopy structure of the TssJLM complex revealed that it has a diameter of ~18 nm in the periplasm, which is larger than the size of peptidoglycan pores (~2 nm), hence questioning how the T6SS membrane complex crosses the peptidoglycan layer. Here, we report that the MltE housekeeping lytic transglycosylase (LTG) is required for T6SS assembly in enteroaggregative Escherichia coli Protein-protein interaction studies further demonstrated that MltE is recruited to the periplasmic domain of TssM. In addition, we show that TssM significantly stimulates MltE activity in vitro and that MltE is required for the late stages of T6SS membrane complex assembly. Collectively, our data provide the first example of domestication and activation of a LTG encoded within the core genome for the assembly of a secretion system.
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Affiliation(s)
- Yoann G Santin
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Univ - CNRS, Marseille Cedex 20, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Univ - CNRS, Marseille Cedex 20, France
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42
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Stanger FV, de Beer TAP, Dranow DM, Schirmer T, Phan I, Dehio C. The BID Domain of Type IV Secretion Substrates Forms a Conserved Four-Helix Bundle Topped with a Hook. Structure 2016; 25:203-211. [PMID: 27889208 DOI: 10.1016/j.str.2016.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/07/2016] [Accepted: 10/25/2016] [Indexed: 10/20/2022]
Abstract
The BID (Bep intracellular delivery) domain functions as secretion signal in a subfamily of protein substrates of bacterial type IV secretion (T4S) systems. It mediates transfer of (1) relaxases and the attached DNA during bacterial conjugation, and (2) numerous Bartonella effector proteins (Beps) during protein transfer into host cells infected by pathogenic Bartonella species. Furthermore, BID domains of Beps have often evolved secondary effector functions within host cells. Here, we provide crystal structures for three representative BID domains and describe a novel conserved fold characterized by a compact, antiparallel four-helix bundle topped with a hook. The conserved hydrophobic core provides a rigid scaffold to a surface that, despite a few conserved exposed residues and similarities in charge distribution, displays significant variability. We propose that the genuine function of BID domains as T4S signal may primarily depend on their rigid structure, while the plasticity of their surface may facilitate adaptation to secondary effector functions.
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Affiliation(s)
- Frédéric V Stanger
- Focal Area Infection Biology, Biozentrum University of Basel, 4056 Basel, Switzerland; Focal Area Structural Biology and Biophysics, Biozentrum University of Basel, 4056 Basel, Switzerland
| | - Tjaart A P de Beer
- Focal Area Infection Biology, Biozentrum University of Basel, 4056 Basel, Switzerland
| | - David M Dranow
- Seattle Structural Genomics Center for Infectious Disease, The Center for Infectious Disease Research, Seattle, WA 98109, USA; Beryllium Discovery Corp., Bainbridge Island, WA 98110, USA
| | - Tilman Schirmer
- Focal Area Structural Biology and Biophysics, Biozentrum University of Basel, 4056 Basel, Switzerland.
| | - Isabelle Phan
- Seattle Structural Genomics Center for Infectious Disease, The Center for Infectious Disease Research, Seattle, WA 98109, USA
| | - Christoph Dehio
- Focal Area Infection Biology, Biozentrum University of Basel, 4056 Basel, Switzerland.
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Duarte CM, Basile LA, Zalguizuri A, Lepek VC. The transcriptional factor TtsI is involved in a negative regulation of swimming motility in Mesorhizobium loti MAFF303099. FEMS Microbiol Lett 2016; 363:fnw222. [PMID: 27664056 DOI: 10.1093/femsle/fnw222] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/13/2016] [Accepted: 09/16/2016] [Indexed: 01/10/2023] Open
Abstract
Mesorhizobium loti MAFF303099 has a functional Type III secretion system (T3SS) that is involved in the determination of competitiveness for legume nodulation. Here we demonstrate that the transcriptional factor TtsI, which positively regulates T3SS genes expression, is involved in a negative regulation of M. loti swimming motility in soft-agar. Conditions that induce T3SS expression affect flagella production. The same conditions also affect promoter activity of M. loti visN gene, a homolog to the positive regulator of flagellar genes that has been described in other rhizobia. Defects in T3SS complex assembly at membranes limited the negative regulation of motility by the expression of TtsI.
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44
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Goodwin IP, Kumova OK, Ninio S. A conserved OmpA-like protein in Legionella pneumophila required for efficient intracellular replication. FEMS Microbiol Lett 2016; 363:fnw173. [PMID: 27421957 PMCID: PMC7108532 DOI: 10.1093/femsle/fnw173] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2016] [Indexed: 02/07/2023] Open
Abstract
The OmpA-like protein domain has been associated with peptidoglycan-binding proteins, and is often found in virulence factors of bacterial pathogens. The intracellular pathogen Legionella pneumophila encodes for six proteins that contain the OmpA-like domain, among them the highly conserved uncharacterized protein we named CmpA. Here we set out to characterize the CmpA protein and determine its contribution to intracellular survival of L. pneumophila. Secondary structure analysis suggests that CmpA is an inner membrane protein with a peptidoglycan-binding domain at the C-teminus. A cmpA mutant was able to replicate normally in broth, but failed to compete with an isogenic wild-type strain in an intracellular growth competition assay. The cmpA mutant also displayed significant intracellular growth defects in both the protozoan host Acanthamoeba castellanii and in primary bone marrow-derived macrophages, where uptake into the cells was also impaired. The cmpA phenotypes were completely restored upon expression of CmpA in trans. The data presented here establish CmpA as a novel virulence factor of L. pneumophila that is required for efficient intracellular replication in both mammalian and protozoan hosts. CmpA is an OmpA-like protein in Legionella pneumophila that is required for efficient intracellular replication in both primary macrophages and in the environmental host Acanthamoeba castellanii.
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Affiliation(s)
- Ian P Goodwin
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Ogan K Kumova
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Shira Ninio
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA 19129, USA The Yigal Allon Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, Migdal 14950, Israel
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45
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Lina TT, Farris T, Luo T, Mitra S, Zhu B, McBride JW. Hacker within! Ehrlichia chaffeensis Effector Driven Phagocyte Reprogramming Strategy. Front Cell Infect Microbiol 2016; 6:58. [PMID: 27303657 PMCID: PMC4885862 DOI: 10.3389/fcimb.2016.00058] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/17/2016] [Indexed: 01/02/2023] Open
Abstract
Ehrlichia chaffeensis is a small, gram negative, obligately intracellular bacterium that preferentially infects mononuclear phagocytes. It is the etiologic agent of human monocytotropic ehrlichiosis (HME), an emerging life-threatening tick-borne zoonosis. Mechanisms by which E. chaffeensis establishes intracellular infection, and avoids host defenses are not well understood, but involve functionally relevant host-pathogen interactions associated with tandem and ankyrin repeat effector proteins. In this review, we discuss the recent advances in our understanding of the molecular and cellular mechanisms that underlie Ehrlichia host cellular reprogramming strategies that enable intracellular survival.
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Affiliation(s)
- Taslima T Lina
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Tierra Farris
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Shubhajit Mitra
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Bing Zhu
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Jere W McBride
- Department of Pathology, University of Texas Medical BranchGalveston, TX, USA; Department of Microbiology and Immunology, University of Texas Medical BranchGalveston, TX, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical BranchGalveston, TX, USA; Sealy Center for Vaccine Development, University of Texas Medical BranchGalveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical BranchGalveston, TX, USA
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Zoltner M, Ng WM, Money JJ, Fyfe PK, Kneuper H, Palmer T, Hunter WN. EssC: domain structures inform on the elusive translocation channel in the Type VII secretion system. Biochem J 2016; 473:1941-52. [PMID: 27130157 DOI: 10.1042/BCJ20160257] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 04/29/2016] [Indexed: 11/30/2022]
Abstract
Structural dissection of EssC, a membrane-bound component of the bacterial Type VII secretion system, reveals two β-sandwich domains at the N-terminus and two ATPase domains at the C-terminus. A structure for the potential pore of the secretion system is proposed. The membrane-bound protein EssC is an integral component of the bacterial Type VII secretion system (T7SS), which is a determinant of virulence in important Gram-positive pathogens. The protein is predicted to consist of an intracellular repeat of forkhead-associated (FHA) domains at the N-terminus, two transmembrane helices and three P-loop-containing ATPase-type domains, D1–D3, forming the C-terminal intracellular segment. We present crystal structures of the N-terminal FHA domains (EssC-N) and a C-terminal fragment EssC-C from Geobacillus thermodenitrificans, encompassing two of the ATPase-type modules, D2 and D3. Module D2 binds ATP with high affinity whereas D3 does not. The EssC-N and EssC-C constructs are monomeric in solution, but the full-length recombinant protein, with a molecular mass of approximately 169 kDa, forms a multimer of approximately 1 MDa. The observation of protomer contacts in the crystal structure of EssC-C together with similarity to the DNA translocase FtsK, suggests a model for a hexameric EssC assembly. Such an observation potentially identifies the key, and to date elusive, component of pore formation required for secretion by this recently discovered secretion system. The juxtaposition of the FHA domains suggests potential for interacting with other components of the secretion system. The structural data were used to guide an analysis of which domains are required for the T7SS machine to function in pathogenic Staphylococcus aureus. The extreme C-terminal ATPase domain appears to be essential for EssC activity as a key part of the T7SS, whereas D2 and FHA domains are required for the production of a stable and functional protein.
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Yan S, Wu G. Evolutionary evidence on suitability of SecD as a target for development of antibacterial agents against Staphylococcus aureus. Ecol Evol 2016; 6:1393-410. [PMID: 27087922 PMCID: PMC4775529 DOI: 10.1002/ece3.1951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 11/22/2022] Open
Abstract
Staphylococcus aureus causes many infections and its drug resistance is a worrying challenge for medical care. The SecD subunit of Sec secretion system in methicillin‐resistant S. aureus is an attractive target because SecD dysfunction leads to the death of bacteria and SecD as a target is more efficient than SecA and SecF. Evolution could have made SecD to become insensitive to antibacterial agents although the drugs directly against SecD have yet to develop. So far, no detailed information on SecD evolution has been available, thus 2686 SecD sequences with full taxonomic information from kingdom to species were analyzed. First, the variance of pairwise p‐distance was evaluated for each taxonomic group. Second, the variance was further partitioned into intergroup and intragroup variances for quantification of horizontal and vertical gene transfer. Third, phylogenetic tree was built to trace the evolutionary pathway. The results showed that overall evolution of SecDs appears to have undergone horizontal and vertical gene transfer. Only 0.5% horizontal transfers were found between any two SecDs in S. aureus, 6.8% and 8.8% horizontal transfers were found between any two Staphylococcus SecDs from different and the same species, and only one SecD from S. aureus was located far away from its sister cluster. Thus, statistic and evolutionary analyses demonstrate that the SecDs from staphylococcus species have a small chance of mutating, and provide taxonomic evidence to use the SecD as a potential target for new generation of antibacterial agents against S. aureus.
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Affiliation(s)
- Shaomin Yan
- Guangxi Bioscience and Biotechnology Research Center Guangxi Academy of Sciences 98 Daling Road Nanning Guangxi 530007 China
| | - Guang Wu
- Guangxi Bioscience and Biotechnology Research Center Guangxi Academy of Sciences 98 Daling Road Nanning Guangxi 530007 China
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Abstract
The actin cytoskeleton is a key target of numerous microbial pathogens, including protozoa, fungi, bacteria and viruses. In particular, bacterial pathogens produce and deliver virulence effector proteins that hijack actin dynamics to enable bacterial invasion of host cells, allow movement within the host cytosol, facilitate intercellular spread or block phagocytosis. Many of these effector proteins directly or indirectly target the major eukaryotic actin nucleator, the Arp2/3 complex, by either mimicking nucleation promoting factors or activating upstream small GTPases. In contrast, this review is focused on a recently identified class of effector proteins from Gram-negative bacteria that function as direct actin nucleators. These effector proteins mimic functional activities of formins, WH2-nucleators and Ena/VASP assembly promoting factors demonstrating that bacteria have coopted the complete set of eukaryotic actin assembly pathways. Structural and functional analyses of these nucleators have revealed several motifs and/or mechanistic activities that are shared with eukaryotic actin nucleators. However, functional effects of these proteins during infection extend beyond plain actin polymerization leading to interference with other host cell functions such as vesicle trafficking, cell cycle progression and cell death. Therefore, their use as model systems could not only help in the understanding of the mechanistic details of actin polymerization but also provide novel insights into the connection between actin dynamics and other cellular pathways.
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Affiliation(s)
- Joana N Bugalhão
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Luís Jaime Mota
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Irina S Franco
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-157 Oeiras, Portugal
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Yu Y, Fang L, Zhang Y, Sheng H, Fang W. VgrG2 of type VI secretion system 2 of Vibrio parahaemolyticus induces autophagy in macrophages. Front Microbiol 2015; 6:168. [PMID: 25784905 PMCID: PMC4345815 DOI: 10.3389/fmicb.2015.00168] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/13/2015] [Indexed: 12/21/2022] Open
Abstract
Type VI secretion system (T6SS) is a macromolecular transenvelope machine encoded within the genomes of several proteobacteria species. Vibrio parahaemolyticus contains two putative T6SS systems, VpT6SS1 and VpT6SS2, both contributing to adherence to Caco-2 and/or HeLa cells. However, it remains unknown if these systems are involved in cellular responses. In order to exclude the effects of other virulence factors known to induce cytotoxicity or autophagy, a triple deletion mutant dTTT (with deletion of tdh, and T3SS1 and T3SS2 structural protein genes) was used as the parent strain to construct deletion mutants of T6SS genes. The mutant dTTT-ΔicmF2, but not dTTT-ΔicmF1, reduced autophagic response upon 4 h of infection of the macrophage. Further attempt was made to search for the possible effector proteins that might be responsible for direct induction of autophagy by deletion of the genes encoding Hcp2 and VgrG2, two putative translocons of T6SS2 of V. parahaemolyticus. Deletion of either hcp2 or vgrG2 did reduce the autophagic response. However, increased LC3-II lipidation was seen only in the macrophage cells transfected with pVgrG2, but not with pHcp2. Chloroquinine treatment increased accumulation of LC3-II, suggesting that VgrG2 enhanced autophagic flux. The fact that vgrG2 deletion led to reduced level of intracellular cAMP suggests a possible role of cAMP signaling in autophagic responses to the bacterium. We conclude that VgrG2 of V. parahaemolyticus induces autophagy in macrophages.
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Affiliation(s)
- Ying Yu
- Institute of Health Food, Zhejiang Academy of Medical Sciences, Hangzhou, China ; Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
| | - Lihua Fang
- Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
| | - Yan Zhang
- Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
| | - Hongxia Sheng
- Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
| | - Weihuan Fang
- Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
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Mercante V, Duarte CM, Sánchez CM, Zalguizuri A, Caetano-Anollés G, Lepek VC. The absence of protein Y4yS affects negatively the abundance of T3SS Mesorhizobium loti secretin, RhcC2, in bacterial membranes. Front Plant Sci 2015; 6:12. [PMID: 25688250 PMCID: PMC4311626 DOI: 10.3389/fpls.2015.00012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 01/06/2015] [Indexed: 06/04/2023]
Abstract
Mesorhizobium loti MAFF303099 has a functional type III secretion system (T3SS) that is involved in the determination of nodulation competitiveness on Lotus. The M. loti T3SS cluster contains gene y4yS (mlr8765) that codes for a protein of unknown function (Y4yS). A mutation in the y4yS gene favors the M. loti symbiotic competitive ability on Lotus tenuis cv. Esmeralda and affects negatively the secretion of proteins through T3SS. Here we localize Y4yS in the bacterial membrane using a translational reporter peptide fusion. In silico analysis indicated that this protein presents a tetratricopeptide repeat (TPR) domain, a signal peptide and a canonical lipobox LGCC in the N-terminal sequence. These features that are shared with proteins required for the formation of the secretin complex in type IV secretion systems and in the Tad system, together with its localization, suggest that the y4yS-encoded protein is required for the formation of the M. loti T3SS secretin (RhcC2) complex. Remarkably, analysis of RhcC2 in the wild-type and M. loti y4yS mutant strains indicated that the absence of Y4yS affects negatively the accumulation of normal levels of RhcC2 in the membrane.
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Affiliation(s)
- Virginia Mercante
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde,” Universidad Nacional de San MartínBuenos Aires, Argentina
| | - Cecilia M. Duarte
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde,” Universidad Nacional de San MartínBuenos Aires, Argentina
| | - Cintia M. Sánchez
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde,” Universidad Nacional de San MartínBuenos Aires, Argentina
| | - Andrés Zalguizuri
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde,” Universidad Nacional de San MartínBuenos Aires, Argentina
| | - Gustavo Caetano-Anollés
- Evolutionary Bioinformatics Laboratory, Department of Crop Sciences, University of IllinoisUrbana-Champaign, USA
| | - Viviana C. Lepek
- Instituto de Investigaciones Biotecnológicas “Dr. Rodolfo A. Ugalde,” Universidad Nacional de San MartínBuenos Aires, Argentina
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