101
|
White RC, Cianciotto NP. Assessing the impact, genomics and evolution of type II secretion across a large, medically important genus: the Legionella type II secretion paradigm. Microb Genom 2019; 5. [PMID: 31166887 PMCID: PMC6617341 DOI: 10.1099/mgen.0.000273] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The type II secretion system (T2SS) plays a major role in promoting bacterial survival in the environment and in human hosts. One of the best characterized T2SS is that of Legionella pneumophila, the agent of Legionnaires’ disease. Secreting at least 25 proteins, including degradative enzymes, eukaryotic-like proteins and novel effectors, this T2SS contributes to the ability of L. pneumophila to grow at low temperatures, infect amoebal and macrophage hosts, damage lung tissue, evade the immune system, and undergo sliding motility. The genes encoding the T2SS are conserved across the genus Legionella, which includes 62 species and >30 pathogens in addition to L. pneumophila. The vast majority of effectors associated with L. pneumophila are shared by a large number of Legionella species, hinting at a critical role for them in the ecology of Legionella as a whole. However, no other species has the same repertoire as L. pneumophila, with, as a general rule, phylogenetically more closely related species sharing similar sets of effectors. T2SS effectors that are involved in infection of a eukaryotic host(s) are more prevalent throughout Legionella, indicating that they are under stronger selective pressure. The Legionella T2SS apparatus is closest to that of Aquicella (another parasite of amoebae), and a significant number of L. pneumophila effectors have their closest homologues in Aquicella. Thus, the T2SS of L. pneumophila probably originated within the order Legionellales, with some of its effectors having arisen within that Aquicella-like progenitor, while other effectors derived from the amoebal host, mimiviruses, fungi and less closely related bacteria.
Collapse
Affiliation(s)
- Richard C White
- 1 Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, IL 60611, USA
| | - Nicholas P Cianciotto
- 1 Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, IL 60611, USA
| |
Collapse
|
102
|
Howard SP, Estrozi LF, Bertrand Q, Contreras-Martel C, Strozen T, Job V, Martins A, Fenel D, Schoehn G, Dessen A. Structure and assembly of pilotin-dependent and -independent secretins of the type II secretion system. PLoS Pathog 2019; 15:e1007731. [PMID: 31083688 PMCID: PMC6532946 DOI: 10.1371/journal.ppat.1007731] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 05/23/2019] [Accepted: 03/26/2019] [Indexed: 01/09/2023] Open
Abstract
The type II secretion system (T2SS) is a cell envelope-spanning macromolecular complex that is prevalent in Gram-negative bacterial species. It serves as the predominant virulence mechanism of many bacteria including those of the emerging human pathogens Vibrio vulnificus and Aeromonas hydrophila. The system is composed of a core set of highly conserved proteins that assemble an inner membrane platform, a periplasmic pseudopilus and an outer membrane complex termed the secretin. Localization and assembly of secretins in the outer membrane requires recognition of secretin monomers by two different partner systems: an inner membrane accessory complex or a highly sequence-diverse outer membrane lipoprotein, termed the pilotin. In this study, we addressed the question of differential secretin assembly mechanisms by using cryo-electron microscopy to determine the structures of the secretins from A. hydrophila (pilotin-independent ExeD) and V. vulnificus (pilotin-dependent EpsD). These structures, at approximately 3.5 Å resolution, reveal pentadecameric stoichiometries and C-terminal regions that carry a signature motif in the case of a pilotin-dependent assembly mechanism. We solved the crystal structure of the V. vulnificus EpsS pilotin and confirmed the importance of the signature motif for pilotin-dependent secretin assembly by performing modelling with the C-terminus of EpsD. We also show that secretin assembly is essential for membrane integrity and toxin secretion in V. vulnificus and establish that EpsD requires the coordinated activity of both the accessory complex EpsAB and the pilotin EpsS for full assembly and T2SS function. In contrast, mutation of the region of the S-domain that is normally the site of pilotin interactions has little effect on assembly or function of the ExeD secretin. Since secretins are essential outer membrane channels present in a variety of secretion systems, these results provide a structural and functional basis for understanding the key assembly steps for different members of this vast pore-forming family of proteins.
Collapse
Affiliation(s)
- S. Peter Howard
- Dept. Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Leandro F. Estrozi
- Univ Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Quentin Bertrand
- Univ Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | | | - Timothy Strozen
- Dept. Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Viviana Job
- Univ Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Alexandre Martins
- Univ Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Daphna Fenel
- Univ Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Guy Schoehn
- Univ Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Andréa Dessen
- Univ Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), Grenoble, France
- Brazilian Biosciences National Laboratory (LNBio), CNPEM, Campinas, São Paulo, Brazil
| |
Collapse
|
103
|
Roach R, Mann R, Gambley CG, Chapman T, Shivas RG, Rodoni B. Genomic sequence analysis reveals diversity of Australian Xanthomonas species associated with bacterial leaf spot of tomato, capsicum and chilli. BMC Genomics 2019; 20:310. [PMID: 31014247 PMCID: PMC6480910 DOI: 10.1186/s12864-019-5600-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 03/12/2019] [Indexed: 01/03/2023] Open
Abstract
Background The genetic diversity in Australian populations of Xanthomonas species associated with bacterial leaf spot in tomato, capsicum and chilli were compared to worldwide bacterial populations. The aim of this study was to confirm the identities of these Australian Xanthomonas species and classify them in comparison to overseas isolates. Analysis of whole genome sequence allows for the investigation of bacterial population structure, pathogenicity and gene exchange, resulting in better management strategies and biosecurity. Results Phylogenetic analysis of the core genome alignments and SNP data grouped strains in distinct clades. Patterns observed in average nucleotide identity, pan genome structure, effector and carbohydrate active enzyme profiles reflected the whole genome phylogeny and highlight taxonomic issues in X. perforans and X. euvesicatoria. Circular sequences with similarity to previously characterised plasmids were identified, and plasmids of similar sizes were isolated. Potential false positive and false negative plasmid assemblies were discussed. Effector patterns that may influence virulence on host plant species were analysed in pathogenic and non-pathogenic xanthomonads. Conclusions The phylogeny presented here confirmed X. vesicatoria, X. arboricola, X. euvesicatoria and X. perforans and a clade of an uncharacterised Xanthomonas species shown to be genetically distinct from all other strains of this study. The taxonomic status of X. perforans and X. euvesicatoria as one species is discussed in relation to whole genome phylogeny and phenotypic traits. The patterns evident in enzyme and plasmid profiles indicate worldwide exchange of genetic material with the potential to introduce new virulence elements into local bacterial populations. Electronic supplementary material The online version of this article (10.1186/s12864-019-5600-x) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- R Roach
- Department of Agriculture and Fisheries, Ecosciences Precinct, Brisbane, QLD, Australia. .,Agriculture Victoria Research Division, Department of Economic Development, Jobs, Transport & Resources, AgriBio, La Trobe University, Bundoora, Victoria, 3083, Australia.
| | - R Mann
- Agriculture Victoria Research Division, Department of Economic Development, Jobs, Transport & Resources, AgriBio, La Trobe University, Bundoora, Victoria, 3083, Australia
| | - C G Gambley
- Department of Agriculture and Fisheries, Applethorpe Research Facility, Applethorpe, QLD, Australia
| | - T Chapman
- Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW, Australia
| | - R G Shivas
- Centre for Crop Health, University of Southern Queensland, Toowoomba, QLD, Australia
| | - B Rodoni
- Agriculture Victoria Research Division, Department of Economic Development, Jobs, Transport & Resources, AgriBio, La Trobe University, Bundoora, Victoria, 3083, Australia
| |
Collapse
|
104
|
Skariyachan S, Taskeen N, Ganta M, Venkata Krishna B. Recent perspectives on the virulent factors and treatment options for multidrug-resistant Acinetobacter baumannii. Crit Rev Microbiol 2019; 45:315-333. [PMID: 31012772 DOI: 10.1080/1040841x.2019.1600472] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Acinetobacter baumannii (AB) is one of the most notorious and opportunistic pathogens, which caused high morbidity and mortality rate and World Health Organization (WHO) declared this bacterium as priority-1 pathogen in 2017. The current antibacterial agents, such as colistins, carbapenems, and tigecyclines have limited applications, which necessitate novel and alternative therapeutic remedies. Thus, the understanding of recent perspectives on the virulent factors and antibiotic resistance mechanism exhibited by the bacteria are extremely important. In addition to many combinatorial therapies of antibacterial, there is several natural compounds demonstrated significant antibacterial potential towards these bacteria. The computational systems biology and high throughput screening approaches provide crucial insights in identifying novel drug targets and lead molecules with therapeutics potential. Hence, this review provides profound insight on the recent aspects of the virulent factors associated with AB, role of biofilm formation in drug resistance and the mechanisms of multidrug resistance. This review further illustrates the status of current therapeutic agents, scope, and applications of natural therapeutics, such as herbal medicines and role of computational biology, immunoinformatics and virtual screening in novel lead developments. Thus, this review provides novel insight on latest developments in drug-resistance mechanism of multidrug-resistant A. baumannii (MDRAB) and discovery of probable therapeutic interventions.
Collapse
Affiliation(s)
- Sinosh Skariyachan
- a Department of Biotechnology, Dayananda Sagar College of Engineering , Bangalore , India
| | - Neha Taskeen
- a Department of Biotechnology, Dayananda Sagar College of Engineering , Bangalore , India
| | - Meghana Ganta
- a Department of Biotechnology, Dayananda Sagar College of Engineering , Bangalore , India
| | - Bhavya Venkata Krishna
- a Department of Biotechnology, Dayananda Sagar College of Engineering , Bangalore , India
| |
Collapse
|
105
|
Inhibitors of the Neisseria meningitidis PilF ATPase provoke type IV pilus disassembly. Proc Natl Acad Sci U S A 2019; 116:8481-8486. [PMID: 30948644 DOI: 10.1073/pnas.1817757116] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Despite the availability of antibiotics and vaccines, Neisseria meningitidis remains a major cause of meningitis and sepsis in humans. Due to its extracellular lifestyle, bacterial adhesion to host cells constitutes an attractive therapeutic target. Here, we present a high-throughput microscopy-based approach that allowed the identification of compounds able to decrease type IV pilus-mediated interaction of bacteria with endothelial cells in the absence of bacterial or host cell toxicity. Compounds specifically inhibit the PilF ATPase enzymatic activity that powers type IV pilus extension but remain inefficient on the ATPase that promotes pilus retraction, thus leading to rapid pilus disappearance from the bacterial surface and loss of pili-mediated functions. Structure activity relationship of the most active compound identifies specific moieties required for the activity of this compound and highlights its specificity. This study therefore provides compounds targeting pilus biogenesis, thereby inhibiting bacterial adhesion, and paves the way for a novel therapeutic option for meningococcal infections.
Collapse
|
106
|
Evolutionary Model of Cluster Divergence of the Emergent Marine Pathogen Vibrio vulnificus: From Genotype to Ecotype. mBio 2019; 10:mBio.02852-18. [PMID: 30782660 PMCID: PMC6381281 DOI: 10.1128/mbio.02852-18] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Vibrio vulnificus is an emergent marine pathogen and is the cause of a deadly septicemia. However, the genetic factors that differentiate its clinical and environmental strains and its several biotypes remain mostly enigmatic. In this work, we investigated the underlying genomic properties and population dynamics of the V. vulnificus species to elucidate the traits that make these strains emerge as a human pathogen. The acquisition of different ecological determinants could have allowed the development of highly divergent clusters with different lifestyles within the same environment. However, we identified strains from both clusters in the mucosa of aquaculture species, indicating that manmade niches are bringing strains from the two clusters together, posing a potential risk of recombination and of emergence of novel variants. We propose a new evolutionary model that provides a perspective that could be broadly applicable to other pathogenic vibrios and facultative bacterial pathogens to pursue strategies to prevent their infections. Vibrio vulnificus, an opportunistic pathogen, is the causative agent of a life-threatening septicemia and a rising problem for aquaculture worldwide. The genetic factors that differentiate its clinical and environmental strains remain enigmatic. Furthermore, clinical strains have emerged from every clade of V. vulnificus. In this work, we investigated the underlying genomic properties and population dynamics of the V. vulnificus species from an evolutionary and ecological point of view. Genome comparisons and bioinformatic analyses of 113 V. vulnificus isolates indicate that the population of V. vulnificus is made up of four different clusters. We found evidence that recombination and gene flow between the two largest clusters (cluster 1 [C1] and C2) have drastically decreased to the point where they are diverging independently. Pangenome and phenotypic analyses showed two markedly different lifestyles for these two clusters, indicating commensal (C2) and bloomer (C1) ecotypes, with differences in carbohydrate utilization, defense systems, and chemotaxis, among other characteristics. Nonetheless, we identified frequent intra- and interspecies exchange of mobile genetic elements (e.g., antibiotic resistance plasmids, novel “chromids,” or two different and concurrent type VI secretion systems) that provide high levels of genetic diversity in the population. Surprisingly, we identified strains from both clusters in the mucosa of aquaculture species, indicating that manmade niches are bringing strains from the two clusters together. We propose an evolutionary model of V. vulnificus that could be broadly applicable to other pathogenic vibrios and facultative bacterial pathogens to pursue strategies to prevent their infections and emergence.
Collapse
|
107
|
Gomila M, Moralejo E, Busquets A, Segui G, Olmo D, Nieto A, Juan A, Lalucat J. Draft Genome Resources of Two Strains of Xylella fastidiosa XYL1732/17 and XYL2055/17 Isolated from Mallorca Vineyards. PHYTOPATHOLOGY 2019; 109:222-224. [PMID: 30570447 DOI: 10.1094/phyto-08-18-0298-a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Xylella fastidiosa is a plant-pathogenic bacterium that causes serious diseases in many crops of economic importance and is a quarantine organism in the European Union. This study reports a de novo-assembled draft genome sequence of the first isolates causing Pierce's disease in Europe: X. fastidiosa subsp. fastidiosa strains XYL1732/17 and XYL2055/17. Both strains were isolated from grapevines (Vitis vinifera) showing Pierce's disease symptoms at two different locations in Mallorca, Spain. The XYL1732/17 genome is 2,444,109 bp long, with a G+C content of 51.5%; it contains 2,359 open reading frames and 48 tRNA genes. The XYL2055/17 genome is 2,456,780 bp long, with a G+C content of 51.5%; it contains 2,384 open reading frames and 48 tRNA genes.
Collapse
Affiliation(s)
- Margarita Gomila
- 1 Microbiology (Biology Department), University of the Balearic Islands, 07122 Palma de Mallorca, Spain
| | - Eduardo Moralejo
- 2 Tragsa, Empresa de Transformación Agraria, Delegación de Baleares, 07005 Palma de Mallorca, Spain
| | - Antonio Busquets
- 1 Microbiology (Biology Department), University of the Balearic Islands, 07122 Palma de Mallorca, Spain
| | - Guillem Segui
- 1 Microbiology (Biology Department), University of the Balearic Islands, 07122 Palma de Mallorca, Spain
| | - Diego Olmo
- 3 Serveis de Millora Agrària, Govern Balear, 07009, Palma de Mallorca, Spain; and
| | - Alicia Nieto
- 3 Serveis de Millora Agrària, Govern Balear, 07009, Palma de Mallorca, Spain; and
| | - Andreu Juan
- 4 Servicio de Agricultura, Conselleria de Medi Ambient, Agricultura i Pesca, 07006 Palma de Mallorca, Spain
| | - Jorge Lalucat
- 1 Microbiology (Biology Department), University of the Balearic Islands, 07122 Palma de Mallorca, Spain
| |
Collapse
|
108
|
Ali MM, Provoost A, Maertens L, Leys N, Monsieurs P, Charlier D, Van Houdt R. Genomic and Transcriptomic Changes that Mediate Increased Platinum Resistance in Cupriavidus metallidurans. Genes (Basel) 2019; 10:E63. [PMID: 30669395 PMCID: PMC6357080 DOI: 10.3390/genes10010063] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/11/2019] [Accepted: 01/15/2019] [Indexed: 12/15/2022] Open
Abstract
The extensive anthropogenic use of platinum, a rare element found in low natural abundance in the Earth's continental crust and one of the critical raw materials in the EU innovation partnership framework, has resulted in increased concentrations in surface environments. To minimize its spread and increase its recovery from the environment, biological recovery via different microbial systems is explored. In contrast, studies focusing on the effects of prolonged exposure to Pt are limited. In this study, we used the metal-resistant Cupriavidus metallidurans NA4 strain to explore the adaptation of environmental bacteria to platinum exposure. We used a combined Nanopore⁻Illumina sequencing approach to fully resolve all six replicons of the C. metallidurans NA4 genome, and compared them with the C. metallidurans CH34 genome, revealing an important role in metal resistance for its chromid rather than its megaplasmids. In addition, we identified the genomic and transcriptomic changes in a laboratory-evolved strain, displaying resistance to 160 µM Pt4+. The latter carried 20 mutations, including a large 69.9 kb deletion in its plasmid pNA4_D (89.6 kb in size), and 226 differentially-expressed genes compared to its parental strain. Many membrane-related processes were affected, including up-regulation of cytochrome c and a lytic transglycosylase, down-regulation of flagellar and pili-related genes, and loss of the pNA4_D conjugative machinery, pointing towards a significant role in the adaptation to platinum.
Collapse
Affiliation(s)
- Md Muntasir Ali
- Microbiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, 1050 Brussel, Belgium.
| | - Ann Provoost
- Microbiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
| | - Laurens Maertens
- Microbiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
- Research Unit in Biology of Microorganisms (URBM), Faculty of Sciences, UNamur, 5000 Namur, Belgium.
| | - Natalie Leys
- Microbiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
| | - Pieter Monsieurs
- Microbiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
| | - Daniel Charlier
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, 1050 Brussel, Belgium.
| | - Rob Van Houdt
- Microbiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
| |
Collapse
|
109
|
Bustamante-Brito R, Vera-Ponce de León A, Rosenblueth M, Martínez-Romero JC, Martínez-Romero E. Metatranscriptomic Analysis of the Bacterial Symbiont Dactylopiibacterium carminicum from the Carmine Cochineal Dactylopius coccus (Hemiptera: Coccoidea: Dactylopiidae). Life (Basel) 2019; 9:life9010004. [PMID: 30609847 PMCID: PMC6463064 DOI: 10.3390/life9010004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/14/2018] [Accepted: 12/25/2018] [Indexed: 11/16/2022] Open
Abstract
The scale insect Dactylopius coccus produces high amounts of carminic acid, which has historically been used as a pigment by pre-Hispanic American cultures. Nowadays carmine is found in food, cosmetics, and textiles. Metagenomic approaches revealed that Dactylopius spp. cochineals contain two Wolbachia strains, a betaproteobacterium named Candidatus Dactylopiibacterium carminicum and Spiroplasma, in addition to different fungi. We describe here a transcriptomic analysis indicating that Dactylopiibacterium is metabolically active inside the insect host, and estimate that there are over twice as many Dactylopiibacterium cells in the hemolymph than in the gut, with even fewer in the ovary. Albeit scarce, the transcripts in the ovaries support the presence of Dactylopiibacterium in this tissue and a vertical mode of transmission. In the cochineal, Dactylopiibacterium may catabolize plant polysaccharides, and be active in carbon and nitrogen provisioning through its degradative activity and by fixing nitrogen. In most insects, nitrogen-fixing bacteria are found in the gut, but in this study they are shown to occur in the hemolymph, probably delivering essential amino acids and riboflavin to the host from nitrogen substrates derived from nitrogen fixation.
Collapse
Affiliation(s)
- Rafael Bustamante-Brito
- Center for Genomic Sciences, Universidad Nacional Autónoma de México, UNAM, Cuernavaca, Morelos C.P. 62210, Mexico.
| | - Arturo Vera-Ponce de León
- Center for Genomic Sciences, Universidad Nacional Autónoma de México, UNAM, Cuernavaca, Morelos C.P. 62210, Mexico.
- Department of Ecology, Evolution and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA.
| | - Mónica Rosenblueth
- Center for Genomic Sciences, Universidad Nacional Autónoma de México, UNAM, Cuernavaca, Morelos C.P. 62210, Mexico.
| | - Julio César Martínez-Romero
- Center for Genomic Sciences, Universidad Nacional Autónoma de México, UNAM, Cuernavaca, Morelos C.P. 62210, Mexico.
| | - Esperanza Martínez-Romero
- Center for Genomic Sciences, Universidad Nacional Autónoma de México, UNAM, Cuernavaca, Morelos C.P. 62210, Mexico.
| |
Collapse
|
110
|
Ekundayo TC, Okoh AI. Pathogenomics of Virulence Traits of Plesiomonas shigelloides That Were Deemed Inconclusive by Traditional Experimental Approaches. Front Microbiol 2018; 9:3077. [PMID: 30627119 PMCID: PMC6309461 DOI: 10.3389/fmicb.2018.03077] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 11/29/2018] [Indexed: 12/31/2022] Open
Abstract
One of the major challenges of modern medicine includes the failure of conventional protocols to characterize the pathogenicity of emerging pathogens. This is particularly apparent in the case of Plesiomonas shigelloides. Although a number of infections have been linked to this microorganism, experimental evidence of its virulence factors (VFs), obtained by traditional approaches, is somewhat inconclusive. Hence, it remains unclear whether P. shigelloides is a true or opportunistic one. In the current study, four publicly available whole-genome sequences of P. shigelloides (GN7, NCTC10360, 302-73, and LS1) were profiled using bioinformatics platforms to determine the putative candidate VFs to characterize the bacterial pathogenicity. Overall, 134 unique open reading frames (ORFs) were identified that were homologous or orthologous to virulence genes identified in other pathogens. Of these, 52.24% (70/134) were jointly shared by the strains. The numbers of strain-specific virulence traits were 4 in LS1; 7 in NCTC10360; 10 in 302-73; and 15 in GN7. The pathogenicity islands (PAIs) common to all the strains accounted for 24.07% ORFs. The numbers of PAIs exclusive to each strain were 8 in 302-73; 11 in NCTC10360; 14 in GN7; and 18 in LS1. A PAI encoding Vibrio cholerae ToxR-activated gene d protein was specific to 302-73, GN7, and NCTC10360 strains. Out of 33 antibiotic multi-resistance genes identified, 16 (48.48%) genes were intrinsic to all strains. Further, 17 (22.08%) of 77 antibiotic resistance islands were found in all the strains. Out of 23 identified distinct insertion sequences, 13 were only harbored by strain LS1. The number of intact prophages identified in the strains was 1 in GN7; 2 in 302-73; and 2 in NCTC10360. Further, 1 CRISPR element was identified in LS1; 2 in NCTC10360; and 8 in 302-73. Fifteen (78.95%) of 19 secretion systems and secretion effector variants were identified in all the strains. In conclusion, certain P. shigelloides strains might possess VFs associated with gastroenteritis and extraintestinal infections. However, the role of host factors in the onset of infections should not be undermined.
Collapse
Affiliation(s)
- Temitope C. Ekundayo
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, South Africa
- Applied and Environmental Microbiology Research Group, Department of Biochemistry and Microbiology, University of Fort Hare, Alice, South Africa
- Department of Biological Sciences, University of Medical Sciences, Ondo City, Nigeria
| | - Anthony I. Okoh
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, South Africa
- Applied and Environmental Microbiology Research Group, Department of Biochemistry and Microbiology, University of Fort Hare, Alice, South Africa
| |
Collapse
|
111
|
CpaA Is a Glycan-Specific Adamalysin-like Protease Secreted by Acinetobacter baumannii That Inactivates Coagulation Factor XII. mBio 2018; 9:mBio.01606-18. [PMID: 30563903 PMCID: PMC6299215 DOI: 10.1128/mbio.01606-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ventilator-associated pneumonia and catheter-related bacteremia are the most common and severe infections caused by Acinetobacter baumannii. Besides the capsule, lipopolysaccharides, and the outer membrane porin OmpA, little is known about the contribution of secreted proteins to A. baumannii survival in vivo. Here we focus on CpaA, a potentially recently acquired virulence factor that inhibits blood coagulation in vitro. We identify coagulation factor XII as a target of CpaA, map the cleavage sites, and show that glycosylation is a prerequisite for CpaA-mediated inactivation of factor XII. We propose adding CpaA to a small, but growing list of bacterial proteases that are specific for highly glycosylated components of the host defense system. Antibiotic-resistant Acinetobacter baumannii is increasingly recognized as a cause of difficult-to-treat nosocomial infections, including pneumonia, wound infections, and bacteremia. Previous studies have demonstrated that the metalloprotease CpaA contributes to virulence and prolongs clotting time when added to human plasma as measured by the activated partial thromboplastin time (aPTT) assay. Here, we show that CpaA interferes with the intrinsic coagulation pathway, also called the contact activation system, in human as well as murine plasma, but has no discernible effect on the extrinsic pathway. By utilizing a modified aPTT assay, we demonstrate that coagulation factor XII (fXII) is a target of CpaA. In addition, we map the cleavage by CpaA to two positions, 279-280 and 308-309, within the highly glycosylated proline-rich region of human fXII, and show that cleavage at the 308-309 site is responsible for inactivation of fXII. At both sites, cleavage occurs between proline and an O-linked glycosylated threonine, and deglycosylation of fXII prevents cleavage by CpaA. Consistent with this, mutant fXII (fXII-Thr309Lys) from patients with hereditary angioedema type III (HAEIII) is protected from CpaA inactivation. This raises the possibility that individuals with HAEIII who harbor this mutation may be partially protected from A. baumannii infection if CpaA contributes to human disease. By inactivating fXII, CpaA may attenuate important antimicrobial defense mechanisms such as intravascular thrombus formation, thus allowing A. baumannii to disseminate.
Collapse
|
112
|
Gadwal S, Johnson TL, Remmer H, Sandkvist M. C-terminal processing of GlyGly-CTERM containing proteins by rhombosortase in Vibrio cholerae. PLoS Pathog 2018; 14:e1007341. [PMID: 30352106 PMCID: PMC6219818 DOI: 10.1371/journal.ppat.1007341] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 11/06/2018] [Accepted: 09/17/2018] [Indexed: 11/18/2022] Open
Abstract
Vibrio cholerae and a subset of other Gram-negative bacteria, including Acinetobacter baumannii, express proteins with a C-terminal tripartite domain called GlyGly-CTERM, which consists of a motif rich in glycines and serines, followed by a hydrophobic region and positively charged residues. Here we show that VesB, a V. cholerae serine protease, requires the GlyGly-CTERM domain, the intramembrane rhomboid-like protease rhombosortase, and the type II secretion system (T2SS) for localization at the cell surface. VesB is cleaved by rhombosortase to expose the second glycine residue of the GlyGly-CTERM motif, which is then conjugated to a glycerophosphoethanolamine-containing moiety prior to engagement with the T2SS and outer membrane translocation. In support of this, VesB accumulates intracellularly in the absence of the T2SS, and surface-associated VesB activity is no longer detected when the rhombosortase gene is inactivated. In turn, when VesB is expressed without an intact GlyGly-CTERM domain, VesB is released to the extracellular milieu by the T2SS and does not accumulate on the cell surface. Collectively, our findings suggest that the posttranslational modification of the GlyGly-CTERM domain is essential for cell surface localization of VesB and other proteins expressed with this tripartite extension.
Collapse
Affiliation(s)
- Shilpa Gadwal
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Tanya L. Johnson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States of America
- Department of Chemistry, Eastern Michigan University, Ypsilanti, MI, United States of America
| | - Henriette Remmer
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Maria Sandkvist
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States of America
- * E-mail:
| |
Collapse
|
113
|
Michel-Souzy S, Douzi B, Cadoret F, Raynaud C, Quinton L, Ball G, Voulhoux R. Direct interactions between the secreted effector and the T2SS components GspL and GspM reveal a new effector-sensing step during type 2 secretion. J Biol Chem 2018; 293:19441-19450. [PMID: 30337370 DOI: 10.1074/jbc.ra117.001127] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 10/04/2018] [Indexed: 12/11/2022] Open
Abstract
In many Gram-negative bacteria, the type 2 secretion system (T2SS) plays an important role in virulence because of its capacity to deliver a large amount of fully folded protein effectors to the extracellular milieu. Despite our knowledge of most T2SS components, the mechanisms underlying effector recruitment and secretion by the T2SS remain enigmatic. Using complementary biophysical and biochemical approaches, we identified here two direct interactions between the secreted effector CbpD and two components, XcpYL and XcpZM, of the T2SS assembly platform (AP) in the opportunistic pathogen Pseudomonas aeruginosa Competition experiments indicated that CbpD binding to XcpYL is XcpZM-dependent, suggesting sequential recruitment of the effector by the periplasmic domains of these AP components. Using a bacterial two-hybrid system, we then tested the influence of the effector on the AP protein-protein interaction network. Our findings revealed that the presence of the effector modifies the AP interactome and, in particular, induces XcpZM homodimerization and increases the affinity between XcpYL and XcpZM The observed direct relationship between effector binding and T2SS dynamics suggests an additional synchronizing step during the type 2 secretion process, where the activation of the AP of the T2SS nanomachine is triggered by effector binding.
Collapse
Affiliation(s)
- Sandra Michel-Souzy
- From the CNRS, Aix Marseille Université, Institut de Microbiologie de la Méditerranée (IMM), Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM)/UMR7255, 13009 Marseille, France
| | - Badreddine Douzi
- From the CNRS, Aix Marseille Université, Institut de Microbiologie de la Méditerranée (IMM), Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM)/UMR7255, 13009 Marseille, France.,CNRS, Aix Marseille Université, IMM, Laboratoire de Chimie Bactérienne (LCB)/UMR7283, 13009 Marseille, France, and
| | - Frédéric Cadoret
- From the CNRS, Aix Marseille Université, Institut de Microbiologie de la Méditerranée (IMM), Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM)/UMR7255, 13009 Marseille, France
| | - Claire Raynaud
- From the CNRS, Aix Marseille Université, Institut de Microbiologie de la Méditerranée (IMM), Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM)/UMR7255, 13009 Marseille, France.,CNRS, Aix Marseille Université, IMM, Laboratoire de Chimie Bactérienne (LCB)/UMR7283, 13009 Marseille, France, and
| | - Loïc Quinton
- Laboratory of Mass Spectrometry-MolSys, Department of Chemistry, University of Liège, B4000 Liège, Belgium
| | - Geneviève Ball
- From the CNRS, Aix Marseille Université, Institut de Microbiologie de la Méditerranée (IMM), Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM)/UMR7255, 13009 Marseille, France.,CNRS, Aix Marseille Université, IMM, Laboratoire de Chimie Bactérienne (LCB)/UMR7283, 13009 Marseille, France, and
| | - Romé Voulhoux
- From the CNRS, Aix Marseille Université, Institut de Microbiologie de la Méditerranée (IMM), Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM)/UMR7255, 13009 Marseille, France, .,CNRS, Aix Marseille Université, IMM, Laboratoire de Chimie Bactérienne (LCB)/UMR7283, 13009 Marseille, France, and
| |
Collapse
|
114
|
Arifuzzaman M, Mitra S, Jahan SI, Jakaria M, Abeda T, Absar N, Dash R. A Computational workflow for the identification of the potent inhibitor of type II secretion system traffic ATPase of Pseudomonas aeruginosa. Comput Biol Chem 2018; 76:191-201. [DOI: 10.1016/j.compbiolchem.2018.07.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 06/30/2018] [Accepted: 07/10/2018] [Indexed: 01/04/2023]
|
115
|
Theoharaki C, Chronopoulou E, Vlachakis D, Ataya FS, Giannopoulos P, Maurikou S, Skopelitou K, Papageorgiou AC, Labrou NE. Delineation of the functional and structural properties of the glutathione transferase family from the plant pathogen Erwinia carotovora. Funct Integr Genomics 2018; 19:1-12. [PMID: 29938342 DOI: 10.1007/s10142-018-0618-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/24/2018] [Accepted: 05/31/2018] [Indexed: 01/09/2023]
Abstract
Erwinia carotovora, a widespread plant pathogen that causes soft rot disease in many plants, is considered a major threat in agriculture. Bacterial glutathione transferases (GSTs) play important roles in a variety of metabolic pathways and processes, such as the biodegradation of xenobiotics, protection against abiotic stress, and resistance against antimicrobial drugs. The GST family of canonical soluble enzymes from Erwinia carotovora subsp. atroseptica strain SCRI1043 (EcaGSTs) was investigated. Genome analysis showed the presence of six putative canonical cytoplasmic EcaGSTs, which were revealed by phylogenetic analysis to belong to the well-characterized GST classes beta, nu, phi, and zeta. The analysis also revealed the presence of two isoenzymes that were phylogenetically close to the omega class of GSTs, but formed a distinct class. The EcaGSTs were cloned and expressed in Escherichia coli, and their catalytic activity toward different electrophilic substrates was elucidated. The EcaGSTs catalyzed different types of reactions, although all enzymes were particularly active in reactions involving electrophile substitution. Gene and protein expression profiling conducted under normal culture conditions as well as in the presence of the herbicide alachlor and the xenobiotic 1-chloro-2,4-dinitrobenzene (CDNB) showed that the isoenzyme EcaGST1, belonging to the omega-like class, was specifically induced at both the protein and mRNA levels. EcaGST1 presumably participates in counteracting the xenobiotic toxicity and/or abiotic stress conditions, and may therefore represent a novel molecular target in the development of new chemical treatments to control soft rot diseases.
Collapse
Affiliation(s)
- Christina Theoharaki
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece
| | - Evangelia Chronopoulou
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece
| | - Dimitrios Vlachakis
- Laboratory of Genetics, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece
| | - Farid S Ataya
- Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.,Molecular Biology Department, Genetic Engineering Division, National Research Centre, 33 El-Bohouth St., Dokki, Giza, P.O. 12622, Egypt
| | - Panagiotis Giannopoulos
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece
| | - Sofia Maurikou
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece
| | - Katholiki Skopelitou
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece
| | - Anastassios C Papageorgiou
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, FI-20521, Turku, Finland
| | - Nikolaos E Labrou
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece.
| |
Collapse
|
116
|
Lamouche F, Gully D, Chaumeret A, Nouwen N, Verly C, Pierre O, Sciallano C, Fardoux J, Jeudy C, Szücs A, Mondy S, Salon C, Nagy I, Kereszt A, Dessaux Y, Giraud E, Mergaert P, Alunni B. Transcriptomic dissection of Bradyrhizobium sp. strain ORS285 in symbiosis with Aeschynomene spp. inducing different bacteroid morphotypes with contrasted symbiotic efficiency. Environ Microbiol 2018; 21:3244-3258. [PMID: 29921018 DOI: 10.1111/1462-2920.14292] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 05/18/2017] [Accepted: 05/19/2017] [Indexed: 11/29/2022]
Abstract
To circumvent the paucity of nitrogen sources in the soil legume plants establish a symbiotic interaction with nitrogen-fixing soil bacteria called rhizobia. During symbiosis, the plants form root organs called nodules, where bacteria are housed intracellularly and become active nitrogen fixers known as bacteroids. Depending on their host plant, bacteroids can adopt different morphotypes, being either unmodified (U), elongated (E) or spherical (S). E- and S-type bacteroids undergo a terminal differentiation leading to irreversible morphological changes and DNA endoreduplication. Previous studies suggest that differentiated bacteroids display an increased symbiotic efficiency (E > U and S > U). In this study, we used a combination of Aeschynomene species inducing E- or S-type bacteroids in symbiosis with Bradyrhizobium sp. ORS285 to show that S-type bacteroids present a better symbiotic efficiency than E-type bacteroids. We performed a transcriptomic analysis on E- and S-type bacteroids formed by Aeschynomene afraspera and Aeschynomene indica nodules and identified the bacterial functions activated in bacteroids and specific to each bacteroid type. Extending the expression analysis in E- and S-type bacteroids in other Aeschynomene species by qRT-PCR on selected genes from the transcriptome analysis narrowed down the set of bacteroid morphotype-specific genes. Functional analysis of a selected subset of 31 bacteroid-induced or morphotype-specific genes revealed no symbiotic phenotypes in the mutants. This highlights the robustness of the symbiotic program but could also indicate that the bacterial response to the plant environment is partially anticipatory or even maladaptive. Our analysis confirms the correlation between differentiation and efficiency of the bacteroids and provides a framework for the identification of bacterial functions that affect the efficiency of bacteroids.© 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.
Collapse
Affiliation(s)
- Florian Lamouche
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Djamel Gully
- Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, Montpellier, 34398, France
| | - Anaïs Chaumeret
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Nico Nouwen
- Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, Montpellier, 34398, France
| | - Camille Verly
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Olivier Pierre
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Coline Sciallano
- Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, Montpellier, 34398, France
| | - Joël Fardoux
- Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, Montpellier, 34398, France
| | - Christian Jeudy
- Agroécologie, AgroSup Dijon, INRA, Université Bourgogne Franche-Comté, Dijon, 21065, France
| | - Attila Szücs
- Biological Research Centre, Hungarian Academy of Sciences, Szeged, 6726, Hungary
| | - Samuel Mondy
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Christophe Salon
- Agroécologie, AgroSup Dijon, INRA, Université Bourgogne Franche-Comté, Dijon, 21065, France
| | - István Nagy
- Biological Research Centre, Hungarian Academy of Sciences, Szeged, 6726, Hungary
- Seqomics Biotechnology Ltd, Mórahalom, 6782, Hungary
| | - Attila Kereszt
- Biological Research Centre, Hungarian Academy of Sciences, Szeged, 6726, Hungary
- Seqomics Biotechnology Ltd, Mórahalom, 6782, Hungary
| | - Yves Dessaux
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Eric Giraud
- Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, Montpellier, 34398, France
| | - Peter Mergaert
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Benoit Alunni
- Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| |
Collapse
|
117
|
Type II Secretion-Dependent Aminopeptidase LapA and Acyltransferase PlaC Are Redundant for Nutrient Acquisition during Legionella pneumophila Intracellular Infection of Amoebas. mBio 2018; 9:mBio.00528-18. [PMID: 29666285 PMCID: PMC5904407 DOI: 10.1128/mbio.00528-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Legionella pneumophila genes encoding LapA, LapB, and PlaC were identified as the most highly upregulated type II secretion (T2S) genes during infection of Acanthamoeba castellanii, although these genes had been considered dispensable on the basis of the behavior of mutants lacking either lapA and lapB or plaC A plaC mutant showed even higher levels of lapA and lapB transcripts, and a lapA lapB mutant showed heightening of plaC mRNA levels, suggesting that the role of the LapA/B aminopeptidase is compensatory with respect to that of the PlaC acyltransferase. Hence, we made double mutants and found that lapA plaC mutants have an ~50-fold defect during infection of A. castellanii These data revealed, for the first time, the importance of LapA in any sort of infection; thus, we purified LapA and defined its crystal structure, activation by another T2S-dependent protease (ProA), and broad substrate specificity. When the amoebal infection medium was supplemented with amino acids, the defect of the lapA plaC mutant was reversed, implying that LapA generates amino acids for nutrition. Since the LapA and PlaC data did not fully explain the role of T2S in infection, we identified, via proteomic analysis, a novel secreted protein (NttD) that promotes infection of A. castellanii A lapA plaC nttD mutant displayed an even greater (100-fold) defect, demonstrating that the LapA, PlaC, and NttD data explain, to a significant degree, the importance of T2S. LapA-, PlaC-, and NttD-like proteins had distinct distribution patterns within and outside the Legionella genus. LapA was notable for having as its closest homologue an A. castellanii protein.IMPORTANCE Transmission of L. pneumophila to humans is facilitated by its ability to grow in Acanthamoeba species. We previously documented that type II secretion (T2S) promotes L. pneumophila infection of A. castellanii Utilizing transcriptional analysis and proteomics, double and triple mutants, and crystal structures, we defined three secreted substrates/effectors that largely clarify the role of T2S during infection of A. castellanii Particularly interesting are the unique functional overlap between an acyltransferase (PlaC) and aminopeptidase (LapA), the broad substrate specificity and eukaryotic-protein-like character of LapA, and the novelty of NttD. Linking LapA to amino acid acquisition, we defined, for the first time, the importance of secreted aminopeptidases in intracellular infection. Bioinformatic investigation, not previously applied to T2S, revealed that effectors originate from diverse sources and distribute within the Legionella genus in unique ways. The results of this study represent a major advance in understanding Legionella ecology and pathogenesis, bacterial secretion, and the evolution of intracellular parasitism.
Collapse
|
118
|
Elhosseiny NM, Attia AS. Acinetobacter: an emerging pathogen with a versatile secretome. Emerg Microbes Infect 2018; 7:33. [PMID: 29559620 PMCID: PMC5861075 DOI: 10.1038/s41426-018-0030-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/08/2017] [Accepted: 01/09/2018] [Indexed: 02/06/2023]
Abstract
Acinetobacter baumannii is a notorious pathogen that has emerged as a healthcare nightmare in recent years because it causes serious infections that are associated with high morbidity and mortality rates. Due to its exceptional ability to acquire resistance to almost all available antibiotics, A. baumannii is currently ranked as the first pathogen on the World Health Organization’s priority list for the development of new antibiotics. The versatile range of effectors secreted by A. baumannii represents a large proportion of the virulence arsenal identified in this bacterium to date. Thus, these factors, together with the secretory machinery responsible for their extrusion into the extracellular milieu, are key targets for novel therapeutics that are greatly needed to combat this deadly pathogen. In this review, we provide a comprehensive, up-to-date overview of the organization and regulatory aspects of the Acinetobacter secretion systems, with a special emphasis on their versatile substrates that could be targeted to fight the deadly infections caused by this elusive pathogen.
Collapse
Affiliation(s)
- Noha M Elhosseiny
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Ahmed S Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt.
| |
Collapse
|
119
|
Peterson CP, Sauer C, Chatfield CH. The Extracellular Polymeric Substances of Legionella pneumophila Biofilms Contain Amyloid Structures. Curr Microbiol 2018; 75:736-744. [PMID: 29468303 DOI: 10.1007/s00284-018-1440-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/16/2018] [Indexed: 12/25/2022]
Abstract
Human infection by bacteria of the genus Legionella most often result in the pneumonia known as Legionnaires Disease. Legionella is found as a resident of adherent biofilms in man-made water systems. Disinfection efforts to prevent Legionella infections require a better understanding of the structures that promote Legionella surface attachment and biofilm colonization. Various enzymatic treatments, including multiple carbohydrate-targeting mixtures, failed to disrupt Legionella biofilms, despite the presence of carbohydrates in the biofilms as shown by biochemical methods and concanavalin-A lectin staining. Moreover, Legionella biofilms contained amyloids as detected by three microscopic staining methods (congo red, thioflavin T, and the amyloid-specific antibody WO2). Amyloid structures were seen in biofilms of both L. pneumophila and L. longbeachae, the two Legionella species most associated with human infection. Inhibition of amyloid assembly by congo red and thioflavin T limited both self-aggregation and surface attachment of L. pneumophila, indicating that functional amyloid structures have a key role in initial biofilm formation by these pathogenic bacteria.
Collapse
Affiliation(s)
- Casey P Peterson
- Department of Biological Sciences, SUNY Cortland, Cortland, NY, USA
| | - Cassidy Sauer
- Department of Biological Sciences, SUNY Cortland, Cortland, NY, USA
| | | |
Collapse
|
120
|
Structure and Membrane Topography of the Vibrio-Type Secretin Complex from the Type 2 Secretion System of Enteropathogenic Escherichia coli. J Bacteriol 2018; 200:JB.00521-17. [PMID: 29084860 DOI: 10.1128/jb.00521-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 10/25/2017] [Indexed: 12/11/2022] Open
Abstract
The β-barrel assembly machinery (BAM) complex is the core machinery for the assembly of β-barrel membrane proteins, and inhibition of BAM complex activity is lethal to bacteria. Discovery of integral membrane proteins that are key to pathogenesis and yet do not require assistance from the BAM complex raises the question of how these proteins assemble into bacterial outer membranes. Here, we address this question through a structural analysis of the type 2 secretion system (T2SS) secretin from enteropathogenic Escherichia coli O127:H6 strain E2348/69. Long β-strands assemble into a barrel extending 17 Å through and beyond the outer membrane, adding insight to how these extensive β-strands are assembled into the E. coli outer membrane. The substrate docking chamber of this secretin is shown to be sufficient to accommodate the substrate mucinase SteC.IMPORTANCE In order to cause disease, bacterial pathogens inhibit immune responses and induce pathology that will favor their replication and dissemination. In Gram-negative bacteria, these key attributes of pathogenesis depend on structures assembled into or onto the outer membrane. One of these is the T2SS. The Vibrio-type T2SS mediates cholera toxin secretion in Vibrio cholerae, and in Escherichia coli O127:H6 strain E2348/69, the same machinery mediates secretion of the mucinases that enable the pathogen to penetrate intestinal mucus and thereby establish deadly infections.
Collapse
|
121
|
do Vale A, Pereira C, Osorio CR, dos Santos NMS. The Apoptogenic Toxin AIP56 Is Secreted by the Type II Secretion System of Photobacterium damselae subsp. piscicida. Toxins (Basel) 2017; 9:toxins9110368. [PMID: 29135911 PMCID: PMC5705983 DOI: 10.3390/toxins9110368] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/07/2017] [Accepted: 11/08/2017] [Indexed: 11/16/2022] Open
Abstract
AIP56 (apoptosis-inducing protein of 56 kDa) is a key virulence factor of Photobacterium damselae subsp. piscicida (Phdp), the causative agent of a septicaemia affecting warm water marine fish species. Phdp-associated pathology is triggered by AIP56, a short trip AB toxin with a metalloprotease A domain that cleaves the p65 subunit of NF-κB, an evolutionarily conserved transcription factor that regulates the expression of inflammatory and anti-apoptotic genes and plays a central role in host responses to infection. During infection by Phdp, AIP56 is systemically disseminated and induces apoptosis of macrophages and neutrophils, compromising the host phagocytic defence and contributing to the genesis of pathology. Although it is well established that the secretion of AIP56 is crucial for Phdp pathogenicity, the protein secretion systems operating in Phdp and the mechanism responsible for the extracellular release of the toxin remain unknown. Here, we report that Phdp encodes a type II secretion system (T2SS) and show that mutation of the EpsL component of this system impairs AIP56 secretion. This work demonstrates that Phdp has a functional T2SS that mediates secretion of its key virulence factor AIP56.
Collapse
Affiliation(s)
- Ana do Vale
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-235 Porto, Portugal.
| | - Cassilda Pereira
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-235 Porto, Portugal.
| | - Carlos R Osorio
- Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - Nuno M S dos Santos
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-235 Porto, Portugal.
| |
Collapse
|
122
|
Hiller M, Lang C, Michel W, Flieger A. Secreted phospholipases of the lung pathogen Legionella pneumophila. Int J Med Microbiol 2017; 308:168-175. [PMID: 29108710 DOI: 10.1016/j.ijmm.2017.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/06/2017] [Accepted: 10/22/2017] [Indexed: 11/28/2022] Open
Abstract
Legionella pneumophila is an intracellular pathogen and the main causative agent of Legionnaires' disease, a potentially fatal pneumonia. The bacteria infect both mammalian cells and environmental hosts, such as amoeba. Inside host cells, the bacteria withstand the multifaceted defenses of the phagocyte and replicate within a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). For establishment and maintenance of the infection, L. pneumophila secretes many proteins including effector proteins by means of different secretion systems and outer membrane vesicles. Among these are a large variety of lipolytic enzymes which possess phospholipase/lysophospholipase and/or glycerophospholipid:cholesterol acyltransferase activities. Secreted lipolytic activities may contribute to bacterial virulence, for example via modification of eukaryotic membranes, such as the LCV. In this review, we describe the secretion systems of L. pneumophila, introduce the classification of phospholipases, and summarize the state of the art on secreted L. pneumophila phospholipases. We especially highlight those enzymes secreted via the type II secretion system Lsp, via the type IVB secretion system Dot/Icm, via outer membrane vesicles, and such where the mode of secretion has not yet been defined. We also give an overview on the complexity of their activities, activation mechanisms, localization, growth-phase dependent abundance, and their role in infection.
Collapse
Affiliation(s)
- Miriam Hiller
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Christina Lang
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Wiebke Michel
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany.
| |
Collapse
|
123
|
Naujoks J, Lippmann J, Suttorp N, Opitz B. Innate sensing and cell-autonomous resistance pathways in Legionella pneumophila infection. Int J Med Microbiol 2017; 308:161-167. [PMID: 29097162 DOI: 10.1016/j.ijmm.2017.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 10/20/2017] [Accepted: 10/23/2017] [Indexed: 12/20/2022] Open
Abstract
Legionella pneumophila is a facultative intracellular bacterium which can cause a severe pneumonia called Legionnaires' disease after inhalation of contaminated water droplets and replication in alveolar macrophages. The innate immune system is generally able to sense and -in most cases- control L. pneumophila infection. Comorbidities and genetic risk factors, however, can compromise the immune system and high infection doses might overwhelm its capacity, thereby enabling L. pneumophila to grow and disseminate inside the lung. The innate immune system mediates sensing of L. pneumophila by employing e.g. NOD-like receptors (NLRs), Toll-like receptors (TLRs), as well as the cGAS/STING pathway to stimulate death of infected macrophages as well as production of proinflammatory cytokines and interferons (IFNs). Control of pulmonary L. pneumophila infection is largely mediated by inflammasome-, TNFα- and IFN-dependent macrophage-intrinsic resistance mechanisms. This article summarizes the current knowledge of innate immune responses to L. pneumophila infection in general, and of macrophage-intrinsic defense mechanisms in particular.
Collapse
Affiliation(s)
- Jan Naujoks
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Juliane Lippmann
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Norbert Suttorp
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Bastian Opitz
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Augustenburger Platz 1, 13353 Berlin, Germany; German Center for Lung Research (DZL), Germany.
| |
Collapse
|
124
|
Structure of the calcium-dependent type 2 secretion pseudopilus. Nat Microbiol 2017; 2:1686-1695. [PMID: 28993624 PMCID: PMC5705324 DOI: 10.1038/s41564-017-0041-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 09/11/2017] [Indexed: 11/08/2022]
Abstract
Many Gram-negative bacteria use type 2 secretion systems (T2SS) to secrete proteins involved in virulence and adaptation. Transport of folded proteins via T2SS nanomachines requires the assembly of inner membrane-anchored fibers called pseudopili. Although efficient pseudopilus assembly is essential for protein secretion, structure-based functional analyses are required to unravel the mechanistic link between these processes. Here, we report an atomic model for a T2SS pseudopilus from Klebsiella oxytoca, obtained by fitting the NMR structure of its calcium-bound subunit PulG into the ~ 5 Å resolution cryo-electron microscopy (cryoEM) reconstruction of assembled fibers. This structure reveals the comprehensive network of inter-subunit contacts and unexpected features, including a disordered central region of the PulG helical stem, and highly flexible C-terminal residues on the fiber surface. NMR, mutagenesis and functional analyses highlight the key role of calcium in PulG folding and stability. Fiber disassembly in the absence of calcium provides a basis for pseudopilus length control, essential for protein secretion, and supports the Archimedes' screw model for T2S mechanism.
Collapse
|
125
|
Waack U, Johnson TL, Chedid K, Xi C, Simmons LA, Mobley HLT, Sandkvist M. Targeting the Type II Secretion System: Development, Optimization, and Validation of a High-Throughput Screen for the Identification of Small Molecule Inhibitors. Front Cell Infect Microbiol 2017; 7:380. [PMID: 28894700 PMCID: PMC5581314 DOI: 10.3389/fcimb.2017.00380] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/09/2017] [Indexed: 12/26/2022] Open
Abstract
Nosocomial pathogens that develop multidrug resistance present an increasing problem for healthcare facilities. Due to its rapid rise in antibiotic resistance, Acinetobacter baumannii is one of the most concerning gram-negative species. A. baumannii typically infects immune compromised individuals resulting in a variety of outcomes, including pneumonia and bacteremia. Using a murine model for bacteremia, we have previously shown that the type II secretion system (T2SS) contributes to in vivo fitness of A. baumannii. Here, we provide support for a role of the T2SS in protecting A. baumannii from human complement as deletion of the T2SS gene gspD resulted in a 100-fold reduction in surviving cells when incubated with human serum. This effect was abrogated in the absence of Factor B, a component of the alternative pathway of complement activation, indicating that the T2SS protects A. baumannii against the alternative complement pathway. Because inactivation of the T2SS results in loss of secretion of multiple enzymes, reduced in vivo fitness, and increased sensitivity to human complement, the T2SS may be a suitable target for therapeutic intervention. Accordingly, we developed and optimized a whole-cell high-throughput screening (HTS) assay based on secreted lipase activity to identify small molecule inhibitors of the T2SS. We tested the reproducibility of our assay using a 6,400-compound library. With small variation within controls and a dynamic range between positive and negative controls, the assay had a z-factor of 0.65, establishing its suitability for HTS. Our screen identified the lipase inhibitors Orlistat and Ebelactone B demonstrating the specificity of the assay. To eliminate inhibitors of lipase activity and lipase expression, two counter assays were developed and optimized. By implementing these assays, all seven tricyclic antidepressants present in the library were found to be inhibitors of the lipase, highlighting the potential of identifying alternative targets for approved pharmaceuticals. Although no T2SS inhibitor was identified among the compounds that reduced lipase activity by ≥30%, our small proof-of-concept pilot study indicates that the HTS regimen is simple, reproducible, and specific and that it can be used to screen larger libraries for the identification of T2SS inhibitors that may be developed into novel A. baumannii therapeutics.
Collapse
Affiliation(s)
- Ursula Waack
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn Arbor, MI, United States
| | - Tanya L Johnson
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn Arbor, MI, United States.,Department of Chemistry, Eastern Michigan UniversityYpsilanti, MI, United States
| | - Khalil Chedid
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn Arbor, MI, United States
| | - Chuanwu Xi
- Department of Environmental Health Sciences, University of Michigan School of Public HealthAnn Arbor, MI, United States
| | - Lyle A Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of MichiganAnn Arbor, MI, United States
| | - Harry L T Mobley
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn Arbor, MI, United States
| | - Maria Sandkvist
- Department of Microbiology and Immunology, University of Michigan Medical SchoolAnn Arbor, MI, United States
| |
Collapse
|
126
|
Wang X, Han Q, Chen G, Zhang W, Liu W. A Putative Type II Secretion System Is Involved in Cellulose Utilization in Cytophaga hutchisonii. Front Microbiol 2017; 8:1482. [PMID: 28848505 PMCID: PMC5553014 DOI: 10.3389/fmicb.2017.01482] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/24/2017] [Indexed: 11/23/2022] Open
Abstract
Cytophaga hutchinsonii is a gliding cellulolytic bacterium that degrades cellulose in a substrate contact-dependent manner. Specific proteins are speculated to be translocated to its extracellular milieu or outer membrane surface to participate in adhesion to cellulose and further digestion. In this study, we show that three orthologous genes encoding the major components (T2S-D, -F, and -G) of type II secretion system (T2SS) are involved in cellulose degradation but not in cell motility. The individual disruption of the three t2s genes results in a significantly retarded growth on cellobiose, regenerated amorphous cellulose, and Avicel cellulose. Enzymatic analyses demonstrate that, whereas the endoglucanase activity of the t2s mutant cells is increased, the β-glucosidase activity is remarkably reduced compared to that of WT cells. Further analyses reveal that the t2s mutant cells not only exhibit a different profile of cellulose-bound outer membrane proteins from that of wild-type cells, but also display a significant decrease in their capability to adhere to cellulose. These results indicate that a functional link exits between the putative T2SS and cellulose utilization in C. hutchinsonii, and thus provide a conceptual framework to understand the unique strategy deployed by C. hutchinsonii to assimilate cellulose.
Collapse
Affiliation(s)
- Xia Wang
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong UniversityJinan, China
| | - Qingqing Han
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong UniversityJinan, China
| | - Guanjun Chen
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong UniversityJinan, China
| | - Weixin Zhang
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong UniversityJinan, China
| | - Weifeng Liu
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong UniversityJinan, China
| |
Collapse
|
127
|
Type II Secretion Substrates of Legionella pneumophila Translocate Out of the Pathogen-Occupied Vacuole via a Semipermeable Membrane. mBio 2017. [PMID: 28634242 PMCID: PMC5478897 DOI: 10.1128/mbio.00870-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Legionella pneumophila replicates in macrophages in a host-derived phagosome, termed the Legionella-containing vacuole (LCV). While the translocation of type IV secretion (T4S) effectors into the macrophage cytosol is well established, the location of type II secretion (T2S) substrates in the infected host cell is unknown. Here, we show that the T2S substrate ProA, a metalloprotease, translocates into the cytosol of human macrophages, where it associates with the LCV membrane (LCVM). Translocation is detected as early as 10 h postinoculation (p.i.), which is approximately the midpoint of the intracellular life cycle. However, it is detected as early as 6 h p.i. if ProA is hyperexpressed, indicating that translocation depends on the timing of ProA expression and that any other factors necessary for translocation are in place by that time point. Translocation occurs with all L. pneumophila strains tested and in amoebae, natural hosts for L. pneumophila. It was absent in murine bone marrow-derived macrophages and murine macrophage cell lines. The ChiA chitinase also associated with the cytoplasmic face of the LCVM at 6 h p.i. and in a T2S-dependent manner. Galectin-3 and galectin-8, eukaryotic proteins whose localization is influenced by damage to host membranes, appeared within the LCV of infected human but not murine macrophages beginning at 6 h p.i. Thus, we hypothesize that ProA and ChiA are first secreted into the vacuolar lumen by the activity of the T2S and subsequently traffic into the macrophage cytosol via a novel mechanism that involves a semipermeable LCVM. Infection of macrophages and amoebae plays a central role in the pathogenesis of L. pneumophila, the agent of Legionnaires’ disease. We have previously demonstrated that the T2S system of L. pneumophila greatly contributes to intracellular infection. However, the location of T2S substrates within the infected host cell is unknown. This report presents the first evidence of a L. pneumophila T2S substrate in the host cell cytosol and, therefore, the first evidence of a non-T4S effector trafficking out of the LCV. We also provide the first indication that the LCV is not completely intact but is instead semipermeable and that this occurs in human but not murine macrophages. Given this permeability, we hypothesize that other T2S substrates and LCV lumenal contents can escape into the host cell cytosol. Thus, these substrates may represent a battery of previously unidentified effectors that can interact with host factors and contribute to intracellular infection by L. pneumophila.
Collapse
|
128
|
Thomassin JL, Santos Moreno J, Guilvout I, Tran Van Nhieu G, Francetic O. The trans-envelope architecture and function of the type 2 secretion system: new insights raising new questions. Mol Microbiol 2017; 105:211-226. [DOI: 10.1111/mmi.13704] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Jenny-Lee Thomassin
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Javier Santos Moreno
- Université Paris Diderot (Paris 7) Sorbonne Paris Cité; Paris France
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Ingrid Guilvout
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| | - Guy Tran Van Nhieu
- Laboratory of Intercellular Communication and Microbial Infections; CIRB, Collège de France; 11 Place Marcelin Berthelot 75005 Paris France
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1050; 75005 Paris France
- Centre National de la Recherche Scientifique (CNRS), UMR7241; 75005 Paris France
- MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres; 75005 Paris France
| | - Olivera Francetic
- Department of structural biology and chemistry, Biochemistry of Macromolecular Interactions Unit; Institut Pasteur; 28 rue du Dr Roux 75724 Paris Cedex 15 France
- Centre National de la Recherche Scientifique (CNRS); ERL6002 75724 Paris France
| |
Collapse
|