scholarly journals Dot/Icm Effector Translocation by Legionella longbeachae Creates a Replicative Vacuole Similar to That of Legionella pneumophila despite Translocation of Distinct Effector Repertoires

2015 ◽  
Vol 83 (10) ◽  
pp. 4081-4092 ◽  
Author(s):  
Rebecca E. Wood ◽  
Patrice Newton ◽  
Eleanor A. Latomanski ◽  
Hayley J. Newton
Keyword(s):  
Legionella Pneumophila ◽  
A549 Cells ◽  
Severe Pneumonia ◽  
Rab Gtpase ◽  
Human Pathogens ◽  
Immunofluorescence Analysis ◽  
Content Type ◽  
Extensive Analysis ◽  
Legionnaires Disease ◽  
Environmental Bacteria

Legionellaorganisms are environmental bacteria and accidental human pathogens that can cause severe pneumonia, termed Legionnaires' disease. These bacteria replicate within a pathogen-derived vacuole termed theLegionella-containing vacuole (LCV). Our understanding of the development and dynamics of this vacuole is based on extensive analysis ofLegionella pneumophila. Here, we have characterized theLegionella longbeachaereplicative vacuole (longbeachae-LCV) and demonstrated that, despite important genomic differences, key features of the replicative LCV are comparable to those of the LCV ofL. pneumophila(pneumophila-LCV). We constructed a Dot/Icm-deficient strain by deletingdotBand demonstrated the inability of this mutant to replicate inside THP-1 cells.L. longbeachaedoes not enter THP-1 cells as efficiently asL. pneumophila, and this is reflected in the observation that translocation of BlaM-RalFLLO(where RalFLLOis theL. longbeachaehomologue of RalF) into THP-1 cells by theL. longbeachaeDot/Icm system is less efficient than that byL. pneumophila. This difference is negated in A549 cells whereL. longbeachaeandL. pneumophilainfect with similar entry dynamics. A β-lactamase assay was employed to demonstrate the translocation of a novel family of proteins, theRab-likeeffector (Rle) proteins. Immunofluorescence analysis confirmed that these proteins enter the host cell during infection and display distinct subcellular localizations, with RleA and RleC present on thelongbeachae-LCV. We observed that the host Rab GTPase, Rab1, and the v-SNARE Sec22b are also recruited to thelongbeachae-LCV during the early stages of infection, coinciding with the LCV avoiding endocytic maturation. These studies further our understanding of theL. longbeachaereplicative vacuole, highlighting phenotypic similarities to the vacuole ofL. pneumophilaas well as unique aspects of LCV biology.

scholarly journals More than 18,000 effectors in theLegionellagenus genome provide multiple, independent combinations for replication in human cells

2019 ◽  
Vol 116 (6) ◽  
pp. 2265-2273 ◽  
Author(s):  
Laura Gomez-Valero ◽  
Christophe Rusniok ◽  
Danielle Carson ◽  
Sonia Mondino ◽  
Ana Elena Pérez-Cobas ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Chromatin Modification ◽  
Severe Pneumonia ◽  
Rab Gtpase ◽  
Functional Screening ◽  
Evolutionary Analysis ◽  
Human Pathogen ◽  
Human Pathogens ◽  
Intracellular Replication ◽  
Type Iv

The genusLegionellacomprises 65 species, among whichLegionella pneumophilais a human pathogen causing severe pneumonia. To understand the evolution of an environmental to an accidental human pathogen, we have functionally analyzed 80Legionellagenomes spanning 58 species. Uniquely, an immense repository of 18,000 secreted proteins encoding 137 different eukaryotic-like domains and over 200 eukaryotic-like proteins is paired with a highly conserved type IV secretion system (T4SS). Specifically, we show that eukaryotic Rho- and Rab-GTPase domains are found nearly exclusively in eukaryotes andLegionella. Translocation assays for selected Rab-GTPase proteins revealed that they are indeed T4SS secreted substrates. Furthermore, F-box, U-box, and SET domains were present in >70% of all species, suggesting that manipulation of host signal transduction, protein turnover, and chromatin modification pathways are fundamental intracellular replication strategies for legionellae. In contrast, the Sec-7 domain was restricted toL. pneumophilaand seven other species, indicating effector repertoire tailoring within different amoebae. Functional screening of 47 species revealed 60% were competent for intracellular replication in THP-1 cells, but interestingly, this phenotype was associated with diverse effector assemblages. These data, combined with evolutionary analysis, indicate that the capacity to infect eukaryotic cells has been acquired independently many times within the genus and that a highly conserved yet versatile T4SS secretes an exceptional number of different proteins shaped by interdomain gene transfer. Furthermore, we revealed the surprising extent to which legionellae have coopted genes and thus cellular functions from their eukaryotic hosts, providing an understanding of how dynamic reshuffling and gene acquisition have led to the emergence of major human pathogens.

scholarly journals Metabolism ofmyo-Inositol by Legionella pneumophila Promotes Infection of Amoebae and Macrophages

2016 ◽  
Vol 82 (16) ◽  
pp. 5000-5014 ◽  
Author(s):  
Christian Manske ◽  
Ursula Schell ◽  
Hubert Hilbi
Keyword(s):  
Amino Acids ◽  
Causative Agent ◽  
Legionella Pneumophila ◽  
Parental Strain ◽  
Severe Pneumonia ◽  
Gene Products ◽  
Intracellular Growth ◽  
Content Type ◽  
Mutant Strains ◽  
Legionnaires Disease

ABSTRACTLegionella pneumophilais a natural parasite of environmental amoebae and the causative agent of a severe pneumonia termed Legionnaires' disease. The facultative intracellular pathogen employs a bipartite metabolism, where the amino acid serine serves as the major energy supply, while glycerol and glucose are mainly utilized for anabolic processes. TheL. pneumophilagenome harbors the clusterlpg1653tolpg1649putatively involved in the metabolism of the abundant carbohydratemyo-inositol (here termed inositol). To assess inositol metabolism byL. pneumophila, we constructed defined mutant strains lackinglpg1653orlpg1652, which are predicted to encode the inositol transporter IolT or the inositol-2-dehydrogenase IolG, respectively. The mutant strains were not impaired for growth in complex or defined minimal media, and inositol did not promote extracellular growth. However, upon coinfection ofAcanthamoeba castellanii, the mutants were outcompeted by the parental strain, indicating that the intracellular inositol metabolism confers a fitness advantage to the pathogen. Indeed, inositol added toL. pneumophila-infected amoebae or macrophages promoted intracellular growth of the parental strain, but not of the ΔiolTor ΔiolGmutant, and growth stimulation by inositol was restored by complementation of the mutant strains. The expression of the Piolpromoter and bacterial uptake of inositol required the alternative sigma factor RpoS, a key virulence regulator ofL. pneumophila. Finally, the parental strain and ΔiolGmutant bacteria but not the ΔiolTmutant strain accumulated [U-14C6]inositol, indicating that IolT indeed functions as an inositol transporter. Taken together, intracellularL. pneumophilametabolizes inositol through theiolgene products, thus promoting the growth and virulence of the pathogen.IMPORTANCEThe environmental bacteriumLegionella pneumophilais the causative agent of a severe pneumonia termed Legionnaires' disease. The opportunistic pathogen replicates in protozoan and mammalian phagocytes in a unique vacuole. Amino acids are thought to represent the prime source of carbon and energy forL. pneumophila. However, genome, transcriptome, and proteome studies indicate that the pathogen not only utilizes amino acids as carbon sources but possesses broader metabolic capacities. In this study, we analyzed the metabolism of inositol by extra- and intracellularly growingL. pneumophila. By using genetic, biochemical, and cell biological approaches, we found thatL. pneumophilaaccumulates and metabolizes inositol through theiolgene products, thus promoting the intracellular growth, virulence, and fitness of the pathogen. Our study significantly contributes to an understanding of the intracellular niche of a human pathogen.

scholarly journals Human Lung Tissue Explants Reveal Novel Interactions during Legionella pneumophila Infections

2013 ◽  
Vol 82 (1) ◽  
pp. 275-285 ◽  
Author(s):  
Jens Jäger ◽  
Sebastian Marwitz ◽  
Jana Tiefenau ◽  
Janine Rasch ◽  
Olga Shevchuk ◽  
...  
Keyword(s):  
Lung Tissue ◽  
Legionella Pneumophila ◽  
Human Lung ◽  
Transcriptional Response ◽  
Human Infection ◽  
Bacterial Invasion ◽  
Human Lung Tissue ◽  
Content Type ◽  
Tissue Explants ◽  
Legionnaires Disease

ABSTRACTHistological and clinical investigations describe late stages of Legionnaires' disease but cannot characterize early events of human infection. Cellular or rodent infection models lack the complexity of tissue or have nonhuman backgrounds. Therefore, we developed and applied a novel model forLegionella pneumophilainfection comprising living human lung tissue. We stimulated lung explants withL. pneumophilastrains and outer membrane vesicles (OMVs) to analyze tissue damage, bacterial replication, and localization as well as the transcriptional response of infected tissue. Interestingly, we found that extracellular adhesion ofL. pneumophilato the entire alveolar lining precedes bacterial invasion and replication in recruited macrophages. In contrast, OMVs predominantly bound to alveolar macrophages. Specific damage to septa and epithelia increased over 48 h and was stronger in wild-type-infected and OMV-treated samples than in samples infected with the replication-deficient, type IVB secretion-deficient DotA−strain. Transcriptome analysis of lung tissue explants revealed a differential regulation of 2,499 genes after infection. The transcriptional response included the upregulation of uteroglobin and the downregulation of the macrophage receptor with collagenous structure (MARCO). Immunohistochemistry confirmed the downregulation of MARCO at sites of pathogen-induced tissue destruction. Neither host factor has ever been described in the context ofL. pneumophilainfections. This work demonstrates that the tissue explant model reproduces realistic features of Legionnaires' disease and reveals new functions for bacterial OMVs during infection. Our model allows us to characterize early steps of human infection which otherwise are not feasible for investigations.

scholarly journals Peptidyl-Prolyl-cis/trans-Isomerases Mip and PpiB ofLegionella pneumophilaContribute to Surface Translocation, Growth at Suboptimal Temperature, and Infection

2018 ◽  
Vol 87 (1) ◽  
Author(s):  
J. Rasch ◽  
C. M. Ünal ◽  
A. Klages ◽  
Ü. Karsli ◽  
N. Heinsohn ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Acanthamoeba Castellanii ◽  
Temperature Tolerance ◽  
Lung Damage ◽  
Atypical Pneumonia ◽  
Content Type ◽  
Wide Range ◽  
Legionnaires Disease ◽  
Environmental Fitness ◽  
Sliding Motility

ABSTRACTThe gammaproteobacteriumLegionella pneumophilais the causative agent of Legionnaires’ disease, an atypical pneumonia that manifests itself with severe lung damage.L. pneumophila, a common inhabitant of freshwater environments, replicates in free-living amoebae and persists in biofilms in natural and man-made water systems. Its environmental versatility is reflected in its ability to survive and grow within a broad temperature range as well as its capability to colonize and infect a wide range of hosts, including protozoa and humans. Peptidyl-prolyl-cis/trans-isomerases (PPIases) are multifunctional proteins that are mainly involved in protein folding and secretion in bacteria. InL. pneumophilathe surface-associated PPIase Mip was shown to facilitate the establishment of the intracellular infection cycle in its early stages. The cytoplasmic PpiB was shown to promote cold tolerance. Here, we set out to analyze the interrelationship of these two relevant PPIases in the context of environmental fitness and infection. We demonstrate that the PPIases Mip and PpiB are important for surfactant-dependent sliding motility and adaptation to suboptimal temperatures, features that contribute to the environmental fitness ofL. pneumophila. Furthermore, they contribute to infection of the natural hostAcanthamoeba castellaniias well as human macrophages and human explanted lung tissue. These effects were additive in the case of sliding motility or synergistic in the case of temperature tolerance and infection, as assessed by the behavior of the double mutant. Accordingly, we propose that Mip and PpiB are virulence modulators ofL. pneumophilawith compensatory action and pleiotropic effects.

scholarly journals The Legionella pneumophila Metaeffector Lpg2505 (MesI) Regulates SidI-Mediated Translation Inhibition and Novel Glycosyl Hydrolase Activity

2020 ◽  
Vol 88 (5) ◽  
Author(s):  
Ashley M. Joseph ◽  
Adrienne E. Pohl ◽  
Theodore J. Ball ◽  
Troy G. Abram ◽  
David K. Johnson ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Glycosyl Hydrolase ◽  
Protein Translation ◽  
Effector Proteins ◽  
Hydrolase Activity ◽  
Intracellular Replication ◽  
Content Type ◽  
Translation Inhibition ◽  
Legionnaires Disease ◽  
The Impact

ABSTRACT Legionella pneumophila, the etiological agent of Legionnaires’ disease, employs an arsenal of hundreds of Dot/Icm-translocated effector proteins to facilitate replication within eukaryotic phagocytes. Several effectors, called metaeffectors, function to regulate the activity of other Dot/Icm-translocated effectors during infection. The metaeffector Lpg2505 is essential for L. pneumophila intracellular replication only when its cognate effector, SidI, is present. SidI is a cytotoxic effector that interacts with the host translation factor eEF1A and potently inhibits eukaryotic protein translation by an unknown mechanism. Here, we evaluated the impact of Lpg2505 on SidI-mediated phenotypes and investigated the mechanism of SidI function. We determined that Lpg2505 binds with nanomolar affinity to SidI and suppresses SidI-mediated inhibition of protein translation. SidI binding to eEF1A and Lpg2505 is not mutually exclusive, and the proteins bind distinct regions of SidI. We also discovered that SidI possesses GDP-dependent glycosyl hydrolase activity and that this activity is regulated by Lpg2505. We have therefore renamed Lpg2505 MesI (metaeffector of SidI). This work reveals novel enzymatic activity for SidI and provides insight into how intracellular replication of L. pneumophila is regulated by a metaeffector.

scholarly journals Involvement of Fractalkine/CX3CL1 Expression by Dendritic Cells in the Enhancement of Host Immunity against Legionella pneumophila

2005 ◽  
Vol 73 (9) ◽  
pp. 5350-5357 ◽  
Author(s):  
Toshiaki Kikuchi ◽  
Sita Andarini ◽  
Hong Xin ◽  
Kazunori Gomi ◽  
Yutaka Tokue ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Host Defense ◽  
Legionella Pneumophila ◽  
Recombinant Adenovirus ◽  
Severe Pneumonia ◽  
Adenovirus Vector ◽  
Recombinant Adenovirus Vector ◽  
Legionnaires Disease

ABSTRACT Legionnaires' disease is clinically manifested as severe pneumonia caused by Legionella pneumophila. However, the dendritic cell (DC)-centered immunological framework of the host defense against L. pneumophila has not been fully delineated. For this study, we focused on a potent chemoattractant for lymphocytes, fractalkine/CX3CL1, and observed that the fractalkine expression of DCs was somewhat up-regulated when they encountered L. pneumophila. We therefore hypothesized that fractalkine expressed by Legionella-capturing DCs is involved in the induction of T-cell-mediated immune responses against Legionella, which would be enhanced by a genetic modulation of DCs to overexpress fractalkine. In vivo immunization-challenge experiments demonstrated that DCs modified with a recombinant adenovirus vector to overexpress fractalkine (AdFKN) and pulsed with heat-killed Legionella protected immunized mice from a lethal Legionella infection and that the generation of in vivo protective immunity depended on the host lymphocyte subsets, including CD4+ T cells, CD8+ T cells, and B cells. Consistent with this, immunization with AdFKN/Legionella/DC induced significantly higher levels of serum anti-Legionella antibodies of several isotypes than those induced by control immunizations. Further analysis of spleen cells from the immunized mice indicated that the AdFKN/Legionella/DC immunization elicited Th1-dominated immune responses to L. pneumophila. These observations suggest that fractalkine may play an important role in the DC-mediated host defense against intracellular pathogens such as L. pneumophila.

scholarly journals Development of a DNA Microarray Method for Detection and Identification of All 15 Distinct O-Antigen Forms of Legionella pneumophila

2013 ◽  
Vol 79 (21) ◽  
pp. 6647-6654 ◽  
Author(s):  
Boyang Cao ◽  
Fangfang Yao ◽  
Xiangqian Liu ◽  
Lu Feng ◽  
Lei Wang
Keyword(s):  
Dna Microarray ◽  
Legionella Pneumophila ◽  
Detection Sensitivity ◽  
Immunological Methods ◽  
Clinical Samples ◽  
Content Type ◽  
O Antigen ◽  
Detection And Identification ◽  
Legionnaires Disease ◽  
Reference Strains

ABSTRACTLegionellais ubiquitous in many environments. At least 50 species and 70 serogroups of the Gram-negative bacterium have been identified. Of the 50 species, 20 are pathogenic, andLegionella pneumophilais responsible for the great majority (approximately 90%) of the Legionnaires' disease cases that occur. Furthermore, of the 15L. pneumophilaserogroups identified, O1 alone causes more than 84% of the Legionnaires' disease cases that occur worldwide. Rapid and reliable assays for the detection and identification ofL. pneumophilain water, environmental, and clinical samples are in great demand.L. pneumophilabacteria are traditionally identified by their O antigens by immunological methods. We have recently developed an O serogroup-specific DNA microarray for the detection of all 15 distinct O-antigen forms ofL. pneumophila, including serogroups O1 to O15. A total of 35 strains were used to verify the specificity of the microarray, including 15L. pneumophilaO-antigen standard reference strains and sevenL. pneumophilaclinical isolates as target strains, seven reference strains of other non-pneumophila Legionellaspecies as closely related strains, and six non-Legionellabacterial species as nonrelated strains. The detection sensitivity was 1 ng of genomic DNA or 0.4 CFU/ml in water samples with filter enrichment and plate culturing. This study demonstrated that the microarray allows specific, sensitive, and reproducible detection ofL. pneumophilaserogroups. To the best of our knowledge, this is the first report of a microarray serotyping method for all 15 distinct O-antigen forms ofL. pneumophila.

scholarly journals The Legionella longbeachae Icm/Dot Substrate SidC Selectively Binds Phosphatidylinositol 4-Phosphate with Nanomolar Affinity and Promotes Pathogen Vacuole-Endoplasmic Reticulum Interactions

2014 ◽  
Vol 82 (10) ◽  
pp. 4021-4033 ◽  
Author(s):  
Stephanie Dolinsky ◽  
Ina Haneburger ◽  
Adam Cichy ◽  
Mandy Hannemann ◽  
Aymelt Itzen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Legionella Pneumophila ◽  
Severe Pneumonia ◽  
Biological Data ◽  
Effector Proteins ◽  
Host Cells ◽  
Titration Calorimetry ◽  
Dependent Manner ◽  
Content Type ◽  
Phosphatidylinositol 4

ABSTRACTLegionellaspp. cause the severe pneumonia Legionnaires' disease. The environmental bacteria replicate intracellularly in free-living amoebae and human alveolar macrophages within a distinct, endoplasmic reticulum (ER)-derived compartment termed theLegionella-containing vacuole (LCV). LCV formation requires the bacterial Icm/Dot type IV secretion system (T4SS) that translocates into host cells a plethora of different “effector” proteins, some of which anchor to the pathogen vacuole by binding to phosphoinositide (PI) lipids. Here, we identified by unbiased pulldown assays inLegionella longbeachaelysates a 111-kDa SidC homologue as the major phosphatidylinositol 4-phosphate [PtdIns(4)P]-binding protein. The PI-binding domain was mapped to a 20-kDa P4C [PtdIns(4)Pbinding of SidC] fragment. Isothermal titration calorimetry revealed that SidC ofL. longbeachae(SidCLlo) binds PtdIns(4)Pwith aKd(dissociation constant) of 71 nM, which is 3 to 4 times lower than that of the SidC orthologue ofLegionella pneumophila(SidCLpn). Upon infection of RAW 264.7 macrophages withL. longbeachae, endogenous SidCLloor ectopically produced SidCLpnlocalized in an Icm/Dot-dependent manner to the PtdIns(4)P-positive LCVs. AnL. longbeachaeΔsidCdeletion mutant was impaired for calnexin recruitment to LCVs inDictyostelium discoideumamoebae and outcompeted by wild-type bacteria inAcanthamoeba castellanii. Calnexin recruitment was restored by SidCLloor its orthologues SidCLpnand SdcALpn. Conversely, calnexin recruitment was restored by SidCLloinL. pneumophilalackingsidCandsdcA. Together, biochemical, genetic, and cell biological data indicate that SidCLlois anL. longbeachaeeffector that binds through a P4C domain with high affinity to PtdIns(4)Pon LCVs, promotes ER recruitment to the LCV, and thus plays a role in pathogen-host interactions.

scholarly journals Exploitation of Phosphoinositides by the Intracellular Pathogen, Legionella pneumophila

2020 ◽  
Author(s):  
Colleen M. Pike ◽  
Rebecca R. Noll ◽  
M. Ramona Neunuebel
Keyword(s):  
Membrane Trafficking ◽  
Legionella Pneumophila ◽  
Pathogenic Bacteria ◽  
Severe Pneumonia ◽  
Bacterial Proteins ◽  
Specific Host ◽  
Spatiotemporal Regulation ◽  
Host Membrane ◽  
Membrane Compartments ◽  
Legionnaires Disease

Manipulation of host phosphoinositide lipids has emerged as a key survival strategy utilized by pathogenic bacteria to establish and maintain a replication-permissive compartment within eukaryotic host cells. The human pathogen, Legionella pneumophila, infects and proliferates within the lung’s innate immune cells causing severe pneumonia termed Legionnaires’ disease. This pathogen has evolved strategies to manipulate specific host components to construct its intracellular niche termed the Legionella-containing vacuole (LCV). Paramount to LCV biogenesis and maintenance is the spatiotemporal regulation of phosphoinositides, important eukaryotic lipids involved in cell signaling and membrane trafficking. Through a specialized secretion system, L. pneumophila translocates multiple proteins that target phosphoinositides in order to escape endolysosomal degradation. By specifically binding phosphoinositides, these proteins can anchor to the cytosolic surface of the LCV or onto specific host membrane compartments, to ultimately stimulate or inhibit encounters with host organelles. Here, we describe the bacterial proteins involved in binding and/or altering host phosphoinositide dynamics to support intracellular survival of L. pneumophila.

scholarly journals More than 16,000 effectors in theLegionellagenus genome provide multiple, independent combinations for replication in human cells

2018 ◽  
Author(s):  
Laura Gomez-Valero ◽  
Christophe Rusniok ◽  
Danielle Carson ◽  
Sonia Mondino ◽  
Ana Elena Pérez-Cobas ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Secreted Proteins ◽  
Rab Gtpase ◽  
Functional Screening ◽  
Evolutionary Analysis ◽  
Human Pathogen ◽  
Human Pathogens ◽  
Intracellular Replication ◽  
Bacterial Genus ◽  
Gene Acquisition

SignificanceLegionella pneumophilais a bacterial pathogen causing outbreaks of a lethal pneumonia. The genusLegionellacomprises 65 species for which aquatic amoebae are the natural reservoirs. Using functional and comparative genomics to deconstruct the entire bacterial genus we reveal the surprising parallel evolutionary trajectories that have led to the emergence of human pathogenicLegionella.An unexpectedly large and unique repository of secreted proteins (>16,000) containing eukaryotic-like proteins acquired from all domains of life (plant, animal, fungal, archaea) is contrasting with a highly conserved type 4 secretion system. This study reveals an unprecedented environmental reservoir of bacterial virulence factors, and provides a new understanding of how reshuffling and gene-acquisition from environmental eukaryotic hosts, may allow for the emergence of human pathogens.AbstractThe bacterial genusLegionellacomprises 65 species among, whichLegionella pneumophilais a human pathogen causing severe pneumonia. To understand the evolution of an environmental to an accidental human pathogen, we have functionally analyzed 80Legionellagenomes spanning 58 species. Uniquely, an immense repository of 16,000 secreted proteins encoding 137 different eukaryotic-like domains and more than 200 eukaryotic-like proteins is paired with a highly conserved T4SS. Specifically, we show that eukaryotic Rho and Rab GTPase domains are found nearly exclusively in eukaryotes andLegionellaspecies. Translocation assays for selected Rab-GTPase proteins revealed that they are indeed T4SS secreted substrates. Furthermore, F/U-box and SET domains were present in >70% of all species suggesting that manipulation of host signal transduction, protein turnover and chromatin modification pathways, respectively are fundamental intracellular replication strategies forLegionellae. In contrast, the Sec-7 domain was restricted toL. pneumophilaand seven other species, indicating effector repertoire tailoring within different amoebae. Functional screening of 47 species revealed 60% were competent for intracellular replication in THP-1 cells, but interestingly this phenotype was associated with diverse effector assemblages. These data, combined with evolutionary analysis indicate that the capacity to infect eukaryotic cells has been acquired independently many times within the genus and that a highly conserved yet versatile T4SS secretes an exceptional number of different proteins shaped by inter-domain gene transfer. Furthermore we revealed the surprising extent to which legionellae have co-opted genes and thus cellular functions from their eukaryotic hosts and provides a new understanding of how dynamic reshuffling and gene-acquisition has led to the emergence of major human pathogens.

Sign in / Sign up

Export Citation Format

Share Document