scholarly journals SssP1, aStreptococcus suisFimbria-Like Protein Transported by the SecY2/A2 System, Contributes to Bacterial Virulence

2018 ◽  
Vol 84 (18) ◽  
Author(s):  
Yue Zhang ◽  
Pengpeng Lu ◽  
Zihao Pan ◽  
Yinchu Zhu ◽  
Jiale Ma ◽  
...  
Keyword(s):  
Cell Surface ◽  
Streptococcus Suis ◽  
Secretory Protein ◽  
Genomic Islands ◽  
Host Cells ◽  
Genome Comparison ◽  
Immunogold Electron Microscopy ◽  
Infection Model ◽  
Content Type ◽  
Zoonotic Pathogen

ABSTRACTStreptococcus suisis an important Gram-positive pathogen in the swine industry and is an emerging zoonotic pathogen for humans. In our previous work, we found a virulentS. suisstrain, CZ130302, belonging to a novel serotype, Chz, to be associated with acute meningitis in piglets. However, its underlying mechanisms of pathogenesis remain poorly understood. In this study, we sequenced and analyzed the complete genomes of three Chz serotype strains, including strain CZ130302 and two avirulent strains, HN136 and AH681. By genome comparison, we found two putative genomic islands (GIs) uniquely encoded in strain CZ130302 and designated them 50K GI and 58K GI. In mouse infection model, the deletion of 50K and 58K GIs caused 270-fold and 3-fold attenuation of virulence, respectively. Notably, we identified a complete SecY2/A2 system, coupled with its secretory protein SssP1 encoded in the 50K GI, which contributed to the pathogenicity of strain CZ130302. Immunogold electron microscopy and immunofluorescence analyses indicated that SssP1 could form fimbria-like structures that extend outward from the bacterial cell surface. ThesssP1mutation also attenuated bacterial adherence in human laryngeal epithelial (HEp-2) cells and human brain microvessel endothelial cells (HBMECs) compared with the wild type. Furthermore, we showed that two analogous Ig-like subdomains of SssP1 have sialic acid binding capacities. In conclusion, our results revealed that the 50K GI and the inside SecY2/A2 system gene cluster are related to the virulence of strain CZ130302, and we clarified a newS. suispathogenesis mechanism mediated by the secretion protein SssP1.IMPORTANCEStreptococcus suisis an important zoonotic pathogen. Here, we managed to identify key factors to clarify the virulence ofS. suisstrain CZ130302 from a novel serotype, Chz. Notably, it was shown that a fimbria-like structure was significantly connected to the pathogenicity of the CZ130302 strain by comparative genomics analysis and animal infection assays. The mechanisms of how the CZ130302 strain constructs these fimbria-like structures in the cell surface by genes encoding and production transport were subsequently elucidated. Biosynthesis of the fimbria-like structure was achieved by the production of SssP1 glycoproteins, and its construction was dependent on the SecA2/Y2 secretion system. This study identified a visible fimbria-like protein, SssP1, participating in adhesion to host cells and contributing to the virulence inS. suis. These findings will promote a better understanding of the pathogenesis ofS. suis.

scholarly journals Complete Genome Sequences of Two Streptococcus suis Strains Isolated from Asymptomatic Pigs

2020 ◽  
Vol 9 (47) ◽  
Author(s):  
Atsuko Minowa-Nozawa ◽  
Takashi Nozawa ◽  
Daisuke Takamatsu ◽  
Akemi Yoshida ◽  
Kazunori Murase ◽  
...  
Keyword(s):  
Complete Genome ◽  
Streptococcus Suis ◽  
Genome Sequences ◽  
Content Type ◽  
Zoonotic Pathogen ◽  
Economic Problems ◽  
Serious Infections

ABSTRACT Streptococcus suis is an important zoonotic pathogen that causes major economic problems in the pig industry worldwide and serious infections in humans, including meningitis and septicemia. Here, we report the complete genome sequences of two strains isolated from asymptomatic pigs.

scholarly journals Intracellular Trafficking and Persistence of Acinetobacter baumannii Requires Transcription Factor EB

mSphere ◽  
2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Raquel Parra-Millán ◽  
David Guerrero-Gómez ◽  
Rafael Ayerbe-Algaba ◽  
Maria Eugenia Pachón-Ibáñez ◽  
Antonio Miranda-Vizuete ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Acinetobacter Baumannii ◽  
Intracellular Trafficking ◽  
Nuclear Translocation ◽  
A549 Cells ◽  
Lung Epithelial Cells ◽  
Host Cells ◽  
Infection Model ◽  
Content Type ◽  
Transcription Factor Eb

ABSTRACT Acinetobacter baumannii is a significant human pathogen associated with hospital-acquired infections. While adhesion, an initial and important step in A. baumannii infection, is well characterized, the intracellular trafficking of this pathogen inside host cells remains poorly studied. Here, we demonstrate that transcription factor EB (TFEB) is activated after A. baumannii infection of human lung epithelial cells (A549). We also show that TFEB is required for the invasion and persistence inside A549 cells. Consequently, lysosomal biogenesis and autophagy activation were observed after TFEB activation which could increase the death of A549 cells. In addition, using the Caenorhabditis elegans infection model by A. baumannii , the TFEB orthologue HLH-30 was required for survival of the nematode to infection, although nuclear translocation of HLH-30 was not required. These results identify TFEB as a conserved key factor in the pathogenesis of A. baumannii . IMPORTANCE Adhesion is an initial and important step in Acinetobacter baumannii infections. However, the mechanism of entrance and persistence inside host cells is unclear and remains to be understood. In this study, we report that, in addition to its known role in host defense against Gram-positive bacterial infection, TFEB also plays an important role in the intracellular trafficking of A. baumannii in host cells. TFEB was activated shortly after A. baumannii infection and is required for its persistence within host cells. Additionally, using the C. elegans infection model by A. baumannii , the TFEB orthologue HLH-30 was required for survival of the nematode to infection, although nuclear translocation of HLH-30 was not required.

scholarly journals Capsular Polysaccharide of Erysipelothrix rhusiopathiae, the Causative Agent of Swine Erysipelas, and Its Modification with Phosphorylcholine

2012 ◽  
Vol 80 (11) ◽  
pp. 3993-4003 ◽  
Author(s):  
Fang Shi ◽  
Tomoyuki Harada ◽  
Yohsuke Ogawa ◽  
Hiroshi Ono ◽  
Mayumi Ohnishi-Kameyama ◽  
...  
Keyword(s):  
Cell Surface ◽  
Capsular Polysaccharide ◽  
Genetic Locus ◽  
Hot Water ◽  
Mycoplasma Species ◽  
Phylogenetic Position ◽  
Close Relative ◽  
Immunogold Electron Microscopy ◽  
Erysipelothrix Rhusiopathiae ◽  
Content Type

ABSTRACTThe capsule has been implicated in the virulence of the swine pathogenErysipelothrix rhusiopathiae, a rod-shaped, intracellular Gram-positive bacterium that has a unique phylogenetic position in the phylumFirmicutesand is a close relative ofMollicutes(mycoplasma species). In this study, we analyzed the genetic locus and composition of the capsular polysaccharide (CPS) of the Fujisawa strain ofE. rhusiopathiae. Genome analysis of the Fujisawa strain revealed that the genetic locus for capsular polysaccharide synthesis (cps) is located next to anlicoperon, which is involved in the incorporation and expression of phosphorylcholine (PCho). Reverse transcription-PCR analysis showed thatcpsandlicare transcribed as a single mRNA, indicating that the loci form an operon. Using the cell surface antigen-specific monoclonal antibody (MAb) ER21 as a probe, the capsular materials were isolated from the Fujisawa strain by hot water extraction and treatment with DNase, RNase, pronase, andN-acetylmuramidase SG, followed by anion-exchange and gel filtration chromatography. The materials were then analyzed by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. The CPS ofE. rhusiopathiaeis heterogeneous and consists of the major monosaccharides galacturonic acid, galactose, mannose, glucose, arabinose, xylose, andN-acetylglucosamine and some minor monosaccharides containing ribose, rhamnose, andN-acetylgalactosamine. In addition, the capsule is modified by PCho, which comigrates with the capsular materials, as determined by Western immunoblotting, and colocalizes on the cell surface, as determined by immunogold electron microscopy. Virulence testing of PCho-defective mutants in mice demonstrated that PCho is critical for the virulence of this organism.

scholarly journals In VivoPharmacodynamics of Cefquinome in a Neutropenic Mouse Thigh Model of Streptococcus suis Serotype 2 at Varied Initial Inoculum Sizes

2015 ◽  
Vol 60 (2) ◽  
pp. 1114-1120 ◽  
Author(s):  
Chunna Guo ◽  
Xiaoping Liao ◽  
Mingru Wang ◽  
Feng Wang ◽  
Chaoqun Yan ◽  
...  
Keyword(s):  
Severe Disease ◽  
Streptococcus Suis ◽  
Dose Fractionation ◽  
Fourth Generation ◽  
Maximum Effect ◽  
Infection Model ◽  
Human Beings ◽  
Content Type

ABSTRACTStreptococcus suisserotype 2 is an emerging zoonotic pathogen and causes severe disease in both pigs and human beings. Cefquinome (CEQ), a fourth-generation cephalosporin, exhibits broad-spectrum activity against Gram-positive bacteria such asS. suis. This study evaluated thein vitroandin vivoantimicrobial activities of CEQ against four strains ofS. suisserotype 2 in a murine neutropenic thigh infection model. We investigated the effect of varied inoculum sizes (106to 108CFU/thigh) on the pharmacokinetic (PK)/pharmacodynamic (PD) indices and magnitudes of a particular PK/PD index or dose required for efficacy. Dose fractionation studies included total CEQ doses ranging from 0.625 to 640 mg/kg/24 h. Data were analyzed via a maximum effect (Emax) model using nonlinear regression. The PK/PD studies demonstrated that the percentage of time that serum drug levels were above the MIC of free drug (%ƒT>MIC) in a 24-h dosing interval was the primary index driving the efficacy of both inoculum sizes (R2= 91% andR2= 63%). CEQ doses of 2.5 and 40 mg/kg body weight produced prolonged postantibiotic effects (PAEs) of 2.45 to 8.55 h. Inoculum sizes had a significant influence on CEQ efficacy. Compared to the CEQ exposure and dosages in tests using standard inocula, a 4-fold dose (P= 0.006) and a 2-fold exposure time (P= 0.01) were required for a 1-log kill using large inocula of 108CFU/thigh.

scholarly journals An Inside Job: Hacking into Janus Kinase/Signal Transducer and Activator of Transcription Signaling Cascades by the Intracellular Protozoan Toxoplasma gondii

2011 ◽  
Vol 80 (2) ◽  
pp. 476-482 ◽  
Author(s):  
Eric Y. Denkers ◽  
David J. Bzik ◽  
Barbara A. Fox ◽  
Barbara A. Butcher
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Secretory Protein ◽  
Effector Proteins ◽  
Janus Kinase ◽  
Host Cells ◽  
Cytokine Signaling ◽  
Signal Transducer ◽  
Content Type ◽  
Transcription 3

ABSTRACTThe intracellular protozoanToxoplasma gondiiis well known for its skill at invading and living within host cells. New discoveries are now also revealing the astounding ability of the parasite to inject effector proteins into the cytoplasm to seize control of the host cell. This review summarizes recent advances in our understanding of one such secretory protein called ROP16. This molecule is released from rhoptries into the host cell during invasion. The ROP16 molecule acts as a kinase, directly activating both signal transducer and activator of transcription 3 (STAT3) and STAT6 signaling pathways. In macrophages, an important and preferential target cell of parasite infection, the injection of ROP16 has multiple consequences, including downregulation of proinflammatory cytokine signaling and macrophage deviation to an alternatively activated phenotype.

scholarly journals Excreted Cytoplasmic Proteins Contribute to Pathogenicity in Staphylococcus aureus

2016 ◽  
Vol 84 (6) ◽  
pp. 1672-1681 ◽  
Author(s):  
Patrick Ebner ◽  
Janina Rinker ◽  
Minh Thu Nguyen ◽  
Peter Popella ◽  
Mulugeta Nega ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Host Cell ◽  
Host Cells ◽  
Infection Model ◽  
Bacterial Cells ◽  
Host Matrix ◽  
Content Type ◽  
Cell Internalization ◽  
Cytoplasmic Proteins ◽  
The Impact

Excretion of cytoplasmic proteins in pro- and eukaryotes, also referred to as “nonclassical protein export,” is a well-known phenomenon. However, comparatively little is known about the role of the excreted proteins in relation to pathogenicity. Here, the impact of two excreted glycolytic enzymes, aldolase (FbaA) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), on pathogenicity was investigated inStaphylococcus aureus. Both enzymes bound to certain host matrix proteins and enhanced adherence of the bacterial cells to host cells but caused a decrease in host cell invasion. FbaA and GAPDH also bound to the cell surfaces of staphylococcal cells by interaction with the major autolysin, Atl, that is involved in host cell internalization. Surprisingly, FbaA showed high cytotoxicity to both MonoMac 6 (MM6) and HaCaT cells, while GAPDH was cytotoxic only for MM6 cells. Finally, the contribution of external FbaA and GAPDH toS. aureuspathogenicity was confirmed in an insect infection model.

scholarly journals Entamoeba histolytica Cell Surface Calreticulin Binds Human C1q and Functions in Amebic Phagocytosis of Host Cells

2012 ◽  
Vol 80 (6) ◽  
pp. 2008-2018 ◽  
Author(s):  
Archana Vaithilingam ◽  
Jose E. Teixeira ◽  
Peter J. Miller ◽  
Bradley T. Heron ◽  
Christopher D. Huston
Keyword(s):  
Cell Surface ◽  
Entamoeba Histolytica ◽  
Calcium Ionophore ◽  
Surface Expression ◽  
Surface Proteins ◽  
Host Cells ◽  
Content Type ◽  
Amebic Dysentery ◽  
Host Cell Apoptosis ◽  
Phagocytic Cups

ABSTRACTPhagocytosis of host cells is characteristic of tissue invasion by the intestinal amebaEntamoeba histolytica, which causes amebic dysentery and liver abscesses.Entamoeba histolyticainduces host cell apoptosis and uses ligands, including C1q, on apoptotic cells to engulf them. Two mass spectrometry analyses identified calreticulin in amebic phagosome preparations, and, in addition to its function as an endoplasmic reticulum chaperone, calreticulin is believed to be the macrophage receptor for C1q. The purpose of this study was to determine if calreticulin functions as anE. histolyticaC1q receptor during phagocytosis of host cells. Calreticulin was localized to the surface ofE. histolyticaduring interaction with both Jurkat lymphocytes and erythrocytes and was present in over 75% of phagocytic cups during amebic erythrophagocytosis. Presence of calreticulin on the cell surface was further demonstrated using a method that selectively biotinylated cell surface proteins and by flow cytometry using trophozoites overexpressing epitope-tagged calreticulin. Regulated overexpression of calreticulin increasedE. histolytica's ability to phagocytose apoptotic lymphocytes and calcium ionophore-treated erythrocytes but had no effect on amebic adherence to or destruction of cell monolayers or surface expression of the GalNAc lectin and serine-richE. histolyticaprotein (SREHP) receptors. Finally,E. histolyticacalreticulin bound specifically to apoptotic lymphocytes and to human C1q. Collectively, these data implicate cell surface calreticulin as a receptor for C1q duringE. histolyticaphagocytosis of host cells.

scholarly journals Strain-Specific Features of Extracellular Polysaccharides and Their Impact on Lactobacillus plantarum-Host Interactions

2016 ◽  
Vol 82 (13) ◽  
pp. 3959-3970 ◽  
Author(s):  
I-Chiao Lee ◽  
Graziano Caggianiello ◽  
Iris I. van Swam ◽  
Nico Taverne ◽  
Marjolein Meijerink ◽  
...  
Keyword(s):  
Cell Surface ◽  
Lactobacillus Plantarum ◽  
Surface Properties ◽  
Gene Clusters ◽  
Host Cells ◽  
Extracellular Polysaccharides ◽  
Bacterial Strains ◽  
Strain Specificity ◽  
Content Type ◽  
Health Promoting

ABSTRACTLactobacilli are found in diverse environments and are widely applied as probiotic, health-promoting food supplements. Polysaccharides are ubiquitously present on the cell surface of lactobacilli and are considered to contribute to the species- and strain-specific probiotic effects that are typically observed. TwoLactobacillus plantarumstrains, SF2A35B and Lp90, have an obvious ropy phenotype, implying high extracellular polysaccharide (EPS) production levels. In this work, we set out to identify the genes involved in EPS production in theseL. plantarumstrains and to demonstrate their role in EPS production by gene deletion analysis. A modelL. plantarumstrain, WCFS1, and its previously constructed derivative that produced reduced levels of EPS were included as reference strains. The constructed EPS-reduced derivatives were analyzed for the abundance and sugar compositions of their EPS, revealingcps2-like gene clusters in SF2A35B and Lp90 responsible for major EPS production. Moreover, these mutant strains were tested for phenotypic characteristics that are of relevance for their capacity to interact with the host epithelium in the intestinal tract, including bacterial surface properties as well as survival under the stress conditions encountered in the gastrointestinal tract (acid and bile stress). In addition, the Toll-like receptor 2 (TLR2) signaling and immunomodulatory capacities of the EPS-negative derivatives and their respective wild-type strains were compared, revealing strain-specific impacts of EPS on the immunomodulatory properties. Taken together, these experiments illustrate the importance of EPS inL. plantarumstrains as a strain-specific determinant in host interaction.IMPORTANCEThis study evaluates the role of extracellular polysaccharides that are produced by different strains ofLactobacillus plantarumin the determination of the cell surface properties of these bacteria and their capacity to interact with their environment, including their signaling to human host cells. The results clearly show that the consequences of removal of these polysaccharides are very strain specific, illustrating the diverse and unpredictable roles of these polysaccharides in the environmental interactions of these bacterial strains. In the context of the use of lactobacilli as health-promoting probiotic organisms, this study exemplifies the importance of strain specificity.

scholarly journals Binding of Host Cell Surface Protein Disulfide Isomerase by Anaplasma phagocytophilum Asp14 Enables Pathogen Infection

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryan S. Green ◽  
Waheeda A. Naimi ◽  
Lee D. Oliver ◽  
Nathaniel O’Bier ◽  
Jaehyung Cho ◽  
...  
Keyword(s):  
Cell Surface ◽  
Disulfide Bonds ◽  
Protein Disulfide Isomerase ◽  
Host Cells ◽  
Content Type ◽  
Granulocytic Anaplasmosis ◽  
C Terminus ◽  
Host Cell Surface ◽  
Protein Disulfide

ABSTRACT Diverse intracellular pathogens rely on eukaryotic cell surface disulfide reductases to invade host cells. Pharmacologic inhibition of these enzymes is cytotoxic, making it impractical for treatment. Identifying and mechanistically dissecting microbial proteins that co-opt surface reductases could reveal novel targets for disrupting this common infection strategy. Anaplasma phagocytophilum invades neutrophils by an incompletely defined mechanism to cause the potentially fatal disease granulocytic anaplasmosis. The bacterium’s adhesin, Asp14, contributes to invasion by virtue of its C terminus engaging an unknown receptor. Yeast-two hybrid analysis identified protein disulfide isomerase (PDI) as an Asp14 binding partner. Coimmunoprecipitation confirmed the interaction and validated it to be Asp14 C terminus dependent. PDI knockdown and antibody-mediated inhibition of PDI reductase activity impaired A. phagocytophilum infection of but not binding to host cells. Infection during PDI inhibition was rescued when the bacterial but not host cell surface disulfide bonds were chemically reduced with tris(2-carboxyethyl)phosphine-HCl (TCEP). TCEP also restored bacterial infectivity in the presence of an Asp14 C terminus blocking antibody that otherwise inhibits infection. A. phagocytophilum failed to productively infect myeloid-specific-PDI conditional-knockout mice, marking the first demonstration of in vivo microbial dependency on PDI for infection. Mutational analyses identified the Asp14 C-terminal residues that are critical for binding PDI. Thus, Asp14 binds and brings PDI proximal to A. phagocytophilum surface disulfide bonds that it reduces, which enables cellular and in vivo infection. IMPORTANCE Anaplasma phagocytophilum infects neutrophils to cause granulocytic anaplasmosis, an emerging potentially fatal disease and the second-most common tick-borne illness in the United States. Treatment options are limited, and no vaccine exists. Due to the bacterium’s obligatory intracellular lifestyle, A. phagocytophilum survival and pathogenesis are predicated on its ability to enter host cells. Understanding its invasion mechanism will yield new targets for preventing bacterial entry and, hence, disease. We report a novel entry pathway in which the A. phagocytophilum outer membrane protein Asp14 binds host cell surface protein disulfide isomerase via specific C-terminal residues to promote reduction of bacterial surface disulfide bonds, which is critical for cellular invasion and productive infection in vivo. Targeting the Asp14 C terminus could be used to prevent/treat granulocytic anaplasmosis. Our findings have broad implications, as a thematically similar approach could be applied to block infection by other intracellular microbes that exploit cell surface reductases.

scholarly journals Role for the Burkholderia pseudomallei Type Three Secretion System Cluster 1bpscNGene in Virulence

2011 ◽  
Vol 79 (9) ◽  
pp. 3659-3664 ◽  
Author(s):  
Tanya D'Cruze ◽  
Lan Gong ◽  
Puthayalai Treerat ◽  
Georg Ramm ◽  
John D. Boyce ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Burkholderia Pseudomallei ◽  
Gene Clusters ◽  
Secretion System ◽  
Host Cells ◽  
Infection Model ◽  
Content Type ◽  
Type Three Secretion System ◽  
Type Three Secretion

ABSTRACTBurkholderia pseudomallei, the causal agent of melioidosis, employs a number of virulence factors during its infection of mammalian cells. One such factor is the type three secretion system (TTSS), which is proposed to mediate the transport and secretion of bacterial effector molecules directly into host cells. TheB. pseudomalleigenome contains three TTSS gene clusters (designated TTSS1, TTSS2, and TTSS3). Previous research has indicated that neither TTSS1 nor TTSS2 is involved inB. pseudomalleivirulence in a hamster infection model. We have characterized aB. pseudomalleimutant lacking expression of the predicted TTSS1 ATPase encoded bybpscN. This mutant was significantly attenuated for virulence in a respiratory melioidosis mouse model of infection. In addition, analysesin vitroshowed diminished survival and replication in RAW264.7 cells and an increased level of colocalization with the autophagy marker protein LC3 but an unhindered ability to escape from phagosomes. Taken together, these data provide evidence that the TTSS1bpscNgene product plays an important role in the intracellular survival ofB. pseudomalleiand the pathogenesis of murine infection.

Sign in / Sign up

Export Citation Format

Share Document