scholarly journals The Fungal Effector Mlp37347 Alters Plasmodesmata Fluxes and Enhances Susceptibility to Pathogen

2021 ◽  
Vol 9 (6) ◽  
pp. 1232
Author(s):  
Md. Saifur Rahman ◽  
Mst Hur Madina ◽  
Mélodie B. Plourde ◽  
Karen Cristine Gonçalves dos Santos ◽  
Xiaoqiang Huang ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Transcriptome Profiling ◽  
Host Cells ◽  
Rust Disease ◽  
Callose Deposition ◽  
In Silico Docking ◽  
Poplar Trees ◽  
Genomic Studies ◽  
Green Fluorescent ◽  
Poplar Leaf

Melampsora larici-populina (Mlp) is a devastating pathogen of poplar trees, causing the defoliating poplar leaf rust disease. Genomic studies have revealed that Mlp possesses a repertoire of 1184 small secreted proteins (SSPs), some of them being characterized as candidate effectors. However, how they promote virulence is still unclear. This study investigates the candidate effector Mlp37347’s role during infection. We developed a stable Arabidopsis transgenic line expressing Mlp37347 tagged with the green fluorescent protein (GFP). We found that the effector accumulated exclusively at plasmodesmata (PD). Moreover, the presence of the effector at plasmodesmata favors enhanced plasmodesmatal flux and reduced callose deposition. Transcriptome profiling and a gene ontology (GO) analysis of transgenic Arabidopsis plants expressing the effector revealed that the genes involved in glucan catabolic processes are up-regulated. This effector has previously been shown to interact with glutamate decarboxylase 1 (GAD1), and in silico docking analysis supported the strong binding between Mlp37347 and GAD1 in this study. In infection assays, the effector promoted Hyalonoperospora arabidopsidis growth but not bacterial growth. Our investigation suggests that the effector Mlp37347 targets PD in host cells and promotes parasitic growth.

scholarly journals Nature and consequences of interactions between Salmonella enterica serovar Dublin and host cells in cattle

2019 ◽  
Vol 50 (1) ◽  
Author(s):  
Prerna Vohra ◽  
Christina Vrettou ◽  
Jayne C. Hope ◽  
John Hopkins ◽  
Mark P. Stevens
Keyword(s):  
Lymph Nodes ◽  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Large Animal ◽  
Ileal Mucosa ◽  
Zoonotic Infections ◽  
Infected Cells ◽  
Green Fluorescent ◽  
Salmonella Enterica Serovar Dublin

AbstractSalmonella enterica is a veterinary and zoonotic pathogen of global importance. While murine and cell-based models of infection have provided considerable knowledge about the molecular basis of virulence of Salmonella, relatively little is known about salmonellosis in naturally-affected large animal hosts such as cattle, which are a reservoir of human salmonellosis. As in humans, Salmonella causes bovine disease ranging from self-limiting enteritis to systemic typhoid-like disease and exerts significant economic and welfare costs. Understanding the nature and consequences of Salmonella interactions with bovine cells will inform the design of effective vaccines and interventions to control animal and zoonotic infections. In calves challenged orally with S. Dublin expressing green fluorescent protein (GFP) we observed that the bacteria were predominantly extracellular in the distal ileal mucosa and within gut-associated lymph nodes 48 h post-infection. Intracellular bacteria, identified by flow cytometry using the GFP signal, were predominantly within MHCII+ macrophage-like cells. In contrast to observations from murine models, these S. Dublin-infected cells had elevated levels of MHCII and CD40 compared to both uninfected cells from the same tissue and cells from the cognate tissue of uninfected animals. Moreover, no gross changes of the architecture of infected lymph nodes were observed as was described previously in a mouse model. In order to further investigate Salmonella-macrophage interactions, net replication of S. enterica serovars that differ in virulence in cattle was measured in bovine blood-derived macrophages by enumeration of gentamicin-protected bacteria and fluorescence dilution, but did not correlate with host-specificity.

scholarly journals Localization of GFP in Frozen Sections from Unfixed Mouse Tissues: Immobilization of a Highly Soluble Marker Protein by Formaldehyde Vapor

2003 ◽  
Vol 51 (3) ◽  
pp. 401-404 ◽  
Author(s):  
Harald Jockusch ◽  
Sylvana Voigt ◽  
Daniel Eberhard
Keyword(s):  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Striated Muscle ◽  
Host Cells ◽  
Frozen Sections ◽  
Mouse Tissues ◽  
Transplantation Experiment ◽  
Green Fluorescent ◽  
Cryostat Sections ◽  
Unfixed Cryostat

Green fluorescent protein (GFP) and its variants, such as enhanced GFP (EGFP), have been introduced into mammalian cells by transgenes, e.g., to distinguish donor from host cells after transplantation. Free GFP is extremely soluble and leaks out from liquid-covered cryostat sections so that fixation of whole organs before sectioning has been mandatory. This precludes the analysis of serial sections with respect to fixation-sensitive enzyme activities and antigens. We describe here a vapor fixation for sections from unfixed cryostat blocks of tissue that allows unrestricted enzyme and immunohistochemistry on adjacent sections, as demonstrated for cross-striated muscle and other tissues from EGFP transgenic “green mice” and for a transplantation experiment.

scholarly journals A C-Terminal Domain Targets the Pseudomonas aeruginosa Cytotoxin ExoU to the Plasma Membrane of Host Cells

2006 ◽  
Vol 74 (5) ◽  
pp. 2552-2561 ◽  
Author(s):  
Shira D. P. Rabin ◽  
Jeffrey L. Veesenmeyer ◽  
Kathryn T. Bieging ◽  
Alan R. Hauser
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Death ◽  
Plasma Membrane ◽  
Hela Cells ◽  
Type Iii Secretion ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Type Iii ◽  
C Terminus ◽  
Green Fluorescent

ABSTRACT ExoU, a phospholipase injected into host cells by the type III secretion system of Pseudomonas aeruginosa, leads to rapid cytolytic cell death. Although the importance of ExoU in infection is well established, the mechanism by which this toxin kills host cells is less clear. To gain insight into how ExoU causes cell death, we examined its subcellular localization following transfection or type III secretion/translocation into HeLa cells. Although rapid cell lysis precluded visualization of wild-type ExoU by fluorescence microscopy, catalytically inactive toxin was readily detected at the periphery of HeLa cells. Biochemical analysis confirmed that ExoU was targeted to the membrane fraction of transfected cells. Visualization of ExoU peptides fused with green fluorescent protein indicated that the domain responsible for this targeting was in the C terminus of ExoU, between residues 550 and 687. Localization to the plasma membrane occurred within 1 h of expression, which is consistent with the kinetics of cytotoxicity. Together, these results indicate that a domain between residues 550 and 687 of ExoU targets this toxin to the plasma membrane, a process that may be important in cytotoxicity.

scholarly journals 2A Protease Is Not a Prerequisite for Poliovirus Replication

2010 ◽  
Vol 84 (12) ◽  
pp. 5947-5957 ◽  
Author(s):  
Hiroko Igarashi ◽  
Yasuko Yoshino ◽  
Miwako Miyazawa ◽  
Hitoshi Horie ◽  
Seii Ohka ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Rna Replication ◽  
Full Length ◽  
Host Cells ◽  
Progeny Virus ◽  
Coding Sequence ◽  
Foreign Genes ◽  
Green Fluorescent ◽  
Replication Activity ◽  
Efficient Viral Replication

ABSTRACT Poliovirus (PV) 2Apro has been considered important for PV replication and is known to be toxic to host cells. A 2Apro-deficient PV would potentially be less toxic and ideal as a vector. To examine whether 2Apro is needed to form progeny virus, a full-length cDNA of dicistronic (dc) PV with (pOME) or without (pOMEΔ2A) 2Apro was constructed in the strain PV1(M)OM. RNAs of both pOME and pOMEΔ2A were capable of forming progeny viruses, called OME and OMEΔ2A, respectively. In their ability to induce a cytopathic effect (CPE), the strains ranked as OMEΔ2A < OME ≒ PV1(M)OM. These results suggest that 2Apro is not essential for full-length dc PV to form progeny virus and that it contributes to the efficient viral replication and/or induction of a CPE. To clarify whether 2Apro is essential for P1-null (lacking the entire coding sequence for capsid proteins) PV, the RNA replication activity of P1-null PV (pOMΔP1) or P1-null PV without 2Apro (pOMΔP1Δ2A) or without both 2Apro and 2B (pOMΔP1Δ2AΔ2B) was examined. The RNAs of pOMΔP1 and pOMΔP1Δ2A could replicate and form progeny viruses under a trans supply of P1 protein, whereas the RNA of pOMΔP1Δ2AΔ2B could not. These results suggest that 2Apro is not needed for the replication of P1-null PV, although it is important for PV RNA replication and inducing a CPE. To know whether a 2Apro-deficient PV can be used as a vector, a P1-null PV containing the enhanced green fluorescent protein (EGFP) coding sequence with or without 2Apro was examined. It expressed fluorescent protein. This result suggests that 2Apro-deficient PV can express foreign genes.

Detection and localization of the endophyte Undifilum oxytropis in locoweed tissues

Botany ◽  
2012 ◽  
Vol 90 (12) ◽  
pp. 1229-1236 ◽  
Author(s):  
Roxanna Reyna ◽  
Peter Cooke ◽  
Daniel Grum ◽  
Daniel Cook ◽  
Rebecca Creamer
Keyword(s):  
Electron Microscopy ◽  
Fluorescent Protein ◽  
Growth Patterns ◽  
Host Cells ◽  
Economic Losses ◽  
Thin Sections ◽  
Oxytropis Sericea ◽  
Pathogenic Interaction ◽  
Green Fluorescent ◽  
Detection And Localization

Poisoning of livestock owing to grazing on locoweeds results in significant economic losses in the western United States. Some Oxytropis spp. locoweeds contain a seed-transmitted endophytic fungus, Undifilum oxytropis, which produces the toxic alkaloid swainsonine. We sought to localize and characterize growth patterns of the fungus within leaves and petioles of Oxytropis lambertii Pursh and Oxytropis sericea Nutt. to help define the types of interactions between the fungus and its hosts. Vegetative hyphae were observed within locoweed tissues using integrated imaging. Topographical images from scanning electron microscopy revealed the presence of the endophyte in the pith tissue of petioles. The fungus was identified between plant cells but did not appear to penetrate host cells. Transmission electron microscopy images of thin sections revealed that hyphae were closely associated with host cell walls. Oxytropis sericea was innoculated with green fluorescent protein-transformed U. oxytropis and observed by confocal microscopy, confirming the presence of the endophyte hyphae in leaves and petioles. The fungus was identified only in the pith of petioles using fluorescence and in the vascular bundle throughout extracellular spaces in leaves. These results revealed no signs of a pathogenic interaction between plant and fungus and support the hypothesis of a mutualistic or commensal relationship.

scholarly journals Microtubule-Independent Motility and Nuclear Targeting of Adenoviruses with Fluorescently Labeled Genomes

2001 ◽  
Vol 75 (5) ◽  
pp. 2421-2434 ◽  
Author(s):  
Jolanta B. Glotzer ◽  
Anne-Isabelle Michou ◽  
Adam Baker ◽  
Mediyha Saltik ◽  
Matt Cotten
Keyword(s):  
Fluorescent Protein ◽  
Host Cells ◽  
Live Cells ◽  
Wild Type ◽  
Nuclear Targeting ◽  
Microtubule Network ◽  
Entry Pathway ◽  
Green Fluorescent ◽  
Affect Gene Expression ◽  
Intracellular Motility

ABSTRACT A novel adenovirus system for analyzing the adenovirus entry pathway has been developed that contains green fluorescent protein bound to the encapsidated viral DNA (AdLite viruses). AdLite viruses enter host cells and accumulate around the nuclei and near the microtubule organizing centers (MTOC). In live cells, individual AdLite particles were observed trafficking both toward and away from the nucleus. Depolymerization of microtubules during infection prevented AdLite accumulation around the MTOC; however, it did not abolish perinuclear localization of AdLite particles. Furthermore, depolymerization of microtubules did not affect AdLite motility and did not affect gene expression from wild-type adenovirus and adenovirus-derived vectors. These data revealed that adenovirus intracellular motility and nuclear targeting can be supported by a mechanism that does not rely on the microtubule network.

scholarly journals Yersinia pestis YopK Inhibits Bacterial Adhesion to Host Cells by Binding to the Extracellular Matrix Adaptor Protein Matrilin-2

2017 ◽  
Vol 85 (8) ◽  
Author(s):  
Yafang Tan ◽  
Wanbing Liu ◽  
Qingwen Zhang ◽  
Shiyang Cao ◽  
Haihong Zhao ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Hela Cells ◽  
Bacterial Adhesion ◽  
Type Iii Secretion ◽  
Fluorescent Protein ◽  
Adaptor Protein ◽  
Innate Immune ◽  
Host Cells ◽  
Content Type ◽  
Green Fluorescent

ABSTRACT Pathogenic yersiniae harbor a type III secretion system (T3SS) that injects Yersinia outer protein (Yop) into host cells. YopK has been shown to control Yop translocation and prevent inflammasome recognition of the T3SS by the innate immune system. Here, we demonstrate that YopK inhibits bacterial adherence to host cells by binding to the extracellular matrix adaptor protein matrilin-2 (MATN2). YopK binds to MATN2, and deleting amino acids 91 to 124 disrupts binding of YopK to MATN2. A yopK null mutant exhibits a hyperadhesive phenotype, which could be responsible for the established Yop hypertranslocation phenotype of yopK mutants. Expression of YopK, but not YopKΔ91–124, in a yopK mutant restored the wild-type phenotypes of adhesion and Yop translocation, suggesting that binding to MATN2 might be essential for YopK to inhibit bacterial adhesion and negatively regulate Yop translocation. A green fluorescent protein (GFP)-YopK fusion specifically binds to the endogenous MATN2 on the surface of HeLa cells, whereas GFP-YopKΔ91–124 cannot. Addition of purified YopK protein during infection decreased adhesion of Y. pestis to HeLa cells, while YopKΔ91–124 protein showed no effect. Taking these results together, we propose a model that the T3SS-secreted YopK hinders bacterial adhesion to HeLa cells by binding to MATN2, which is ubiquitously exposed on eukaryotic cells.

scholarly journals Dengue virus M protein contains a proapoptotic sequence referred to as ApoptoM

2003 ◽  
Vol 84 (10) ◽  
pp. 2781-2793 ◽  
Author(s):  
Adeline Catteau ◽  
Olga Kalinina ◽  
Marie-Christine Wagner ◽  
Vincent Deubel ◽  
Marie-Pierre Courageot ◽  
...  
Keyword(s):  
Hepg2 Cells ◽  
Fluorescent Protein ◽  
Apoptotic Cell ◽  
Host Cells ◽  
M Protein ◽  
Apoptotic Pathway ◽  
Apoptosis Protein ◽  
Infected Cells ◽  
Human Hepatoma Hepg2 Cells ◽  
Green Fluorescent

The induction of apoptotic cell death is a prominent cytopathic effect of dengue (DEN) viruses. One of the key questions to be addressed is which viral components induce apoptosis in DEN virus-infected cells. This study investigated whether the small membrane (M) protein was involved in the induction of apoptosis by DEN virus. This was addressed by using a series of enhanced green fluorescent protein-fused DEN proteins. Evidence is provided that intracellular production of the M ectodomains (residues M-1 to M-40) of all four DEN serotypes triggered apoptosis in host cells such as mouse neuroblastoma Neuro 2a and human hepatoma HepG2 cells. The M ectodomains of the wild-type strains of Japanese encephalitis, West Nile and yellow fever viruses also had proapoptotic properties. The export of the M ectodomain from the Golgi apparatus to the plasma membrane appeared to be essential for the initiation of apoptosis. The study found that anti-apoptosis protein Bcl-2 protected HepG2 cells against the death-promoting activity of the DEN M ectodomain. This suggests that the M ectodomain exerts its cytotoxic effects by activating a mitochondrial apoptotic pathway. The cytotoxicity of the DEN M ectodomain reflected the intrinsic proapoptotic properties of the nine carboxy-terminal amino acids (residues M-32 to M-40) designated ApoptoM. Residue M-36 was unique in that it modulated the death-promoting activity of the M ectodomain. Defining the ApoptoM-activated signalling pathways leading to apoptosis will provide the basis for studying how the M protein might play a key role in the fate of the flavivirus-infected cells.

scholarly journals Interaction of Pasteurella multocida with Free-Living Amoebae

2005 ◽  
Vol 71 (9) ◽  
pp. 5458-5464 ◽  
Author(s):  
Matthew J. Hundt ◽  
Carmel G. Ruffolo
Keyword(s):  
Pasteurella Multocida ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Free Living ◽  
Fowl Cholera ◽  
Transmission Electron ◽  
Membrane Bound ◽  
Green Fluorescent ◽  
First Time

ABSTRACT Pasteurella multocida is a highly infectious, facultative intracellular bacterium which causes fowl cholera in birds. This study reports, for the first time, the observed interaction between P. multocida and free-living amoebae. Amoebal trophozoites were coinfected with fowl-cholera-causing P. multocida strain X-73 that expressed the green fluorescent protein (GFP). Using confocal fluorescence microscopy, GFP expressing X-73 was located within the trophozoite. Transmission electron microscopy of coinfection preparations revealed clusters of intact X-73 cells in membrane-bound vacuoles within the trophozoite cytoplasm. A coinfection assay employing gentamicin to kill extracellular bacteria was used to assess the survival and replication of P. multocida within amoebae. In the presence of amoebae, the number of recoverable intracellular X-73 cells increased over a 24-h period; in contrast, X-73 cultured alone in assay medium showed a consistent decline in growth. Cytotoxicity assays and microscopy showed that X-73 was able to lyse and exit the amoebal cells approximately 18 h after coinfection. The observed interaction between P. multocida and amoebae can be considered as an infective process as the bacterium was able to invade, survive, replicate, and lyse the amoebal host. This raises the possibility that similar interactions occur in vivo between P. multocida and host cells. Free-living amoebae are ubiquitous within water and soil environments, and P. multocida has been observed to survive within these same ecosystems. Thus, our findings suggest that the interaction between P. multocida and amoebae may occur within the natural environment.

scholarly journals Functional Regions of the Pseudomonas aeruginosa Cytotoxin ExoU

2005 ◽  
Vol 73 (1) ◽  
pp. 573-582 ◽  
Author(s):  
Shira D. P. Rabin ◽  
Alan R. Hauser
Keyword(s):  
Amino Acids ◽  
Pseudomonas Aeruginosa ◽  
Green Fluorescent Protein ◽  
Amino Acid ◽  
Hela Cells ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Phospholipase Activity ◽  
C Terminus ◽  
Green Fluorescent

ABSTRACT ExoU, a potent patatin-like phospholipase, causes rapid cell death following its injection into host cells by the Pseudomonas aeruginosa type III secretion system. To better define regions of ExoU required for cytotoxicity, transposon-based linker insertion mutagenesis followed by site-directed mutagenesis of individual residues was employed by using a Saccharomyces cerevisiae model system. Random insertion of five amino acids identified multiple regions within ExoU that are required for cell killing. Five regions were chosen for further characterization: three corresponded to the oxyanion hole, hydrolase motif, and catalytic aspartate motif of the patatin-like domain within the N-terminal half of ExoU; one corresponded to an uncharacterized part of the patatin-like domain; and one corresponded to a region near the C terminus. Specific individual amino acid substitutions in each of the four N-terminal regions prevented killing of yeast and significantly reduced phospholipase activity. Whereas five amino acid insertions in the fifth region near the C terminus markedly reduced cytotoxicity and phospholipase activity, substitution of individual amino acids did not abolish either activity. To determine whether each of the five identified regions of ExoU was also essential for cytotoxicity in human cells, representative mutant forms of ExoU fused to green fluorescent protein were expressed in HeLa cells. These variants of ExoU were readily visualized and caused minimal cytotoxicity to HeLa cells, while wild-type ExoU fused to green fluorescent protein induced significant cell lysis and no detectable fluorescence. Thus, a minimum of five regions, including one which is well removed from the patatin-like domain, are required for the cytotoxicity and phospholipase activity of ExoU.

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