scholarly journals The Small RNA Chaperone Hfq Is Required for the Virulence of Yersinia pseudotuberculosis

2010 ◽  
Vol 78 (5) ◽  
pp. 2034-2044 ◽  
Author(s):  
Chelsea A. Schiano ◽  
Lauren E. Bellows ◽  
Wyndham W. Lathem
Keyword(s):  
Yersinia Pseudotuberculosis ◽  
Bacterial Species ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Systemic Infection ◽  
Protein Translation ◽  
Effector Proteins ◽  
Proper Function ◽  
Mesenteric Lymph Nodes ◽  
Protein Activity

ABSTRACT Bacterial small, noncoding RNAs (sRNAs) participate in the posttranscriptional regulation of gene expression, often by affecting protein translation, transcript stability, and/or protein activity. For proper function, many sRNAs rely on the chaperone Hfq, which mediates the interaction of the sRNA with its target mRNA. Recent studies have demonstrated that Hfq contributes to the pathogenesis of a number of bacterial species, suggesting that sRNAs play an essential role in the regulation of virulence. The enteric pathogen Yersinia pseudotuberculosis causes the disease yersiniosis. Here we show that Hfq is required by Y. pseudotuberculosis to cause mortality in an intragastric mouse model of infection, and a strain lacking Hfq is attenuated 1,000-fold compared to the wild type. Hfq is also required for virulence through the intraperitoneal route of infection and for persistence of the bacterium in the Peyer's patches, mesenteric lymph nodes, and spleen, suggesting a role for Hfq in systemic infection. Furthermore, the Δhfq mutant of Y. pseudotuberculosis is hypermotile and displays increased production of a biosurfactant-like substance, reduced intracellular survival in macrophages, and decreased production of type III secretion effector proteins. Together, these data demonstrate that Hfq plays a critical role in the virulence of Y. pseudotuberculosis by participating in the regulation of multiple steps in the pathogenic process and further highlight the unique role of Hfq in the virulence of individual pathogens.

scholarly journals The transcription factor SlHY5 regulates the ripening of tomato fruit at both the transcriptional and translational levels

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Weihao Wang ◽  
Peiwen Wang ◽  
Xiaojing Li ◽  
Yuying Wang ◽  
Shiping Tian ◽  
...  
Keyword(s):  
Fruit Ripening ◽  
Nutritional Quality ◽  
Ribosomal Proteins ◽  
Anthocyanin Biosynthesis ◽  
Tomato Fruit ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Protein Translation ◽  
Transcriptional Level ◽  
Translation Efficiency

AbstractLight plays a critical role in plant growth and development, but the mechanisms through which light regulates fruit ripening and nutritional quality in horticultural crops remain largely unknown. Here, we found that ELONGATED HYPOCOTYL 5 (HY5), a master regulator in the light signaling pathway, is required for normal fruit ripening in tomato (Solanum lycopersicum). Loss of function of tomato HY5 (SlHY5) impairs pigment accumulation and ethylene biosynthesis. Transcriptome profiling identified 2948 differentially expressed genes, which included 1424 downregulated and 1524 upregulated genes, in the Slhy5 mutants. In addition, genes involved in carotenoid and anthocyanin biosynthesis and ethylene signaling were revealed as direct targets of SlHY5 by chromatin immunoprecipitation. Surprisingly, the expression of a large proportion of genes encoding ribosomal proteins was downregulated in the Slhy5 mutants, and this downregulation pattern was accompanied by a decrease in the abundance of ribosomal proteins. Further analysis demonstrated that SlHY5 affected the translation efficiency of numerous ripening-related genes. These data indicate that SlHY5 regulates fruit ripening both at the transcriptional level by targeting specific molecular pathways and at the translational level by affecting the protein translation machinery. Our findings unravel the regulatory mechanisms of SlHY5 in controlling fruit ripening and nutritional quality and uncover the multifaceted regulation of gene expression by transcription factors.

scholarly journals The Tat Substrate SufI Is Critical for the Ability of Yersinia pseudotuberculosis To Cause Systemic Infection

2017 ◽  
Vol 85 (4) ◽  
Author(s):  
Ummehan Avican ◽  
Tugrul Doruk ◽  
Yngve Östberg ◽  
Anna Fahlgren ◽  
Åke Forsberg
Keyword(s):  
Stress Responses ◽  
Pathogenic Bacteria ◽  
Yersinia Pseudotuberculosis ◽  
Systemic Infection ◽  
Mesenteric Lymph Nodes ◽  
Content Type ◽  
Twin Arginine Translocation ◽  
Genes Encoding ◽  
Folded Proteins

ABSTRACT The twin arginine translocation (Tat) system targets folded proteins across the inner membrane and is crucial for virulence in many important human-pathogenic bacteria. Tat has been shown to be required for the virulence of Yersinia pseudotuberculosis, and we recently showed that the system is critical for different virulence-related stress responses as well as for iron uptake. In this study, we wanted to address the role of the Tat substrates in in vivo virulence. Therefore, 22 genes encoding potential Tat substrates were mutated, and each mutant was evaluated in a competitive oral infection of mice. Interestingly, a ΔsufI mutant was essentially as attenuated for virulence as the Tat-deficient strain. We also verified that SufI was Tat dependent for membrane/periplasmic localization in Y. pseudotuberculosis. In vivo bioluminescent imaging of orally infected mice revealed that both the ΔsufI and ΔtatC mutants were able to colonize the cecum and Peyer's patches (PPs) and could spread to the mesenteric lymph nodes (MLNs). Importantly, at this point, neither the ΔtatC mutant nor the ΔsufI mutant was able to spread systemically, and they were gradually cleared. Immunostaining of MLNs revealed that both the ΔtatC and ΔsufI mutants were unable to spread from the initial infection foci and appeared to be contained by neutrophils, while wild-type bacteria readily spread to establish multiple foci from day 3 postinfection. Our results show that SufI alone is required for the establishment of systemic infection and is the major cause of the attenuation of the ΔtatC mutant.

scholarly journals Superantigen YPMa Exacerbates the Virulence ofYersinia pseudotuberculosis in Mice

2000 ◽  
Vol 68 (5) ◽  
pp. 2553-2559 ◽  
Author(s):  
Christophe Carnoy ◽  
Chantal Mullet ◽  
Heide Müller-Alouf ◽  
Emmanuelle Leteurtre ◽  
Michel Simonet
Keyword(s):  
Yersinia Pseudotuberculosis ◽  
Systemic Infection ◽  
Peyer's Patches ◽  
Peyer’S Patches ◽  
Wild Type ◽  
Bacterial Inoculation ◽  
Mesenteric Lymph Nodes ◽  
Strain Determination ◽  
Mouse Model Of Infection

ABSTRACT Yersinia pseudotuberculosis, a gram-negative bacterium responsible for enteric and systemic infection in humans, produces a superantigenic toxin designated YPMa (Y. pseudotuberculosis-derived mitogen). To assess the role of YPMa in the pathogenesis of Y. pseudotuberculosis, we constructed a superantigen-deficient mutant and compared its virulence in a mouse model of infection to the virulence of the wild-type strain. Determination of the survival rate after intravenous (i.v.) bacterial inoculation of OF1 mice clearly showed that inactivation ofypmA, encoding YPMa, reduced the virulence of Y. pseudotuberculosis. Mice infected i.v. with 104 and 105 wild-type bacteria died within 9 days, whereas mice infected with the ypmA mutant survived 12 and 3 days longer, respectively. This decreased virulence of the ypmAmutant strain was not due to an impaired colonization of the spleen, liver, or lungs. In contrast to i.v. challenge, bacterial inoculation by the intragastric (i.g.) route did not reveal any difference in virulence between wild-type Y. pseudotuberculosis and theypmA mutant since the 50% lethal doses were identical for both strains. Moreover, inactivation of ypmA gene did not affect the bacterial growth of Y. pseudotuberculosis in Peyer's patches, mesenteric lymph nodes (MLNs), and spleen after oral infection. Histological studies of spleen, liver, lungs, heart, Peyer's patches, and MLNs after i.v. or i.g. challenge with the wild type or the ypmA mutant did not reveal any feature that can be specifically related to YPMa. Our data show that the superantigenic toxin YPMa contributes to the virulence of Y. pseudotuberculosis in systemic infection in mice.

scholarly journals FliZ Regulates Expression of the Salmonella Pathogenicity Island 1 Invasion Locus by Controlling HilD Protein Activity in Salmonella enterica Serovar Typhimurium

2010 ◽  
Vol 192 (23) ◽  
pp. 6261-6270 ◽  
Author(s):  
Jessica E. Cott Chubiz ◽  
Yekaterina A. Golubeva ◽  
Dongxia Lin ◽  
Lucas D. Miller ◽  
James M. Slauch
Keyword(s):  
Salmonella Enterica ◽  
Direct Injection ◽  
Systemic Disease ◽  
Systemic Infection ◽  
Pathogenicity Island ◽  
Effector Proteins ◽  
Negative Regulator ◽  
Bacterial Invasion ◽  
Protein Activity ◽  
Environmental Signals

ABSTRACT A prerequisite for Salmonella enterica to cause both intestinal and systemic disease is the direct injection of effector proteins into host intestinal epithelial cells via a type three secretion system (T3SS); the T3SS genes are carried on Salmonella pathogenicity island 1 (SPI1). These effector proteins induce inflammatory diarrhea and bacterial invasion. Expression of the SPI1 T3SS is tightly regulated in response to environmental signals through a variety of global regulatory systems. We have previously shown that three AraC-like regulators, HilD, HilC, and RtsA, act in a complex feed-forward regulatory loop to control the expression of the hilA gene, which encodes the direct regulator of the SPI1 structural genes. In this work, we characterize a major positive regulator of this system, the flagellar protein FliZ. Through genetic and biochemical analyses, we show that FliZ posttranslationally controls HilD to positively regulate hilA expression. This mechanism is independent of other flagellar components and is not mediated through the negative regulator HilE or through FliZ-mediated RpoS regulation. We demonstrate that FliZ controls HilD protein activity and not stability. FliZ regulates HilD in the absence of Lon protease, previously shown to degrade HilD. Indeed, it appears that FliZ, rather than HilD, is the most relevant target of Lon as it relates to SPI1 expression. Mutants lacking FliZ are significantly attenuated in their ability to colonize the intestine but are unaffected during systemic infection. The intestinal attenuation is partially dependent on SPI1, but FliZ has additional pleiotropic effects.

The role of mass spectrometry analysis in bacterial effector characterization

2017 ◽  
Vol 474 (16) ◽  
pp. 2779-2784 ◽  
Author(s):  
Nichollas E. Scott ◽  
Elizabeth L. Hartland
Keyword(s):  
Mass Spectrometry ◽  
Cell Biology ◽  
Critical Role ◽  
Effector Proteins ◽  
Mass Spectrometry Analysis ◽  
Protein Activity ◽  
Post Translational Modifications ◽  
Spectrometry Analysis ◽  
New Generation

Many secreted bacterial effector proteins play a critical role in host–pathogen interactions by mediating a variety of post-translational modifications, some of which do not occur natively within the eukaryotic proteome. The characterization of bacterial effector protein activity remains an important step to understanding the subversion of host cell biology during pathogen infection and although molecular biology and immunochemistry remain critical tools for gaining insights into bacterial effector functions, increasingly mass spectrometry (MS) and proteomic approaches are also playing an indispensable role. The focus of this editorial is to highlight the strengths of specific MS approaches and their utility for the characterization of bacterial effector activity. With the capability of new generation MS instrumentation, MS-based technologies can provide information that is inaccessible using traditional molecular or immunochemical approaches.

scholarly journals Yersinia-induced Apoptosis In Vivo Aids in the Establishment of a Systemic Infection of Mice

1998 ◽  
Vol 188 (11) ◽  
pp. 2127-2137 ◽  
Author(s):  
Denise M. Monack ◽  
Joan Mecsas ◽  
Donna Bouley ◽  
Stanley Falkow
Keyword(s):  
Mutant Strain ◽  
Yersinia Pseudotuberculosis ◽  
Bacterial Load ◽  
Systemic Infection ◽  
Wild Type ◽  
Mesenteric Lymph Nodes ◽  
Induced Apoptosis ◽  
Factor Α

Pathogenic Yersinia cause a systemic infection in mice that is dependent on the presence of a large plasmid encoding a number of secreted virulence proteins called Yops. We previously demonstrated that a plasmid-encoded Yop, YopJ, was essential for inducing apoptosis in cultured macrophages. Here we report that YopJ is a virulence factor in mice and is important for the establishment of a systemic infection. The oral LD50 for a yopJ mutant Yersinia pseudotuberculosis increases 64-fold compared with wild-type. Although the yopJ mutant strain is able to reach the spleen of infected mice, the mutant strain seldom reaches the same high bacterial load that is seen with wild-type Yersinia strain and begins to be cleared from infected spleens on day 4 after infection. Furthermore, when in competition with wild-type Yersinia in a mixed infection, the yopJ mutant strain is deficient for spread from the Peyer's patches to other lymphoid tissue. We also show that wild-type Yersinia induces apoptosis in vivo of Mac-1+ cells from infected mesenteric lymph nodes or spleens, as measured by quantitative flow cytometry of TUNEL (Tdt-mediated dUTP–biotin nick-end labeling)-positive cells. The levels of Mac-1+, TUNEL+ cells from tissue infected with the yopJ mutant strain were equivalent to the levels detected in cells from uninfected tissue. YopJ is necessary for the suppression of TNF-α production seen in macrophages infected with wild-type Yersinia, based on previous in vitro studies (Palmer, L.E., S. Hobbie, J.E. Galan, and J.B. Bliska. 1998. Mol. Microbiol. 27:953–965). We conclude here that YopJ plays a role in the establishment of a systemic infection by inducing apoptosis and that this is consistent with the ability to suppress the production of the proinflammatory cytokine tumor necrosis factor α.

Recent Advances in the Function of the 67 kDa Laminin Receptor and its Targeting for Personalized Therapy in Cancer

2017 ◽  
Vol 23 (32) ◽  
pp. 4745-4757 ◽  
Author(s):  
Ada Pesapane ◽  
Pia Ragno ◽  
Carmine Selleri ◽  
Nunzia Montuori
Keyword(s):  
Cell Adhesion ◽  
Cancer Progression ◽  
Ribosome Biogenesis ◽  
Critical Role ◽  
Protein Translation ◽  
Basement Membranes ◽  
Laminin Receptor ◽  
Cell Surface Receptor ◽  
Future Application ◽  
Neoplastic Cells

The 67 kDa high affinity laminin receptor (67LR) is a non-integrin cell surface receptor for laminin, the major component of basement membranes. Interactions between 67LR and laminin play a major role in mediating cell adhesion, migration, proliferation and survival. 67LR derives from homo- or hetero-dimerization of a 37 kDa cytosolic precursor (37LRP), most probably by fatty acid acylation. Interestingly, 37LRP, also called p40 or OFA/iLR (oncofetal antigen/immature laminin receptor), is a multifunctional protein with a dual activity in the cytoplasm and in the nucleus. In the cytoplasm, 37LRP it is associated with the 40S subunit of ribosome, playing a critical role in protein translation and ribosome biogenesis while in the nucleus it is tightly associated with nuclear structures, and bound to components of the cytoskeleton, such as tubulin and actin. 67LR is mainly localized in the cell membrane, concentrated in lipid rafts. Acting as a receptor for laminin is not the only function of 67LR; indeed, it also acts as a receptor for viruses, bacteria and prions. 67LR expression is increased in neoplastic cells and correlates with an enhanced invasive and metastatic potential. The primary function of 67LR in cancer is to promote tumor cell adhesion to basement membranes, the first step in the invasion-metastasis cascade. Thus, 67LR is overexpressed in neoplastic cells as compared to their normal counterparts and its overexpression is considered a molecular marker of metastatic aggressiveness in cancer of many tissues, including breast, lung, ovary, prostate, stomach, thyroid and also in leukemia and lymphoma. Thus, inhibiting 67LR binding to laminin could be a feasible approach to block cancer progression. Here, we review the current understanding of the structure and function of this molecule, highlighting its role in cancer invasion and metastasis and reviewing the various therapeutic options targeting this receptor that could have a promising future application.

Modulation of Gut Microbiota through Dietary Phytochemicals as a Novel Anti-infective Strategy

2020 ◽  
Vol 17 (4) ◽  
pp. 498-506 ◽  
Author(s):  
Pavan K. Mujawdiya ◽  
Suman Kapur
Keyword(s):  
Microbial Community ◽  
Quorum Sensing ◽  
Population Density ◽  
Gut Microbiota ◽  
Biofilm Formation ◽  
Chemical Interaction ◽  
Bacterial Species ◽  
Critical Role ◽  
Bacterial Cells ◽  
Gut Microbes

: Quorum Sensing (QS) is a phenomenon in which bacterial cells communicate with each other with the help of several low molecular weight compounds. QS is largely dependent on population density, and it triggers when the concentration of quorum sensing molecules accumulate in the environment and crosses a particular threshold. Once a certain population density is achieved and the concentration of molecules crosses a threshold, the bacterial cells show a collective behavior in response to various chemical stimuli referred to as “auto-inducers”. The QS signaling is crucial for several phenotypic characteristics responsible for bacterial survival such as motility, virulence, and biofilm formation. Biofilm formation is also responsible for making bacterial cells resistant to antibiotics. : The human gut is home to trillions of bacterial cells collectively called “gut microbiota” or “gut microbes”. Gut microbes are a consortium of more than 15,000 bacterial species and play a very crucial role in several body functions such as metabolism, development and maturation of the immune system, and the synthesis of several essential vitamins. Due to its critical role in shaping human survival and its modulating impact on body metabolisms, the gut microbial community has been referred to as “the forgotten organ” by O`Hara et al. (2006) [1]. Several studies have demonstrated that chemical interaction between the members of bacterial cells in the gut is responsible for shaping the overall microbial community. : Recent advances in phytochemical research have generated a lot of interest in finding new, effective, and safer alternatives to modern chemical-based medicines. In the context of antimicrobial research various plant extracts have been identified with Quorum Sensing Inhibitory (QSI) activities among bacterial cells. This review focuses on the mechanism of quorum sensing and quorum sensing inhibitors isolated from natural sources.

scholarly journals RNA-binding proteins La and HuR cooperatively modulate translation repression of PDCD4 mRNA

2020 ◽  
pp. jbc.RA120.014894
Author(s):  
Ravi Kumar ◽  
Dipak Kumar Poria ◽  
Partho Sarothi Ray
Keyword(s):  
Inflammatory Response ◽  
Chronic Inflammation ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Mrna Translation ◽  
Suppressor Gene ◽  
Cooperative Action ◽  
Translation Repression

Post-transcriptional regulation of gene expression plays a critical role in controlling the inflammatory response. An uncontrolled inflammatory response results in chronic inflammation, often leading to tumorigenesis. Programmed cell death 4 (PDCD4) is a pro-inflammatory tumor-suppressor gene which helps to prevent the transition from chronic inflammation to cancer. PDCD4 mRNA translation is regulated by an interplay between the oncogenic microRNA miR-21 and the RNA-binding protein (RBP) HuR in response to LPS stimulation, but the role of other regulatory factors remain unknown. Here we report that the RBP Lupus antigen (La) interacts with the 3’UTR of PDCD4 mRNA and prevents miR-21-mediated translation repression. While LPS causes nuclear-cytoplasmic translocation of HuR, it enhances cellular La expression. Remarkably, La and HuR were found to bind cooperatively to the PDCD4 mRNA and mitigate miR-21-mediated translation repression. The cooperative action of La and HuR reduced cell proliferation and enhanced apoptosis, reversing the pro-oncogenic function of miR-21. Together, these observations demonstrate a cooperative interplay between two RBPs, triggered differentially by the same stimulus, which exerts a synergistic effect on PDCD4 expression and thereby helps maintain a balance between inflammation and tumorigenesis.

scholarly journals The microbiota is dispensable for the early stages of peripheral regulatory T cell induction within mesenteric lymph nodes

2021 ◽  
Author(s):  
Carolin Wiechers ◽  
Mangge Zou ◽  
Eric Galvez ◽  
Michael Beckstette ◽  
Maria Ebel ◽  
...  
Keyword(s):  
T Cell ◽  
Lymph Nodes ◽  
Regulatory T Cell ◽  
De Novo ◽  
Bacterial Species ◽  
Short Chain Fatty Acids ◽  
Mesenteric Lymph Nodes ◽  
Direct Role ◽  
Early Stages ◽  
Mesenteric Lymph

AbstractIntestinal Foxp3+ regulatory T cell (Treg) subsets are crucial players in tolerance to microbiota-derived and food-borne antigens, and compelling evidence suggests that the intestinal microbiota modulates their generation, functional specialization, and maintenance. Selected bacterial species and microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), have been reported to promote Treg homeostasis in the intestinal lamina propria. Furthermore, gut-draining mesenteric lymph nodes (mLNs) are particularly efficient sites for the generation of peripherally induced Tregs (pTregs). Despite this knowledge, the direct role of the microbiota and their metabolites in the early stages of pTreg induction within mLNs is not fully elucidated. Here, using an adoptive transfer-based pTreg induction system, we demonstrate that neither transfer of a dysbiotic microbiota nor dietary SCFA supplementation modulated the pTreg induction capacity of mLNs. Even mice housed under germ-free (GF) conditions displayed equivalent pTreg induction within mLNs. Further molecular characterization of these de novo induced pTregs from mLNs by dissection of their transcriptomes and accessible chromatin regions revealed that the microbiota indeed has a limited impact and does not contribute to the initialization of the Treg-specific epigenetic landscape. Overall, our data suggest that the microbiota is dispensable for the early stages of pTreg induction within mLNs.

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