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  • 1
    Language: English
    In: PLoS Pathogens, 2017, Vol.13(4), p.e1006312
    Description: The invasion of epithelial cells by Salmonella enterica serovar Typhimurium is a very tightly regulated process. Signaling cascades triggered by different environmental and physiological signals converge to control HilD, an AraC regulator that coordinates the expression of several virulence...
    Keywords: Life Sciences ; Genetics ; Biology
    ISSN: 1553-7366
    E-ISSN: 1553-7374
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  • 2
    Language: English
    In: PLoS genetics, June 2018, Vol.14(6), pp.e1007401
    Description: Invasion of epithelial cells by Salmonella enterica requires expression of genes located in the pathogenicity island I (SPI-1). The expression of SPI-1 genes is very tightly regulated and activated only under specific conditions. Most studies have focused on the regulatory pathways that induce SPI-1 expression. Here, we describe a new regulatory circuit involving CRP-cAMP, a widely established metabolic regulator, in silencing of SPI-1 genes under non-permissive conditions. In CRP-cAMP-deficient strains we detected a strong upregulation of SPI-1 genes in the mid-logarithmic growth phase. Genetic analyses revealed that CRP-cAMP modulates the level of HilD, the master regulator of Salmonella invasion. This regulation occurs at the post-transcriptional level and requires the presence of a newly identified regulatory motif within the hilD 3'UTR. We further demonstrate that in Salmonella the Hfq-dependent sRNA Spot 42 is under the transcriptional repression of CRP-cAMP and, when this transcriptional repression is relieved, Spot 42 exerts a positive effect on hilD expression. In vivo and in vitro assays indicate that Spot 42 targets, through its unstructured region III, the 3'UTR of the hilD transcript. Together, our results highlight the biological relevance of the hilD 3'UTR as a hub for post-transcriptional control of Salmonella invasion gene expression.
    Keywords: Gene Expression Regulation, Bacterial ; Bacterial Proteins -- Genetics ; Cyclic Amp -- Metabolism ; Cyclic Amp Receptor Protein -- Metabolism ; Genomic Islands -- Genetics ; Salmonella Typhimurium -- Pathogenicity ; Transcription Factors -- Genetics
    ISSN: 15537390
    E-ISSN: 1553-7404
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  • 3
    Language: English
    In: https://doi.org/10.1371/journal.ppat.1006312
    Description: The invasion of epithelial cells by Salmonella enterica serovar Typhimurium is a very tightly regulated process. Signaling cascades triggered by different environmental and physiological signals converge to control HilD, an AraC regulator that coordinates the expression of several virulence factors. The expression of hilD is modulated at several steps of the expression process. Here, we report that the invasion of epithelial cells by S. Typhimurium strains lacking the Gre factors, GreA and GreB, is impaired. By interacting with the RNA polymerase secondary channel, the Gre factors prevent backtracking of paused complexes to avoid arrest during transcriptional elongation. Our results indicate that the Gre factors are required for the expression of the bacterial factors needed for epithelial cell invasion by modulating expression of HilD. This regulation does not occur at transcription initiation and depends on the capacity of the Gre factors to prevent backtracking of the RNA polymerase. Remarkably, genetic analyses indicate that the 3'-untranslated region (UTR) of hilD is required for Gre-mediated regulation of hilD expression. Our data provide new insight into the complex regulation of S. Typhimurium virulence and highlight the role of the hilD 3'-UTR as a regulatory motif.
    Keywords: Salmonel·La ; Transcripció Genètica ; Epiteli ; Salmonella ; Genetic Transcription ; Epithelium
    ISSN: 1553-7374
    Source: Universitat de Barcelona
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  • 4
    Language: English
    In: https://doi.org/10.1371/journal.pgen.1007401
    Description: Invasion of epithelial cells by Salmonella enterica requires expression of genes located in the pathogenicity island I (SPI-1). The expression of SPI-1 genes is very tightly regulated and activated only under specific conditions. Most studies have focused on the regulatory pathways that induce SPI-1 expression. Here, we describe a new regulatory circuit involving CRP-cAMP, a widely established metabolic regulator, in silencing of SPI-1 genes under non-permissive conditions. In CRP-cAMP-deficient strains we detected a strong upregulation of SPI-1 genes in the mid-logarithmic growth phase. Genetic analyses revealed that CRP-cAMP modulates the level of HilD, the master regulator of Salmonella invasion. This regulation occurs at the post-transcriptional level and requires the presence of a newly identified regulatory motif within the hilD 3'UTR. We further demonstrate that in Salmonella the Hfq-dependent sRNA Spot 42 is under the transcriptional repression of CRP-cAMP and, when this transcriptional repression is relieved, Spot 42 exerts a positive effect on hilD expression. In vivo and in vitro assays indicate that Spot 42 targets, through its unstructured region III, the 3'UTR of the hilD transcript. Together, our results highlight the biological relevance of the hilD 3'UTR as a hub for post-transcriptional control of Salmonella invasion gene expression.
    Keywords: Salmonel·La ; Expressió Gènica ; Salmonella ; Gene Expression
    ISSN: 1553-7390
    Source: Universitat de Barcelona
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  • 5
    Language: Spanish
    Description: [spa] El género Salmonella, está compuesto de bacterias Gram-negativas, no esporuladas, en forma de bacilo. Salmonella tiene importante relevancia a nivel de salud pública ya que es uno de los principales patógenos entéricos tanto en países desarrollados como en vías de desarrollo. En los casos de gastroenteritis notificados en España, Salmonella se posiciona en segundo lugar, después de Campylobacter. En este trabajo se utilizó como organismo modelo de estudio S. enterica serovar Typhimurium (S. Typhimurium), que en humanos causa salmonelosis, gastroenteritis caracterizada por diarrea inflamatoria, originada normalmente tras la ingestión de alimentos o agua contaminados. Los genes de virulencia de S. Typhimurium están localizados mayoritariamente dentro de islas de patogenicidad (SPI). Los genes codificados en la SPI-1 promueben la invasión de células eucariotas, la regulación de la expresión de los genes de la SPI-1 está mediada por HiIA codificada en el gen, hilA, presente en la misma SPI-1. HiIA activa la expresión de los genes que codifican para la síntesis de un sistema de secreción de tipo 3 (T3SS) encargado de secretar e inyectar proteínas efectoras dentro de la célula hospedadora. La expresión de hilA se encuentra bajo el control de unl bucle de regulación, comprendido por las proteínas HiID, HiIC y RtsA. HiID es el regulador predominante de este sistema, mientras que HiIC y RtsA se encargan de amplificar la señal de activación. Por su parte, los genes que contiene la SPI-2, están implicados en causar infecciones sistémicas y la proliferación intracelular de la bacteria. Los factores Gre son factores que regulan la elongación de la transcripción génica en procariotas. Son conocidos por promover la actividad endorribonucleotídica de la ARN polimerasa (ARNpol) cuando ésta se encuentra en un estado de pausa por retroceso causado durante la elongación de la transcripción. A pesar de que los factores Gre han sido bien caracterizados en otras enterobacterias como Escherichia coli, en Salmonella no existen estudios que describan el papel de los factores Gre en la fisiología celular. Así, el objetivo principal de esta tesis doctoral fue estudiar el papel de los factores Gre en la fisiología y patogenicidad de Salmonella. En este estudio describimos que los factores Gre forman parte de la compleja red reguladora de la expresión de los genes de la SPI-1 y SPI-2 de Salmonella. Los resultados obtenidos indican que los factores Gre de Salmonella son esenciales para la correcta expresión de las proteínas efectoras codificadas dentro de la SPI-1 (SipA, SipC y SipD) y fuera de ella (SopE), y que también juegan un papel importante en la motilidad de la célula bacteriana, fenotipos predominantes en la patogenicidad. Se pudo determinar que la regulación de la expresión de los genes de la SPI-1 y la SPI-2 por parte de los factores Gre, es a través de la regulación transcripcional del gen hilD. La regulación mediada por los factores Gre requiere de la región 3'UTR del gen hilD. Además demostramos que la actividad antipausa de la transcripción de los factores Gre es necesaria para la correcta expresi formación de biofilm en Salmonella. Esta regulación al parecer también es ejercida en una región UTR, en este caso en la región 5’UTR del gen csgD, y es independiente de la temperatura. En análisis transcriptómicos mediante la técnica de microarrays, se observó que los factores Gre de Salmonella estarían implicados en la correcta expresión de muchos de los genes adquiridos horizontalmente (HGT) como son los genes presentes en las islas de patogenicidad, plásmidos y fagos. También se observó que existe un elevado número de genes distribuidos en diferentes categorías funcionales, que son corregulados por los factores Gre en conjunto con la proteína DksA, proteína que incrementa la fidelidad de la transcripción al disminuir la tasa de incorporación incorrecta de nucleótidos. Estos resultados indican que el patrón general de expresión génica de Salmonella es el resultado de una compleja interacción entre los factores Gre y la proteína DksA, que implica el control mutuo, competición por la unión a la ARNpol, y la acción similar u opuesta sobre la actividad de la ARNpol. Con los resultados presentados en esta tesis doctoral se puede concluir que los factores Gre forman parte de la compleja red de regulación de los genes de virulencia de Salmonella.ón de hilD.
    Description: [eng] Gre factors regulate gene transcription elongation in prokaryotes. In Escherichia coli they promote cleavage of the nascent RNA transcript within the elongation complex when the RNA polymerase is paused by a backtracking. Although the Gre factors have been characterized in other enterobacteria, in Salmonella there are not studies about their role in cellular physiology. The main objective of this thesis was to study the role of Gre factors in physiology and pathogenicity of Salmonella. In this study we describe Gre factors that are part of the complex regulatory network of gene expression of Salmonella pathogenicity island-1 (SPI-1) and SPI-2. The results indicate that Gre factors are pivotal in the control of predominant phenotypes in pathogenicity. They are essential for the correct expression of effector proteins encoded within (SipA, SipC and SipD) and outside SPI-1 (SopE), and they also play an important role in motility of the bacterial cell. It was determined that the regulation of gene expression of SPI-1 and SPI-2 by Gre factors is through transcriptional regulation of hilD gene. Regulation mediated by Gre factors requires hilD 3'UTR region. We demonstrated that Gre antipausa activity during transcription is necessary for the correct expression of hilD. It was also observed that Gre factors play an important role in transcriptional expression of csgD, main regulator of biofilm formation in Salmonella. This regulation is also apparently exerted through the 5'UTR region of the csgD gene, and is temperature- independent. In transcriptome analysis using Microarray, it was observed that Gre factors are implicated in the correct expression of many horizontally transferred genes (HGT) such as genes present in pathogenicity islands, plasmids and phages. It was also noted that there is a large number of genes distributed into different functional categories, which are co-regulated by Gre factors together with DksA protein, a protein that increases the accuracy of the transcript to decrease the rate of nucleotide missincorporation. These results indicate that the overall pattern of gene expression of Salmonella is the result of a complex interaction between Gre factors and DksA protein, involving the mutual control, competition for binding to ARNpol, and similar or opposite action on ARNpol activity. We can conclude that Gre factors are part of complex regulatory network of virulence genes of Salmonella.
    Keywords: Bacteris Patògens ; Salmonel·La ; Pathogenic Bacteria ; Salmonella
    Source: Universitat de Barcelona
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  • 6
    Language: Spanish
    Description: El género Salmonella, está compuesto de bacterias Gram-negativas, no esporuladas, en forma de bacilo. Salmonella tiene importante relevancia a nivel de salud pública ya que es uno de los principales patógenos entéricos tanto en países desarrollados como en vías de desarrollo. En los casos de gastroenteritis notificados en España, Salmonella se posiciona en segundo lugar, después de Campylobacter. En este trabajo se utilizó como organismo modelo de estudio S. enterica serovar Typhimurium (S. Typhimurium), que en humanos causa salmonelosis, gastroenteritis caracterizada por diarrea inflamatoria, originada normalmente tras la ingestión de alimentos o agua contaminados. Los genes de virulencia de S. Typhimurium están localizados mayoritariamente dentro de islas de patogenicidad (SPI). Los genes codificados en la SPI-1 promueben la invasión de células eucariotas, la regulación de la expresión de los genes de la SPI-1 está mediada por HiIA codificada en el gen, hilA, presente en la misma SPI-1. HiIA activa la expresión de los genes que codifican para la síntesis de un sistema de secreción de tipo 3 (T3SS) encargado de secretar e inyectar proteínas efectoras dentro de la célula hospedadora. La expresión de hilA se encuentra bajo el control de unl bucle de regulación, comprendido por las proteínas HiID, HiIC y RtsA. HiID es el regulador predominante de este sistema, mientras que HiIC y RtsA se encargan de amplificar la señal de activación. Por su parte, los genes que contiene la SPI-2, están implicados en causar infecciones sistémicas y la proliferación intracelular de la bacteria. Los factores Gre son factores que regulan la elongación de la transcripción génica en procariotas. Son conocidos por promover la actividad endorribonucleotídica de la ARN polimerasa (ARNpol) cuando ésta se encuentra en un estado de pausa por retroceso causado durante la elongación de la transcripción. A pesar de que los factores Gre han sido bien caracterizados en otras enterobacterias como Escherichia coli, en Salmonella no existen estudios que describan el papel de los factores Gre en la fisiología celular. Así, el objetivo principal de esta tesis doctoral fue estudiar el papel de los factores Gre en la fisiología y patogenicidad de Salmonella. En este estudio describimos que los factores Gre forman parte de la compleja red reguladora de la expresión de los genes de la SPI-1 y SPI-2 de Salmonella. Los resultados obtenidos indican que los factores Gre de Salmonella son esenciales para la correcta expresión de las proteínas efectoras codificadas dentro de la SPI-1 (SipA, SipC y SipD) y fuera de ella (SopE), y que también juegan un papel importante en la motilidad de la célula bacteriana, fenotipos predominantes en la patogenicidad. Se pudo determinar que la regulación de la expresión de los genes de la SPI-1 y la SPI-2 por parte de los factores Gre, es a través de la regulación transcripcional del gen hilD. La regulación mediada por los factores Gre requiere de la región 3'UTR del gen hilD. Además demostramos que la actividad antipausa de la transcripción de los factores Gre es necesaria para la correcta expresi formación de biofilm en Salmonella. Esta regulación al parecer también es ejercida en una región UTR, en este caso en la región 5’UTR del gen csgD, y es independiente de la temperatura. En análisis transcriptómicos mediante la técnica de microarrays, se observó que los factores Gre de Salmonella estarían implicados en la correcta expresión de muchos de los genes adquiridos horizontalmente (HGT) como son los genes presentes en las islas de patogenicidad, plásmidos y fagos. También se observó que existe un elevado número de genes distribuidos en diferentes categorías funcionales, que son corregulados por los factores Gre en conjunto con la proteína DksA, proteína que incrementa la fidelidad de la transcripción al disminuir la tasa de incorporación incorrecta de nucleótidos. Estos resultados indican que el patrón general de expresión génica de Salmonella es el resultado de una compleja interacción entre los factores Gre y la proteína DksA, que implica el control mutuo, competición por la unión a la ARNpol, y la acción similar u opuesta sobre la actividad de la ARNpol. Con los resultados presentados en esta tesis doctoral se puede concluir que los factores Gre forman parte de la compleja red de regulación de los genes de virulencia de Salmonella.ón de hilD.
    Description: Gre factors regulate gene transcription elongation in prokaryotes. In Escherichia coli they promote cleavage of the nascent RNA transcript within the elongation complex when the RNA polymerase is paused by a backtracking. Although the Gre factors have been characterized in other enterobacteria, in Salmonella there are not studies about their role in cellular physiology. The main objective of this thesis was to study the role of Gre factors in physiology and pathogenicity of Salmonella. In this study we describe Gre factors that are part of the complex regulatory network of gene expression of Salmonella pathogenicity island-1 (SPI-1) and SPI-2. The results indicate that Gre factors are pivotal in the control of predominant phenotypes in pathogenicity. They are essential for the correct expression of effector proteins encoded within (SipA, SipC and SipD) and outside SPI-1 (SopE), and they also play an important role in motility of the bacterial cell. It was determined that the regulation of gene expression of SPI-1 and SPI-2 by Gre factors is through transcriptional regulation of hilD gene. Regulation mediated by Gre factors requires hilD 3'UTR region. We demonstrated that Gre antipausa activity during transcription is necessary for the correct expression of hilD. It was also observed that Gre factors play an important role in transcriptional expression of csgD, main regulator of biofilm formation in Salmonella. This regulation is also apparently exerted through the 5'UTR region of the csgD gene, and is temperature- independent. In transcriptome analysis using Microarray, it was observed that Gre factors are implicated in the correct expression of many horizontally transferred genes (HGT) such as genes present in pathogenicity islands, plasmids and phages. It was also noted that there is a large number of genes distributed into different functional categories, which are co-regulated by Gre factors together with DksA protein, a protein that increases the accuracy of the transcript to decrease the rate of nucleotide missincorporation. These results indicate that the overall pattern of gene expression of Salmonella is the result of a complex interaction between Gre factors and DksA protein, involving the mutual control, competition for binding to ARNpol, and similar or opposite action on ARNpol activity. We can conclude that Gre factors are part of complex regulatory network of virulence genes of Salmonella.
    Keywords: Bacteris Patògens ; Bacterias Patógenas ; Pathogenic Bacteria ; Salmonel·La ; Salmonella ; Ciències Experimentals I Matemàtiques ; 579
    Source: TDX (Tesis Doctorals en Xarxa)
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  • 7
    Language: English
    Description: The invasion of epithelial cells by Salmonella enterica serovar Typhimurium is a very tightly regulated process. Signaling cascades triggered by different environmental and physiological signals converge to control HilD, an AraC regulator that coordinates the expression of several virulence factors. The expression of hilD is modulated at several steps of the expression process. Here, we report that the invasion of epithelial cells by S. Typhimurium strains lacking the Gre factors, GreA and GreB, is impaired. By interacting with the RNA polymerase secondary channel, the Gre factors prevent backtracking of paused complexes to avoid arrest during transcriptional elongation. Our results indicate that the Gre factors are required for the expression of the bacterial factors needed for epithelial cell invasion by modulating expression of HilD. This regulation does not occur at transcription initiation and depends on the capacity of the Gre factors to prevent backtracking of the RNA polymerase. Remarkably, genetic analyses indicate that the 3'-untranslated region (UTR) of hilD is required for Gre-mediated regulation of hilD expression. Our data provide new insight into the complex regulation of S. Typhimurium virulence and highlight the role of the hilD 3'-UTR as a regulatory motif.
    Keywords: Salmonel·La ; Transcripció Genètica ; Epiteli ; Salmonella ; Genetic Transcription ; Epithelium
    Source: RECERCAT (Dipòsit de la Recerca de Catalunya)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    Description: Invasion of epithelial cells by Salmonella enterica requires expression of genes located in the pathogenicity island I (SPI-1). The expression of SPI-1 genes is very tightly regulated and activated only under specific conditions. Most studies have focused on the regulatory pathways that induce SPI-1 expression. Here, we describe a new regulatory circuit involving CRP-cAMP, a widely established metabolic regulator, in silencing of SPI-1 genes under non-permissive conditions. In CRP-cAMP-deficient strains we detected a strong upregulation of SPI-1 genes in the mid-logarithmic growth phase. Genetic analyses revealed that CRP-cAMP modulates the level of HilD, the master regulator of Salmonella invasion. This regulation occurs at the post-transcriptional level and requires the presence of a newly identified regulatory motif within the hilD 3'UTR. We further demonstrate that in Salmonella the Hfq-dependent sRNA Spot 42 is under the transcriptional repression of CRP-cAMP and, when this transcriptional repression is relieved, Spot 42 exerts a positive effect on hilD expression. In vivo and in vitro assays indicate that Spot 42 targets, through its unstructured region III, the 3'UTR of the hilD transcript. Together, our results highlight the biological relevance of the hilD 3'UTR as a hub for post-transcriptional control of Salmonella invasion gene expression.
    Keywords: Salmonel·La ; Expressió Gènica ; Salmonella ; Gene Expression
    Source: RECERCAT (Dipòsit de la Recerca de Catalunya)
    Library Location Call Number Volume/Issue/Year Availability
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