Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Type of Medium
Language
Year
  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 27 March 2012, Vol.109(13), pp.E757-64
    Description: SgrS RNA is a model for the large class of Hfq-associated small RNAs that act to posttranscriptionally regulate bacterial mRNAs. The function of SgrS is well-characterized in nonpathogenic Escherichia coli, where it was originally shown to counteract glucose-phosphate stress by acting as a repressor of the ptsG mRNA, which encodes the major glucose transporter. We have discovered additional SgrS targets in Salmonella Typhimurium, a pathogen related to E. coli that recently acquired one-quarter of all genes by horizontal gene transfer. We show that the conserved short seed region of SgrS that recognizes ptsG was recruited to target the Salmonella-specific sopD mRNA of a secreted virulence protein. The SgrS-sopD interaction is exceptionally selective; we find that sopD2 mRNA, whose gene arose from sopD duplication during Salmonella evolution, is deaf to SgrS because of a nonproductive G-U pair in the potential SgrS-sopD2 RNA duplex vs. G-C in SgrS-sopD. In other words, SgrS discriminates the two virulence factor mRNAs at the level of a single hydrogen bond. Our study suggests that bacterial pathogens use their large suites of conserved Hfq-associated regulators to integrate horizontally acquired genes into existing posttranscriptional networks, just as conserved transcription factors are recruited to tame foreign genes at the DNA level. The results graphically illustrate the importance of the seed regions of bacterial small RNAs to select new targets with high fidelity and suggest that target predictions must consider all or none decisions by individual seed nucleotides.
    Keywords: Phylogeny ; Base Pairing -- Genetics ; Gene Transfer, Horizontal -- Genetics ; RNA, Bacterial -- Genetics ; Salmonella -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Applied and Environmental Microbiology, 2010, Vol. 76(19), p.6514
    Description: The food-borne pathogen Escherichia coli O157:H7 is commonly exposed to organic acid in processed and preserved foods, allowing adaptation and the development of tolerance to pH levels otherwise lethal. Since little is known about the molecular basis of adaptation of E. coli to organic acids, we studied K-12 MG1655 and O157:H7 Sakai during exposure to acetic, lactic, and hydrochloric acid at pH 5.5. This is the first analysis of the pH-dependent transcriptomic response of stationary-phase E. coli. Thirty-four genes and three intergenic regions were upregulated by both strains during exposure to all acids. This universal acid response included genes involved in oxidative, envelope, and cold stress resistance and iron and manganese uptake, as well as 10 genes of unknown function. Acidulant- and strain-specific responses were also revealed. The acidulant-specific response reflects differences in the modes of microbial inactivation, even between weak organic acids. The two strains exhibited similar responses to lactic and hydrochloric acid, while the response to acetic acid was distinct. Acidulant-dependent differences between the strains involved induction of genes involved in the heat shock response, osmoregulation, inorganic ion and nucleotide transport and metabolism, translation, and energy production. E. coli O157:H7-specific acid-inducible genes were identified, suggesting that the enterohemorrhagic E. coli strain possesses additional molecular mechanisms contributing to acid resistance that are absent in K-12. While E. coli K-12 was most resistant to lactic and hydrochloric acid, O157:H7 may have a greater ability to survive in more complex acidic environments, such as those encountered in the host and during food processing.
    Keywords: Gene Expression Profiling ; Gene Expression Regulation, Bacterial ; Stress, Physiological ; Acids -- Toxicity ; Carboxylic Acids -- Toxicity ; Escherichia Coli K12 -- Drug Effects ; Escherichia Coli O157 -- Drug Effects;
    ISSN: 0099-2240
    ISSN: 00992240
    E-ISSN: 10985336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Journal of bacteriology, 01 July 2017, Vol.199(13)
    Description: Deep sequencing has revolutionized our understanding of the bacterial RNA world and has facilitated the identification of 280 small RNAs (sRNAs) in Despite the suspicions that sRNAs may play important roles in pathogenesis, the functions of most sRNAs remain unknown. To advance our understanding of RNA biology in virulence, we searched for sRNAs required for bacterial invasion into nonphagocytic cells. After screening 75 sRNAs, we discovered that the ablation of InvS caused a significant decrease of invasion into epithelial cells. A proteomic analysis showed that InvS modulated the levels of several type III secreted proteins. The level of PrgH, a type III secretion apparatus protein, was significantly lower in the absence of InvS, consistent with the known roles of PrgH in effector secretion and bacterial invasion. We discovered that InvS modulates expression and hence flagellar gene expression and motility. We propose that InvS coordinates the increase of PrgH and decrease in FimZ that promote efficient invasion into nonphagocytic cells. Salmonellosis continues to be the most common foodborne infection reported by the CDC in the United States. Central to pathogenesis is the ability to invade nonphagocytic cells and to replicate inside host cells. Invasion genes are known to be regulated by protein transcriptional networks, but little is known about the role played by small RNAs (sRNAs) in this process. We have identified a novel sRNA, InvS, that is involved in invasion. Our result will likely provide an opportunity to better understand the fundamental question of how regulates invasion gene expression and may inform strategies for therapeutic intervention.
    Keywords: Salmonella ; Gene Regulation ; Host Cell Invasion ; Noncoding RNA ; Bacterial Proteins -- Metabolism ; Epithelial Cells -- Microbiology ; Salmonella Typhimurium -- Physiology
    ISSN: 00219193
    E-ISSN: 1098-5530
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    In: Molecular Microbiology, April 2015, Vol.96(2), pp.263-275
    Description:  yphimurium isolate 23580 represents a recently identified 313 lineage of invasive non‐typhoidal Salmonellae (i). One of the differences between this lineage and other non‐i. Typhimurium isolates is the presence of prophage 1. This prophage encodes a gene, implicated in ‐antigen modification. is essential for maintaining ‐antigen length in isolate 23580, since a mutant yields a short ‐antigen. This phenotype can be complemented by or very closely related genes. The short ‐antigen of the mutant was also compensated by deletion of the 1 phage tailspike gene in the 23580 chromosome. This tailspike protein has a putative endorhamnosidase domain and thus may mediate ‐antigen cleavage. Expression of the gene is, in contrast to expression of many other operons, not subject to phase variation and transcriptional analysis suggests that is produced under a variety of conditions. Additionally, expression is necessary and sufficient to provide protection against 1 phage infection of an otherwise susceptible strain. These data are consistent with a model in which mediates modification of the 1 phage ‐antigen receptor in lysogenic 23580, and thereby preve superinfection by itself and other phage that uses the same ‐antigen co‐receptor. Many invasive Salmonella Typhimurium isolates contain a unique phage, BTP1. Evidence indicates that a BTP1 phage encoded gene modifies the O‐antigen subunits of the surface‐exposed lipopolysaccharide with an acetyl group. BTP1 phage lysogens in which this gene is deleted exhibited a unique short O‐antigen phenotype. Expression of the modifying gene prevented both BTP1 and P22 phage from cleaving the O‐antigen and gaining access to the surface for successful infection.
    Keywords: Antigens – Analysis ; Genetic Research – Analysis ; Cells (Biology) – Analysis ; Mitogens – Analysis ; Genes – Analysis;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Molecular Microbiology, August 2010, Vol.77(3), pp.771-786
    Description: The transcriptional regulator CsgD of serovar Typhimurium ( Typhimurium) is a major regulator of biofilm formation required for the expression of , which encodes curli fimbriae, and , coding for a diguanylate cyclase. CsgD is a response regulator with an N‐terminal receiver domain with a conserved aspartate (D59) as a putative target site for phosphorylation and a C‐terminal LuxR‐like helix–turn–helix DNA binding motif, but the mechanisms of target gene activation remained unclear. To study the DNA‐binding properties of CsgD we used electrophoretic mobility shift assays and DNase I footprint analysis to show that unphosphorylated CsgD‐His binds specifically to the and promoter regions. transcription analysis revealed that CsgD‐His is crucial for the expression of and . CsgD‐His is phosphorylated by acetyl phosphate , which decreases its DNA‐binding properties. The functional impact of D59 was demonstrated as Typhimurium strains expressing modified CsgD protein (D59E and D59N) were dramatically reduced in biofilm formation due to decreased protein stability and DNA‐binding properties in the case of D59E. In summary, our findings suggest that the response regulator CsgD functions in its unphosphorylated form under the conditions of biofilm formation investigated in this study.
    Keywords: Promoters ; Phosphorylation ; Pili ; DNA ; Transcription ; Acetyl Phosphate ; Deoxyribonuclease ; Biofilms ; Electrophoretic Mobility ; Transcription Activation ; Salmonella Enterica ; Salmonella Typhimurium ; Animal Diseases;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Applied and environmental microbiology, July 2013, Vol.79(14), pp.4376-84
    Description: Consumers trust commercial food production to be safe, and it is important to strive to improve food safety at every level. Several outbreaks of food-borne disease have been caused by Salmonella strains associated with dried food. Currently we do not know the mechanisms used by Salmonella enterica serovar Typhimurium to survive in desiccated environments. The aim of this study was to discover the responses of S. Typhimurium ST4/74 at the transcriptional level to desiccation on a stainless steel surface and to subsequent rehydration. Bacterial cells were dried onto the same steel surfaces used during the production of dry foods, and RNA was recovered for transcriptomic analysis. Subsequently, dried cells were rehydrated and were again used for transcriptomic analysis. A total of 266 genes were differentially expressed under desiccation stress compared with a static broth culture. The osmoprotectant transporters proP, proU, and osmU (STM1491 to STM1494) were highly upregulated by drying. Deletion of any one of these transport systems resulted in a reduction in the long-term viability of S. Typhimurium on a stainless steel food contact surface. The proP gene was critical for survival; proP deletion mutants could not survive desiccation for long periods and were undetectable after 4 weeks. Following rehydration, 138 genes were differentially expressed, with upregulation observed for genes such as proP, proU, and the phosphate transport genes (pstACS). In time, this knowledge should prove valuable for understanding the underlying mechanisms involved in pathogen survival and should lead to improved methods for control to ensure the safety of intermediate- and low-moisture foods.
    Keywords: Desiccation ; Stainless Steel ; Transcriptome ; Amino Acid Transport Systems, Neutral -- Genetics ; Bacterial Proteins -- Genetics ; Salmonella Typhimurium -- Physiology
    ISSN: 00992240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Applied and environmental microbiology, October 2015, Vol.81(19), pp.6800-11
    Description: Common salt (NaCl) is frequently used by the food industry to add flavor and to act as a humectant in order to reduce the water content of a food product. The improved health awareness of consumers is leading to a demand for food products with reduced salt content; thus, manufacturers require alternative water activity-reducing agents which elicit the same general effects as NaCl. Two examples include KCl and glycerol. These agents lower the water activity of a food matrix and also contribute to limit the growth of the microbiota, including foodborne pathogens. Little is currently known about how foodborne pathogens respond to these water activity-lowering agents. Here we examined the response of Salmonella enterica serovar Typhimurium 4/74 to NaCl, KCl, and glycerol at three time points, using a constant water activity level, compared with the response of a control inoculum. All conditions induced the upregulation of gluconate metabolic genes after 6 h of exposure. Bacteria exposed to NaCl and KCl demonstrated the upregulation of the osmoprotective transporter mechanisms encoded by the proP, proU, and osmU (STM1491 to STM1494) genes. Glycerol exposure elicited the downregulation of these osmoadaptive mechanisms but stimulated an increase in lipopolysaccharide and membrane protein-associated genes after 1 h. The most extensive changes in gene expression occurred following exposure to KCl. Because many of these genes were of unknown function, further characterization may identify KCl-specific adaptive processes that are not stimulated by NaCl. This study shows that the response of S. Typhimurium to different humectants does not simply reflect reduced water activity and likely involves systems that are linked to specific humectants.
    Keywords: Food Industry ; Hygroscopic Agents -- Pharmacology ; Salmonella Typhimurium -- Drug Effects
    ISSN: 00992240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 15 May 2012, Vol.109(20), pp.E1277-86
    Description: More than 50 y of research have provided great insight into the physiology, metabolism, and molecular biology of Salmonella enterica serovar Typhimurium (S. Typhimurium), but important gaps in our knowledge remain. It is clear that a precise choreography of gene expression is required for Salmonella infection, but basic genetic information such as the global locations of transcription start sites (TSSs) has been lacking. We combined three RNA-sequencing techniques and two sequencing platforms to generate a robust picture of transcription in S. Typhimurium. Differential RNA sequencing identified 1,873 TSSs on the chromosome of S. Typhimurium SL1344 and 13% of these TSSs initiated antisense transcripts. Unique findings include the TSSs of the virulence regulators phoP, slyA, and invF. Chromatin immunoprecipitation revealed that RNA polymerase was bound to 70% of the TSSs, and two-thirds of these TSSs were associated with σ(70) (including phoP, slyA, and invF) from which we identified the -10 and -35 motifs of σ(70)-dependent S. Typhimurium gene promoters. Overall, we corrected the location of important genes and discovered 18 times more promoters than identified previously. S. Typhimurium expresses 140 small regulatory RNAs (sRNAs) at early stationary phase, including 60 newly identified sRNAs. Almost half of the experimentally verified sRNAs were found to be unique to the Salmonella genus, and 〈20% were found throughout the Enterobacteriaceae. This description of the transcriptional map of SL1344 advances our understanding of S. Typhimurium, arguably the most important bacterial infection model.
    Keywords: Gene Expression Regulation, Bacterial -- Genetics ; RNA, Small Untranslated -- Genetics ; Regulatory Sequences, Ribonucleic Acid -- Genetics ; Salmonella Typhimurium -- Genetics ; Transcription, Genetic -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 2018, Vol. 115(11), pp. E2614-E2623
    Description: Salmonella enterica serovar Typhimurium ST313 is a relatively newly emerged sequence type that is causing a devastating epidemic of bloodstream infections across sub-Saharan Africa. Analysis of hundreds of Salmonella genomes has revealed that ST313 is closely related to the ST19 group of S. Typhimurium that cause gastroenteritis across the world. The core genomes of ST313 and ST19 vary by only similar to 1,000 SNPs. We hypothesized that the phenotypic differences that distinguish African Salmonella from ST19 are caused by certain SNPs that directly modulate the transcription of virulence genes. Here we identified 3,597 transcriptional start sites of the ST313 strain D23580, and searched for a gene-expression signature linked to pathogenesis of Salmonella. We identified a SNP in the promoter of the pgtE gene that caused high expression of the PgtE virulence factor in African S. Typhimurium, increased the degradation of the factor B component of human complement, contributed to serum resistance, and modulated virulence in the chicken infection model. We propose that high levels of PgtE expression by African S. Typhimurium ST313 promote bacterial survival and dissemination during human infection. Our finding of a functional role for an extragenic SNP shows that approaches used to deduce the evolution of virulence in bacterial pathogens should include a focus on noncoding regions of the genome.
    Keywords: Salmonella ; Noncoding Genome ; Transcriptomics ; Evolution Of Virulence ; Host Adaptation ; Medical And Health Sciences ; Clinical Medicine ; Infectious Medicine ; Medicin Och Hälsovetenskap ; Klinisk Medicin ; Infektionsmedicin
    ISSN: 0027-8424
    E-ISSN: 10916490
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    In: Molecular Microbiology, September 2011, Vol.81(5), pp.1144-1165
    Description: GcvB is one of the most highly conserved Hfq‐associated small RNAs in Gram‐negative bacteria and was previously reported to repress several ABC transporters for amino acids. To determine the full extent of GcvB‐mediated regulation in , we combined a genome‐wide experimental approach with biocomputational target prediction. Comparative pulse expression of wild‐type versus mutant sRNA variants revealed that GcvB governs a large post‐transcriptional regulon, impacting ∼1% of all genes via its conserved G/U‐rich domain R1. Complementary predictions of C/A‐rich binding sites in mRNAs and reporter fusion experiments increased the number of validated GcvB targets to more than 20, and doubled the number of regulated amino acid transporters. Unlike the previously described targeting via the single R1 domain, GcvB represses the glycine transporter CycA by exceptionally redundant base‐pairing. This novel ability of GcvB is focused upon the one target that could feedback‐regulate the glycine‐responsive synthesis of GcvB. Several newly discovered mRNA targets involved in amino acid metabolism, including the global regulator Lrp, question the previous assumption that GcvB simply acts to limit unnecessary amino acid uptake. Rather, GcvB rewires primary transcriptional control circuits and seems to act as a distinct regulatory node in amino acid metabolism.
    Keywords: Glycine -- Physiological Aspects ; Genetic Research -- Physiological Aspects ; Genomics -- Physiological Aspects ; Messenger Rna -- Physiological Aspects;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages