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
Language
Year
  • 1
    Language: English
    In: Journal of Bacteriology, March, 2011, Vol.193(5-6), p.1427(9)
    Description: The capability of Salmonella enterica serovar Typhimurium strain 14028 (S. Typhimurium 14028) to utilize myo-inositol (MI) is determined by the genomic island GEI4417/4436 carrying the iol genes that encode enzymes, transporters, and a repressor responsible for the MI catabolic pathway. In contrast to all bacteria investigated thus far, S. Typhimurium 14028 growing on MI as the sole carbon source is characterized by a remarkable long lag phase of 40 to 60 h. We report here that on solid medium with MI as the sole carbon source, this human pathogen exhibits a bistable phenotype characterized by a dissection into large colonies and a slow-growing bacterial background. This heterogeneity is reversible and therefore not caused by mutation, and it is not observed in the absence of the iol gene repressor IoIR nor in the presence of at least 0.55% C[O.sub.2]. Bistability is correlated with the activity of the iolE promoter ([P.sub.iolE]), but not of [P.sub.iolC] or [P.sub.iolD], as shown by promoter-gfp fusions. On the single-cell level, fluorescence microscopy and flow cytometry analysis revealed a gradual switch of [P.sub.iolE] from the "off" to the "on" status during the late lag phase and the transition to the log phase. Deletion of iolR or the addition of 0.1% NaHC[O.sub.3] induced an early growth start of S. Typhimurium 14028 in minimal medium with MI. The addition of ethoxyzolamide, an inhibitor of carboanhydrases, elongated the lag phase in the presence of bicarbonate. The positive-feedback loop via repressor release and positive induction by bicarbonate-C[O.sub.2] might allow S. Typhimurium 14028 to adapt to rapidly changing environments. The phenomenon described here is a novel example of bistability in substrate degradation, and, to our knowledge, is the first demonstration of gene regulation by bicarbonate-C[O.sub.2] in Salmonella. doi: 10.1128/JB.00043-10
    Keywords: Salmonella Typhimurium -- Genetic Aspects ; Salmonella Typhimurium -- Physiological Aspects ; Inositol -- Physiological Aspects ; Genetic Regulation -- Physiological Aspects
    ISSN: 0021-9193
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Journal of Bacteriology, Jan, 2009, Vol.191(1-2), p.545(10)
    Description: Knockout mutation of STM4432 resulted in a growth-deficient phenotype of Salmonella enterica serovar Typhimurium in the presence of myo-inositol (MI) as the sole carbon source. STM4432 is part of a 22.6-kb genomic island which spans STM4417 to STM4436 (genomic island 4417/4436) and is responsible for MI degradation. Genome comparison revealed the presence of this island in only six Salmonella strains and a high variability of the iol gene organization in gram-negative bacteria. Upon nonpolar deletion of 11 island loci, the genes involved in six enzymatic steps of the MI pathway were identified. The generation time of S. enterica serovar Typhimurium in minimal medium with MI decreases with higher concentrations of this polyol. Reverse transcriptase PCR showed five separate transcriptional units encompassing the genes iolA-iolB, iolE-iolG1, iolC1-iolC2, iolD1-iolD2-iolG2, and iolI2-iolH. Luciferase reporter assays revealed a strong induction of their promoters in the presence of MI but not glucose. The main regulator, Io1R, was identified due to a reduced lag phase of a strain mutated in STM4417 (iolR). Deletion of iolR resulted in stimulation of the iol operons, indicating its negative effect on the iol genes of S. enterica serovar Typhimurium in rich medium at a transcriptional level. Bandshift assays demonstrated the binding of this putative repressor to promoter sequences of iolA, iolC1, and iolD1. Binding of IolR to its own promoter and induced iolR expression in an IolR-negative background demonstrate that its transcription is autoregulated. This is the first characterization of MI degradation in a gram-negative bacterium, revealing a complex transcriptional organization and regulation of the S. enterica serovar Typhimurium iol genes.
    Keywords: Salmonella Enteritidis -- Genetic Aspects ; Salmonella Enteritidis -- Physiological Aspects ; Inositol -- Physiological Aspects
    ISSN: 0021-9193
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: The Journal of Bacteriology, 2011, Vol. 193(6), p.1427
    Description: The capability of Salmonella enterica serovar Typhimurium strain 14028 (S. Typhimurium 14028) to utilize myo-inositol (MI) is determined by the genomic island GEI4417/4436 carrying the iol genes that encode enzymes, transporters, and a repressor responsible for the MI catabolic pathway. In contrast to all bacteria investigated thus far, S. Typhimurium 14028 growing on MI as the sole carbon source is characterized by a remarkable long lag phase of 40 to 60 h. We report here that on solid medium with MI as the sole carbon source, this human pathogen exhibits a bistable phenotype characterized by a dissection into large colonies and a slow-growing bacterial background. This heterogeneity is reversible and therefore not caused by mutation, and it is not observed in the absence of the iol gene repressor IolR nor in the presence of at least 0.55% CO(2). Bistability is correlated with the activity of the iolE promoter (P(iolE)), but not of P(iolC) or P(iolD), as shown by promoter-gfp fusions. On the single-cell level, fluorescence microscopy and flow cytometry analysis revealed a gradual switch of P(iolE) from the "off" to the "on" status during the late lag phase and the transition to the log phase. Deletion of iolR or the addition of 0.1% NaHCO(3) induced an early growth start of S. Typhimurium 14028 in minimal medium with MI. The addition of ethoxyzolamide, an inhibitor of carboanhydrases, elongated the lag phase in the presence of bicarbonate. The positive-feedback loop via repressor release and positive induction by bicarbonate-CO(2) might allow S. Typhimurium 14028 to adapt to rapidly changing environments. The phenomenon described here is a novel example of bistability in substrate degradation, and, to our knowledge, is the first demonstration of gene regulation by bicarbonate-CO(2) in Salmonella.
    Keywords: Biology;
    ISSN: 0021-9193
    ISSN: 00219193
    E-ISSN: 10985530
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Microbiology (Reading, England), January 2010, Vol.156(Pt 1), pp.128-38
    Description: In Salmonella enterica serovar Typhimurium, the genomic island GEI4417/4436 has recently been identified to be responsible for myo-inositol (MI) utilization. Here, two of the four island-encoded permeases are identified as the MI transporters of this pathogen. In-frame deletion of iolT1 (STM4418) led to a severe growth defect, and deletion of iolT1 (STM4419) to a slight growth defect in the presence of MI. These phenotypes could be complemented by providing the putative transporter genes in trans. Bioluminescence-based reporter assays demonstrated a strong induction of their promoters P(iolT1) and P(iolT2) in the presence of MI but not of glucose. Deletion of iolR, which encodes the negative regulator of most genes involved in MI degradation, resulted in upregulation of P(iolT1) and P(iolT2), indicating that the expression of IolT1 and IolT2 is repressed by IolR. This finding was supported by bandshift assays using purified IolR. Both transporters are located in the membrane when expressed in Escherichia coli. Heterologously expressed IolT1 had its optimal activity at pH 5.5. Together with the strongly reduced MI uptake in the presence of protonophores, this indicates that IolT1 operates as a proton symporter. Using myo-[1,2-[(3)H](N)]inositol, a saturable uptake activity of IolT1 with a K(m) value between 0.49 and 0.79 mM was determined in DH5alpha expressing IolT1, in S. enterica serovar Typhimurium strain 14028, and in mutant 14028 DeltaiolT2. Phylogenetic analysis of IolT1 identified putative MI transporters in Gram-negative bacteria also able to utilize MI.
    Keywords: Genomic Islands ; Bacterial Proteins -- Metabolism ; Inositol -- Metabolism ; Membrane Transport Proteins -- Metabolism ; Salmonella Typhimurium -- Metabolism
    ISSN: 13500872
    E-ISSN: 1465-2080
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Molecular Microbiology, November 2014, Vol.94(3), pp.700-712
    Description: In serovar yphimurium (. yphimurium), the genomic island 4417/4436 is responsible for the utilization of ‐inositol () as carbon and energy source. Here, we report the characterization of a novel, island‐encoded positive autoregulator termed (4423) that is specific to certain strains and strain 1a able to use . was essential for growth with this polyol and also contributed to . yphimurium proliferation in swine caecum content. Providing higher copy numbers of reduced the long lag phase of 2 days during growth of . yphimurium in medium by 50%. In a heterologous host, expression of activated the transcription from the promoter of /, whose products catalyse the initial two steps in degradation. Episomal expression of / rescued the otherwise zero growth phenotype of a deletion mutant in medium. Gel mobility shift assays with purified demonstrated directed interaction of with its own promoter and that of . The repressor bound the promoter, implying that is part of the regulon. Taken together, the regulator is a trigger to accelerate the switch from more easily accessible nutrients to utilization by . yphimurium.
    Keywords: Orphans ; Inositol ; Salmonella ; Polyols;
    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: 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 ...
  • 7
    In: Journal Of The National Cancer Institute, 2012, Vol. 104(13), pp.1005-1020
    Description: Background Multiple myeloma is a malignancy characterized by the expansion of a plasma cell clone that localizes to the human bone marrow. Myeloma cells and bone marrow stromal cells produce soluble factors that promote the survival and progression of multiple myeloma. Interleukin 16 (IL-16) is involved in regulating the migration and proliferation of normal leukocytes. However, the role of IL-16 in human cancers, including multiple myeloma, is unclear. Methods We investigated IL-16 expression in cell lines (n = 10) and in the bone marrow of myeloma patients (n = 62) and healthy bone marrow donors (n = 12) by quantitative reverse transcription-polymerase chain reaction, immunoblot analysis, enzyme-linked immunosorbent assay, flow cytometry, and immunohistochemistry. Transfection of two human multiple myeloma cell lines with small interfering RNAs was used to examine the effect of IL-16 gene silencing on apoptosis by flow cytometry, on proliferation by bromodeoxyuridine incorporation, and on colony formation. Protein neutralization assays were performed by treating multiple myeloma cells with a monoclonal antibody against the carboxyl-terminal fragment of IL-16. All statistical tests were two-sided. Results IL-16 was strongly overexpressed in the bone marrow of myeloma patients compared with healthy donors. Myeloma cell lines as well as primary tumor cells from myeloma patients constitutively expressed IL-16 and its receptors CD4 and/or CD9 and spontaneously secreted soluble IL-16. Silencing of IL-16 reduced the proliferative activity of myeloma cells by approximately 80% compared with untreated cells (mean relative proliferative activity IL-16 siRNA vs untransfected cells, EJM cells: 20.1%, 95% confidence interval [CI] = 14.3% to 26.0%, P = .03; KMS-12-BM cells: 22.8%, 95% CI = 5.5% to 40.0%, P= .04), and addition of a recombinant carboxyl-terminal IL-16 peptide reversed that effect. A monoclonal antibody directed against IL-16 or its receptors had a comparably strong growth-inhibiting effect on the tumor cells. Conclusions IL-16 is an important growth-promoting factor in multiple myeloma and a candidate for novel diagnostic, prognostic, and therapeutic applications for this incurable human malignancy. DOI: 10.1093/jnci/djs257
    Keywords: Multiple Myeloma -- Diagnosis ; Multiple Myeloma -- Development And Progression ; Multiple Myeloma -- Physiological Aspects ; Interleukins -- Research ; Interleukins -- Physiological Aspects ; Cell Lines -- Research ; Cell Lines -- Physiological Aspects;
    ISSN: 0027-8874
    E-ISSN: 1460-2105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: 2013, Vol.8(12), p.e84382
    Description: The nucleoid-associated protein FIS is a global regulator of gene expression and chromosome structure in Escherichia coli and Salmonella enterica . Despite the importance of FIS for infection and intracellular invasion, very little is known about the regulation of S. enterica fis expression. Under standard laboratory growth conditions, fis is highly expressed during rapid growth but is then silenced as growth slows. However, if cells are cultured in non-aerated conditions, fis expression is sustained during stationary phase. This led us to test whether the redox-sensing transcription factors ArcA and FNR regulate S. enterica fis . Deletion of FNR had no detectable effect, whereas deletion of ArcA had the unexpected effect of further elevating fis expression in stationary phase. ArcA required RpoS for induction of fis expression, suggesting that ArcA indirectly affects fis expression. Other putative regulators were found to play diverse roles: FIS acted directly as an auto-repressor (as expected), whereas CRP had little direct effect on fis expression. Deleting regions of the fis promoter led to the discovery of a novel anaerobically-induced transcription start site (P fis -2) upstream of the primary transcription start site (P fis -1). Promoter truncation also revealed that the shortest functional fis promoter was incapable of sustained expression. Moreover, fis expression was observed to correlate directly with DNA supercoiling in non-aerated conditions. Thus, the full-length S. enterica fis promoter region may act as a topological switch that is sensitive to stress-induced duplex destabilisation and up-regulates expression in non-aerated conditions.
    Keywords: Research Article
    E-ISSN: 1932-6203
    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, 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 ...
  • 10
    Language: English
    In: Current Opinion in Biotechnology, 2011, Vol.22(2), pp.200-210
    Description: ► Overview of 50 . Typhimurium transcriptomic studies dating from 2003 to 2010. ► Wealth of transcriptomics but few datasets from . Typhimurium infection. ► Genes that are highly expressed during infection often play a direct role in virulence. ► Lack of published studies of Salmonella gene expression during food processing. ► Understanding global gene expression datasets continues to be a challenge. The first decade of transcriptomic studies of serovar Typhimurium focused upon gene expression , and during the infection of mammalian cells. The published regulons and stimulons show that the three Type Three Secretion Systems of Typhimurium respond to a diverse range of environmental conditions, and are controlled by a hierarchy of regulatory proteins. The integration of generated transcriptomic data with global gene expression of Typhimurium during infection is beginning to yield valuable information. The coordinated regulation of Salmonella gene expression is a key process for survival, adaptation and virulence capacities of the pathogen.
    Keywords: Engineering
    ISSN: 0958-1669
    E-ISSN: 1879-0429
    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