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
  • Gene Expression
Type of Medium
Language
Year
  • 1
    Language: English
    In: Journal of bacteriology, December 2014, Vol.196(23), pp.4012-25
    Description: Haemophilus ducreyi causes the sexually transmitted disease chancroid and a chronic limb ulceration syndrome in children. In humans, H. ducreyi is found in an abscess and overcomes a hostile environment to establish infection. To sense and respond to membrane stress, bacteria utilize two-component systems (TCSs) and extracytoplasmic function (ECF) sigma factors. We previously showed that activation of CpxRA, the only intact TCS in H. ducreyi, does not regulate homologues of envelope protein folding factors but does downregulate genes encoding envelope-localized proteins, including many virulence determinants. H. ducreyi also harbors a homologue of RpoE, which is the only ECF sigma factor in the organism. To potentially understand how H. ducreyi responds to membrane stress, here we defined RpoE-dependent genes using transcriptome sequencing (RNA-Seq). We identified 180 RpoE-dependent genes, of which 98% were upregulated; a major set of these genes encodes homologues of envelope maintenance and repair factors. We also identified and validated a putative RpoE promoter consensus sequence, which was enriched in the majority of RpoE-dependent targets. Comparison of RpoE-dependent genes to those controlled by CpxR showed that each transcription factor regulated a distinct set of genes. Given that RpoE activated a large number of genes encoding envelope maintenance and repair factors and that CpxRA represses genes encoding envelope-localized proteins, these data suggest that RpoE and CpxRA appear to play distinct yet complementary roles in regulating envelope homeostasis in H. ducreyi.
    Keywords: Gene Expression Regulation, Bacterial ; Stress, Physiological ; Bacterial Proteins -- Metabolism ; Cell Membrane -- Physiology ; Haemophilus Ducreyi -- Physiology ; Protein Kinases -- Metabolism ; Sigma Factor -- Metabolism
    ISSN: 00219193
    E-ISSN: 1098-5530
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Journal of Bacteriology, 2013, Vol.195(15-16), p.3486(17)
    Description: Haemophilus ducreyi causes chancroid, a genital ulcer disease that facilitates the transmission of human immunodeficiency virus type 1. In humans, H. ducreyi is surrounded by phagocytes and must adapt to a hostile environment to survive. To sense and respond to environmental cues, bacteria frequently use two-component signal transduction (2CST) systems. The only obvious 2CST system in H. ducreyi is CpxRA; CpxR is a response regulator, and CpxA is a sensor kinase. Previous studies by Hansen and coworkers showed that CpxR directly represses the expression of dsrA, the lspB-lspA2 operon, and the flp operon, which are required for virulence in humans. They further showed that CpxA functions predominantly as a phosphatase in vitro to maintain the expression of virulence determinants. Since a cpxA mutant is avirulent while a cpxR mutant is fully virulent in humans, CpxA also likely functions predominantly as a phosphatase in vivo. To better understand the role of H. ducreyi CpxRA in controlling virulence determinants, here we defined genes potentially regulated by CpxRA by using RNA-Seq. Activation of CpxR by deletion of cpxA repressed nearly 70% of its targets, including seven established virulence determinants. Inactivation of CpxR by deletion of cpxR differentially regulated few genes and increased the expression of one virulence determinant. We identified a CpxR binding motif that was enriched in downregulated but not upregulated targets. These data reinforce the hypothesis that CpxA phosphatase activity plays a critical role in controlling H. ducreyi virulence in vivo. Characterization of the downregulated genes may offer new insights into pathogenesis.
    Keywords: Chancroid – Causes of ; Gene Expression – Research ; Hemophilus Infections – Research ; Virulence (Microbiology) – Research
    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: Journal of bacteriology, August 2013, Vol.195(15), pp.3486-502
    Description: Haemophilus ducreyi causes chancroid, a genital ulcer disease that facilitates the transmission of human immunodeficiency virus type 1. In humans, H. ducreyi is surrounded by phagocytes and must adapt to a hostile environment to survive. To sense and respond to environmental cues, bacteria frequently use two-component signal transduction (2CST) systems. The only obvious 2CST system in H. ducreyi is CpxRA; CpxR is a response regulator, and CpxA is a sensor kinase. Previous studies by Hansen and coworkers showed that CpxR directly represses the expression of dsrA, the lspB-lspA2 operon, and the flp operon, which are required for virulence in humans. They further showed that CpxA functions predominantly as a phosphatase in vitro to maintain the expression of virulence determinants. Since a cpxA mutant is avirulent while a cpxR mutant is fully virulent in humans, CpxA also likely functions predominantly as a phosphatase in vivo. To better understand the role of H. ducreyi CpxRA in controlling virulence determinants, here we defined genes potentially regulated by CpxRA by using RNA-Seq. Activation of CpxR by deletion of cpxA repressed nearly 70% of its targets, including seven established virulence determinants. Inactivation of CpxR by deletion of cpxR differentially regulated few genes and increased the expression of one virulence determinant. We identified a CpxR binding motif that was enriched in downregulated but not upregulated targets. These data reinforce the hypothesis that CpxA phosphatase activity plays a critical role in controlling H. ducreyi virulence in vivo. Characterization of the downregulated genes may offer new insights into pathogenesis.
    Keywords: Gene Expression Regulation, Bacterial ; Bacterial Proteins -- Metabolism ; Haemophilus Ducreyi -- Genetics ; Phosphoprotein Phosphatases -- Metabolism ; Protein Kinases -- Metabolism ; Repressor Proteins -- Metabolism ; Virulence Factors -- Biosynthesis
    ISSN: 00219193
    E-ISSN: 1098-5530
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: PLoS ONE, 01 January 2015, Vol.10(4), p.e0124373
    Description: Haemophilus ducreyi resists the cytotoxic effects of human antimicrobial peptides (APs), including α-defensins, β-defensins, and the cathelicidin LL-37. Resistance to LL-37, mediated by the sensitive to antimicrobial peptide (Sap) transporter, is required for H. ducreyi virulence in humans. Cationic APs are attracted to the negatively charged bacterial cell surface. In other gram-negative bacteria, modification of lipopolysaccharide or lipooligosaccharide (LOS) by the addition of positively charged moieties, such as phosphoethanolamine (PEA), confers AP resistance by means of electrostatic repulsion. H. ducreyi LOS has PEA modifications at two sites, and we identified three genes (lptA, ptdA, and ptdB) in H. ducreyi with homology to a family of bacterial PEA transferases. We generated non-polar, unmarked mutants with deletions in one, two, or all three putative PEA transferase genes. The triple mutant was significantly more susceptible to both α- and β-defensins; complementation of all three genes restored parental levels of AP resistance. Deletion of all three PEA transferase genes also resulted in a significant increase in the negativity of the mutant cell surface. Mass spectrometric analysis revealed that LptA was required for PEA modification of lipid A; PtdA and PtdB did not affect PEA modification of LOS. In human inoculation experiments, the triple mutant was as virulent as its parent strain. While this is the first identified mechanism of resistance to α-defensins in H. ducreyi, our in vivo data suggest that resistance to cathelicidin LL-37 may be more important than defensin resistance to H. ducreyi pathogenesis.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Infection and immunity, August 2015, Vol.83(8), pp.3281-92
    Description: The (p)ppGpp-mediated stringent response is important for bacterial survival in nutrient limiting conditions. For maximal effect, (p)ppGpp interacts with the cofactor DksA, which stabilizes (p)ppGpp's interaction with RNA polymerase. We previously demonstrated that (p)ppGpp was required for the virulence of Haemophilus ducreyi in humans. Here, we constructed an H. ducreyi dksA mutant and showed it was also partially attenuated for pustule formation in human volunteers. To understand the roles of (p)ppGpp and DksA in gene regulation in H. ducreyi, we defined genes potentially altered by (p)ppGpp and DksA deficiency using transcriptome sequencing (RNA-seq). In bacteria collected at stationary phase, lack of (p)ppGpp and DksA altered expression of 28% and 17% of H. ducreyi open reading frames, respectively, including genes involved in transcription, translation, and metabolism. There was significant overlap in genes differentially expressed in the (p)ppGpp mutant relative to the dksA mutant. Loss of (p)ppGpp or DksA resulted in the dysregulation of several known virulence determinants. Deletion of dksA downregulated lspB and rendered the organism less resistant to phagocytosis and increased its sensitivity to oxidative stress. Both mutants had reduced ability to attach to human foreskin fibroblasts; the defect correlated with reduced expression of the Flp adhesin proteins in the (p)ppGpp mutant but not in the dksA mutant, suggesting that DksA regulates the expression of an unknown cofactor(s) required for Flp-mediated adherence. We conclude that both (p)ppGpp and DksA serve as major regulators of H. ducreyi gene expression in stationary phase and have both overlapping and unique contributions to pathogenesis.
    Keywords: Bacterial Proteins -- Metabolism ; Chancroid -- Microbiology ; Guanosine Tetraphosphate -- Metabolism ; Haemophilus Ducreyi -- Metabolism
    ISSN: 00199567
    E-ISSN: 1098-5522
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Infection and immunity, May 2016, Vol.84(5), pp.1514-1525
    Description: Haemophilus ducreyi causes the sexually transmitted disease chancroid in adults and cutaneous ulcers in children. In humans, H. ducreyi resides in an abscess and must adapt to a variety of stresses. Previous studies (D. Gangaiah, M. Labandeira-Rey, X. Zhang, K. R. Fortney, S. Ellinger, B. Zwickl, B. Baker, Y. Liu, D. M. Janowicz, B. P. Katz, C. A. Brautigam, R. S. MunsonJr, E. J. Hansen, and S. M. Spinola, mBio 5:e01081-13, 2014, http://dx.doi.org/10.1128/mBio.01081-13) suggested that H. ducreyi encounters growth conditions in human lesions resembling those found in stationary phase. However, how H. ducreyi transcriptionally responds to stress during human infection is unknown. Here, we determined the H. ducreyi transcriptome in biopsy specimens of human lesions and compared it to the transcriptomes of bacteria grown to mid-log, transition, and stationary phases. Multidimensional scaling showed that the in vivo transcriptome is distinct from those of in vitro growth. Compared to the inoculum (mid-log-phase bacteria), H. ducreyi harvested from pustules differentially expressed ∼93 genes, of which 62 were upregulated. The upregulated genes encode homologs of proteins involved in nutrient transport, alternative carbon pathways (l-ascorbate utilization and metabolism), growth arrest response, heat shock response, DNA recombination, and anaerobiosis. H. ducreyi upregulated few genes (hgbA, flp-tad, and lspB-lspA2) encoding virulence determinants required for human infection. Most genes regulated by CpxRA, RpoE, Hfq, (p)ppGpp, and DksA, which control the expression of virulence determinants and adaptation to a variety of stresses, were not differentially expressed in vivo, suggesting that these systems are cycling on and off during infection. Taken together, these data suggest that the in vivo transcriptome is distinct from those of in vitro growth and that adaptation to nutrient stress and anaerobiosis is crucial for H. ducreyi survival in humans.
    Keywords: Adaptation, Physiological ; Gene Expression Profiling ; Stress, Physiological ; Carbon -- Metabolism ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Physiology
    ISSN: 00199567
    E-ISSN: 1098-5522
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    In: Infection and Immunity, 2001, Vol. 69(3), p.1483
    Description: Haemophilus ducreyi expresses several putative virulence factors in vitro. Isogenic mutant-to-parent comparisons have been performed in a human model of experimental infection to examine whether specific gene products are involved in pathogenesis. Several mutants (momp, ftpA, losB, lst, cdtC, and hhdB) were as virulent as the parent in the human model, suggesting that their gene products did not play a major role in pustule formation. However, we could not exclude the possibility that the gene of interest was not expressed during the initial stages of infection. Biopsies of pustules obtained from volunteers infected with H. ducreyi were subjected to reverse transcription-PCR. Transcripts corresponding to momp, ftpA, losB, lst, cdtB, and hhdA were expressed in vivo. In addition, transcripts for other putative virulence determinants such as ompA2, tdhA, lspA1, and lspA2 were detected in the biopsies. These results indicate that although several candidate virulence determinants are expressed during experimental infection, they do not have a major role in the initial stages of pathogenesis.
    Keywords: Chancroid -- Microbiology ; Haemophilus Ducreyi -- Genetics ; RNA, Bacterial -- Biosynthesis ; RNA, Messenger -- Biosynthesis;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Int. J. of Computational Biology and Drug Design, 2014, Vol 7 Issue 2/3, pp 195 - 213
    Description: High throughput bacterial RNA-Seq experiments can generate extremely high and imbalanced sequencing coverage. Over- or under-estimation of gene expression levels will hinder accurate gene differential expression analysis. Here we evaluated strategies to identify expression differences of genes with high coverage in bacterial transcriptome data using either raw sequence reads or unique reads with duplicate fragments removed. In addition, we proposed a generalised linear model (GLM) based approach to identify imbalance in read coverage based on sequence compositions. Our results show that analysis using raw reads identifies more differentially expressed genes with more accurate fold change than using unique reads. We also demonstrate the presence of sequence composition related biases that are independent of gene expression levels and experimental conditions. Finally, genes that still show strong coverage imbalance after correction were tagged using statistical approach.
    Keywords: bacterial transcriptome sequencing; RNA-Seq; gene differential expression; coverage imbalance; tri-nucleotides; GLM; generalised linear modelling; computational biology; RNA sequences; gene expression levels.
    ISSN: 1756-0756
    ISSN: 17560756
    ISSN: 1756-0764
    ISSN: 17560764
    E-ISSN: 1756-0764
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    In: Journal of Bacteriology, Feb, 1996, Vol.178(3-4), p.808(9)
    Description: A study was conducted to determine the role of the pili expressed by Haemophilus ducreyi in the pathogenesis of the genital ulcer disease chancroid. A gene encoding the 24K protein of fine, tangled pili, termed ftpA, was isolated and examined by molecular techniques. The results showed that the FtpA protein lacked homology with other pilins, but shared homoloy with proteins that polymerize ordered rings in Escherichia coli and Treponema pallidum.
    Keywords: Hemophilus Infections -- Genetic Aspects
    ISSN: 0021-9193
    E-ISSN: 10985530
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: The Journal of infectious diseases, 01 March 2009, Vol.199(5), pp.684-92
    Description: A gene expression study of Haemophilus ducreyi identified the hypothetical lipoprotein HD0192, renamed here "fibrinogen binder A" (FgbA), as being preferentially expressed in vivo. To test the role played by fgbA in virulence, an isogenic fgbA mutant (35000HPfgbA) was constructed using H. ducreyi 35000HP, and 6 volunteers were experimentally infected with 35000HP or 35000HPfgbA. The overall pustule-formation rate was 61.1% at parent sites and 22.2% at mutant sites (P = .019). Papules were significantly smaller at mutant sites than at parent sites (13.3 vs. 37.9 mm(2); P = .002) 24 h after inoculation. Thus, fgbA contributed significantly to the virulence of H. ducreyi in humans. In vitro experiments demonstrated that fgbA encodes a fibrinogen-binding protein; no other fibrinogen-binding proteins were identified in 35000HP. fgbA was conserved among clinical isolates of both class I and II H. ducreyi strains, supporting the finding that fgbA is important for H. ducreyi infection.
    Keywords: Bacterial Proteins -- Metabolism ; Chancroid -- Microbiology ; Fibrinogen -- Metabolism ; Haemophilus Ducreyi -- Genetics ; Lipoproteins -- Metabolism
    ISSN: 0022-1899
    E-ISSN: 15376613
    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