Article

The gonococcal Fur-regulated tbpA and tbpB genes are expressed during natural mucosal gonococcal infection.

Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, 650 Albany Street, Room 637, Boston, Massachusetts 02118, USA.
Infection and Immunity (Impact Factor: 4.16). 08/2005; 73(7):4281-7. DOI: 10.1128/IAI.73.7.4281-4287.2005
Source: PubMed

ABSTRACT Iron is limiting in the human host, and bacterial pathogens respond to this environment by regulating gene expression through the ferric uptake regulator protein (Fur). In vitro studies have demonstrated that Neisseria gonorrhoeae controls the expression of several critical genes through an iron- and Fur-mediated mechanism. While most in vitro experiments are designed to determine the response of N. gonorrhoeae to an exogenous iron concentration of zero, these organisms are unlikely to be exposed to such severe limitations of iron in vivo. To determine if N. gonorrhoeae expresses iron- and Fur-regulated genes in vivo during uncomplicated gonococcal infection, we examined gene expression profiles of specimens obtained from male subjects with urethral infections. RNA was isolated from urethral swab specimens and used as a template to amplify, by reverse transcriptase PCR (RT-PCR), gonococcal genes known to be regulated by iron and Fur (tbpA, tbpB, and fur). The constitutively expressed gonococcal rmp gene was used as a positive control. RT-PCR analysis indicated that gonorrhea-positive specimens where rmp expression was seen were also 93% (51/55) fbpA positive, 87% (48/55) tbpA positive, and 86% (14 of 16 tested) tbpB positive. In addition, we detected a fur transcript in 79% (37 of 47 tested) of positive specimens. We also measured increases in levels of immunoglobulin G antibody against TbpA (91%) and TbpB (73%) antigens in sera from infected male subjects compared to those in uninfected controls. A positive trend between tbpA gene expression and TbpA antibody levels in sera indicated a relationship between levels of gene expression and immune response in male subjects infected with gonorrhea for the first time. These results indicate that gonococcal iron- and Fur-regulated tbpA and tbpB genes are expressed in gonococcal infection and that male subjects with mucosal gonococcal infections exhibit antibodies to these proteins.

Full-text

Available from: Lee M Wetzler, Apr 28, 2015
0 Followers
 · 
83 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: It is well established that the ferric uptake regulatory protein (Fur) functions as a transcriptional repressor in diverse microorganisms. Recent studies demonstrated that Fur also functions as a transcriptional activator. In this study we defined Fur-mediated activation of gene transcription in the sexually transmitted disease pathogen Neisseria gonorrhoeae. Analysis of 37 genes which were previously determined to be iron induced and which contained putative Fur boxes revealed that only 30 of these genes exhibited reduced transcription in a gonococcal fur mutant strain. Fur-mediated activation was established by examining binding of Fur to the putative promoter regions of 16 Fur-activated genes with variable binding affinities observed. Only ∼50% of the newly identified Fur-regulated genes bound Fur in vitro, suggesting that additional regulatory circuits exist which may function through a Fur-mediated indirect mechanism. The gonococcal Fur-activated genes displayed variable transcription patterns in a fur mutant strain, which correlated with the position of the Fur box in each (promoter) region. These results suggest that Fur-mediated direct transcriptional activation is fulfilled by multiple mechanisms involving either competing with a repressor or recruiting RNA polymerase. Collectively, our studies have established that gonococcal Fur functions as an activator of gene transcription through both direct and indirect mechanisms.
    Journal of bacteriology 01/2012; 194(7):1730-42. DOI:10.1128/JB.06176-11 · 2.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Ferric Uptake Regulatory protein (Fur) has been shown to function as a repressor of transcription in a number of diverse microorganisms. However, recent studies have established that Fur can function at a global level as both an activator and a repressor of transcription through both direct and indirect mechanisms. Fur mediated indirect activation occurs via the repression of additional repressor proteins, or small regulatory RNAs, thereby activating transcription of a previously silent gene. Fur mediates direct activation through binding of Fur to the promoter regions of genes. Whereas the repressive mechanism of Fur has been thoroughly investigated, emerging studies on direct and indirect Fur mediated activation mechanisms have revealed novel global regulatory circuits.
    Journal of bacteriology 08/2012; 194(23). DOI:10.1128/JB.00262-12 · 2.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Ferric uptake regulatory protein (Fur) is a transcriptional regulatory protein that functions to control gene transcription in response to iron in a number of pathogenic bacteria. In this study, we applied a label-free, quantitative and high-throughput analysis method, Interferometric Reflectance Imaging Sensor (IRIS), to rapidly characterize Fur-DNA interactions in vitro with predicted Fur binding sequences in the genome of Neisseria gonorrhoeae, the causative agent of the sexually transmitted disease gonorrhea. IRIS can easily be applied to examine multiple protein-protein, protein-nucleotide and nucleotide-nucleotide complexes simultaneously and demonstrated here that seventy percent of the predicted Fur boxes in promoter regions of iron-induced genes bound to Fur in vitro with a range of affinities as observed using this microarray screening technology. Combining binding data with mRNA expression levels in a gonococcal fur mutant strain allowed us to identify five new gonococcal genes under Fur-mediated direct regulation.
    PLoS ONE 05/2014; 9(5):e96832. DOI:10.1371/journal.pone.0096832 · 3.53 Impact Factor