Translational gene expression control in Chlamydia trachomatis.
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ABSTRACT:
SUBMITTER: Grieshaber NA
PROVIDER: S-EPMC8794103 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Chlamydia trachomatis is maintained through a complex bi-phasic developmental cycle that incorporates numerous processes that are poorly understood. This is reflective of the previous paucity of genetic tools available. The recent advent of a method for transforming Chlamydia has enabled the development of essential molecular tools to better study these medically important bacteria. Critical for the study of Chlamydia biology and pathogenesis, is a system for tightly controlled inducible gene expression. To accomplish this, a new shuttle vector was generated with gene expression controlled by the Tetracycline repressor and anhydryotetracycline. Evaluation of GFP expression by this system demonstrated tightly controlled gene regulation with rapid protein expression upon induction and restoration of transcription repression following inducer removal. Additionally, induction of expression could be detected relatively early during the developmental cycle and concomitant with conversion into the metabolically active form of Chlamydia. Uniform and strong GFP induction was observed during middle stages of the developmental cycle. Interestingly, variable induced GFP expression by individual organisms within shared inclusions during later stages of development suggesting metabolic diversity is affecting induction and/or expression. These observations support the strong potential of this molecular tool to enable numerous experimental analyses for a better understanding of the biology and pathogenesis of Chlamydia.
| S-EPMC3792055 | biostudies-literature
Project description:Study aimed to characterize the expression of antioxidant genes SOD1 and SOD2 in Chlamydia trachomatis-induced recurrent spontaneous aborters and further determine their role by in silico analysis. First void urine was collected from 130 non-pregnant women with history of recurrent spontaneous abortion (RSA) (Group I) and 130 non-pregnant women (Group II; control) attending Obstetrics and Gynecology Department, SJH, New Delhi, India. C. trachomatis detection was performed by conventional PCR in urine. Gene expression of SOD1 and SOD2 was performed by quantitative real-time PCR. Further, its interacting partners were studied by in silico analysis. 22 patients were positive for C. trachomatis in Group I. Significant upregulation was observed for SOD2 gene in C. trachomatis-infected RSA patients while SOD1 was found to be downregulated. Increased concentration of oxidative stress biomarkers 8-hydroxyguanosine and 8-isoprostane was found in C. trachomatis-infected RSA patients. Protein-protein interaction (PPI) of SOD proteins and its interacting partners viz.; CCS, GPX1, GPX2, GPX3, GPX4, GPX5, GPX7, GPX8, CAT, PRDX1, TXN, SIRT3, FOXO3, and AKT1 were found to be involved in MAPK, p53 and foxo signaling pathways. Molecular pathways involved in association with SODs indicate reactive oxygen species (ROS) detoxification, apoptotic pathways and cell cycle regulation. Overall data revealed alleviated levels of SOD2 gene and decreased expression of SOD1 gene in response to C. trachomatis-infection leading to production of oxidative stress and RSA.
| S-EPMC9424283 | biostudies-literature
Project description:Chlamydia trachomatis is an obligate intracellular pathogen that replicates in a vacuole termed the inclusion. Many of the interactions of chlamydiae with the host cell are dependent upon bacterial protein synthesis and presumably exposure of these proteins to the cytosol. Because of the dearth of genetic tools for chlamydiae, previous studies examining secreted proteins required the use of heterologous bacterial systems. Recent advances in genetic manipulation of chlamydia now allow for transformation of the bacteria with plasmids. We describe here a shuttle vector system, pBOMB4, that permits expression of recombinant proteins under constitutive or conditional promoter control. We show that the inclusion membrane protein IncD is secreted in a type III-dependent manner from Yersinia pseudotuberculosis and also secreted from C. trachomatis in infected cells where it localizes appropriately to the inclusion membrane. IncD truncated of the first 30 amino acids containing the secretion signal is no longer secreted and is retained by the bacteria. Cytosolic exposure of secreted proteins can be confirmed by using CyaA, GSK, or microinjection assays. A protein predicted to be retained within the bacteria, NrdB is indeed localized to the chlamydia. In addition, we have shown that the chlamydial effector protein, CPAF, which is secreted into the host cell cytosol by a Sec-dependent pathway, also accesses the cytosol when expressed from this system. These assays should prove useful to assess the secretion of other chlamydial proteins that are potentially exposed to the cytosol of the host cell.
| S-EPMC3993338 | biostudies-literature
Project description:Chlamydia trachomatis is a bacterial obligate intracellular parasite and a significant cause of human disease, including sexually transmitted infections and trachoma. The bacterial RNA polymerase-binding protein DksA is a transcription factor integral to the multicomponent bacterial stress response pathway known as the stringent response. The genome of C. trachomatis encodes a DksA ortholog (DksACt) that is maximally expressed at 15-20 h post infection, a time frame correlating with the onset of transition between the replicative reticulate body (RB) and infectious elementary body (EB) forms of the pathogen. Ectopic overexpression of DksACt in C. trachomatis prior to RB-EB transitions during infection of HeLa cells resulted in a 39.3% reduction in overall replication (yield) and a 49.6% reduction in recovered EBs. While the overall domain organization of DksACt is similar to the DksA ortholog of Escherichia coli (DksAEc), DksACt did not functionally complement DksAEc. Transcription of dksACt is regulated by tandem promoters, one of which also controls expression of nrdR, encoding a negative regulator of deoxyribonucleotide biosynthesis. The phenotype resulting from ectopic expression of DksACt and the correlation between dksACt and nrdR expression is consistent with a role for DksACt in the C. trachomatis developmental cycle.
| S-EPMC9126822 | biostudies-literature
Project description:DNA sequencing of the major outer membrane protein (MOMP) gene (omp1) from Chlamydia trachomatis shows that some strains have a mosaic structure suggestive of homologous recombination between two distinct omp1 genes. On the basis of this conjecture, we attempted to clone by complementation and sequence the chlamydial recA homolog from C. trachomatis serovar L2. Chlamydial genomic DNA was partially restricted with XbaI, and fragments of 2 to 4 kb were ligated into pUC19. The recombinant plasmid was electroporated into Escherichia coli HB101 (RecA-), and colonies were selected in the presence of methyl methanesulfonate (MMS). A 2.1-kb fragment of C. trachomatis DNA in pUC19 conferred relative MMS resistance to E. coli HB101. When this recombinant plasmid (pX203) was electroporated into E. coli JC14604 (RecA- lacZ), lac+ recombinants were isolated. Rabbit polyclonal antibodies produced to purified E. coli RecA were immunoreactive in an immunoblot assay with a 35-kDa antigen in RecA- strains of E. coli transformed with pX203. The 2.1-kb insert was cycle sequenced by the dideoxy chain termination method. An open reading frame of 1,056 bp encoding 352 amino acids that had 44% sequence identity with E. coli RecA was identified. The finding of a recA homolog in C. trachomatis suggests that homologous recombination may occur in this organism. The cloned C. trachomatis RecA-encoding gene will be useful for the construction of a recA mutant once a gene transfer system is developed for chlamydiae.
| S-EPMC173048 | biostudies-other
Project description:Chlamydiae possess an intracellular developmental cycle defined by the orderly interconversion of infectious, metabolically inactive elementary bodies and noninfectious, dividing reticulate bodies. Only a few stage-specific genes have been cloned and sequenced, including the late-stage cysteine-rich protein operon and two late-stage genes encoding histone-like proteins. The aims of this study were to identify additional late-stage genes of Chlamydia trachomatis, analyze the upstream DNA sequence of late genes, and determine the sigma factor requirement of late genes. Stage-specific RNA, made by chlamydiae isolated from host cells, was used to probe C. trachomatis genomic libraries. Two new late genes, designated ltuA and ltuB, were identified, cloned, and sequenced. The predicted peptides encoded by ltuA and ltuB do not bear strong homology to known proteins, and the function of the new late genes is not known. The 5' ends of the transcripts of ltuA, ltuB, the cysteine-rich protein operon, and the two histone-like genes (hctA and hctB) were mapped, and a consensus -10 promoter region of TATAAT was derived from their upstream DNA sequences. In vitro transcription from templates encoding the promoter regions of ltuA, ltuB, and hctA cloned into the transcription assay vector pUC19-spf was found to be strongly stimulated by the addition of recombinant chlamydial sigma 66, while transcription from the putative hctB promoter region cloned in pUC19-spf was not detected in either the presence or absence of added sigma 66. These results suggest that the transcription of at least some chlamydial late-stage genes is dependent on sigma 66, which is homologous to the major sigma factors of other eubacteria.
| S-EPMC177170 | biostudies-other
Project description:Chlamydia trachomatis, an obligate intracellular pathogen, is a leading worldwide cause of ocular and urogenital diseases. Advances have been made in our understanding of the nine-member polymorphic membrane protein (Pmp) gene (pmp) family of C. trachomatis. However, there is only limited information on their biologic role, especially for biological variants (biovar) and clinical strains.We evaluated expression for pmps throughout development for reference strains E/Bour and L2/434, representing different biovars, and for clinical E and L2 strains. Immunoreactivity of patient sera to recombinant (r)Pmps was also determined. All pmps were expressed at two hours. pmpA had the lowest expression but was up-regulated at 12 h for all strains, indicating involvement in reticulate body development. For pmpD, expression peaked at 36 h. Additionally, 57.7% of sera from infected and 0% from uninfected adolescents were reactive to rPmpD (p = 0.001), suggesting a role in immunogenicity. pmpF had the highest expression levels for all clinical strains and L2/434 with differential expression of the pmpFE operon for the same strains. Sera were nonreactive to rPmpF despite immunoreactivity to rMOMP and rPmpD, suggesting that PmpF is not associated with humoral immune responses. pmpFE sequences for clinical strains were identical to those of the respective reference strains. We identified the putative pmpFE promoter, which was, surprisingly, 100% conserved for all strains. Analyses of ribosomal binding sites, RNase E, and hairpin structures suggested complex regulatory mechanism(s) for this >6 Kb operon.The dissimilar expression of the same pmp for different C. trachomatis strains may explain different strain-specific needs and phenotypic distinctions. This is further supported by the differential immunoreactivity to rPmpD and rPmpF of sera from patients infected with different strains. Furthermore, clinical E strains did not correlate with the E reference strain at the gene expression level, reinforcing the need for expansive studies of clinical strains.
| S-EPMC1963315 | biostudies-literature
Project description:By comparing two fully sequenced genomes of Chlamydia trachomatis using competitive hybridization on DNA microarrays, a logarithmic correlation was demonstrated between the signal ratio of the arrays and the 75-99% range of nucleotide identities of the genes. Variable genes within 14 uncharacterized strains of C. trachomatis were identified by array analysis and verified by DNA sequencing. These genes may be crucial for understanding chlamydial virulence and pathogenesis.
| S-EPMC463075 | biostudies-literature
Project description:Chlamydia trachomatis is an obligate intracellular pathogen that replicates in a membrane-bound vacuole termed the inclusion. Early in the infection cycle, the pathogen extensively modifies the inclusion membrane through incorporation of numerous type III secreted effector proteins, called inclusion membrane proteins (Incs). These proteins are characterized by a bilobed hydrophobic domain of 40 amino acids. The presence of this domain has been used to predict up to 59 putative Incs for C. trachomatis; however, localization to the inclusion membrane with specific antibodies has been demonstrated for only about half of them. Here, we employed recently developed genetic tools to verify the localization of predicted Incs that had not been previously localized to the inclusion membrane. Expression of epitope-tagged putative Incs identified 10 that were previously unverified as inclusion membrane localized and thus authentic Incs. One novel Inc and 3 previously described Incs were localized to inclusion membrane microdomains, as evidenced by colocalization with phosphorylated Src (p-Src). Several predicted Incs did not localize to the inclusion membrane but instead remained associated with the bacteria. Using Yersinia as a surrogate host, we demonstrated that many of these are not secreted via type III secretion, further suggesting they may not be true Incs. Collectively, our results highlight the utility of genetic tools for demonstrating secretion from chlamydia. Further mechanistic studies aimed at elucidating effector function will advance our understanding of how the pathogen maintains its unique intracellular niche and mediates interactions with the host.
| S-EPMC4645406 | biostudies-literature
Project description:The aim of this study was to perform a comprehensive gene expression analysis of cytokines, chemokines, and their receptors in Chlamydia trachomatis-infected human monocytes in order to elucidate molecular aspects of their involvement in the host response. Peripheral blood mononuclear cells from three healthy donors were separated and infected with C. trachomatis elementary bodies serovar K (UW/31/Cx) at a multiplicity of infection of 5:1. Three time points of infection were studied by gene expression analysis using microarray: 4 hours (active infection), 1 day (transition), and 7 days (persistent infection). Expression levels of selected genes were confirmed by quantitative real-time reverse transcription-polymerase chain reaction. Transcripts encoding 10 cytokines, chemokines, and receptors were found to be upregulated exclusively in the early, active phase of the infection as compared to four genes in the late, persistent state of the infection. Apart from receptors, both the level and the number of transcripts encoding inflammatory products decreased with ongoing infection. Four genes (interferon-gamma, macrophage inflammatory protein [MIP]-1-alpha, MIP-1-beta, and interleukin-2 receptor-gamma) were constantly expressed over a period of 7 days. The current study provides data on the induction of mRNA encoding cytokines, chemokines, and their receptors in C. trachomatis-infected human monocytes. This pro-inflammatory gene expression profile of the monocytic host cell showed several differences between active and persistent chlamydial infections.
| S-EPMC2206345 | biostudies-literature