scholarly journals Variable Expression Patterns of Mycobacterium tuberculosis PE_PGRS Genes: Evidence that PE_PGRS16 and PE_PGRS26 Are Inversely Regulated In Vivo

2006 ◽  
Vol 188 (10) ◽  
pp. 3721-3725 ◽  
Author(s):  
Veerabadran Dheenadhayalan ◽  
Giovanni Delogu ◽  
Maurizio Sanguinetti ◽  
Giovanni Fadda ◽  
Michael J. Brennan
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Expression Profile ◽  
Expression Patterns ◽  
Constitutive Expression ◽  
Growth Conditions ◽  
Variable Expression

ABSTRACT Evaluation of expression of 16 PE_PGRS genes present in Mycobacterium tuberculosis under various growth conditions demonstrated constitutive expression of 7 genes, variable expression of 7 genes, and no expression of 2 genes. An inverse expression profile for genes PE_PGRS16 and PE_PGRS26 was observed to occur in macrophages and in mice infected with M. tuberculosis. Variable expression of PE_PGRS proteins could have implications for their role in the immunopathogenesis of tuberculosis.

scholarly journals Individual Mycobacterium tuberculosis Resuscitation-Promoting Factor Homologues Are Dispensable for Growth In Vitro and In Vivo

2004 ◽  
Vol 72 (1) ◽  
pp. 515-526 ◽  
Author(s):  
JoAnn M. Tufariello ◽  
William R. Jacobs, ◽  
John Chan
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Stationary Phase ◽  
Essential Gene ◽  
Micrococcus Luteus ◽  
Expression Patterns ◽  
Active Growth ◽  
Prolonged Incubation ◽  
Aerosol Infection

ABSTRACT Mycobacterium tuberculosis possesses five genes with significant homology to the resuscitation-promoting factor (Rpf) of Micrococcus luteus. The M. luteus Rpf is a secreted ∼16-kDa protein which restores active growth to cultures of M. luteus rendered dormant by prolonged incubation in stationary phase. More recently, the Rpf-like proteins of M. tuberculosis have been shown to stimulate the growth of extended-stationary-phase cultures of Mycobacterium bovis BCG. These data suggest that the Rpf proteins can influence the growth of mycobacteria; however, the studies do not demonstrate specific functions for the various members of this protein family, nor do they assess the function of M. tuberculosis Rpf homologues in vivo. To address these questions, we have disrupted each of the five rpf-like genes in M. tuberculosis Erdman, and analyzed the mutants for their growth in vitro and in vivo. In contrast to M. luteus, for which rpf is an essential gene, we find that all of the M. tuberculosis rpf deletion mutant strains are viable; in addition, all show growth kinetics similar to Erdman wild type both in vitro and in mouse organs following aerosol infection. Analysis of rpf expression in M. tuberculosis cultures from early log phase through late stationary phase indicates that expression of the rpf-like genes is growth phase-dependent, and that the expression patterns of the five M. tuberculosis rpf genes, while overlapping to various degrees, are not uniform. We also provide evidence that mycobacterial rpf genes are expressed in vivo in the lungs of mice acutely infected with virulent M. tuberculosis.

scholarly journals Urban airborne particle exposure impairs human lung and blood Mycobacterium tuberculosis immunity

Thorax ◽  
2019 ◽  
Vol 74 (7) ◽  
pp. 675-683 ◽  
Author(s):  
Martha Torres ◽  
Claudia Carranza ◽  
Srijata Sarkar ◽  
Yolanda Gonzalez ◽  
Alvaro Osornio Vargas ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mexico City ◽  
Mononuclear Cells ◽  
Immune Cell ◽  
Human Lung ◽  
Constitutive Expression ◽  
In Vitro Exposure ◽  
Ifn Γ

RationaleAssociations between urban (outdoor) airborne particulate matter (PM) exposure and TB and potential biological mechanisms are poorly explored.ObjectivesTo examine whether in vivo exposure to urban outdoor PM in Mexico City and in vitro exposure to urban outdoor PM2.5 (< 2.5 µm median aerodynamic diameter) alters human host immune cell responses to Mycobacterium tuberculosis.MethodsCellular toxicity (flow cytometry, proliferation assay (MTS assay)), M. tuberculosis and PM2.5 phagocytosis (microscopy), cytokine-producing cells (Enzyme-linked immune absorbent spot (ELISPOT)), and signalling pathway markers (western blot) were examined in bronchoalveolar cells (BAC) and peripheral blood mononuclear cells (PBMC) from healthy, non-smoking, residents of Mexico City (n=35; 13 female, 22 male). In vivo-acquired PM burden in alveolar macrophages (AM) was measured by digital image analysis.Measurements and main resultsIn vitro exposure of AM to PM2.5 did not affect M. tuberculosis phagocytosis. High in vivo-acquired AM PM burden reduced constitutive, M. tuberculosis and PM-induced interleukin-1β production in freshly isolated BAC but not in autologous PBMC while it reduced constitutive production of tumour necrosis factor-alpha in both BAC and PBMC. Further, PM burden was positively correlated with constitutive, PM, M. tuberculosis and purified protein derivative (PPD)-induced interferon gamma (IFN-γ) in BAC, and negatively correlated with PPD-induced IFN-γ in PBMC.ConclusionsInhalation exposure to urban air pollution PM impairs important components of the protective human lung and systemic immune response against M. tuberculosis. PM load in AM is correlated with altered M. tuberculosis-induced cytokine production in the lung and systemic compartments. Chronic PM exposure with high constitutive expression of proinflammatory cytokines results in relative cellular unresponsiveness.

scholarly journals Deletion of the Mycobacterium tuberculosis α-Crystallin-Like hspX Gene Causes Increased Bacterial Growth In Vivo

2006 ◽  
Vol 74 (2) ◽  
pp. 861-868 ◽  
Author(s):  
Yanmin Hu ◽  
Farahnaz Movahedzadeh ◽  
Neil G. Stoker ◽  
Anthony R. M. Coates
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Constitutive Expression ◽  
Active Role ◽  
Structural Genes ◽  
Wild Type ◽  
Major Antigen ◽  
Oxide Stress ◽  
Unusual Phenotype

ABSTRACT Hypervirulent mutants of Mycobacterium tuberculosis, whose growth rates are higher in vivo, have now been reported to have mutations in both regulatory and structural genes, but the basis for this unusual phenotype is not understood. One hypervirulence gene, dosR (devR, Rv2031c), activates transcription of approximately 50 genes in this pathogen in response to hypoxia and nitric oxide stress. The most dramatic activation (∼80-fold) is activation of the hspX (acr, Rv2031c) gene, which encodes a 16-kDa α-crystallin-like protein that is a major antigen. In this study we found that a Δacr mutant exhibited increased growth following infection of BALB/c mice in vivo and in both resting and activated macrophages in vitro (as measured by the number of CFU). The increased growth in macrophages was equal to that of a ΔdosR mutant, while introduction of a constitutively expressed hspX gene reduced the ΔdosR virulence to wild-type levels. These results suggest that the increased number of CFU of the ΔdosR mutant was largely due to loss of hspX expression. We also confirmed that constitutive expression of hspX slows growth in vitro, and we propose that hspX plays an active role in slowing the growth of M. tuberculosis in vivo immediately following infection.

scholarly journals Transcriptional Analysis of the Principal Cell Division Gene, ftsZ, of Mycobacterium tuberculosis

2005 ◽  
Vol 187 (7) ◽  
pp. 2540-2550 ◽  
Author(s):  
Sougata Roy ◽  
Parthasarathi Ajitkumar
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Division ◽  
Growth Conditions ◽  
Principal Cell ◽  
Transcriptional Analysis ◽  
Upstream Region ◽  
Reading Frame ◽  
Multiple Promoters ◽  
Promoter Fusion

ABSTRACT Multiple promoters drive the expression of the principal cell division gene, ftsZ, in bacterial systems. Primer extension analysis of total RNA from Mycobacterium tuberculosis and a Mycobacterium smegmatis transformant containing 1.117 kb of the upstream region of M. tuberculosis ftsZ and promoter fusion studies identified six ftsZ transcripts and their promoters in the ftsQ open reading frame and ftsQ-ftsZ intergenic region. The presence of multiple promoters reflects the requirement to maintain a high basal level of, or to differentially regulate, FtsZ expression during different growth conditions of the pathogen in vivo.

scholarly journals Analysis of Expression Profile of Mammalian Cell Entry (mce) Operons of Mycobacterium tuberculosis

2003 ◽  
Vol 71 (10) ◽  
pp. 6083-6087 ◽  
Author(s):  
Ashwani Kumar ◽  
Mridula Bose ◽  
Vani Brahmachari
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Expression Profile ◽  
In Silico ◽  
Infected Animal ◽  
In Silico Analysis ◽  
Cell Entry ◽  
Animal Tissues ◽  
Mce Operons ◽  
Silico Analysis

ABSTRACT The sequencing of the complete genome of M. tuberculosis H37Rv has resulted in the recognition of four mce operons in its genome by in silico analysis. In an attempt to understand the significance of the redundancy of mce operons, we analyzed the expression profile of mce operons after different periods of growth in culture as well as during in vivo infection. Our results strongly suggest that mce1 is expressed as a polycistronic message. In culture from day 8 to day 12, expression of only mce1 was observed, but as the cultures progress towards stationary phase the expression profile of mce operons was altered; the transcripts of the mce1 operon were barely detected while those of the mce4 operon were prominent. In an analysis of the expression of mce operons in tubercle material collected from infected animal tissues, we detected the expression of mce1, -3 and -4. Our results imply that mce operons other than mce1 are also expressed during infection and that it is necessary to examine their role in pathogenesis.

scholarly journals Paraspeckles are subpopulation-specific nuclear bodies that are not essential in mice

2011 ◽  
Vol 193 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Shinichi Nakagawa ◽  
Takao Naganuma ◽  
Go Shioi ◽  
Tetsuro Hirose
Keyword(s):  
Adult Mouse ◽  
Expression Patterns ◽  
Physiological Role ◽  
Growth Conditions ◽  
Nuclear Bodies ◽  
Cellular Functions ◽  
Mouse Tissues

Nuclei of higher organisms are well structured and have multiple, distinct nuclear compartments or nuclear bodies. Paraspeckles are recently identified mammal-specific nuclear bodies ubiquitously found in most cells cultured in vitro. To investigate the physiological role of paraspeckles, we examined the in vivo expression patterns of two long noncoding RNAs, NEAT1_1 and NEAT1_2, which are essential for the architectural integrity of nuclear bodies. Unexpectedly, these genes were only strongly expressed in a particular subpopulation of cells in adult mouse tissues, and prominent paraspeckle formation was observed only in the cells highly expressing NEAT1_2. To further investigate the cellular functions of paraspeckles, we created an animal model lacking NEAT1 by gene targeting. These knockout mice were viable and fertile under laboratory growth conditions, showing no apparent phenotypes except for the disappearance of paraspeckles. We propose that paraspeckles are nonessential, subpopulation-specific nuclear bodies formed secondary to particular environmental triggers.

scholarly journals Dormancy Phenotype Displayed by Extracellular Mycobacterium tuberculosis within Artificial Granulomas in Mice

2004 ◽  
Vol 200 (5) ◽  
pp. 647-657 ◽  
Author(s):  
Petros C. Karakousis ◽  
Tetsuyuki Yoshimatsu ◽  
Gyanu Lamichhane ◽  
Samuel C. Woolwine ◽  
Eric L. Nuermberger ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Expression Patterns ◽  
Latent Tuberculosis ◽  
Interferon Γ ◽  
Hollow Fibers ◽  
In Vivo Model ◽  
Antimicrobial Susceptibility Pattern ◽  
Tuberculosis Chemotherapy ◽  
Survival Patterns

Mycobacterium tuberculosis residing within pulmonary granulomas and cavities represents an important reservoir of persistent organisms during human latent tuberculosis infection. We present a novel in vivo model of tuberculosis involving the encapsulation of bacilli in semidiffusible hollow fibers that are implanted subcutaneously into mice. Granulomatous lesions develop around these hollow fibers, and in this microenvironment, the organisms demonstrate an altered physiologic state characterized by stationary-state colony-forming unit counts and decreased metabolic activity. Moreover, these organisms show an antimicrobial susceptibility pattern similar to persistent bacilli in current models of tuberculosis chemotherapy in that they are more susceptible to the sterilizing drug, rifampin, than to the bactericidal drug isoniazid. We used this model of extracellular persistence within host granulomas to study both gene expression patterns and mutant survival patterns. Our results demonstrate induction of dosR (Rv3133c) and 20 other members of the DosR regulon believed to mediate the transition into dormancy, and that relMtb is required for Mycobacterium tuberculosis survival during extracellular persistence within host granulomas. Interestingly, the dormancy phenotype of extracellular M. tuberculosis within host granulomas appears to be immune mediated and interferon-γ dependent.

scholarly journals Increased pathology in lungs of mice after infection with an α-crystallin mutant of Mycobacterium tuberculosis: changes in cathepsin proteases and certain cytokines

Microbiology ◽  
2006 ◽  
Vol 152 (1) ◽  
pp. 233-244 ◽  
Author(s):  
Julie N. Stewart ◽  
Hilda N. Rivera ◽  
Russell Karls ◽  
Frederick D. Quinn ◽  
Jesse Roman ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Granulomatous Inflammation ◽  
Serum Levels ◽  
Growth Conditions ◽  
High Serum ◽  
Pcr Analysis ◽  
Intracellular Growth ◽  
Cathepsin Proteases ◽  
The Matrix

Latency and reactivation are a significant problem that contributes to the incidence, transmission and pathogenesis of tuberculosis. The mechanisms involved in these processes, at the level of both the bacillus and the host, are poorly understood. In Mycobacterium tuberculosis the α-crystallin (acr) gene has been linked to latency, because it is highly expressed during hypoxic growth conditions. Deletion of the acr gene in M. tuberculosis H37Rv (Δacr strain) was previously shown to reduce the intracellular growth of bacilli in macrophages; however, its impact on pathogenesis in vivo was unknown. This study demonstrated that infection of C57BL6 mice with Δacr results in lung bacillary loads 1-2 log units higher in comparison to parental H37Rv. Haematoxylin/eosin staining of lungs revealed exacerbated pathology characterized by extensive obliteration of alveolar air spaces by granulomatous inflammation. RT-PCR analysis and immunostaining of lungs showed that infection with either H37Rv or Δacr results in the differential expression of lysosomal cathepsin proteases. A slight increase in the expression of the matrix-degrading acidic-type cathepsins B, D and H was noted in Δacr-infected mice and was associated with clusters of macrophages within lung granulomas. Δacr-infected mice also showed high serum levels of TNF-α, IFN-γ and G-CSF, suggesting that Acr may play a role in modulating the host response to infection.

scholarly journals Light-driven carbon dioxide reduction to methane by nitrogenase in a photosynthetic bacterium

2016 ◽  
Vol 113 (36) ◽  
pp. 10163-10167 ◽  
Author(s):  
Kathryn R. Fixen ◽  
Yanning Zheng ◽  
Derek F. Harris ◽  
Sudipta Shaw ◽  
Zhi-Yong Yang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Rhodopseudomonas Palustris ◽  
Constitutive Expression ◽  
Photosynthetic Bacterium ◽  
Carbon Dioxide Reduction ◽  
Growth Conditions ◽  
Cyclic Photophosphorylation ◽  
Femo Cofactor ◽  
Reduce Carbon Dioxide

Nitrogenase is an ATP-requiring enzyme capable of carrying out multielectron reductions of inert molecules. A purified remodeled nitrogenase containing two amino acid substitutions near the site of its FeMo cofactor was recently described as having the capacity to reduce carbon dioxide (CO2) to methane (CH4). Here, we developed the anoxygenic phototroph, Rhodopseudomonas palustris, as a biocatalyst capable of light-driven CO2 reduction to CH4 in vivo using this remodeled nitrogenase. Conversion of CO2 to CH4 by R. palustris required constitutive expression of nitrogenase, which was achieved by using a variant of the transcription factor NifA that is able to activate expression of nitrogenase under all growth conditions. Also, light was required for generation of ATP by cyclic photophosphorylation. CH4 production by R. palustris could be controlled by manipulating the distribution of electrons and energy available to nitrogenase. This work shows the feasibility of using microbes to generate hydrocarbons from CO2 in one enzymatic step using light energy.

scholarly journals Transcriptomic Analysis of Aggregatibacter actinomycetemcomitans Core and Accessory Genes in Different Growth Conditions

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 282 ◽  
Author(s):  
Tjokro ◽  
Kittichotirat ◽  
Torittu ◽  
Ihalin ◽  
Bumgarner ◽  
...  
Keyword(s):  
Gene Pool ◽  
Expression Patterns ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Growth Conditions ◽  
Genomic Islands ◽  
Accessory Gene ◽  
The Core ◽  
Accessory Genes ◽  
Core Genes

Aggregatibacter actinomycetemcomitans genome can be divided into an accessory gene pool (found in some but not all strains) and a core gene pool (found in all strains). The functions of the accessory genes (genomic islands and non-island accessory genes) are largely unknown. We hypothesize that accessory genes confer critical functions for A. actinomycetemcomitans in vivo. This study examined the expression patterns of accessory and core genes of A. actinomycetemcomitans in distinct growth conditions. We found similar expression patterns of island and non-island accessory genes, which were generally lower than the core genes in all growth conditions. The median expression levels of genomic islands were 29%–37% of the core genes in enriched medium but elevated to as high as 63% of the core genes in nutrient-limited media. Several putative virulence genes, including the cytolethal distending toxin operon, were found to be activated in nutrient-limited conditions. In conclusion, genomic islands and non-island accessory genes exhibited distinct patterns of expression from the core genes and may play a role in the survival of A. actinomycetemcomitans in nutrient-limited environments.

Sign in / Sign up

Export Citation Format

Share Document