Peptidyl prolyl isomerases (PPIases) are well-conserved protein-folding enzymes that moonlight as regulators of bacterial virulence. Peptidyl prolyl isomerase A, PPiA (Rv0009) is a secretory protein of Mycobacterium tuberculosis that possesses sequence and structural similarity to eukaryotic cyclophilins. In this study, we validated the interaction of PPiA with stimulator of interferon genes (STING) using both, Escherichia coli-based and mammalian in vitro expression systems.
View Article and Find Full Text PDFMycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis. Here, a macrophage infection model was used to unravel the role of the histone deacetylase sirtuin 6 (SIRT6) in Mtb-triggered regulation of the innate immune response. Mtb infection downregulated microRNA-26a and upregulated its target SIRT6.
View Article and Find Full Text PDFIonic homeostasis is essential for the survival and replication of Mycobacterium tuberculosis within its host. Low potassium ion concentrations trigger a transition of M. tuberculosis into dormancy.
View Article and Find Full Text PDFInfection of macrophages with Mycobacterium tuberculosis induces innate immune responses designed to clear the invading bacterium. However, bacteria often survive within the intracellular environment by exploiting these responses triggered by macrophages. Here, the role of the orphan nuclear receptor Nur77 (Nr4a1) in regulating the response of macrophages infected with M.
View Article and Find Full Text PDFHelicobacter pylori is a gram-negative microaerophilic bacterium and is associated with gastrointestinal diseases ranging from peptic ulcer and gastritis to gastric cancer and mucosa-associated lymphoid tissue lymphoma. In our laboratory, the transcriptomes and miRnomes of AGS cells infected with H. pylori have been profiled, and an miRNA-mRNA network has been constructed.
View Article and Find Full Text PDFTwo-component systems (TCSs) are required for the ability of to respond to stress. The paired TCS, SenX3-RegX3 is known to respond to phosphate starvation and acid stress. The other stress conditions under which RegX3 is required for to mount an appropriate response, remain incompletely understood.
View Article and Find Full Text PDFThe transcriptional network of Mycobacterium tuberculosis is designed to enable the organism to withstand host-associated stresses and to exploit the host milieu for its own survival and multiplication. Rv0081 (MT0088) is a transcriptional regulator whose interplay with other gene regulatory proteins and role in enabling M. tuberculosis to thrive within its host is incompletely understood.
View Article and Find Full Text PDFNon-coding RNAs have emerged as critical regulators of the immune response to infection. MicroRNAs (miRNAs) are small non-coding RNAs which regulate host defense mechanisms against viruses, bacteria and fungi. They are involved in the delicate interplay between , the causative agent of tuberculosis (TB), and its host, which dictates the course of infection.
View Article and Find Full Text PDFcan survive within its host for extended periods of time without any clinical symptoms of disease and reactivate when the immune system is weakened. A detailed understanding of how enters into and exits out of dormancy, is necessary in order to develop new strategies for tackling tuberculosis. Omics methodologies are unsupervised and unbiased to any hypothesis, making them useful tools for the discovery of new drug targets.
View Article and Find Full Text PDFSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of coronavirus induced disease-2019 (COVID-19), is a type of common cold virus responsible for a global pandemic which requires immediate measures for its containment. India has the world's largest population aged between 10 and 40 years. At the same time, India has a large number of individuals with diabetes, hypertension and kidney diseases, who are at a high risk of developing COVID-19.
View Article and Find Full Text PDFTwo-component systems (TCSs) are central to the ability of to respond to stress. One such paired TCS is SenX3-RegX3, which responds to phosphate starvation. Here we show that RegX3 is required for to withstand low pH, one of the challenges encountered by the bacterium in the host environment, and that RegX3 activates the cytosolic redox sensor WhiB3 to launch an appropriate response to acid stress.
View Article and Find Full Text PDFThe modification of chromatin influences host transcriptional programs during bacterial infection, at times skewing the balance in favor of pathogen survival. To test the role of chromatin modifications during Mycobacterium tuberculosis infection, we analysed genome-wide deposition of H3K4me3 marks in macrophages infected with either avirulent M. tuberculosis H37Ra or virulent H37Rv, by chromatin immunoprecipitation, followed by sequencing.
View Article and Find Full Text PDFInfection of macrophages by Mycobacterium tuberculosis elicits an immune response that clears the bacterium. However, the bacterium is able to subvert the innate immune response. Differential expression of transcription factors (TFs) is central to the dynamic balance of this interaction.
View Article and Find Full Text PDFTuberculosis is a global health problem, with a third of the world's population infected with the bacillus, Mycobacterium tuberculosis. The problem is exacerbated by the emergence of multidrug resistant and extensively drug resistant strains. The search for new drug targets is therefore a priority for researchers in the field.
View Article and Find Full Text PDFCell Microbiol
September 2018
Aberrant expression of microRNAs (miRNAs) is associated with tumour progression, extracellular matrix remodelling, and cell proliferation. miRNAs modulate host gene expression during infection by pathogens such as Helicobacter pylori, which is associated with varying degrees of gastric pathology. In order to gain insight into the regulation of gene expression by miRNAs during H.
View Article and Find Full Text PDFMycobacterium tuberculosis employs two-component systems (TCSs) for survival within its host. The TCS MtrAB is conserved among mycobacteria. The response regulator MtrA is essential in M.
View Article and Find Full Text PDFPLoS Pathog
May 2017
For efficient clearance of Mycobacterium tuberculosis (Mtb), macrophages tilt towards M1 polarization leading to the activation of transcription factors associated with the production of antibacterial effector molecules such as nitric oxide (NO) and proinflammatory cytokines such as interleukin 1 β (IL-1β) and tumor necrosis factor α (TNF-α). At the same time, resolution of inflammation is associated with M2 polarization with increased production of arginase and cytokines such as IL-10. The transcriptional and post-transcriptional mechanisms that govern the balance between M1 and M2 polarization, and bacteria-containing processes such as autophagy and trafficking of Mtb to lysosomes, are incompletely understood.
View Article and Find Full Text PDFThe genome of M. tuberculosis (Mtb) encodes eleven paired two component systems (TCSs) consisting of a sensor kinase (SK) and a response regulator (RR). The SKs sense environmental signals triggering RR-dependent gene expression pathways that enable the bacterium to adapt in the host milieu.
View Article and Find Full Text PDFAutophagy plays a crucial role in the control of bacterial burden during Mycobacterium tuberculosis infection. MicroRNAs (miRNAs) are small non-coding RNAs that regulate immune signalling and inflammation in response to challenge by pathogens. Appreciating the potential of host-directed therapies designed to control autophagy during mycobacterial infection, we focused on the role of miRNAs in regulating M.
View Article and Find Full Text PDFMacrophages play an important role in the establishment of infection by intracellular pathogens. Mycobacterium tuberculosis is known to inhibit apoptosis and to downregulate immune responses of host cells using various strategies, including activation of peroxisome proliferator-activated receptor (PPAR)γ. Mannose-capped lipoarabinomannan (ManLAM) is one of the known bacterial effectors that plays a role in subversion of host immunity and activation of PPARγ.
View Article and Find Full Text PDFCoordinated bacterial cell septation and cell wall biosynthesis require formation of protein complexes at the sites of division and elongation, in a temporally controlled manner. The protein players in these complexes remain incompletely understood in mycobacteria. Using in vitro and in vivo assays, we showed that Rv2147c (or SepF) of Mycobacterium tuberculosis interacts with the principal driver of cytokinesis, FtsZ.
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