Structure-function relationship of PE11 esterase of Mycobacterium tuberculosis with respect to its role in virulence.

The lipolytic enzymes of Mycobacterium tuberculosis play a critical role in immunomodulation and virulence. Among these proteins, PE11 which also belongs to the PE/PPE family, is the smallest (∼10.8 kDa) and play a significant role in cell wall remodelling and virulence.

Divergent downstream biosynthetic pathways are supported by L-cysteine synthases of .

's () autarkic lifestyle within the host involves rewiring its transcriptional networks to combat host-induced stresses. With the help of RNA sequencing performed under various stress conditions, we identified that genes belonging to sulfur metabolism pathways are significantly upregulated during oxidative stress. Using an integrated approach of microbial genetics, transcriptomics, metabolomics, animal experiments, chemical inhibition, and rescue studies, we investigated the biological role of non-canonical L-cysteine synthases, CysM and CysK2.

Depletion of essential mycobacterial gene glmM reduces pathogen survival and induces host-protective immune responses against tuberculosis.

The limitations of TB treatment are the long duration and immune-dampening effects of anti-tuberculosis therapy. The Cell wall plays a crucial role in survival and virulence; hence, enzymes involved in its biosynthesis are good therapeutic targets. Here, we identify Mycobacterium tuberculosis (Mtb) GlmM, (GlmM) engaged in the UDP-GlcNAc synthesis pathway as an essential enzyme.

The PPE2 protein of Mycobacterium tuberculosis is secreted during infection and facilitates mycobacterial survival inside the host.

Mycobacterium tuberculosis secrets various effector proteins to evade host immune responses for facilitating its intracellular survival. The bacterial genome encodes several unique PE/PPE family proteins, which have been implicated to play important role in mycobacterial pathogenesis. A member of this family, PPE2 have been shown to contain a monopartite nuclear localization signal (NLS) and a DNA binding domain.

The heparin-binding hemagglutinin protein of Mycobacterium tuberculosis is a nucleoid-associated protein.

Nucleoid-associated proteins (NAPs) regulate multiple cellular processes such as gene expression, virulence, and dormancy throughout bacterial species. NAPs help in the survival and adaptation of Mycobacterium tuberculosis (Mtb) within the host. Fourteen NAPs have been identified in Escherichia coli; however, only seven NAPs are documented in Mtb.

Phosphorylation of CFP10 modulates virulence.

Secreted virulence factors play a critical role in bacterial pathogenesis. Virulence effectors not only help bacteria to overcome the host immune system but also aid in establishing infection. , which causes tuberculosis in humans, encodes various virulence effectors.

GWAS and functional studies suggest a role for altered DNA repair in the evolution of drug resistance in .

The emergence of drug resistance in () is alarming and demands in-depth knowledge for timely diagnosis. We performed genome-wide association analysis using 2237 clinical strains of to identify novel genetic factors that evoke drug resistance. In addition to the known direct targets, we identified for the first time, a strong association between mutations in DNA repair genes and the multidrug-resistant phenotype.

The unique N-terminal region of Mycobacterium tuberculosis sigma factor A plays a dominant role in the essential function of this protein.

SigA (σ) is an essential protein and the primary sigma factor in Mycobacterium tuberculosis (Mtb). However, due to the absence of genetic tools, our understanding of the role and regulation of σ activity and its molecular attributes that help modulate Mtb survival is scant. Here, we generated a conditional gene replacement of σ in Mtb and showed that its depletion results in a severe survival defect in vitro, ex vivo, and in vivo in a murine infection model.

Codon optimality has minimal effect on determining translation efficiency in mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb) is a slow-growing, intracellular pathogen that exhibits a high GC-rich genome. Several factors, including the GC content of the genome, influence the evolution of specific codon usage biases in genomes. As a result, the Mtb genome exhibits strong biases for amino acid usage and codon usage.

Protocol for competition and sequencing of mycobacterium isolated from infected guinea pigs.

We describe steps for gDNA isolation from mycobacterium strains isolated from guinea pig lungs. We detail steps for infection of guinea pigs with , followed by growth, gDNA isolation, and whole genome sequencing. We also describe an competition experiment to determine the selective advantage of one strain over another.

Hydrophobicity of Cholic Acid-Derived Amphiphiles Dictates the Antimicrobial Specificity.

The unique structural components of cell membranes of Gram-positive bacteria, Gram-negative bacteria, and mycobacteria provide an excellent therapeutic target for developing highly specific antimicrobials. Here, we report the synthesis of nine cholic acid (CA)-derived amphiphiles, where three hydroxyl groups of CA were tethered to dimethylamino pyridine and the C24-carboxyl group was conjugated with different alkyl chains. Structure-activity investigations revealed that amphiphile harboring a methyl group has antimicrobial activity against mycobacterial species.

Mycobacterium tuberculosis Transcription Factor EmbR Regulates the Expression of Key Virulence Factors That Aid in and Survival.

Mycobacterium tuberculosis encodes ~200 transcription factors that modulate gene expression under different microenvironments in the host. Even though high-throughput chromatin immunoprecipitation sequencing and transcriptome sequencing (RNA-seq) studies have identified the regulatory network for ~80% of transcription factors, many transcription factors remain uncharacterized. EmbR is one such transcription factor whose regulon and biological function are yet to be elucidated.

The Error-Prone Polymerase DnaE2 Mediates the Evolution of Antibiotic Resistance in Persister Mycobacterial Cells.

Applying antibiotics to susceptible bacterial cultures generates a minor population of persisters that remain susceptible to antibiotics but can endure them for extended periods. Recent reports suggest that antibiotic persisters (APs) of mycobacteria experience oxidative stress and develop resistance upon treatment with lethal doses of ciprofloxacin or rifampicin. However, the mechanisms driving the emergence of resistance remained unclear.

Development of a Highly Specific, Selective, and Sensitive Fluorescent Probe for Detection of Mycobacteria in Human Tissues.

Tuberculosis (TB), including extrapulmonary TB, is responsible for more than one million deaths in a year worldwide. Existing methods of mycobacteria detection have poor sensitivity, selectivity, and specificity, especially in human tissues. Herein, the synthesis of a cholic acid-derived fluorescent probe (P4) that can specifically stain the mycobacterium species is presented.

A hydrogel-based implantable multidrug antitubercular formulation outperforms oral delivery.

We present a non-immunogenic, injectable, low molecular weight, amphiphilic hydrogel-based drug delivery system (TB-Gel) that can entrap a cocktail of four front-line antitubercular drugs, isoniazid, rifampicin, pyrazinamide, and ethambutol. We showed that TB-Gel is more effective than oral delivery of the combination of four drugs in reducing the mycobacterial infection in mice. Results show that half the dose of chemotherapeutic drugs is sufficient to achieve a comparable therapeutic effect to that of oral delivery.

Redox homeostasis in Mycobacterium tuberculosis is modulated by a novel actinomycete-specific transcription factor.

Mycobacterium tuberculosis (Mtb) has evolved diverse cellular processes in response to the multiple stresses it encounters within the infected host. We explored available TnSeq datasets to identify transcription factors (TFs) that are essential for Mtb survival inside the host. The analysis identified a single TF, Rv1332 (AosR), conserved across actinomycetes with a so-far uncharacterized function.

Unique C-terminal extension and interactome of Mycobacterium tuberculosis GlmU impacts it's in vivo function and the survival of pathogen.

N-acetyl glucosamine-1-phosphate uridyltransferase (GlmU) is a bifunctional enzyme involved in the biosynthesis of Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). UDP-GlcNAc is a critical precursor for the synthesis of peptidoglycan and other cell wall components. The absence of a homolog in eukaryotes makes GlmU an attractive target for therapeutic intervention.

Compromised base excision repair pathway in Mycobacterium tuberculosis imparts superior adaptability in the host.

Tuberculosis caused by Mycobacterium tuberculosis (Mtb) is a significant public health concern, exacerbated by the emergence of drug-resistant TB. To combat the host's dynamic environment, Mtb encodes multiple DNA repair enzymes that play a critical role in maintaining genomic integrity. Mtb possesses a GC-rich genome, rendering it highly susceptible to cytosine deaminations, resulting in the occurrence of uracils in the DNA.

Deletion of serine/threonine-protein kinase pknL from Mycobacterium tuberculosis reduces the efficacy of isoniazid and ethambutol.

Serine/threonine-protein kinases in Mycobacterium tuberculosis (Mtb) form a preeminent regulatory system required to establish and maintain the infection in the host. Herein, we sought to decipher the biological role of PknL with the help of a gene replacement mutant RvΔpknL. Deletion of pknL results in the compromised growth under redox stress.

Mycobacterium tuberculosis Peptidyl Prolyl Isomerase A Interacts With Host Integrin Receptor to Exacerbate Disease Progression.

Attenuated intracellular survival of Mycobacterium tuberculosis (Mtb) secretory gene mutants exemplifies their role as virulence factors. Mtb peptidyl prolyl isomerase A (PPiA) assists in protein folding through cis/trans isomerization of prolyl bonds. Here, we show that PPiA abets Mtb survival and aids in disease progression by exploiting host-associated factors.

Deletion of Abates Reactivation of Latent Mycobacterium tuberculosis in Mice.

Eradication of tuberculosis (TB), caused by (), has been a challenge due to its uncanny ability to survive in a dormant state inside host granulomas for decades. rewires its metabolic and redox regulatory networks to survive in the hostile hypoxic and nutrient-limiting environment, facilitating the formation of drug-tolerant persisters. Previously, we showed that protein kinase G (PknG), a virulence factor required for lysosomal escape, aids in metabolic adaptation, thereby promoting the survival of nonreplicating mycobacteria.

Methylation of two-component response regulator MtrA in mycobacteria negatively modulates its DNA binding and transcriptional activation.

Post-translational modifications such as phosphorylation, nitrosylation, and pupylation modulate multiple cellular processes in Mycobacterium tuberculosis. While protein methylation at lysine and arginine residues is widespread in eukaryotes, to date only two methylated proteins in Mtb have been identified. Here, we report the identification of methylation at lysine and/or arginine residues in nine mycobacterial proteins.

Host sirtuin 2 as an immunotherapeutic target against tuberculosis.

() employs plethora of mechanisms to hijack the host defence machinery for its successful survival, proliferation and persistence. Here, we show that upregulates one of the key epigenetic modulators, NAD+ dependent histone deacetylase Sirtuin 2 (SIRT2), which upon infection translocate to the nucleus and deacetylates histone H3K18, thus modulating the host transcriptome leading to enhanced macrophage activation. Furthermore, in specific T cells, SIRT2 deacetylates NFκB-p65 at K310 to modulate T helper cell differentiation.

exploits host ATM kinase for survival advantage through SecA2 secretome.

() produces inflections in the host signaling networks to create a favorable milieu for survival. The virulent strain, caused double strand breaks (DSBs), whereas the non-virulent strain triggered single-stranded DNA generation. The effectors secreted by SecA2 pathway were essential and adequate for the genesis of DSBs.