Altered serine metabolism promotes drug tolerance in via a WhiB7-mediated adaptive stress response.

is an emerging opportunistic pathogen responsible for chronic lung diseases, especially in patients with cystic fibrosis. Treatment failure of infections is primarily associated with intrinsic or acquired antibiotic resistance. However, there is growing evidence that antibiotic tolerance, i.

Druggable redox pathways against Mycobacterium abscessus in cystic fibrosis patient-derived airway organoids.

Mycobacterium abscessus (Mabs) drives life-shortening mortality in cystic fibrosis (CF) patients, primarily because of its resistance to chemotherapeutic agents. To date, our knowledge on the host and bacterial determinants driving Mabs pathology in CF patient lung remains rudimentary. Here, we used human airway organoids (AOs) microinjected with smooth (S) or rough (R-)Mabs to evaluate bacteria fitness, host responses to infection, and new treatment efficacy.

In vivo imaging of MmpL transporters reveals distinct subcellular locations for export of mycolic acids and non-essential trehalose polyphleates in the mycobacterial outer membrane.

The mycobacterial cell envelope consists of a typical plasma membrane, surrounded by a complex cell wall and a lipid-rich outer membrane. The biogenesis of this multilayer structure is a tightly regulated process requiring the coordinated synthesis and assembly of all its constituents. Mycobacteria grow by polar extension and recent studies showed that cell envelope incorporation of mycolic acids, the major constituent of the cell wall and outer membrane, is coordinated with peptidoglycan biosynthesis at the cell poles.

De novo synthesized polyunsaturated fatty acids operate as both host immunomodulators and nutrients for .

Successful control of (Mtb) infection by macrophages relies on immunometabolic reprogramming, where the role of fatty acids (FAs) remains poorly understood. Recent studies unraveled Mtb's capacity to acquire saturated and monounsaturated FAs via the Mce1 importer. However, upon activation, macrophages produce polyunsaturated fatty acids (PUFAs), mammal-specific FAs mediating the generation of immunomodulatory eicosanoids.

Rv0180c contributes to Mycobacterium tuberculosis cell shape and to infectivity in mice and macrophages.

Mycobacterium tuberculosis, the main causative agent of human tuberculosis, is transmitted from person to person via small droplets containing very few bacteria. Optimizing the chance to seed in the lungs is therefore a major adaptation to favor survival and dissemination in the human population. Here we used TnSeq to identify genes important for the early events leading to bacterial seeding in the lungs.

Mycobacteria-host interactions in human bronchiolar airway organoids.

Respiratory infections remain a major global health concern. Tuberculosis is one of the top 10 causes of death worldwide, while infections with Non-Tuberculous Mycobacteria are rising globally. Recent advances in human tissue modeling offer a unique opportunity to grow different human "organs" in vitro, including the human airway, that faithfully recapitulates lung architecture and function.

Phosphopantetheinyl transferase binding and inhibition by amidino-urea and hydroxypyrimidinethione compounds.

Owing to their role in activating enzymes essential for bacterial viability and pathogenicity, phosphopantetheinyl transferases represent novel and attractive drug targets. In this work, we examined the inhibitory effect of the aminido-urea 8918 compound against the phosphopantetheinyl transferases PptAb from Mycobacterium abscessus and PcpS from Pseudomonas aeruginosa, two pathogenic bacteria associated with cystic fibrosis and bronchiectasis, respectively. Compound 8918 exhibits inhibitory activity against PptAb but displays no activity against PcpS in vitro, while no antimicrobial activity against Mycobacterium abscessus or Pseudomonas aeruginosa could be detected.

Parallel in vivo experimental evolution reveals that increased stress resistance was key for the emergence of persistent tuberculosis bacilli.

Pathogenomic evidence suggests that Mycobacterium tuberculosis (MTB) evolved from an environmental ancestor similar to Mycobacterium canettii, a rare human pathogen. Although the adaptations responsible for this transition are poorly characterized, the ability to persist in humans seems to be important. We set out to identify the adaptations contributing to the evolution of persistence in MTB.

and BCG Moreau Fumarate Reductase Operons Produce Different Polypeptides That May Be Related to Non-canonical Functions.

Tuberculosis is a world widespread disease, caused by (). Although considered an obligate aerobe, this organism can resist life-limiting conditions such as microaerophily mainly due to its set of enzymes responsible for energy production and coenzyme restoration under these conditions. One of these enzymes is fumarate reductase, an heterotetrameric complex composed of a catalytic (FrdA), an iron-sulfur cluster (FrdB) and two transmembrane (FrdC and FrdD) subunits involved in anaerobic respiration and important for the maintenance of membrane potential.

Molecular Basis for Extender Unit Specificity of Mycobacterial Polyketide Synthases.

is the causative agent of the tuberculosis disease, which claims more human lives each year than any other bacterial pathogen. and other mycobacterial pathogens have developed a range of unique features that enhance their virulence and promote their survival in the human host. Among these features lies the particular cell envelope with high lipid content, which plays a substantial role in mycobacterial pathogenicity.

Phthiocerol Dimycocerosates From Increase the Membrane Activity of Bacterial Effectors and Host Receptors.

() synthesizes a variety of atypical lipids that are exposed at the cell surface and help the bacterium infect macrophages and escape elimination by the cell's immune responses. In the present study, we investigate the mechanism of action of one family of hydrophobic lipids, the phthiocerol dimycocerosates (DIM/PDIM), major lipid virulence factors. DIM are transferred from the envelope of to host membranes during infection.

Mycobacterium bovis BCG moreau is naturally deficient in homologous recombination.

The ability to perform genetic manipulation of mycobacteria is important for characterization of gene function. Homologous recombination-based protocols are frequently used for reverse genetics studies with mycobacteria. It is known that Mycobacteriumbovis BCG Russia, closely related to M.

The final assembly of trehalose polyphleates takes place within the outer layer of the mycobacterial cell envelope.

Trehalose polyphleates (TPP) are high-molecular-weight, surface-exposed glycolipids present in a broad range of nontuberculous mycobacteria. These compounds consist of a trehalose core bearing polyunsaturated fatty acyl substituents (called phleic acids) and a straight-chain fatty acid residue and share a common basic structure with trehalose-based glycolipids produced by TPP production starts in the cytosol with the formation of a diacyltrehalose intermediate. An acyltransferase, called PE, subsequently catalyzes the transfer of phleic acids onto diacyltrehalose to form TPP, and an MmpL transporter promotes the export of TPP or its precursor across the plasma membrane.

Efficient method for targeted gene disruption by homologous recombination in Mycobacterium avium subspecie paratuberculosis.

Targeted gene disruption by homologous recombination, has been widely used in mycobacterium species to understand the genetic basis of virulence and persistence in the host and to develop efficacious potential live vaccines. However, in slow growing pathogenic mycobacteria as Mycobacterium avium subsp paratuberculosis (MAP), these methods have been inefficient, in part due to the low frequency of legitimate homologous recombination. Another feature of mycobacteria is the low efficiency of transformation; therefore, some years ago, a phage-mediated transduction process was developed to introduce DNA into mycobacteria.

The Lipid Virulence Factors of Exert Multilayered Control over Autophagy-Related Pathways in Infected Human Macrophages.

Autophagy is an important innate immune defense mechanism that controls () growth inside macrophages. Autophagy machinery targets -containing phagosomes via xenophagy after damage to the phagosomal membrane due to the Type VII secretion system Esx-1 or via LC3-associated phagocytosis without phagosomal damage. Conversely, restricts autophagy-related pathways via the production of various bacterial protein factors.

Conformational flexibility of coenzyme A and its impact on the post-translational modification of acyl carrier proteins by 4'-phosphopantetheinyl transferases.

One central question surrounding the biosynthesis of fatty acids and polyketide-derived natural products is how the 4'-phosphopantetheinyl transferase (PPTase) interrogates the essential acyl carrier protein (ACP) domain to fulfill the initial activation step. The triggering factor of this study was the lack of structural information on PPTases at physiological pH, which could bias our comprehension of the mechanism of action of these important enzymes. Structural and functional studies on the family II PPTase PptAb of Mycobacterium abscessus show that pH has a profound effect on the coordination of metal ions and on the conformation of endogenously bound coenzyme A (CoA).

CR3 Engaged by PGL-I Triggers Syk-Calcineurin-NFATc to Rewire the Innate Immune Response in Leprosy.

, the causative agent of leprosy, is unique amongst human pathogens in its capacity to produce the virulence factor phenolic glycolipid (PGL)-I. In addition to mediating bacterial tropism for neurons, PGL-I interacts with Complement Receptor (CR)3 on macrophages (MPs) to promote infection. We demonstrate here that PGL-I binding to CR3 also enhances bacterial invasion of both polymorphonuclear neutrophils (PMNs) and dendritic cells (DCs).

Preclinical assessment of a new live attenuated Mycobacterium tuberculosis Beijing-based vaccine for tuberculosis.

Tuberculosis still claims more lives than any other pathogen, and a vaccine better than BCG is urgently needed. One of the challenges for novel TB vaccines is to protect against all Mycobacterium tuberculosis lineages, including the most virulent ones, such as the Beijing lineage. Here we developed a live attenuated M.

The conical shape of DIM lipids promotes infection of macrophages.

Phthiocerol dimycocerosate (DIM) is a major virulence factor of the pathogen (). While this lipid promotes the entry of into macrophages, which occurs via phagocytosis, its molecular mechanism of action is unknown. Here, we combined biophysical, cell biology, and modeling approaches to reveal the molecular mechanism of DIM action on macrophage membranes leading to the first step of infection.

PGL I expression in live bacteria allows activation of a CD206/PPARγ cross-talk that may contribute to successful Mycobacterium leprae colonization of peripheral nerves.

Mycobacterium leprae, an obligate intracellular bacillus, infects Schwann cells (SCs), leading to peripheral nerve damage, the most severe leprosy symptom. In the present study, we revisited the involvement of phenolic glycolipid I (PGL I), an abundant, private, surface M. leprae molecule, in M.

Mycobacterial Phenolic Glycolipids Selectively Disable TRIF-Dependent TLR4 Signaling in Macrophages.

Phenolic glycolipids (PGLs) are cell wall components of a subset of pathogenic mycobacteria, with immunomodulatory properties. Here, we show that in addition, PGLs exert antibactericidal activity by limiting the production of nitric oxide synthase (iNOS) in mycobacteria-infected macrophages. PGL-mediated downregulation of iNOS was complement receptor 3-dependent and comparably induced by bacterial and purified PGLs.

Protein O-mannosylation deficiency increases LprG-associated lipoarabinomannan release by Mycobacterium tuberculosis and enhances the TLR2-associated inflammatory response.

Protein O-mannosylation is crucial for the biology of Mycobacterium tuberculosis but the key mannosylated protein(s) involved and its(their) underlying function(s) remain unknown. Here, we demonstrated that the M. tuberculosis mutant (Δpmt) deficient for protein O-mannosylation exhibits enhanced release of lipoarabinomannan (LAM) in a complex with LprG, a lipoprotein required for LAM translocation to the cell surface.

ESX-1 and phthiocerol dimycocerosates of Mycobacterium tuberculosis act in concert to cause phagosomal rupture and host cell apoptosis.

Although phthiocerol dimycocerosates (DIM) are major virulence factors of Mycobacterium tuberculosis (Mtb), the causative agent of human tuberculosis, little is known about their mechanism of action. Localized in the outer membrane of mycobacterial pathogens, DIM are predicted to interact with host cell membranes. Interaction with eukaryotic membranes is a property shared with another virulence factor of Mtb, the early secretory antigenic target EsxA (also known as ESAT-6).