Inhibition of toll-like receptor 2 (TLR-2)-mediated response in human alveolar epithelial cells by mycolic acids and Mycobacterium tuberculosis mce1 operon mutant.

In human lungs, the earliest encounter of Mycobacterium tuberculosis, the agent of tuberculosis, involves alveolar epithelial cells. Droplets expectorated by a patient with tuberculosis are likely to contain a mixed population of M. tuberculosis cells in different physiologic and metabolic states from the lung lesions of the patient.

Posttreatment reactivation of tuberculosis in mice caused by Mycobacterium tuberculosis disrupted in mce1R.

Background: The reactivation of tuberculosis arises in persons who are latently infected and in those who have been previously treated. The mechanism of the reactivation of tuberculosis in either situation is not well understood. A 13-gene mce1 operon of Mycobacterium tuberculosis was previously shown to be associated with latent infection in mice and may also play a role in reactivation.

Attenuation of Mycobacterium tuberculosis functionally disrupted in a fatty acyl-coenzyme A synthetase gene fadD5.

One key adaptation that Mycobacterium tuberculosis established to survive long term in vivo is a reliance on lipids as an energy source. M. tuberculosis H37Rv has 36 fadD genes annotated as putative fatty acyl-coenzyme A (CoA) synthetase genes, which encode enzymes that activate fatty acids for metabolism.

Attenuated activation of macrophage TLR9 by DNA from virulent mycobacteria.

Alveolar macrophages are the first line of host defence against mycobacteria, but an insufficient host response allows survival of bacteria within macrophages. We aimed to investigate the role of Toll-like receptor 9 (TLR9) activation in macrophage defence against mycobacteria. Human in vitro differentiated macrophages as well as human and mouse alveolar macrophages showed TLR9 mRNA and protein expression.

Mycobacterium tuberculosis strains disrupted in mce3 and mce4 operons are attenuated in mice.

The Mycobacterium tuberculosis genome contains four copies of an operon called mce (mce1-4). Previously we reported that M. tuberculosis disrupted in the mce1 operon is more virulent than wild-type M.

Enhanced mortality despite control of lung infection in mice aerogenically infected with a Mycobacterium tuberculosis mce1 operon mutant.

Mycobacterium tuberculosis causes a variety of host clinical outcomes. We previously showed that M. tuberculosis disrupted in an operon called mce1 proliferates unchecked in BALB/c mouse lungs.

Vaccine efficacy of an attenuated but persistent Mycobacterium tuberculosis cysH mutant.

The emergence of drug-resistant Mycobacterium tuberculosis strains and the widespread occurrence of AIDS demand newer and more efficient control of tuberculosis. The protective efficacy of the current Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccine is highly variable. Therefore, development of an effective new vaccine has gained momentum in recent years.

5'-Adenosinephosphosulphate reductase (CysH) protects Mycobacterium tuberculosis against free radicals during chronic infection phase in mice.

A major obstacle to tuberculosis (TB) control is the problem of chronic TB infection (CTBI). Here we report that 5'-adenosinephosphosulphate reductase (CysH), an enzyme essential for the production of reduced-sulphur-containing metabolites, is critical for Mycobacterium tuberculosis (Mtb) survival in chronic infection phase in mice. Disruption of cysH rendered Mtb auxotrophic for cysteine and methionine, and attenuated virulence in BALB/c and C57BL/6 immunocompetent mice.

A sulfated metabolite produced by stf3 negatively regulates the virulence of Mycobacterium tuberculosis.

Sulfated molecules have been shown to modulate isotypic interactions between cells of metazoans and heterotypic interactions between bacterial pathogens or symbionts and their eukaryotic host cells. Mycobacterium tuberculosis, the causative agent of tuberculosis, produces sulfated molecules that have eluded functional characterization for decades. We demonstrate here that a previously uncharacterized sulfated molecule, termed S881, is localized to the outer envelope of M.

Identification, function and structure of the mycobacterial sulfotransferase that initiates sulfolipid-1 biosynthesis.

Sulfolipid-1 (SL-1) is an abundant sulfated glycolipid and potential virulence factor found in Mycobacterium tuberculosis. SL-1 consists of a trehalose-2-sulfate (T2S) disaccharide elaborated with four lipids. We identified and characterized a conserved mycobacterial sulfotransferase, Stf0, which generates the T2S moiety of SL-1.

Trehalose is required for growth of Mycobacterium smegmatis.

Mycobacteria contain high levels of the disaccharide trehalose in free form as well as within various immunologically relevant glycolipids such as cord factor and sulfolipid-1. By contrast, most bacteria use trehalose solely as a general osmoprotectant or thermoprotectant. Mycobacterium tuberculosis and Mycobacterium smegmatis possess three pathways for the synthesis of trehalose.

Discovery of sulfated metabolites in mycobacteria with a genetic and mass spectrometric approach.

The study of the metabolome presents numerous challenges, first among them being the cataloging of its constituents. A step in this direction will be the development of tools to identify metabolites that share common structural features. The importance of sulfated molecules in cell-cell communication motivated us to develop a rapid two-step method for identifying these metabolites in microorganisms, particularly in pathogenic mycobacteria.

5'-adenosinephosphosulfate lies at a metabolic branch point in mycobacteria.

Bacterial sulfate assimilation pathways provide for activation of inorganic sulfur for the biosynthesis of cysteine and methionine, through either adenosine 5'-phosphosulfate (APS) or 3'-phosphoadenosine 5'-phosphosulfate (PAPS) as intermediates. PAPS is also the substrate for sulfotransferases that produce sulfolipids, putative virulence factors, in Mycobacterium tuberculosis such as SL-1. In this report, genetic complementation using Escherichia coli mutant strains deficient in APS kinase and PAPS reductase was used to define the M.

Mechanisms of pyrazinamide resistance in mycobacteria: importance of lack of uptake in addition to lack of pyrazinamidase activity.

Mycobacteria are known to acquire resistance to the antituberculous drug pyrazinamide (PZA) through mutations in the gene encoding pyrazinamidase (PZase), an enzyme that converts PZA into pyrazinoic acid, the presumed active form of PZA against bacteria. Additional mechanisms of resistance to the drug are known to exist but have not been fully investigated. Among these is the non-uptake of the pro-drug, a possibility investigated in the present study.