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Self-poisoning of Mycobacterium tuberculosis by targeting GlgE in an alpha-glucan pathway.

ABSTRACT: New chemotherapeutics are urgently required to control the tuberculosis pandemic. We describe a new pathway from trehalose to alpha-glucan in Mycobacterium tuberculosis comprising four enzymatic steps mediated by TreS, Pep2, GlgE (which has been identified as a maltosyltransferase that uses maltose 1-phosphate) and GlgB. Using traditional and chemical reverse genetics, we show that GlgE inactivation causes rapid death of M. tuberculosis in vitro and in mice through a self-poisoning accumulation of maltose 1-phosphate. Poisoning elicits pleiotropic phosphosugar-induced stress responses promoted by a self-amplifying feedback loop where trehalose-forming enzymes are upregulated. Moreover, the pathway from trehalose to alpha-glucan exhibited a synthetic lethal interaction with the glucosyltransferase Rv3032, which is involved in biosynthesis of polymethylated alpha-glucans, because key enzymes in each pathway could not be simultaneously inactivated. The unique combination of maltose 1-phosphate toxicity and gene essentiality within a synthetic lethal pathway validates GlgE as a distinct potential drug target that exploits new synergistic mechanisms to induce death in M. tuberculosis.

SUBMITTER: Kalscheuer R

PROVIDER: S-EPMC3256575 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Self-poisoning of Mycobacterium tuberculosis by targeting GlgE in an alpha-glucan pathway.

Kalscheuer Rainer R Syson Karl K Veeraraghavan Usha U Weinrick Brian B Biermann Karolin E KE Liu Zhen Z Sacchettini James C JC Besra Gurdyal G Bornemann Stephen S Jacobs William R WR

Nature chemical biology 20100321 5

New chemotherapeutics are urgently required to control the tuberculosis pandemic. We describe a new pathway from trehalose to alpha-glucan in Mycobacterium tuberculosis comprising four enzymatic steps mediated by TreS, Pep2, GlgE (which has been identified as a maltosyltransferase that uses maltose 1-phosphate) and GlgB. Using traditional and chemical reverse genetics, we show that GlgE inactivation causes rapid death of M. tuberculosis in vitro and in mice through a self-poisoning accumulation ...[more]

PMID: 20305657

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Project description:UNLABELLED:Tumor necrosis factor alpha (TNF) plays a critical role in the control of Mycobacterium tuberculosis, in part by augmenting T cell responses through promoting macrophage phagolysosomal fusion (thereby optimizing CD4(+) T cell immunity by enhancing antigen presentation) and apoptosis (a process that can lead to cross-priming of CD8(+) T cells). M. tuberculosis can evade antituberculosis (anti-TB) immunity by inhibiting host cell TNF production via expression of specific mycobacterial components. We hypothesized that M. tuberculosis mutants with an increased capacity to induce host cell TNF production (TNF-enhancing mutants) and thus with enhanced immunogenicity can be useful for vaccine development. To identify mycobacterial genes that regulate host cell TNF production, we used a TNF reporter macrophage clone to screen an H37Rv M. tuberculosis cosmid library constructed in M. smegmatis The screen has identified a set of TNF-downregulating mycobacterial genes that, when deleted in H37Rv, generate TNF-enhancing mutants. Analysis of mutants disrupted for a subset of TNF-downregulating genes, annotated to code for triacylglycerol synthases and fatty acyl-coenzyme A (acyl-CoA) synthetase, enzymes that concern lipid biosynthesis and metabolism, has revealed that these strains can promote macrophage phagolysosomal fusion and apoptosis better than wild-type (WT) bacilli. Immunization of mice with the TNF-enhancing M. tuberculosis mutants elicits CD4(+) and CD8(+) T cell responses that are superior to those engendered by WT H37Rv. The results suggest that TNF-upregulating M. tuberculosis genes can be targeted to enhance the immunogenicity of mycobacterial strains that can serve as the substrates for the development of novel anti-TB vaccines. IMPORTANCE:One way to control tuberculosis (TB), which remains a major global public health burden, is by immunization with an effective vaccine. The efficacy of Mycobacterium bovis BCG, the only currently approved TB vaccine, is inconsistent. Tumor necrosis factor alpha (TNF) is a cytokine that plays an important role in controlling TB. M. tuberculosis, the causative agent of TB, can counter this TNF-based defense by decreasing host cell TNF production. This study identified M. tuberculosis genes that can mediate inhibition of TNF production by macrophage (an immune cell critical to the control of TB). We have knocked out a number of these genes to generate M. tuberculosis mutants that can enhance macrophage TNF production. Immunization with these mutants in mice triggered a T cell response stronger than that elicited by the parental bacillus. Since T cell immunity is pivotal in controlling M. tuberculosis, the TNF-enhancing mutants can be used to develop novel TB vaccines.

Dataset Information

Self-poisoning of Mycobacterium tuberculosis by targeting GlgE in an alpha-glucan pathway.

Publications

Self-poisoning of Mycobacterium tuberculosis by targeting GlgE in an alpha-glucan pathway.

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