Mechanistic and functional insights into fatty acid activation in Mycobacterium tuberculosis

National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India.
Nature Chemical Biology (Impact Factor: 12.95). 01/2009; 5(3):166-173. DOI: 10.1038/nchembio.143

ABSTRACT The recent discovery of fatty acyl-AMP ligases (FAALs) in Mycobacterium tuberculosis (Mtb) provided a new perspective of fatty acid activation. These proteins convert fatty acids to the corresponding adenylates, which are intermediates of acyl-CoA–synthesizing fatty acyl-CoA ligases (FACLs). Presently, it is not evident how obligate pathogens such as Mtb have evolved such new themes of functional versatility and whether the activation of fatty acids to acyladenylates could indeed be a general mechanism. Here, based on elucidation of the first structure of an FAAL protein and by generating loss-of-function and gain-of-function mutants that interconvert FAAL and FACL activities, we demonstrate that an insertion motif dictates formation of acyladenylate. Because FAALs in Mtb are crucial nodes in the biosynthetic network of virulent lipids, inhibitors directed against these proteins provide a unique multipronged approach to simultaneously disrupting several pathways.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Regulator of Antimicrobial-Assisted Survival), encoded by Rv1219c in Mycobacterium tuberculosis and bcg_1279c in Mycobacterium bovis BCG, plays an important role in mycobacterial survival in prolonged stationary phase and during murine infection. Here we demonstrate that long chain acyl-CoA derivatives (oleoyl-CoA and to lesser extent palmitoyl-CoA) modulate RaaS binding to DNA and the expression of the genes downstream that encode ATP-dependent efflux pumps. Moreover, exogenously added oleic acid influenced RaaS-mediated mycobacterial improvement of survival and the expression of the RaaS regulon. Our data suggest that long chain acyl-CoA derivatives serve as biological indicators of the bacterial metabolic state. Dysregulation of efflux pumps can be used eliminate non-growing mycobacteria.
    The Journal of biological chemistry. 07/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract Over a decade ago, the analysis of the complete sequence of the genome of the human pathogen Mycobacterium tuberculosis revealed an unexpectedly high number of open reading frames encoding proteins with homology to polyketide synthases (PKSs). PKSs form a large family of fascinating multifunctional enzymes best known for their involvement in the biosynthesis of hundreds of polyketide natural products with diverse biological activities. The surprising polyketide biosynthesis capacity of M. tuberculosis has been investigated since its initial inference from genome analysis. This investigation has been based on the genes found in M. tuberculosis or their orthologs found in other Mycobacterium species. Today, the majority of the PKS-encoding genes of M. tuberculosis have been linked to specific biosynthetic pathways required for the production of unique lipids or glycolipid conjugates that are critical for virulence and/or components of the extraordinarily complex mycobacterial cell envelope. This review provides a synopsis of the most relevant studies in the field and an overview of our current understanding of the involvement of PKSs and several other polyketide production pathway-associated proteins in critical biosynthetic pathways of M. tuberculosis and other mycobacteria. In addition, the most relevant studies on PKS-containing biosynthetic pathways leading to production of metabolites from mycobacteria other than M. tuberculosis are reviewed.
    Critical Reviews in Biochemistry and Molecular Biology 03/2014; · 5.58 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Tuberculosis is considered to be one of the world's deadliest disease with 2 million deaths each year. The need for new antitubercular drugs is further exacerbated by the emergence of drug-resistance strains. Despite multiple recent efforts, the majority of the hits discovered by traditional target-based screening showed low efficiency in vivo. Therefore, there is heightened demand for whole-cell based approaches directly using host-pathogen systems. The phenotypic host-pathogen assay described here is based on the monitoring of GFP-expressing Mycobacterium marinum during infection of the amoeba Acanthamoeba castellanii. The assay showed straight-forward medium-throughput scalability, robustness and ease of manipulation, demonstrating its qualities as an efficient compound screening system. Validation with a series of known antitubercular compounds highlighted the advantages of the assay in comparison to previously published macrophage-Mycobacterium tuberculosis-based screening systems. Combination with secondary growth assays based on either GFP-expressing D. discoideum or M. marinum allowed us to further fine-tune compound characterization by distinguishing and quantifying growth inhibition, cytotoxic properties and antibiotic activities of the compounds. The simple and relatively low cost system described here is most suitable to detect anti-infective compounds, whether they present antibiotic activities or not, in which case they might exert anti-virulence or host defense boosting activities, both of which are largely overlooked by classical screening approaches.
    PLoS ONE 01/2014; 9(1):e87834. · 3.53 Impact Factor

Full-text (2 Sources)

Available from
Jun 2, 2014