Dataset Information

Mycobacterium tuberculosis LipE Has a Lipase/Esterase Activity and Is Important for Intracellular Growth and In Vivo Infection.

ABSTRACT: Mycobacterium tuberculosis Rv3775 (LipE) was annotated as a putative lipase. However, its lipase activity has never been characterized, and its precise role in tuberculosis (TB) pathogenesis has not been thoroughly studied to date. We overexpressed and purified the recombinant LipE (rLipE) protein and demonstrated that LipE has a lipase/esterase activity. rLipE prefers medium-chain ester substrates, with the maximal activity on hexanoate. Its activity is the highest at 40°C and pH?9. We determined that rLipE hydrolyzes trioctanoate. Using site-directed mutagenesis, we confirmed that the predicted putative activity triad residues Ser97, Gly342, and His363 are essential for the lipase activity of rLipE. The expression of the lipE gene was induced under stressed conditions mimicking M. tuberculosis' intracellular niche. The gene-disrupting mutation of lipE led to significantly reduced bacterial growth inside THP-1 cells and human peripheral blood mononuclear cell-derived macrophages and attenuated M. tuberculosis infection in mice (with ?8-fold bacterial load reduction in mouse lungs). Our data suggest that LipE functions as a lipase and is important for M. tuberculosis intracellular growth and in vivo infection.

SUBMITTER: Yang D

PROVIDER: S-EPMC6921666 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Mycobacterium tuberculosis LipE Has a Lipase/Esterase Activity and Is Important for Intracellular Growth and In Vivo Infection.

Yang Dong D Li Shaoji S Stabenow Jennifer J Zalduondo Lillian L Kong Ying Y

Infection and immunity 20191217 1

Mycobacterium tuberculosis Rv3775 (LipE) was annotated as a putative lipase. However, its lipase activity has never been characterized, and its precise role in tuberculosis (TB) pathogenesis has not been thoroughly studied to date. We overexpressed and purified the recombinant LipE (rLipE) protein and demonstrated that LipE has a lipase/esterase activity. rLipE prefers medium-chain ester substrates, with the maximal activity on hexanoate. Its activity is the highest at 40°C and pH 9. We d ...[more]

PMID: 31636137

Similar Datasets

Project description:We previously reported that Mycobacterium tuberculosis triggers macrophage necrosis in vitro at a threshold intracellular load of ~25 bacilli. This suggests a model for tuberculosis where bacilli invading lung macrophages at low multiplicity of infection proliferate to burst size and spread to naïve phagocytes for repeated cycles of replication and cytolysis. The current study evaluated that model in vivo, an environment significantly more complex than in vitro culture. In the lungs of mice infected with M. tuberculosis by aerosol we observed three distinct mononuclear leukocyte populations (CD11b(-) CD11c(+/hi), CD11b(+/lo) CD11c(lo/-), CD11b(+/hi) CD11c(+/hi)) and neutrophils hosting bacilli. Four weeks after aerosol challenge, CD11b(+/hi) CD11c(+/hi) mononuclear cells and neutrophils were the predominant hosts for M. tuberculosis while CD11b(+/lo) CD11c(lo/-) cells assumed that role by ten weeks. Alveolar macrophages (CD11b(-) CD11c(+/hi)) were a minority infected cell type at both time points. The burst size model predicts that individual lung phagocytes would harbor a range of bacillary loads with most containing few bacilli, a smaller proportion containing many bacilli, and few or none exceeding a burst size load. Bacterial load per cell was enumerated in lung monocytic cells and neutrophils at time points after aerosol challenge of wild type and interferon-γ null mice. The resulting data fulfilled those predictions, suggesting a median in vivo burst size in the range of 20 to 40 bacilli for monocytic cells. Most heavily burdened monocytic cells were nonviable, with morphological features similar to those observed after high multiplicity challenge in vitro: nuclear condensation without fragmentation and disintegration of cell membranes without apoptotic vesicle formation. Neutrophils had a narrow range and lower peak bacillary burden than monocytic cells and some exhibited cell death with release of extracellular neutrophil traps. Our studies suggest that burst size cytolysis is a major cause of infection-induced mononuclear cell death in tuberculosis.

Project description:Mycobacterium tuberculosis remains a significant threat to global health. Macrophages are the host cell for M. tuberculosis infection, and although bacteria are able to replicate intracellularly under certain conditions, it is also clear that macrophages are capable of killing M. tuberculosis if appropriately activated. The outcome of infection is determined at least in part by the host-pathogen interaction within the macrophage; however, we lack a complete understanding of which host pathways are critical for bacterial survival and replication. To add to our understanding of the molecular processes involved in intracellular infection, we performed a chemical screen using a high-content microscopic assay to identify small molecules that restrict mycobacterial growth in macrophages by targeting host functions and pathways. The identified host-targeted inhibitors restrict bacterial growth exclusively in the context of macrophage infection and predominantly fall into five categories: G-protein coupled receptor modulators, ion channel inhibitors, membrane transport proteins, anti-inflammatories, and kinase modulators. We found that fluoxetine, a selective serotonin reuptake inhibitor, enhances secretion of pro-inflammatory cytokine TNF-α and induces autophagy in infected macrophages, and gefitinib, an inhibitor of the Epidermal Growth Factor Receptor (EGFR), also activates autophagy and restricts growth. We demonstrate that during infection signaling through EGFR activates a p38 MAPK signaling pathway that prevents macrophages from effectively responding to infection. Inhibition of this pathway using gefitinib during in vivo infection reduces growth of M. tuberculosis in the lungs of infected mice. Our results support the concept that screening for inhibitors using intracellular models results in the identification of tool compounds for probing pathways during in vivo infection and may also result in the identification of new anti-tuberculosis agents that work by modulating host pathways. Given the existing experience with some of our identified compounds for other therapeutic indications, further clinically-directed study of these compounds is merited.

Dataset Information

Mycobacterium tuberculosis LipE Has a Lipase/Esterase Activity and Is Important for Intracellular Growth and In Vivo Infection.

Publications

<i>Mycobacterium tuberculosis</i> LipE Has a Lipase/Esterase Activity and Is Important for Intracellular Growth and <i>In Vivo</i> Infection.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets