Lipid composition and transcriptional response of Mycobacterium tuberculosis grown under iron-limitation in continuous culture: identification of a novel wax ester

Bacon, Joanna; Dover, Lynn G.; Hatch, Kim A.; Zhang, Yi; Gomes, Jessica M.; Kendall, Sharon L.; Wernisch, Lorenz; Stoker, Neil G.; Butcher, Philip D.; Besra, Gurdyal S.; Marsh, Philip

doi:10.1099/mic.0.2006/004317-0

Cited by 83 publications

(55 citation statements)

References 39 publications

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“…These data build on evidence that suggest that Mtb actively modulates its lipid composition in response to the changing microenvironment. Thus, this lipidomic approach provides a working platform for the analyses of more-refi ned in vitro growth culture models that incorporate defi ned stress factors ( 19,(41)(42)(43)(44)(45)(46)(47)(48), as well as comparative analyses of lipid profi les from Mtb cells isolated from infected tissues. Such in vivo studies would provide valuable insight into the metabolism and physiology of Mtb .…”

Section: Discussionmentioning

confidence: 99%

“…The Mtb LipidDB does not take into consideration mass shifts due to oxidation or degradation of lipids, which may be keys to a complete understanding of Mtb lipid metabolism. Only well-defi ned lipids were included in the database; a novel and recently described wax ester lipid identifi ed from Mtb cultivated under iron-limiting conditions was not included because of its partial structural elucidation ( 48 ). Biosynthetic lipid intermediates, such as phosphatidic acid, acyl-CoA, and sugar-linked decaprenol phosphates, were also not included in the database.…”

Section: Discussionmentioning

confidence: 99%

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Lipidomic analyses of Mycobacterium tuberculosis based on accurate mass measurements and the novel “Mtb LipidDB”

Sartain

Dick

Rithner

et al. 2011

Journal of Lipid Research

130

137

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pathogenesis ( 4-6 ). The abundance and biological importance of the Mtb lipids has resulted in extensive and elegant studies to elucidate their structures and functions ( 1-3 ). In many cases, the lipids of Mtb are unique to this pathogen or shared only with other members of this genus.Earlier studies demonstrate variability in lipid profi les among different strains of Mtb ( 7-11 ) and that minor variations in the structure of individual lipids can occur with changes in the growth environment (12)(13)(14)(15)(16)(17)(18)(19)(20). However, targeted and nontargeted assays that monitor changes in Mtb lipid profi les are generally performed by traditional TLC-based methods ( 21 ), and global lipidomics analyses in Mtb have been restricted due to limits in the technology to detect and rapidly identify a large number of lipids in a single experiment. Two-dimensional NMR was recently applied to examine global mycobacterial lipid profi les, and this approach allowed for the identifi cation of key lipid differences in 13 C-enriched cellular extracts ( 22 ). Although this approach easily detects changes in lipid patterns, it is limited by the complexity of the NMR spectra and the overlapping chemical properties of many lipids. Alternatively, MS-based lipidomic strategies allowing simultaneous detection, identifi cation, and quantifi cation of structurally diverse lipid components of Mtb also were evaluated. Leavell and Leary ( 23 ) developed an algorithm to analyze high-resolution Fourier transform-ion cyclotron Abstract The cellular envelope of Mycobacterium tuberculosis is highly distinctive and harbors a wealth of unique lipids possessing diverse structural and biological properties. However, the ability to conduct global analyses on the full complement of M. tuberculosis lipids has been missing from the repertoire of tools applied to the study of this important pathogen. We have established methods to detect and identify lipids from all major M. tuberculosis lipid classes through LC/MS lipid profi ling. This methodology is based on efficient chromatographic separation and automated ion identifi cation through accurate mass determination and searching of a newly created database ( Mtb LipidDB) that contains 2,512 lipid entities. We demonstrate the sensitive detection of molecules representing all known classes of M. tuberculosis lipids from a single crude extract. We also demonstrate the ability of this methodology to identify changes in lipid content in response to cellular growth phases. This work provides a customizable framework and resource to facilitate future studies on mycobacterial lipid biosynthesis and

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Lipidomic analyses of Mycobacterium tuberculosis based on accurate mass measurements and the novel “Mtb LipidDB”

Sartain

Dick

Rithner

et al. 2011

Journal of Lipid Research

130

137

View full text Add to dashboard Cite

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“…in resting or activated mouse macrophages, and in vivo, using the mouse lung model of infection. The results of these studies have recently been reviewed (2,29). The complete gene expression profile of M. tuberculosis growing in mouse macrophages was defined by Schnappinger et al (52) and more recently by Rachman et al (44).…”

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confidence: 99%

Global Transcriptional Profile of Mycobacterium tuberculosis during THP-1 Human Macrophage Infection

Fontán¹,

Aris²,

Ghanny³

et al. 2008

Infect Immun

161

179

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Mycobacterium tuberculosis is the causative agent of tuberculosis, a disease that together with human immunodeficiency virus (HIV) and malaria, is one of the main causes of mortality due to an infectious agent (31). According to the WHO, onethird of the world's population is infected asymptomatically with M. tuberculosis, representing a large reservoir of infection (11). To block further transmission and reactivation in the already-infected population, it is necessary to develop improved intervention strategies that require a better understanding of the host-pathogen interaction.Infection of a mammalian host by M. tuberculosis usually occurs by the aerosol route, and the lung is typically the principal organ affected. The bacteria initially reside in alveolar macrophages (18), where they are usually able to replicate. In order to identify M. tuberculosis components that may be responsible for successful bacterial intracellular survival, many individual genes whose expression levels are up regulated by the microorganism inside the phagosome have been analyzed (16). DNA microarray technology has made it possible to analyze the M. tuberculosis global transcriptional response to different stimuli. Experiments have been carried out in broth culture, using conditions that may mimic the macrophage environment (i.e., low pH, cell wall stress, starvation, hypoxia, heat shock, etc.) in resting or activated mouse macrophages, and in vivo, using the mouse lung model of infection. The results of these studies have recently been reviewed (2, 29). The complete gene expression profile of M. tuberculosis growing in mouse macrophages was defined by Schnappinger et al. tuberculosis has to face a DNA-and cell envelope-damaging environment that is rich in fatty acid and deficient in iron. The transcriptional profile of M. tuberculosis infecting human lungs indicates that the bacteria regulate genes involved in the evasion of the immune system (45). A similar analysis of M. tuberculosis in human monocyte-derived macrophages after 7 days of infection suggested the relevance of bacterial genes involved in transcriptional regulation (8). In addition, M. tuberculosis genes that are essential for the survival of bacteria in mouse macrophages and in mouse lungs have been identified by using the transposon site hybridization technique (46) and designer arrays for defined mutant analysis (30).In this work, we analyzed the gene expression profile of M. tuberculosis strain H37Rv infecting human macrophage-like THP-1 cells. These cells treated with phorbol-myristate acetate (PMA) differentiate into mature macrophages, providing a good model for analyzing the interaction of M. tuberculosis with primary macrophages in terms of receptor expression, bacterial uptake, survival, and replication (59). It has been demonstrated that after infection with M. tuberculosis, THP-1 cells, in a manner similar to that of monocyte-derived macrophages, produce low levels of oxygen radicals and do not produce nitric oxide (55). Moreover, THP-1 cells are a good mod...

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“…Previously published microarray data suggest that Rv0485 is upregulated upon macrophage infection and in iron-limited media (3,46). This may suggest that genes usually activated by Rv0485 are involved in inducing the typical macrophage response to infection.…”

Section: Discussionmentioning

confidence: 91%

The Transcriptional Regulator Rv0485 Modulates the Expression of a pe and ppe Gene Pair and Is Required for Mycobacterium tuberculosis Virulence

et al. 2009

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The pe and ppe genes are unique to mycobacteria and are widely speculated to play a role in tuberculosis pathogenesis. However, little is known about how expression of these genes is controlled. Elucidating the regulatory control of genes found exclusively in mycobacteria, such as the pe and ppe gene families, may be key to understanding the success of this pathogen. In this study, we used a transposon mutagenesis approach to elucidate pe and ppe regulation. This resulted in the identification of Rv0485, a previously uncharacterized transcriptional regulator. Microarray and quantitative real-time PCR analysis confirmed that disruption of Rv0485 reduced the expression of the pe13 and ppe18 gene pair (Rv1195 and Rv1196), defined the Rv0485 regulon, and emphasized the lack of global regulation of pe and ppe genes. The in vivo phenotype of the Rv0485 transposon mutant strain (Rv0485::Tn) was investigated in the mouse model, where it was demonstrated that the mutation has minimal effect on bacterial organ burden. Despite this, disruption of Rv0485 allowed mice to survive for significantly longer, with substantially reduced lung pathology in comparison with mice infected with wild-type Mycobacterium tuberculosis. Infection of immune-deficient SCID mice with the Rv0485::Tn strain also resulted in extended survival times, suggesting that Rv0485 plays a role in modulation of innate immune responses. This is further supported by the finding that disruption of Rv0485 resulted in reduced secretion of proinflammatory cytokines by infected murine macrophages. In summary, we have demonstrated that disruption of a previously uncharacterized transcriptional regulator, Rv0485, results in reduced expression of pe13 and ppe18 and attenuation of M. tuberculosis virulence.

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Lipid composition and transcriptional response of Mycobacterium tuberculosis grown under iron-limitation in continuous culture: identification of a novel wax ester

Cited by 83 publications

References 39 publications

Lipidomic analyses of Mycobacterium tuberculosis based on accurate mass measurements and the novel “Mtb LipidDB”

Lipidomic analyses of Mycobacterium tuberculosis based on accurate mass measurements and the novel “Mtb LipidDB”

Global Transcriptional Profile of Mycobacterium tuberculosis during THP-1 Human Macrophage Infection

The Transcriptional Regulator Rv0485 Modulates the Expression of a pe and ppe Gene Pair and Is Required for Mycobacterium tuberculosis Virulence

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