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Expedient synthesis of the heneicosasaccharyl mannose capped arabinomannan of the Mycobacterium tuberculosis cellular envelope by glycosyl carbonate donors.

ABSTRACT: The global incidence of tuberculosis is increasing at an alarming rate, and Mycobacterium tuberculosis (Mtb) is the causative agent for tuberculosis, a disease with high mortality. Lipoarabinomannan (LAM) is one of the major components of the Mtb cellular envelope and is an attractive scaffold for developing anti-tubercular drugs, vaccines and diagnostics. Herein, a highly convergent strategy is developed to synthesize heneicosasaccharyl arabinomannan for the first time. The arabinomannan synthesized in this endeavour has several 1,2-trans or ?-Araf linkages and three 1,2-cis or ?-Araf linkages end capped with 1,2-trans or ?-Manp linkages. All the key glycosidations were performed with alkynyl carbonate glycosyl donors under [Au]/[Ag] catalysis conditions, which gave excellent yields and stereoselectivity even for the reactions between complex and branched oligosaccharides. The resultant allyl oligosaccharide was globally deprotected to obtain the heneicosasaccharyl arabinomannan as a propyl glycoside. In summary, heneicosasaccharyl mannose capped arabinomannan synthesis was achieved in 56 steps with 0.016% overall yield.

SUBMITTER: Islam M

PROVIDER: S-EPMC5398307 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Expedient synthesis of the heneicosasaccharyl mannose capped arabinomannan of the <i>Mycobacterium tuberculosis</i> cellular envelope by glycosyl carbonate donors.

Islam Maidul M Shinde Ganesh P GP Hotha Srinivas S

Chemical science 20161115 3

The global incidence of tuberculosis is increasing at an alarming rate, and <i>Mycobacterium tuberculosis</i> (Mtb) is the causative agent for tuberculosis, a disease with high mortality. Lipoarabinomannan (LAM) is one of the major components of the Mtb cellular envelope and is an attractive scaffold for developing anti-tubercular drugs, vaccines and diagnostics. Herein, a highly convergent strategy is developed to synthesize heneicosasaccharyl arabinomannan for the first time. The arabinomannan ...[more]

PMID: 28451321

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Project description:CD4+ T cells have a central role in controlling Mtb infection (1). Despite immune control, Mtb persists by interfering with macrophage and T cell function, allowing for pathogen survival. Our group has demonstrated direct and indirect inhibition of CD4+ T cell activation by different Mtb molecules including lipoproteins LpqH, LprA and LprG, and ManLAM (2-5). ManLAM is an abundant glycolipid in the Mtb cell wall and interferes with TCR signaling by down-regulating phosphorylation of Lck, CD3, ZAP70 and LAT (6). Activation through the TCR-CD3 complex leads to marked changes in the proteome of T cells. Entry into cell cycle, production of cytokines and differentiation from naïve to effector and memory T cell are all reflected in the production and modification of multiple proteins. Mass spectrometry (MS) has been used to characterize TCR complex formation (7-11) and the effect of a range of stressors on the T cell proteome (12-14). Recent advances have overcome technical issues in quantitative MS and allow analysis of the complexity and dynamic range of the cellular proteome (15). To extract biological meaning different bioinformatic tools have been developed for MS based cellular studies (16, 17). In this study we used label-free quantitative MS to characterize the effect of ManLAM on the proteome of activated CD4+ T cells. Approximately 5000 peptides were identified and quantitated from three biological experimental datasets in primary murine CD4+ T cells treated with or without ManLAM and activated with anti-CD3 and anti-CD28 monoclonal antibodies (mAb). Peptides with varying abundance were selected by likelihood ratio based statistical significance by comparing the intensities under different experimental conditions. ManLAM treatment resulted in abundance changes for 149 peptides representing 131 proteins in the activated CD4+ T cell proteome that affected a variety of enriched cluster modules and pathways. Validation experiments confirmed Man LAM induced inhibition of Proliferating Cell Nuclear Antigen (PCNA) that regulates cell cycle progression. Protein-protein interaction (PPI) network analysis revealed a central role for the Akt/mTOR signaling pathway. WB studies revealed decreased phosphorylation of both Akt and mTOR in ManLAM treated CD4+ T cells as well as decreased expression of Otub1, a key molecule regulated by mTOR. Thus disruption of the activated CD4+ T cell proteome by ManLAM-mediated inhibition of proximal TCR signaling is primarily mediated through inhibition of Akt-mTOR signaling.

Dataset Information

Expedient synthesis of the heneicosasaccharyl mannose capped arabinomannan of the Mycobacterium tuberculosis cellular envelope by glycosyl carbonate donors.

Publications

Expedient synthesis of the heneicosasaccharyl mannose capped arabinomannan of the <i>Mycobacterium tuberculosis</i> cellular envelope by glycosyl carbonate donors.

Similar Datasets

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