5-Methylthiopentose: a new substituent on lipoarabinomannan in Mycobacterium tuberculosis |
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Authors: | Treumann Achim Xidong Feng McDonnell Liam Derrick Peter J Ashcroft Alison E Chatterjee Delphi Homans Steve W |
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Institution: | Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK. |
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Abstract: | We have identified and characterised in several strains of Mycobacterium tuberculosis a new 5-methylthiopentose substituent on lipoarabinomannan (LAM). The 5-methylthiopentose was initially observed in heteronuclear (1)H-(13)C-NMR spectra of intact, (13)C-enriched LAM. Oligosaccharides carrying this substituent were released from (13)C-enriched LAM and from unlabelled LAM using an endo-arabinanase from Cellulomonas gellida. The presence of the methylthio group in these oligosaccharides was established using NMR, high-resolution Fourier-transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry using a Q-TOF mass spectrometer. The 5-methylthiopentose is linked to a terminal mannose in the cap structures of these oligosaccharides as evidenced by tandem mass spectrometry and by NMR. We suggest interference with the signal transduction mechanisms of infected macrophages as a possible function for this newly discovered LAM substituent. |
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Keywords: | lipoarabinomannan Mycobacterium cell wall NMR FTICR |
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