Related Experiment Videos
The presence of beta-D-ribosyl-1-monophosphodecaprenol in mycobacteria
1Department of Chemistry, University of Louvain, Belgium.
Abstract:
Biosynthesis of the cell envelope in mycobacteria is largely unknown; however, several antituberculosis drugs apparently interfere with this process. Recently, we described a lipid intermediate for the biosynthesis of the cell wall arabinogalactan/arabinomannan of Mycobacterium smegmatis: beta-D-arabinofuranosyl-1-monophosphodecaprenol (Wolucka, B. A., McNeil, M. R., de Hoffmann, E., Chojnacki, T., and Brennan, P. J. (1994) J. Biol. Chem. 269, 23328-23335). In the present work, by means of gas chromatography-mass spectrometry, fast atom bombardment tandem mass spectrometry, and proton NMR, the major pentose-containing component of the polyprenyl-P-sugar family from M. smegmatis was characterized as beta-D-ribosyl-1-monophosphodecaprenol (decaprenyl-P-ribose). Additionally, the structure of a minor arabinose-containing compound, beta-D-arabinosyl-1-monophosphooctahydroheptaprenol, could be deduced. In vivo labeling experiments with [14C]glucose demonstrated unequivocally that decaprenyl-P-ribose is actively synthesized in Mycobacterium tuberculosis H37Ra and Mycobacterium avium serovar 4. It is proposed that decaprenyl-P-ribose could be a precursor for the biosynthesis of either some unknown ribose-containing cell envelope polymers of mycobacteria or the arabinan part of the cell wall arabinogalactan/arabinomannan due to the presence of a 2'-epimerase activity at some late stages of the arabinogalactan/arabinomannan biosynthesis.
Insights
Mycobacterial cell envelope biosynthesis is clarified with the identification of decaprenyl-P-ribose as a key lipid-intermediate. This finding provides new insights into the synthesis of essential cell wall components in Mycobacterium tuberculosis.
Area of Science:
- Microbiology
- Biochemistry
- Cell Biology
Background:
- The biosynthesis of the mycobacterial cell envelope is not fully understood.
- Several antituberculosis drugs target this process.
- A previously identified lipid intermediate is beta-D-arabinofuranosyl-1-monophosphodecaprenol.
Purpose of the Study:
- To characterize the major pentose-containing component of the polyprenyl-P-sugar family in Mycobacterium smegmatis.
- To investigate the synthesis and potential role of this component in mycobacteria.
Main Methods:
- Gas chromatography-mass spectrometry (GC-MS)
- Fast atom bombardment tandem mass spectrometry (FAB-MS/MS)
- Proton nuclear magnetic resonance (1H NMR) spectroscopy
- In vivo labeling with [14C]glucose
Main Results:
- The major pentose-containing lipid-intermediate was identified as beta-D-ribosyl-1-monophosphodecaprenol (decaprenyl-P-ribose).
- A minor arabinose-containing compound, beta-D-arabinosyl-1-monophosphooctahydroheptaprenol, was also characterized.
- Decaprenyl-P-ribose is actively synthesized in Mycobacterium tuberculosis H37Ra and Mycobacterium avium.
Conclusions:
- Decaprenyl-P-ribose is a significant precursor in mycobacterial cell envelope biosynthesis.
- It may be involved in the synthesis of unknown ribose-containing polymers or the arabinan portion of the cell wall.
- The findings suggest a potential role for 2'-epimerase activity in arabinogalactan/arabinomannan biosynthesis.