THE PRESENCE OF BETA-D-RIBOSYL-1-MONOPHOSPHODECAPRENOL IN MYCOBACTERIA

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 biosynth esis of the cell wall arabinogalactan/arabinomannan of Mycobacterium s megmatis: 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 mean s of gas chromatography-mass spectrometry, fast atom bombardment tande m mass spectrometry, and proton NMR, the major pentose-containing comp onent of the polyprenyl-P-sugar family from M. smegmatis was character ized as beta-D-ribosyl-1-monophosphodecaprenol (decaprenyl-P-ribose). Additionally, the structure of a minor arabinose-containing compound, ta-D-arabinosyl-1-monophosphooctahydroheptaprenol, could be deduced. I n vivo labeling experiments with [C-14]glucose demonstrated unequivoca lly that decaprenyl-P-ribose is actively synthesized in Mycobacterium tuberculosis H37Ra and Mycobacterium avium serovar 4. It is proposed t hat decaprenyl-P-ribose could be a precursor for the biosynthesis of e ither some unknown ribose-containing cell envelope polymers of mycobac teria or the arabinan part of the cell wall arabinogalactan/arabinoman nan due to the presence of a 2'-epimerase activity at some late stages of the arabinogalactan/arabinomannan biosynthesis.