Structural definition of arabinomannans from Mycobacterium bovis BCG

The structures of the hydrophilic parietal and cellular arabinomannans isol ated from Mycobacterium bovis BCG cell wall [Nigou et al. (1997) J Biol Che m 272: 23094-103] were investigated. Their molecular mass as determined by MALDI-TOF mass spectrometry was around 16 kDa. Concerning cap structure, ca pillary electrophoresis analysis demonstrated that dimannoside (Man rho alp ha 1 --> 2Man rho) was the most abundant motif (65-75%). Using two-dimensio nal H-1-C-13 NMR spectroscopy, the mannan core was unambiguously demonstrat ed to be composed of --> 6Man rho alpha 1 --> backbone substituted at some O-2 by a single Man rho unit. The branching degree was determined as 84%. F inally, arabinomannans were found to be devoid of the phosphatidyl-myo-inos itol anchor and, by aminonaphthalene disulfonate tagging, the mannan core w as shown to contain a reducing end. This constitutes the main difference be tween arabinomannans and lipoarabinomannans from Mycobacterium bovis BCG.