Chemistry of the lyxose-containing mycobacteriophage receptors of Mycobacterium phlei/Mycobacterium smegmatis.

Mycobacterium phlei (strain Timothy) (Mycobacterium smegmatis ATCC 19249) is characterized by the presence of a family of alkali-labile glycolipids, reminiscent of the trehalose-containing lipooligosaccharide class of antigens but lacking the nonreducing trehalose core. Through a combination of methylation analyses, 1H and 13C NMR, two-dimensional 1H/1H and 1H/13C NMR, fast atom bombardment-mass spectrometry, gas chromatography-mass spectrometry, and other analytical techniques, these new structures were shown to possess three distinct features. Firstly, they contained the pentose D-lyxose (Lyx), rarely found in biology, but an epimer of D-arabinose, a key component of the mycobacterial cell wall arabinogalactan and lipoarabinomannnan. Thus, it was apparent that these glycolipids are the same as those described by Bisso et al. and attributed with phage receptor properties [Bisso, G., Castelnuovo, G., Nardelli, M.-G., Orefici, G., Arancia, G., Lanéelle, G., Asselineau, C., & Asselineau, J. (1976) Biochemie 58, 87-97]. Secondly, the complex oligosaccharides within the glycolipids contain the repeating units Lyxn(6-O-CH3-Glc)m and Lyxn(6-O-CH3-Glc)mMan1, where n+m equal to approximately 16 glycosyl residues. Thirdly, the M. phlei glycolipids were found to be heavily O-acylated, such that every D-Lyx residue invariably possesses an acyl function at position -2 and, in some instances, at both positions -2 and -4. The chemical characterization of these glycolipids, not feasible 20 years ago, clearly demonstrates that they are distinct from the type- and species-specific glycopeptidolipids, lipooligosaccharides, phenolic glycolipids, and the genus-specific phosphatidylinositol-based lipoglycans of mycobacteria. This present and previous studies begin to define the precise structural requirements responsible for the attachment of mycobacteriophage to the host cell wall.