Synthesis of an unusual polar glycopeptidolipid in glucose-limited culture of Mycobacterium smegmatis.

There has been a general understanding that Mycobacterium smegmatis produces only apolar glycopeptidolipid (GPL), similar in structure to serovar non-specific GPL of Mycobacterium avium. In this study, synthesis of polar GPL in carbon-starved M. smegmatis is reported. Mass spectrometric analysis suggests the polar GPL to be a hyperglycosylated species. The earlier structural studies of polar GPLs from M. avium have invariably shown the presence of an oligosaccharide appendage to D-allo-Thr. However, a further chemical analysis using beta-elimination of the newly found polar GPL in M. smegmatis shows that the molecule still contains a monosaccharide at the D-allo-Thr, thus suggesting a new form of polar GPL.