Structures of the Glycopeptidolipid Antigens from Serovars in the Mycobacterium avium/Mycobacterium intracellulare/Mycobacterium scrofulaceum Serocomplex

Abstract

The C-mycosidic glycopeptidolipid typing antigens from all serovars in the M. avium/M. intracellulare/M. scrofulaceum complex were examined to varying extents. Detailed analysis of those from serovars 8, 9, 16 and 25 show that the antigens consist of short acetylated oligosaccharides linked to a common fatty acyl-peptidyl-O-(3,4-di-O-methylrhamnose) core. The oligosaccharide units, in a form suitable for chemical studies, were liberated as oligosaccharide alditols on treatment of the glycopeptidolipids with alkaline borohydride solution. The alditol in the reduced oligosaccharides from all sources is 6-deoxytalitol. Rhamnose is also always present, indicating that a basal disaccharide, rhamnosyl-6-deoxytalosyl, is always linked to the allo-threonine in the acylpeptide. In addition, the oligosaccharides from the glycopeptidolipids of each serovar are distinguished by their own individualistic sugars: 3-O-methylglucose in serovar 8; 2,3-di-O-methylfucose in serovar 9; 2-O-methylfucose in serovar 25; 4-O-methylrhamnose in the oligosaccharide from 1 of the 2 glycopeptidolipids in serovar 16 and apparently another rhamnosyl substituent in the other oligosaccharide. The glycopeptidolipid antigens in their structural principals, cellular location and physiological role bear a striking miniscular resemblance to cell wall components of other bacteria such as the O-antigenic and R-antigenic lipopolysaccharides.