Peptidoglycolipid nature of the superficial cell wall sheath of smooth-colony-forming mycobacteria.

The most superficial cell wall layer present in smooth-colony-forming mycobacteria was isolated from serovar 20 of the Mycobacterium avium-Mycobacterium intracellulare-Mycobacterium scrofulaceum (MAIS) serocomplex and examined chemically and by electron microscopy. Most (70 to 80%) of the fibrillar material consisted of an array of serologically active, acetylated C-myosidic peptidoglycoplipids with the basic structure (formula, see text) but in which the location of acetyl groups and the arrangement of monosaccharides have not been defined. Apparently, all serovars within the MAIS complex are characterized by structurally related superficies in which the monoglycosyl-lipopeptide portion is invariable but the oligosaccharide attachment is peculiar to each serovar. These unique inert structures may be an important factor in shielding the pathogen within phagolysosomes from lysosomal enzymes.