Characterization of three intermediates in the biosynthesis of teichuronic acid of Micrococcus luteus.

Teichuronic acid, the Micrococcus luteus cell wall polysaccharide which consists of D-glucose and N-acetyl-D-mannosaminuronic acid, is synthesized in vitro from uridine diphosphate N-acetyl-D-glucosamine, uridine diphosphate N-acetyl-D-mannosaminuronic acid, and uridine diphosphate D-glucose in a series of reactions catalyzed by a particulate enzyme preparation. Several lipid-linked intermediates are formed, of which the first three are called components A, B, and C. The formation of these intermediates is inhibited by tunicamycin. The lipid moiety of the intermediates is approximately 95% undecaprenol and 5% dodecaprenol as determined by mass spectrometry. The oligosaccharide moieties of components B and C are the disaccharide, N-acetyl-D-mannosaminuronyl-(1,3)-N-acetyl-D-glucosamine, and the trisaccharide, N-acetyl-D-mannosaminuronyl-(1,4)-N-acetyl-D-mannosaminuronyl++ +-(1, 3)-N-acetyl-D-glucosamine, respectively, as determined by the complete degradation of the former and partial degradation of the latter by the alkaline beta-elimination reaction. The saccharide and lipid moieties of the intermediates are linked through pyrophosphate. Thus, component A is P1-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate, component B is P1-N-acetyl-D-mannosaminuronyl-(1, 3)-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate, and component C is P1-N-acetyl-D-mannosaminuronyl-(1,4)-N-acetyl-D-mannosaminurony l-(1, 3)-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate.