Initial reactions in biosynthesis of teichuronic acid of Micrococcus lysodeikticus cell walls

The in vitro biosynthesis of teichuronic acid, the cell wall polysaccharide of Micrococcus lysodeikticus, occurs in two stages. In the initial stage, the particulate enzyme fraction utilizes uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) and uridine diphosphate N-acetylmannosaminuronic acid (UDP-ManNAcUA) to form three intermediates. N-Acetylglucosamine is transferred from UDP-GlcNAc to a carrier lipid present in the particulate enzyme fraction to form the first intermediate, GlcNAc carrier lipid. N-Acetylmannosaminuronic acid is then transferred from UDP-ManNAcUA to the GlcNAc carrier lipid to form ManNAcUA-GlcNAc carrier lipid, the second intermediate. Finally, the transfer of an additional N-acetylmannosaminuronic acid residue from UDP-ManNAcUA yields the third intermediate, (ManNAcUA)2-GlcNAc carrier lipid. Reactions involving UDP-ManNAcUA release uridine diphosphate. Concomitant synthesis of peptidoglycan or membrane mannan inhibits the synthesis of the teichuronic acid intermediates, thereby providing indirect evidence that the carrier lipid is undecaprenol monophosphate.