Reactions of second stage of biosynthesis of teichuronic acid of Micrococcus lysodeikticus cell walls.

ROHR,~ AND JOHN S. ANDERSON(~ From the Department of Biochemistry, College of Biological Sciences, University of Minnesota, St. Paul, Minnesota 55108 A polysaccharide of alternating glucose and N-acetylman- nosaminuronic acid residues is formed in the second stage of teichuronic acid biosynthesis by the particulate enzyme fraction of Micrococcus lysodeikticus. Di(N-acetylmannosa- minuronylj-N-acetylglucosaminyl carrier lipid, the third in- termediate formed in the initial stage of teichuronic acid synthesis, serves as an acceptor for the sequential and alter- nating addition of glucose residues from uridine diphos- phate glucose and N-acetylmannosaminuronic acid residues from uridine diphosphate N-acetylmannosaminuronic acid. Glucosyl - di (N - acetylmannosaminuronyl j-N - acetylglu- cosaminyl carrier lipid and N-acetylmannosaminuronylglu- cosyl-di(N-acetylmannosaminuronyl) - N-acetylglucosami- nyl carrier lipid are intermediates formed by the action of the glucosyltransferase and the N-acetylmannosaminuron- yltransferase, respectively. Both uridine diphosphate glu- cose and uridine diphosphate N-acetylmannosaminuronic acid produce uridine diphosphate in an amount stoichiomet- ric with the incorporation of monosaccharide residues into teichuronic acid. The transferases which catalyze the second stage of tei- churonic acid synthesis are solubilized from the particulate enzyme fraction by Triton X-100. The glucosyltransferase can be selectively released at 5 to 10 mM magnesium ion, whereas at a concentration of 1 mM or less the N-acetylman- nosaminuronyltransferase is also solubilized.