Biosynthesis of Streptococcal Cell Walls: N -Acetyl- d -Muramic Acid

Abstract

Glucose- 1 - 14 C and acetylglucosamine- 1 - 14 C were added singly and together with equal amounts of the unlabeled reciprocal to Brain Heart Infusion and used for the culture of Streptococcus pyogenes . The labeling pattern of the rhamnose, glucosamine, and muramic acid in the cell wall supported an intermediary role for acetylglucosamine in providing the C1-C6 moiety of muramic acid. Although radioactivity in the C2-C9 portion of muramic acid suggested that some of the lactyl group (C7-C9) came from glycolytic products, there was also considerable contribution to it from noncarbohydrate sources. Using cell-free extracts, we were unable to demonstrate biosynthesis of acetylmuramic acid, either free or nucleotide-bound, while glycolysis was occurring. The formation of uridine diphosphoacetylmuramic acid has been reported by others who used uridine diphospho- N -acetyl- d -glucosamine, phosphoenolpyruvate, reduced nicotinamide adenine dinucleotide, and reduced nicotinamide adenine dinucleotide phosphate. However, we did not detect the formation of this compound.