Enzymatic Deacetylation of N-Acetylglucosamine Residues in Cell Wall Peptidoglycan

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Abstract
An enzyme which catalyzes the hydrolysis of acetamido groups of N-acetylglucosamine residues in cell wall peptidoglycan was found in the supernatant and 20,000 × g pellet fractions of Bacillus cereus. Autolysis of the latter fraction resulted in solubilization and activation of the deacetylase. Among various bacteria, strains of B. cereus which contain high proportions of iV-unsubstituted glucosamine residues in their cell wall peptidoglycan components are particularly rich in the deacetylase. The peptidoglycan deacetylase is distinguishable from N-acetylglucosamine-6-phosphate deacetylase [EC 3.5.1.25] on the basis of their cellular distribution and chromatographic behavior. The rate of reaction of the deacetylase with (N-acetylglucosaminyl-N-acetylmuramic acid)3 [abbreviated as (GlcNAc-MurNAc)23 is less than 1/100 of that with peptidoglycan, while the enzyme is inactive towards (GlcNAc-MurNAc)23 GlcNAc-MurNAc, and monomeric .W-acetylglucosamine derivatives. The enzyme also deacetylates partially O-hydroxyethylated chitin. The concentrations of peptidoglycan and partially O-hydroxyethylated chitin required for half-maximum activities were found to be 0.29 and 6.9 mg per ml (or 0.17 and 20 mM with respect to JV-acetylglucosamine residues), respectively. The occurrence of this enzyme accounts for the formation of cell wall peptidoglycan N-unsubstituted at the glucosamine residues.