The pgdA gene encodes for a peptidoglycan N-acetylglucosamine deacetylase in Streptococcus pneumoniae

Analytical work on the fractionation of the glycan strands of Streptococcus pneumoniae cell wall has led to the observation that an unusually high pro portion of hexosamine units (over 80% of the glucosamine and 10% of the mur amic acid residues) was not N-acetylated, explaining the resistance of the peptidoglycan to the hydrolytic action of lysozyme, a muramidase that cleav es in the glycan backbone. A gene, pgdA, was identified as encoding for the peptidoglycan N-acetylglucosamine deacetylase A with amino acid sequence s imilarity to fungal chitin deacetylases and rhizobial NodB chitooligosaccha ride deacetylases. Pneumococci in which pgdA was inactivated by insertion d uplication mutagenesis produced fully N-acetylated glycan and became hypers ensitive to exogenous lysozyme in the stationary phase of growth. The pgdA gene may contribute to pneumococcal virulence by providing protection again st host lysozyme, which is known to accumulate in high concentrations at in fection sites.