A Polysaccharide Deacetylase Gene (pdaA) Is Required for Germination and for Production of Muramic δ-Lactam Residues in the Spore Cortex of Bacillus subtilis

The predicted amino acid sequence of Bacillus subtilis yfjS (renamed pdaA) exhibits high similarity to those of several polysaccharide deacetylases. β-Galactosidase fusion experiments and results of Northern hybridization with sporulation sigma mutants indicated that the pdaA gene is transcribed by Eσ(G) RNA polymerase. pdaA-deficient spores were bright by phase-contrast microscopy, and the spores were induced to germination on the addition of l-alanine. Germination-associated spore darkening, a slow and partial decrease in absorbance, and slightly lower dipicolinic acid release compared with that by the wild-type strain were observed. In particular, the release of hexosamine-containing materials was lacking in the pdaA mutant. Muropeptide analysis indicated that the pdaA-deficient spores completely lacked muramic δ-lactam. A pdaA-gfp fusion protein constructed in strain 168 and pdaA-deficient strains indicated that the protein is localized in B. subtilis spores. The biosynthetic pathway of muramic δ-lactam is discussed.