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. beta-Galactosidase fusion experiments and results of Northern hybridization with sporulation sigma mutants indicated that the pdaA gene is transcribed by Esigma(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 delta-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 delta-lactam is discussed.