EVIDENCE THAT DIPICOLINIC ACID IS COVALENTLY BOUND TO SPECIFIC MACROMOLECULES IN SPORES OF BACILLUS-SUBTILIS

Two dipicolinic acid (DPA)-binding macromolecules with molecular masse s of about 440 kDa and 230 kDa were detected in the soluble fractions of dormant and germinated spores of Bacillus subtilis using native PAG E and an immunological technique. In SDS-PAGE, only one band with the molecular mass of about 50 kDa was found. Proteinase K partially diges ted the 440-kDa macromolecule of dormant spores to convert it into a 2 30-kDa one, and completely digested both the 440-kDa and 230-kDa bands of germinated spores. DNase I did not affect either DPA-binding macro molecules. This suggests that the two DPA-binding macromolecules are o f similar origin, their main component is protein and a conformational change may occur during germination. DPA was not dissociated from the DPA-binding macromolecules by extensive dialysis and SDS treatment, s uggesting the presence of a covalent bonding.