Participates in a DNA-damage check-point. DisA forms globular foci that rapidly scan along the chromosomes searching for lesions. Has also diadenylate cyclase activity, catalyzing the condensation of 2 ATP molecules into cyclic di-AMP (c-di-AMP). c-di-AMP likely acts as a signaling molecule that may couple DNA integrity with a cellular process. To a lesser extent, can also use ADP as substrate to produce c-di-AMP. Does not convert GTP to c-di-GMP. Also exhibits residual ATPase and ADPase activities in vitro. 2 ATP = 3',3'-c-di-AMP + 2 diphosphate Magnesium. Can also use Mn(2+), and, to a lesser extent, Co(2+). Cannot use Ni(2+), Ca(2+) and Fe(2+). Diadenylate cyclase activity is inhibited by the interaction with RadA. Is more active at pH 8.0 rather than at pH 7.0 or pH 6.0. Homooctamer. Interacts with RadA. The N-terminal catalytic domain contributes to tetramerization and the C-terminal domain provides additional dimerization. Both domains are required for full catalytic activity. The C-terminal domain may play a role in stabilizing the active conformation. Belongs to the DisA family.