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. 2 ATP = 3',3'-c-di-AMP + 2 diphosphate Homooctamer. Belongs to the DisA family.