Diadenylate cyclase that catalyzes the condensation of 2 ATP molecules into cyclic di-AMP (c-di-AMP). c-di-AMP is a second messenger for intracellular signal transduction involved in the control of important regulatory processes such as osmoregulation. Is essential for H.volcanii. Overexpression of DacZ leads to cell death, suggesting the need for tight regulation of c-di-AMP levels. Cannot use GTP as substrate. 2 ATP = 3',3'-c-di-AMP + 2 diphosphate Cannot use Mg(2+), Ca(2+), Ni(2+) or Co(2+) instead of Mn(2+) as cofactor. Is constantly expressed at different growth phases in rich and selective media. It was not possible to obtain a strain in which the dacZ gene was deleted in standard growth conditions, indicating that dacZ is an essential gene. Belongs to the adenylate cyclase family. DacZ subfamily.