Upon coexpression in E.coli stimulates the diadenylate cyclase activity of CdaA about 20-fold (PubMed:23192352). In B.subtilis c-di-AMP is a second messenger that mediates growth, DNA repair and cell wall homeostasis; it is toxic when present in excess (PubMed:26240071). Interacts with CdaA (PubMed:23192352, PubMed:26240071). Constitutively expressed, part of the cdaA-cdaR-glmM-glmS operon (PubMed:23192352). No visible phenotype.