Catalyzes the synthesis of cyclic-di-GMP (c-di-GMP) via the condensation of 2 GTP molecules (By similarity). Involved in the control of the switch from cell motility to adhesion via regulation of cellular levels of c-di-GMP (Probable). Part of a signaling cascade that regulates curli biosynthesis. The cascade is composed of two c-di-GMP control modules, in which c-di-GMP controlled by the DgcE/PdeH pair (module I) regulates the activity of the DgcM/PdeR pair (module II), which in turn regulates activity of the transcription factor MlrA and expression of the master biofilm regulator csgD (PubMed:23708798). 2 GTP = cyclic di-3',5'-guanylate + 2 diphosphate Binds 1 Mg(2+) ion per monomer. Purine metabolism; 3',5'-cyclic di-GMP biosynthesis. Homodimer. Expressed during transition into stationary phase, expression is equal at 28 and 37 degrees Celsius. Expression is RpoS dependent. Decreased biofilm formation, decreased expression of DgcC, a probable diguanylate cyclase and of the curli regulator CsgD (PubMed:19332833). Disruption leads to decreaseded expression of adhesive curli fimbriae genes (PubMed:18765794). Also partially suppresses the reduced motility of a pdeH disruption; concomitant disruption of dosC, dgcE, dgcQ and dgcN completely restores motility, suggesting these 4 genes, together with the c-di-GMP phosphodiesterase PdeH, form a network that regulates cell motility by altering levels of c-di-GMP.