Part of a signaling cascade that regulates curli biosynthesis. The cascade is composed of two cyclic-di-GMP (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). PdeR acts as a trigger enzyme that connects modules I and II. It inhibits DgcM and MlrA by direct interaction. Inhibition is relieved when PdeR binds and degrades c-di-GMP generated by module I (PubMed:17010156, PubMed:23708798). cyclic di-3',5'-guanylate + H2O = 5'-phosphoguanylyl(3'->5')guanosine + H(+) Interacts with DgcM and MlrA. Constitutively expressed at both 28 and 37 degrees Celsius, during transition into stationary phase, more highly expressed on plates than in liquid medium. Expression is RpoS dependent and repressed by H-NS. Leads to overproduction of curli fimbrae and autoaggregation in cultures grown at 28 degrees Celsius.