Global transcriptional regulator that regulates virulence factors production by activating or repressing the expression of a large set of genes in diffusible signal factor (DSF) pathway. Allosterically inhibited by cyclic di-GMP (c-di-GMP), which binds to Clp and abolishes its ability to bind its target gene promoter. Homodimer. Binding of c-di-GMP appears to trigger the active Clp conformation into an open form or inactive state, hence abolishing its DNA-binding ability.