Part of the regulatory cascade that plays a role in the transcriptional regulation of the type III secretion system (T3SS) (PubMed:16714561, PubMed:9045825). Interacts with antiactivator ExsD to inhibit its activity leading to ExsA-mediated transcription (PubMed:15225323, PubMed:16980486). In the absence of inducing signals, ExsE interacts with and inhibits ExsC activity. Homodimer (PubMed:17197437). Interacts with ExsE (PubMed:17197437, PubMed:20536183). Interacts directly with ExsD to form a heterotetrameric complex (PubMed:17197437, PubMed:15225323, PubMed:16980486). Deletion mutant results in a two to three-fold reduction in extracellular exoenzyme S activity representing the efficiency of type III secretion system (T3SS) (PubMed:9045825, PubMed:15225323). Mutant also demonstrates a lag in the induction of cytotoxicity towards Chinese hamster ovary cells and is attenuated for virulence in a mouse pneumonia model (PubMed:16714561).