Does not have quercetin 2,3-dioxygenase activity. Monomer. Induced under conditions that maximally induce expression of the large pathogenicity island (PAI) also called the locus of effacement (LEE). No effect on protein secretion by the type III secretion system (TTSS) encoded in the locus of effacement (LEE). Belongs to the pirin family. Lacks the conserved His residues required for metal binding. Its function must therefore be different from the metal-dependent roles proposed for other family members.