Involved in the biosynthesis of the antibiotic phenazine, a nitrogen-containing heterocyclic molecule having important roles in virulence, competition and biological control. This isochorismatase may remove pyruvate from chorismate during the formation of the phenazine ring structure and/or stabilize the phenazine biosynthetic complex. H2O + isochorismate = (2S,3S)-2,3-dihydroxy-2,3-dihydrobenzoate + pyruvate Antibiotic biosynthesis; phenazine biosynthesis. Belongs to the isochorismatase family.