Involved in the synthesis of o-succinylbenzoic acid, 2,3-dihydroxybenzoic acid and salicylic acid (SA). chorismate = isochorismate Not inhibited by Tyr, Phe or Trp. Optimum pH is 7.0-9.0. Up-regulated by fungal elicitor. Two isoforms can be purified from cell cultures, but they are probably encoded by a single gene and may arise by post-transcriptional modifications. Belongs to the isochorismate synthase family.