Catalyzes the Claisen rearrangement of chorismate to prephenate. Probably involved in the aromatic amino acid biosynthesis. chorismate = prephenate The formation of the complex with AroG activates the chorismate mutase activity. Metabolic intermediate biosynthesis; prephenate biosynthesis; prephenate from chorismate: step 1/1. Homodimer. Interacts with AroG.