Involved in the incorporation of salicylate into the siderophore pyochelin. Catalyzes the elimination of the enolpyruvyl side chain from isochorismate to yield salicylate and pyruvate via a rare pericyclic hydrogen transfer mechanism from C2 to C5. PchB also catalyzes the nonphysiological Claisen rearrangement of chorismate to prephenate in which the pyruvylenol tail is transferred from a C3 ether linkage to a C1-C9 linkage. isochorismate = pyruvate + salicylate chorismate = prephenate Inhibited by endo-oxabicyclic diacid resembling to the conformation of the transition state. kcat is 1.01 sec(-1) for lyase activity (at pH 7.5 and 22 degrees Celsius). kcat is 23.5 sec(-1) for chorismate mutase activity (at pH 7.5 and 22 degrees Celsius). kcat is 106 min(-1) for lyase activity (at pH 7 and 30 degrees Celsius). kcat is 177 sec(-1) for lyase activity (at pH 7.5 and 22 degrees Celsius). kcat is 78 min(-1) for mutase activity (at pH 7 and 30 degrees Celsius). kcat is 106 min(-1) for lyase activity (at pH 7 and 30 degrees Celsius). Optimum pH is 6.8. Siderophore biosynthesis; salicylate biosynthesis. Dimer of dimers. Repressed by iron. Extended N-terminus.