D-erythro-1-(imidazol-4-yl)glycerol 3-phosphate = 3-(imidazol-4-yl)-2-oxopropyl phosphate + H2O Binds 2 manganese ions per subunit. Amino-acid biosynthesis; L-histidine biosynthesis; L-histidine from 5-phospho-alpha-D-ribose 1-diphosphate: step 6/9. Induced by histidine starvation in a GCN4-dependent manner. Present with 2100 molecules/cell in log phase SD medium. Belongs to the imidazoleglycerol-phosphate dehydratase family.