Involved in the biosynthesis of protocatechuate. Catalyzes the catabolic dehydration of 3-dehydroquinate (DHQ) to yield 3-dehydroshikimate. 3-dehydroquinate = 3-dehydroshikimate + H2O Aromatic compound metabolism; 3,4-dihydroxybenzoate biosynthesis; 3,4-dihydroxybenzoate from 3-dehydroquinate: step 1/2. By protocatechuate. Belongs to the type-I 3-dehydroquinase family. Extended N-terminus. Extended N-terminus.