Catalyzes the reversible cyclization of carbamoyl aspartate to dihydroorotate. (S)-dihydroorotate + H2O = H(+) + N-carbamoyl-L-aspartate Binds 2 Zn(2+) ions per subunit. Pyrimidine metabolism; UMP biosynthesis via de novo pathway; (S)-dihydroorotate from bicarbonate: step 3/3. Homodimer. Belongs to the metallo-dependent hydrolases superfamily. DHOase family. Class II DHOase subfamily.