Cytosolic fumarate hydratase that catalyzes the reversible hydration of fumarate to (S)-malate. (S)-malate = fumarate + H2O Binds 1 [4Fe-4S] cluster per subunit. Specifically and competitively inhibited by 2-thiomalate, which coordinates with the catalytic [4Fe-4S] cluster (PubMed:30645090). Weakly inhibited by malonate (PubMed:27528683). kcat is 204.2 sec(-1) for fumarate (in anaerobic conditions) (PubMed:22569531). kcat is 48.6 sec(-1) for fumarate (in aerobic conditions) (PubMed:22569531). kcat is 151.4 sec(-1) for (S)-malate (in anaerobic conditions) (PubMed:22569531). kcat is 24.9 sec(-1) for (S)-malate (in aerobic conditions) (PubMed:22569531). Optimum pH is 9. Homodimer. Belongs to the class-I fumarase family.