Catalyzes the reversible hydration of CO(2) to H(2)CO(3). The main role may be to provide inorganic carbon for the bicarbonate-dependent carboxylation reactions catalyzed by pyruvate carboxylase, acetyl-CoA carboxylase and carbamoyl-phosphate synthetase. Involved in protection against oxidative damage. Acts as a CO(2) chemosensor and induces CO(2)-mediated filamentation. Essential for pathological growth in niches where sufficient CO(2) is not supplied by the host. Necessary for white-to-opaque switching at low CO(2) concentrations. H(+) + hydrogencarbonate = CO2 + H2O Binds 1 zinc ion per subunit. Amines and amino acids act as activators of catalytic activity, whereas natural product-based phenols, dithiocarbamates, aliphatic and aromatic carboxylates, boronic acids, and sulfonamides act as inhibitors of enzymatic activity. Also inhibited by anions such as cyanide and carbonate, and to a lesser extent by sulfate, phenylboronic, and phenyl arsonic acid. Strongly expressed when cells are grown in ambient air but non-detectable when cultured in air enriched with CO(2). Up-regulated by MNL1, HAP43, RCA1, and during early stages of biofilm development. Belongs to the beta-class carbonic anhydrase family.