Cyanobacterial carbonic anhydrases

Carbonic anhydrases (CAs) are ubiquitous zinc metalloenzymes that catalyze the reversible dehydration of HCO3–. These enzymes are encoded by at least five distinct, evolutionarily unrelated gene families, four of which have been found among the cyanobacteria examined to date. However, the distribution and expression of these cyanobacterial α-, β-, γ-, and ∈-CAs and their homologues among species have not yet been investigated in great detail. In this study, the number, distribution, and catalytic function of known and putative CAs and CA-like proteins from a variety of freshwater and marine cyanobacteria are examined.Key words: carbonic anhydrase, carboxysome, CO2-concentrating mechanism, cyanobacteria, Prochlorococcus, Synechococcus, Synechocystis.