This entry represents the probable inorganic carbon transporter subunit DabA, which is part of an energy-coupled inorganic carbon pump together with DabB subunit in DAB operons (DAB1 and DAB2), found in a wide range of bacteria and archaea. Members of this family were previously known as UPF0753. DAB operon is required for CO2 concentrating mechanisms [1]. The substrate of this subunit may be CO2 rather than carbonate ions based on kinetic calculations and in experimental assays in which E.coli was deleted of its carbonic anhydrase genes and expression of DAB2 operon restores its growth. Structural homology modelling suggests that DabA contains a domain that is distantly homologous to a type II beta-carbonic anhydrase (CA).

1: DABs are inorganic carbon pumps found throughout prokaryotic phyla. Desmarais JJ, Flamholz AI, Blikstad C, Dugan EJ, Laughlin TG, Oltrogge LM, Chen AW, Wetmore K, Diamond S, Wang JY, Savage DF; Nat Microbiol. 2019;4:2204-2215. PMID:31406332