Carbonic anhydrases in plants and algae

Abstract

Carbonic anhydrases catalyse the reversible hydration of CO 2 , increasing the interconversion between CO 2 and HCO 3 -+ H + in living organisms. The three evolutionarily unrelated families of carbonic anhydrases are designated a-, b-and g-CA. Animals have only the a-carbonic anhydrase type of carbonic anhydrase, but they contain multiple isoforms of this carbonic anhydrase. In contrast, higher plants, algae and cyanobacteria may contain members of all three CA families. Analysis of the Arabidopsis database reveals at least 14 genes potentially encoding carbonic anhydrases. The database also contains expressed sequence tags (ESTs) with homology to most of these genes. Clearly the number of carbonic anhydrases in plants is much greater than previously thought. Chlamydomonas, a unicellular green alga, is not far behind with five carbonic anhydrases already identified and another in the EST database. In algae, carbonic anhydrases have been found in the mitochondria, the chloroplast thylakoid, the cytoplasm and the periplasmic space. In C 3 dicots, only two carbonic anhydrases have been localized, one to the chloroplast stroma and one to the cytoplasm. A challenge for plant scientists is to identify the number, location and physiological roles of the carbonic anhydrases.

Differential Proteomic Analysis by iTRAQ Reveals the Mechanism of Pyropia haitanensis Responding to High Temperature Stress

“…CA plays a crucial role in the CO 2 -concentrating mechanism (CCM) in algae43. In a previous study, several CA genes ( PhαCA1, PhβCA2, PhβCA3 , and PhγCA1 ) in P. haitanensis were found up-regulated during high temperature stress44.…”

Plant Carbonic Anhydrases: Structures, Locations, Evolution, and Physiological Roles

“…The enzymes are ubiquitous in nature and are an example of convergent evolution, as multiple, structurally and sequentially distinct families of CA have been discovered (Hewett-Emmett and Tashian, 1996). Plants have three types of CA: α-, β-, and γ-type CAs (Moroney et al., 2001). The α-type CA (αCA) was first found in erythrocytes and was the first CA family discovered (Brinkman et al., 1932, Meldrum and Roughton, 1932).…”

CO2 Sensing and CO2 Regulation of Stomatal Conductance: Advances and Open Questions

“…Carbonic anhydrase enzymes functioning in guard cells have been shown to be important for the rapid wild type stomatal movement response to changes in CO 2 levels [40]. These enzymes are beta carbonic anhydrases [40] and the CO 2 response of the alpha and gamma classes of carbonic anhydrases [41] has not yet been determined. Interestingly, complementation of double mutant plants by expressing a structurally-unrelated mammalian carbonic anhydrase preferentially in guard cells restores the WT response [40].…”