CDCA1 FROM THALASSIOSIRA WEISSFLOGII AS REPRESENTATIVE MEMBER OF ZETA-CLASS CAs: GENERAL FEATURES AND BIOTECHNOLOGICAL APPLICATIONS

Carbonic Anhydrases (CAs) are metalloenzymes present both in prokaryotes and eukaryotes, that play important physiological roles in all life kingdoms. In phytoplankton CAs are essential for the acquisition of inorganic carbon for photosynthesis being involved in the carbon concentration mechanism (CCM). Recently, CDCA1, a new CA from the marine diatom Thalassiosira weissflogii has been isolated and classified as the first member of a new CA class, namely zeta-CA class. CDCA1 is a ~ 67.8 kDa enzyme, consisting of three almost identical repeats (R1, R2 and R3) which can functionally substitute Zn2+ or Cd2+ at their active site, an adaptive advantage for diatoms that grow fast in metal-poor environments of the ocean. The high affinity of CDCA1 active site for cadmium makes this enzyme a good candidate for the development of CA-based biosensors for determination of free metal ions in the seawater. Moreover, considering that this enzyme presents a very high catalytic activity for the physiologic reaction, potential biotechnological applications in CO2 capture processes may also be envisaged.