Correlation of carbonic anhydrase and Rubisco in the growth and photosynthesis in the diatom Phaeodactylum tricornutum
Carbonic anhydrase (CA) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) are critical enzymes involved in the CO2-concentrating mechanism (CCM) and carbon fixation in phytoplankton. These enzymes play key roles in photosynthetic carbon acquisition and fixation in diatoms. However, the potential synergistic interactions of the said enzymes remain little understood. In the present study, effects of CA inhibitors on the growth, photosynthetic rate, and Rubisco activities in the diatom Phaeodactylum tricornutum were investigated. Our results showed that the growth and photosynthetic O2 evolution rate of P. tricornutum were significantly inhibited by the intracellular CA (iCA) inhibitor ethoxzolamide (EZ), but not by extracellular CA (eCA) inhibitor acetazolamide (AZ) in the long term. This suggests that the eCA was not necessarily essential for growth and photosynthesis, but rather it was the iCA activity that was more crucial in P. tricornutum. We also found that there is a significant positive correlation between Rubisco and CA activities, suggesting that the two carbon acquisition and fixation components of photosynthesis may have undergone co-evolution to optimize fundamental trade-offs. These results further indicate that the roles of eCA and iCA may also differ among diatom species or strains, and that their functions are tightly correlated with other carbon fixation components.
KeywordsPhaeodactylum tricornutum CA inhibitor Ribulose bisphosphate carboxylase/oxygenase (Rubisco) Carbonic anhydrase Photosynthesis
This study was supported by the National Natural Science Foundation of China (Nos.: 41376156, 40976078) and the Natural Science Foundation of Guangdong Province (No.: S2012010009853).
- Badger MR, Andrews TJ, Whitney SM, Ludwig M, Yellowlees DC, Leggat W, Price GD (1998) The diversity and co-evolution of Rubisco, plastids, pyrenoids and chloroplast-based CO2 concentrating mechanisms in algae. Can J Bot 76:1052–1071Google Scholar
- Falkowski P, Scholes RJ, Boyle E, Canadell J, Canfield D, Elser J, Gruber N, Hibbard K, Högberg P, Linder S, Mackenzie FT, Moore B 3rd, Pedersen T, Rosenthal Y, Seitzinger S, Smetacek V, Steffen W (2000) The global carbon cycle: a test of our knowledge of Earth as a system. Science 290:291–296CrossRefPubMedGoogle Scholar
- Helbling EW, Buma AGJ, Boelen P, van der Strate HJ, Giordanino MVF, Villafañe VE (2011) Increase in Rubisco activity and gene expression due to elevated temperature partially counteracts ultraviolet radiation-induced photoinhibition in the marine diatom Thalassiosira weissflogii. Limnol Oceanogr 56:1330–1342CrossRefGoogle Scholar
- Makino A, Sakashita H, Hidema J, Mae T, Ojima K, Osmond B (1992) Distinctive responses of Ribulose-1,5-bisphosphate carboxylase and carbonic anhydrase in wheat leaves to nitrogen nutrition and their possible relationships to CO2-transfer resistance. Plant Physiol 100:1737–1743CrossRefPubMedPubMedCentralGoogle Scholar
- Raven JA (1994) Carbon fixation and carbon availability in marine phytoplankton. Photosynth Res 34:295–273Google Scholar
- Reed ML, Graham D (1980) Carbonic anhydrase in plants: distribution, properties and possible physiological role. In: Reinhold L, Harborne JB, Swain J (eds) Progress in phytochemistry, vol 7. Pergamon Press, Oxford, pp 48–94Google Scholar
- Willbur KM, Anderson NG (1948) Electronic and colorimetric determination of carbonic anhydrase. J Biol Chem 176:147–154Google Scholar