Research Focus

Approximately 50% of the world’s photosynthesis occurs in the aquatic environment by organisms that employ a carbon concentrating mechanism (CCM). Aquatic photosynthetic organisms have evolved different forms of CCMs to aid the enzyme Rubisco in capturing CO2 from the surrounding environment. One aspect of all CCMs is the critical roles played by various extracellular and intracellular carbonic anhydrases (CAs). CAs are of four sub types namely alpha, beta, gamma and epsilon. Dr. Mitra's Ph.D. research at LSU was focused on the identification and characterizations of some carbonic anhydrase genes in C. reinhardtii, a green alga, with a well studied CO2 concentrating mechanism (CCM).

At the time of her PhD study, five carbonic anhydrases (CAs) were known to exist in C. reinhardtii. She identified two novel genes encoding beta type CA (CAH6 and CAH8) and two gamma CA like genes (GLP1 and GLP2). Two of these proteins, Cah6 (chloroplastic) and GLP1 (cytoplasmic) and a known thylakoid alpha CA (CAH3) protein were over-expressed as recombinant MBP (maltose binding protein)-fusion proteins to assay CA enzyme activities. She demonstrated that the recombinant CAH6 and CAH3 fusion proteins are enzymatically active but GLP1 is not. The purified recombinant CAH6 and CAH3 proteins were used to raise antibodies for immuno-localization and biochemical studies. RNA interference, a powerful gene silencing tool, was employed, along with traditional molecular biological methods like Northern and Western blotting, to study the functional role of CAH6 in the carbon concentrating mechanism (CCM) and photosynthesis.