Investigation of the role of LCI1, a putative inorganic carbon transporter, in the Carbon Concentrating Mechanism of Chlamydomonas reinhardtii
Bratati Mukherjee1, Norikazu Ohnishi2,3, Tomoki Tsujikawa2, Hideya Fukuzawa2, and J.V. Moroney1
1) Dept. of Biological Sciences,Louisiana State University,Baton Rouge, LA70803
2) Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
3) Present Address: Department of Biology, Faculty of Science, Okayama University, Okayama 700-8530, Japan
Chlamydomonas reinhardtii is able to acclimate successfully to low CO2 conditions with the help of a Carbon Concentrating Mechanism (CCM). One of the key features of this mechanism is the uptake and transfer of charged inorganic carbon species across the plasma, chloroplast and thylakoid membranes. To date, the inorganic carbon transport process in this alga has not been completely characterized, although a number of genes encoding putative transporters have been identified. LCI1 is one such candidate transporter gene showing a highly upregulated transcription under low CO2 conditions, and like many of the key CCM genes, is under the regulatory control of CIA5. In recent work, done in collaboration with the Fukuzawa group in Kyoto, LCI1 showed the ability to increase the uptake of inorganic carbon independent of other elements of the CCM. An effort was also made to localize the protein through immunolocalization experiments using different membrane fractions (chloroplast, plasma and thylakoid membranes) and the visualization of the GFP tagged protein in the C. reinhardtii cell using confocal microscopy. A further elucidation of the protein's function is now being attempted through a targeted knockdown of LCI1 expression, using RNAi. This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas "Comparative Genomics" from the Ministry of Education, Culture, Sports, Science and Technology of Japan (17018020 to H. F.), a Research Grant from NISSAN Science Foundation (to N. O.) and a National Science Foundation grant (IOS-0816957 to J.V.M.).
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