Two calcium-dependent protein kinases from Chlamydomonas reinhardtii are transcriptionally regulated by nutrient starvation.

We report here， the transcriptional regulation of 2 Calcium Dependent Protein Kinases in response to nutrient starvation of Chlamydomonas reinhardtii vegetative cells. The CDPK proteins， CDPK1 and CDPK3; share 53% identity among themselves， a maximum of 57% and 52% to higher plants respectively and 42% to apicomplexan protozoans. We expressed a CDPK1-GFP fusion protein in the C. reinhardtii vegetative cells and showed its distribution both in the cell body and the membrane-matrix fraction of the flagella. The fusion protein exhibits mobility shift in the presence of Ca (2+)， confirming its Ca (2+)-binding properties. To the best of our knowledge， this is the first report of transcriptional regulation of CDPKs from a unicellular chlorophyte in response to nutrient starvation namely acetate (A)， phosphorus (P)， and nitrogen (N).