Transition metal transport in the green microalga Chlamydomonas reinhardtii--genomic sequence analysis.

Uptake and export systems play a major role in transition metal homeostasis. The objective of this study was to identify potential metal transport mechanisms in the green microalga Chlamydomonas reinhardtii. We concentrated on the four major transition metal transporter families found in plants and other organisms: the ZIP, CDF and Nramp families, and the CPx-ATPases. Using the information available for these protein families we performed comparative sequence analysis in the recently released genome of C. reinhardtii. Using this approach we were able to identify members of all four transporter families (four ZIPs, one CDF, two CPx-ATPases, and five Nramps). These findings advance our current knowledge of the metal transport processes present in C. reinhardtii. In addition, by subsequent in silico splicing of the genomic sequence we obtained cDNA sequences which led to the identification of ESTs (expressed sequence tags) in the C. reinhardtii EST database. These identified ESTs will be valuable for the cloning and characterization of several metal transporters utilized by the alga.