Characterization of putative acetate transporters in Chlamydomonas reinhardtii

The unicellular green alga C. reinhardtii can grown heterotrophically by consuming acetate in the dark and mixotrophically by using both carbon sources in the light. Despite significant knowledge gained on acetate metabolism, the genes coding for acetate transporter/permease are still unknown in this alga. However, recent analyses1,2 have shown five functionally uncharacterized members of the GPR1/FUN34/yaaH (GFY), a protein family which includes genes involved in carboxylic organic acid uptake/sensing already described in bacteria, yeasts and filamentous fungi. Thus, the five genes identified in C. reinhardtii as GFY1-5 encode for putative acetate transporter proteins given that they are structured in 6 hydrophobic transmembrane helices. They are characterized by a close gene structure (Fig. 1) and very high similarity in their coding sequence (CDS) except at the N-terminus amino acid sequences (Fig. 2). Insertional mutants for the genes GFY1, 2 and 3 are available, and artificial microRNA (amiRNA) technique will be used to generate knock-down mutant for GFY4, 5 and all the 5 genes. Mutants will be used to investigate about the role of this putative acetate transporters by placing them in different culture conditions. Plus, protein localization experiments will already give some clues about a putative peroxisomal localization (Fig. 3). If confirmed, as far as we know this work could represent the first attempt to describe acetate transporters in this microalga.