Isolation, cloning, and gene expression analysis of phosphoglycolate phosphatase from green alga Chlamydomonas reinhardtii

Phosphoglycolate phosphatase (PGPase), a key enzyme in photosynthetic organisms, catalyzes the dephosphorylation of phosphoglycolate, which is largely produced by the oxygenase activity of Rubisco, and is a potent inhibitor of several Calvin cycle enzymes. PGPase (CrPGPase 1) was previously cloned, purified, and characterized from unicellular green Chlamydomonas reinhardtii. In silico analysis revealed two more candidates encoding PGPase enzymes in the C. reinhardtii genome. In this study, we isolated, cloned, and overexpressed three PGPase genes (pgp1, pgp2, pgp3) from C. reinhardtii and performed gene expression analysis at high and low ammonium [NH4+] concentrations. We demonstrate that all three pgp genes encode functionally active PGPases in C. reinhardtii. In addition, we show that pgp1 and pgp2 genes are N-responsive genes and are upregulated under low ammonium concentrations. In silico analysis revealed that PGPase exists mainly in three isoforms in higher plants and algae.