Increase in peroxisome number and the gene expression of putative glyoxysomal enzymes in Chlamydomonas cells supplemented with acetate.

We cultured Chlamydomonas reinhardtii cells in a minimal culture medium supplemented with various concentrations of acetate, fatty acids, ethanol, fatty alcohols, or sucrose. The presence of acetate (0.5 or 1.

Visualization of microbodies in Chlamydomonas reinhardtii.

In Chlorophycean algal cells, these organelles are generally called microbodies because they lack the enzymes found in the peroxisomes of higher plants. Microbodies in some algae contain fewer enzymes than the peroxisomes of higher plants, and some unicellular green algae in Chlorophyceae such as Chlamydomonas reinhardtii do not possess catalase, an enzyme commonly found in peroxisomes. Thus, whether microbodies in Chlorophycean algae are similar to the peroxisomes of higher plants, and whether they use a similar transport mechanism for the peroxisomal targeting signal (PTS), remain unclear.

Peroxisomal targeting signals in green algae.

Peroxisomal enzymatic proteins contain targeting signals (PTS) to enable their import into peroxisomes. These targeting signals have been identified as PTS1 and PTS2 in mammalian, yeast, and higher plant cells; however, no PTS2-like amino acid sequences have been observed in enzymes from the genome database of Cyanidiochyzon merolae (Bangiophyceae), a primitive red algae. In studies on the evolution of PTS, it is important to know when their sequences came to be the peroxisomal targeting signals for all living organisms.