Activity of Brassica napus and Perilla frutescens microsomal ω-3 desaturases expressed in yeast (Saccharomyces cerevisiae)

Yeast transformations with Brassica napus and Perilla frutescens ω-3 desaturases were carried out. Feeding experiments on exogenous 18:2 at 10 mg/L and 100 mg/L for both genes under this investigation showed the same activity levels over the 3 days of the incubation, producing almost the same amount of 18:3. To further investigate the characteristics of B. napus and P. frutescens ω-3 desaturases, a time-course in vivo activity study was conducted. Both enzymes showed the same behavior over the time course, desaturating 18:2 into 18:3. Moreover, the use of 2 different temperatures for incubation (30 °C and 20 °C) did not affect levels of 18:3 in either ω-3 desaturase-expressing yeast lines. The 18:2 caused a change in yeast fatty acid profiles (compared to the wild yeast type), and 16:1 was highly reduced in 18:2-fed yeast lines, especially in the yeast lines with the higher 18:2 level. Amino acid sequence comparisons for some higher plant ω-3 desaturases show that ω-3 desaturases, including B. napus and P. frutescens ω-3 desaturases, are highly conserved amino acid sequences. This is the first report of P. frutescens ω-3 desaturase expression in yeast. All ω-3 desaturases may have the same behaviors if they are expressed under the control of the same promoter and the same conditions.