Fatty acid synthetase from Chlamydomonas reinhardi.

Cell-free extracts of the unicellular green alga, Chlnmydomonas reinhardi, catalyze the incorporation of acetyl-CoA and malonyl-CoA into long chain fatty acids. The fatty acid synthetase is dependent on added acyl carrier protein for activity, regardless if the cells are grown in the light or in the dark. The major products formed from acetyl-CoA and malonyl-CoA by cells in the light period of synchronous growth are pahnitate, stearate, and arachidate, whereas in the dark period of synchronous growth more short fatty acids are formed. Rifampicin has no effect on the appearance of the fatty acid synthetase in synchronous cultures of C. reinhardi, thus suggesting that transcriptional steps necessary for formation of fatty acid synthetase occur in the nucleus. Cycloheximide has no effect on the activity of fatty acid synthetase in the synchronous cultures, whereas spectinomycin reduced the activity significantly. These findings strongly indicate that the chloroplast ribosomes are responsible for the de nouo protein synthesis required for fatty acid synthetase in C. reinhardi.