The Methylerythritol Phosphate Pathway Contributes to Carotenoid But Not Phytol Biosynthesis in <i>Euglena </i><i>g</i><i>racilis</i>

Abstract

The biosynthesis of diadinoxanthin and beta-carotene in Euglena gracilis was examined using [1-13C]-D-glucose and [5,5-2H2]-1-deoxy-D-xylulose. In contrast to previous studies on isoprenoid biosynthesis in E. gracilis, the results demonstrate a role for the methylerythritol phosphate (MEP) pathway, along with the mevalonate pathway, in carotenoid biosynthesis. Interestingly, the MEP pathway is not involved in the biosynthesis of phytol, a result not previously observed for other chloroplast-containing organisms.