On the absence of the glyceraldehyde 3-phosphate/pyruvate pathway for isoprenoid biosynthesis in fungi and yeasts.

The biosynthesis of isopentenyl diphosphate, the central intermediate of isoprenoid formation, was investigated in the fungus Aschersonia aleyrodis and the yeast Rhodotorula glutinis. The incorporation of 13C-labeled glucose or acetate into their isoprenoids showed that ergosterol in both micro-organisms, ubiquinone in R. glutinis and dihydro-ubiquinone, beta-carotene and triterpenes of the hopane series in A. aleyrodis were synthesized via the mevalonate pathway. No evidence for the presence of the alternative mevalonate-independent glyceraldehyde 3-phosphate/pyruvate pathway was found.