Hk. Lichtenthaler et al., BIOSYNTHESIS OF ISOPRENOIDS IN HIGHER-PLANT CHLOROPLASTS PROCEEDS VIAA MEVALONATE-INDEPENDENT PATHWAY, FEBS letters, 400(3), 1997, pp. 271-274
Isopentenyl diphosphate (IPP) is the biological C-5 precursor of isopr
enoids. By labeling experiments using [1-C-13]glucose, higher plants w
ere shown to possess two distinct biosynthetic routes for IPP biosynth
esis: while the cytoplasmic sterols were formed via the acetate/mevalo
nate pathway, the chloroplast-bound isoprenoids (beta-carotene, lutein
, prenyl chains of chlorophylls and plastoquinone-9) were synthesized
via a novel IPP biosynthesis pathway (glyceraldehyde phosphate/pyruvat
e pathway) which was first found in eubacteria and a green alga. The d
ichotomy in isoprenoid biosynthesis in higher plants allows a reasonab
le interpretation of previous odd and inconclusive results concerning
the biosynthesis of chloroplast isoprenoids, which so far had mainly b
een interpreted in the frame of models using compartmentation of the m
evalonate pathway.