Biosynthesis of isoprenoids (carotenoids, sterols, prenyl side-chains of chlorophylls and plastoquinone) via a novel pyruvate/glyceraldehyde 3-phosphate non-mevalonate pathway in the green alga Scenedesmus obliquus.
Isoprenoid biosynthesis was investigated in the green alga Scenedesmus obliquus grown heterotrophically on 13C-labelled glucose and acetate. Several isoprenoid compounds were isolated and investigated by 13C-NMR spectroscopy. According to the 13C-labelling pattern indicated by the 13C-NMR spectra, the biosynthesis of all plastidic isoprenoids investigated (prenyl side-chains of chlorophylls and plastoquinone-9, and the carotenoids beta-carotene and lutein), as well as of the non-plastidic cytoplasmic sterols, does not proceed via the classical acetate/mevalonate pathway (which leads from acetyl-CoA via mevalonate to isopentenyl diphosphate), but via the novel glyceraldehyde 3-phosphate/pyruvate route recently detected in eubacteria. Formation of isopentenyl diphosphate involves the condensation of a C2 unit derived from pyruvate decarboxylation with glyceraldehyde 3-phosphate and a transposition yielding the branched C5 skeleton of isoprenic units.
Schwender
J
J
Botanisches Institut II, Universität Karlsruhe, Germany.
Seemann
M
M
Lichtenthaler
H K
HK
Rohmer
M
M
D002247:Carbon Isotopes; D002338:Carotenoids / Q000096:biosynthesis*; D002734:Chlorophyll / Q000096:biosynthesis*; D000460:Chlorophyta / Q000378:metabolism*; D005986:Glyceraldehyde 3-Phosphate / Q000378:metabolism*; D006038:Glyoxylates / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D010427:Pentose Phosphate Pathway; D010971:Plastoquinone / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism*; D013261:Sterols / Q000096:biosynthesis*; D013729:Terpenes / Q000378:metabolism*
D002247:Carbon Isotopes; D006038:Glyoxylates; D011773:Pyruvates; D013261:Sterols; D013729:Terpenes; D002734:Chlorophyll; D005986:Glyceraldehyde 3-Phosphate; D002338:Carotenoids; D010971:Plastoquinone