Glyceraldehyde 3-Phosphate and Pyruvate as Precursors of Isoprenic Units in an Alternative Non-mevalonate Pathway for Terpenoid Biosynthesis

Incorporation of 13 C-labeled glycerol or pyruvate into the ubiquinone Q8 of Escherichia coli mutants lacking enzymes of the triose phosphate metabolism and of (U- 13 C 6 )glucose into the triterpenoids of the hopane series of Zymomonas mobilis showed that glyceraldehyde 3-phosphate (or eventually glyceraldehyde) and a C 2 unit derived from pyruvate decarboxylation were the only precursors of the C 5 skeleton of isoprenic units in a novel non-mevalonate pathway for isoprenoid biosynthesis in these bacteria.