Incorporation of [2,3-¹³C₂]- and [2,4-¹³C₂]-D-1-deoxyxylulose into ubiquinone of Escherichia coli via the mevalonate-independent pathway for isoprenoid biosynthesis

[2,3-¹³C₂]- and [2,4-¹³C₂]-D-1-deoxyxylulose were synthesized from [2-¹³C]pyruvate and [1-¹³C₂]- or (2-¹³C]-DL-glyceraldehyde using the enzyme D-1-deoxyxylulose 5-phosphate synthase from Escherichia coli which was overexpressed in this bacterium. These doubly-labeled isoprenoid precursors in the mevalonate independent route were incorporated into the ubiquinone of E. coli. ¹J ¹³C/¹³C coupling constants were respectively found in isoprenic units between carbon atoms derived from C-3 and C-4 of isopentenyl diphosphate using the former labeled precursor or between C-3 and C-2 using the latter, indicating that D-1-deoxyxylulose was incorporated without prior degradation into isoprenoids and confirming that the branched isoprenic skeleton resulted from a rearrangement of the straight chain from carbohydrate precursor.