Biosynthesis of [14C]geranylgeranyldiphosphate by a prenyl transferase system from a mutant strain of Gibberella fujikuroi.

[14C]Geranylgeranyldiphosphate was produced by a prenyl transferase system extracted from the mutant strain SG4 of Gibberella fujikuroi (wild-type strain IMI 58289), which is blocked in carotenoid biosynthesis. The fungus was grown in liquid medium containing only potato-dextrose broth. Crude extracts of 12- to 14-day-old mycelia in Tris buffer, pH 8.5, were centrifuged at 100,000g. The supernatant was desalted and used to produce [4,8,12,16-14C]geranylgeranyldiphosphate from R,S-[2-14C]mevalonic acid. Maximum yield of [14C]geranylgeranyldiphosphate was obtained using mycelia from the stationary growth phase with incubation of the enzyme preparation at pH 8.5 for 5 h. Routinely, 65% of the biogenetic available R-mevalonic acid was converted to [14C]geranylgeranyldiphosphate, which was identified by cochromatography with authentic [1-3H]geranylgeranyldiphosphate by means of radio-TLC, radio-HPLC, and hydrolysis to geranylgeraniol.