Didehydrogeranylgeranyl (Delta Delta GG): a fluorescent probe for protein prenylation

The first intrinsically fluorescent analog of geranylgeraniol, (2E,6E,8E,10E,12E,14E)-geranylgeraniol (all-trans-DeltaDeltaGGOH.1) has been synthesized stereoselectively and shown to substitute for the geranylgeranyl (GG) moiety in prenyl transferase reactions and in protein-ligand binding assays. All-trans-DeltaDeltaGGOH 1 showed blue fluorescence in methanol, with lambdaex = 310 nm and lambdaem = 410 nm (epsilon310 = 2.4 x 104 M-1 cm-1), but was only weakly fluorescent in aqueous solution. The prenyl transferase efficiency for DeltaDeltaGGPP 2 as a substrate for yeast protein geranylgeranyl transferase (PGGTase-I) was 60% relative to that for GGPP. The binding of DeltaDeltaGG-AcCysMe 3 to the recombinant Rho GTPase dissociation inhibitor (RhoGDI) had a KD of 15.1 +/- 1.2 muM, 6-fold lower than the affinity of GG-AcCysMe. Thus, the DeltaDeltaGG moiety is a novel fluorophore suitable for studying the interaction and subcellular localization of prenylated small GTPase proteins in signaling complexes.