Role of Cys73 in the thermostability of farnesyl diphosphate synthase from Geobacillus stearothermophilus

Farnesyl diphosphate synthase (FPPase) is an enzyme that catalyzes the condensation between one molecule of dimethylallyl diphosphate (DMAPP) and two molecules of isopentenyl diphosphate (IPP) to produce farnesyl diphosphate (FPP). FPP is an important precursor in the isoprenoid synthesis pathway. In this study, the crystal structure of FPPase from Geobacillus stearothermophilus (GsFPPase) was determined at 2.31 Å resolution. The structure of GsFPPase shows a three-layered all α-helical fold and conserved functional domains similar to other prenyltransferases. We have analyzed the structural features of GsFPPase related to thermostability and compared it with those of human and avian mesophilic FPPases. “Semi-conserved” regions which appear to be possible features contributing to the thermostability of FPPase were found.