The role of histidine-114 of Sulfolobus acidocaldarius geranylgeranyl diphosphate synthase in chain-length determination

Sulfolobus acidocaldarius geranylgeranyl diphosphate synthase yields (all-E )-C-20 prenyl diphosphate as a final product. The three-dimensional model o f the enzyme suggested that removing two bulky residues at 77 and 114 would allow additional prenyl-chain elongation. To test this, we examined severa l mutants with substitutions at 77 and/or 114. As a result, the mutants, F7 7G, F77G and H114A, F77G and H114G, H114A. and H114 gave C-30, C-45, C-50, C-30 and C-40 as the main long product, respectively. These observations in dicate that histidine-114 plays a crucial role in chain-length determinatio n along with phenylalanine-77. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.