The function and properties of heterologously expressed full-length cDNA clones, isolated from a Taxus cDNA library and specific to Taxol biosynthesis, are summarized. Recombinant enzymes are described that catalyze early steps of the pathway, including taxadiene synthase, taxadin-5 alpha -ol-O-acetyltransferase and taxadien-5 alpha -yl acetate IOP-hydroxylase. and that catalyze late steps, including 10-deacetylbaccatin III-10 beta -O-acetyltransferase and taxane 2 alpha -O-benzoyltransferase. The properties of Taxus geranylgeranyl diphosphate synthase are also described, although this synthase does not mediate a committed step of Taxol biosynthesis, it does provide the universal plastidial diterpenoid precursor, geranylgeranyl diphosphate, for initiating Taxol biosynthesis. (C) 2001 Elsevier Science Ltd. All rights reserved.