Terpenoids stand as an important class of natural compounds used for the commercial production of fragrances, flavors, and pharmaceuticals.  For example, the potent antimalarial agent artemisinin is a sesquiterpene lactone endoperoxide derived from the plant Artemisia annua.  Production of sufficient quantities of artemisinin from natural sources to meet current global demands suffers from a combination of low yield, difficulty isolating pure compounds, and resource intensive cultivation.  These hindrances have provoked increased efforts into the production of intermediates to artemisinin in microbial hosts.  Through a combination of protein and metabolic engineering we developed a novel in vivo biosynthesis of a semisynthetic precursor to artemisinin in E. coli at high titers.  Protein engineering of cytochrome P450 BM3 (CYP102) resulted in the novel ability to catalyze the production of a single isomer of artemisinic-11,12-epoxide (artemisinic epoxide) from amorpha-4,11-diene (amorphadiene).  A series of subsequent chemical modifications of artemisinic epoxide can be employed to yield artemisinin.  To this end, saturation mutagenesis was performed on several active site residues following both an analysis of the crystal structure as well as a protein sequence alignment to a native A. annua P450 (CYP71AV1).  This yielded a BM3 mutant capable of catalyzing a highly regio- and enantioselective epoxidation of amorphadiene.  The BM3 mutant producing the highest titers of artemisinic epoxide was also found to catalyze the production of indigo from indole; thus, the inactivation of E. coli chromosomal genes involved in tryptophan degradation was explored as a means to further increase artemisinic epoxide titers.