CYTOCHROME P450-CATALYZED HYDROXYLATION OF TAXA-4(5), 11(12)-DIENE TO TAXAN-4(20), 11(12)-DIEN-5X-OL: THE FIRST OXYGENATION STEP IN TAXOL BIOSYNTHESIS

Authors: HEFNER, JRRY - WASHINGTON STATE UNIV.; RUBENSTEIN, STEVEN - COLORADO STATE UNIVERSITY; KETCHUM, RAYMOND - CORNELL UNIVERSITY; GIBSON, DONNA; CROTEAU, RODNEY - WASHINGTON STATE UNIV.

Submitted to: Chemistry and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Taxol is a potent chemotherapeutic drug with potential against a range of cancers. The very limited supply of this drug from the original source, Pacific yew bark, however, prompted the development of alternative sources of production, including chemical synthesis and cell cultures. The economics of taxol production indicates that biological methods of production, either from the plant or from cultures derived from the plant, are the methods of choice. Improving the production will require a detailed understanding of how taxol is biologically synthesized and the enzymes involved in the pathway. In this report, we have identified one of the first steps in the pathway and the type of enzyme involved at this step. Since this step is slow relative to other steps, manipulating this portion of the biological pathway by genetic means could increase taxol production.

Technical Abstract: Microsomal enzymes from Taxus stem and cultured cells were used to define the first hydroxylation of taxadiene. We confirmed the structure of the reaction product (taxa-4(20),11(12)-diien-5x-ol) by synthesizing this compound. The responsible biological catalyst was characterized as a cytochrome P450 (heme thiolate protein). In vivo studies confirmed that taxadienol is a biosynthetic intermediate and indicated that the hydrolyxation step that produces this product is slow relative to subsequent metabolic transformation.