Cytochrome P450-catalyzed hydroxylation of taxa-4(5),11(12)-diene to taxa-4(20),11(12)-dien-5a-o1: the first oxygenation step in taxol biosynthesis

Abstract

The structure of the first oxygenated intermediate on the taxol pathway establishes that the hydroxylation reaction proceeds with an unusual double bond migration that limits the mechanistic possibilities for subsequent elaboration of the oxetane moiety of taxol. The reaction is catalyzed by a cytochrome P450, suggesting that the seven remaining oxygenation steps in taxol biosynthesis may involve similar catalysts. Because the first oxygenation step is slow relative to subsequent metabolic transformations, it may be possible to speed taxol biosynthesis by isolating and manipulating the gene for the taxadiene-5-hydroxylase that catalyzes this reaction.

A Bioinspired Catalytic Oxygenase Cascade to Generate Complex Oxindoles

“…[4] For instance, generation of the polycyclic taxane precursor 2 from acyclic tetraene 1 is followed by introduction of a 5-a-hydroxy group (3) by a cytochrome-P450-dependent hydroxylase-mediated oxygenase reaction (Scheme 1 a). [5] TET (ten eleven translocation) proteins induce oxidation of 5-methylcytosine (4) into 5-hydroxymethylcytosine (5) and 5-formylcytosine (6, Scheme 1 b) [6] which undergoes decarboxylation and thereby induces DNA demethylation as an epigenetic control. [7] A large class of oxidase and oxygenase enzymes contains copper metal in their active sites to bind and activate O 2 .…”

Trichome Specific Expression: Promoters and Their Applications

“…The first of these oxidations was shown to be at the C5 position of the taxadiene core, which is necessary to form the so-called oxetane ring (Hefner et al, 1996). Subsequently, a gene encoding taxadiene 5--hydroxylase (T-5-OH) was identified and characterized (Jennewein et al, 2004).…”

TAXOIDES: METABOLITOS SECUNDARIOS DEL ÁRBOL DEL TEJO (Taxus spp.)

“…Esta enzima, aparte de su actividad hidroxilativa, tiene condiciones de migración del doble enlace de 4(5) a 4(20). Estos dos pasos metabólicos, ciclización e hidroxilación, son bajos y no se observan por ser limitantes en la velocidad de la biosíntesis del taxol (Hefner et al, 1996). El próximo paso en la ruta de biosíntesis que comienza a formar el taxol es catalizado por una enzima específica: taxadieno-5α-ol-O-acetil transferasa (TDAT) que acila taxa-4(20),11(12)-dien-5α-ol a la posición del C 5 para formar taxa-4(20), 11(12)-dien-5α-yl-acetato.…”

“…Después de la formación del precursor polihidroxilado hipotético por la actividad de la enzima 2α-O-benzoyl These two metabolic steps, cyclization and hydroxylation, are low and not shown because they are constraints in the speed of taxol biosynthesis (Hefner et al, 1996). The next step in the biosynthetic pathway that begins to form taxol is catalyzed by a specific enzyme: taxadiene-5α-ol-O-acetyl transferase (TDAT) that acylates taxa-4(20), 11(12)-dien-5α-ol at the C 5 position to form taxa-4 (20), 11(12)-dien-5α-yl-acetate.…”