Expression profiling of genes involved in paclitaxel biosynthesis for targeted metabolic engineering

WITHDRAWN: TcJAMYC: A bHLH transcription factor that activates paclitaxel biosynthetic pathway genes in yew

“…Figure 5) is strongly activated by MJ is somewhat surprising. The endogenous BAPT transcript was undetectable using RNA gel blot analysis, and up-regulation of mRNA expression from this gene was only detectable using a more sensitive RT-PCR assay (7). This difference in expression between the BAPT reporter construct and the endogenous BAPT gene implies a separate level of regulation of the endogenous gene, perhaps at the posttranscriptional level.…”

“…Prior work in the Taxus system demonstrated a positive correlation between the steady state mRNA abundance of the paclitaxel biosynthetic pathway genes (hereafter referred to as "pathway genes") and MJ elicitation (7). This suggested that increased transcription of pathway genes was occurring in response to MJ elicitation.…”

“…paclitaxel occurs much later (three to six days after elicitation), long after steady state transcript levels of the known pathway genes have returned to normal (7). The mechanism(s) underlying the poor correlation between steady state mRNA levels and accumulation of the desired metabolite paclitaxel are not understood.…”

Endophytes: exploiting biodiversity for the improvement of natural product-based drug discovery

“…While the pursuit of the idea of a microbial paclitaxel source, providing for an inexhaustible supply of this antineoplastic blockbuster and novel taxanes, is being hampered by obtaining disappointingly low yields, the active ingredient is still mainly derived via chemical semisynthesis from the advanced taxoid, 10-deacetylbaccatin III, readily available from the needles of the European yew tree, Taxus baccata, being a renewable source and, to a lesser extent, by means of plant cell culture methods (Leistner 2005;Frense 2007). Nonetheless, the exciting progress that has been made in the elucidation of biosynthetic route leading to paclitaxel in planta due to fundamental works of Croteau and his co-workers (Walker and Croteau 2001;Jennewein et al 2004a, b;Croteau 2005;DeJong et al 2006;Nims et al 2006), as well as the recent advances in microbial genomics (Zazopoulos et al 2003;Stephanopoulos et al 2004;Keller et al 2005;van Lanen and Shen 2006) and combinatorial biosynthesis (Floss 2006;Nguyen 2006;KleinMarcuschamer et al 2007), might still revive and boost the interest in endophytic paclitaxel synthesizers.…”

“…Whole-genome sequence mining (Lautru et al 2005) and genome scanning as an alternative approach, providing an efficient way to discover natural product biosynthetic gene clusters without having the complete genome sequence (Zazopoulos et al 2003); advances in microbial cell fermentation technology (Zengler et al 2005;Weuster-Botzl et al 2007) and metagenomics as a valuable alternative offering a cultivation-independent approach (Schloss and Handelsman 2005); ample successes in heterologous expression and metabolic engineering (among many others: Alper et al 2005;Schmidt et al 2005;Wenzel et al 2005;DeJong et al 2006;Julsing et al 2006;Lindahl et al 2006;Nims et al 2006;Ro et al 2006), the latter being in fact perceived as a progenitor of functional genomics and systems biology (Stephanopoulos et al 2004;Tyo et al 2007) Á to name only a few highlights.…”