Zinc Finger Proteins Act as Transcriptional Repressors of Alkaloid Biosynthesis Genes in Catharanthus roseus

Abstract

In Catharanthus roseus cell suspensions, the expression of several terpenoid indole alkaloid biosynthetic genes, including two genes encoding strictosidine synthase (STR) and tryptophan decarboxylase (TDC), is coordinately induced by fungal elicitors such as yeast extract. To identify molecular mechanisms regulating the expression of these genes, a yeast one-hybrid screening was performed with an elicitor-responsive part of the TDC promoter. This screening identified three members of the Cys 2 /His 2 -type (transcription factor IIIA-type) zinc finger protein family from C. roseus, ZCT1, ZCT2, and ZCT3. These proteins bind in a sequence-specific manner to the TDC and STR promoters in vitro and repress the activity of these promoters in trans-activation assays. In addition, the ZCT proteins can repress the activating activity of APETALA2/ethylene responsefactor domain transcription factors, the ORCAs, on the STR promoter. The expression of the ZCT genes is rapidly induced by yeast extract and methyljasmonate. These results suggest that the ZCT proteins act as repressors in the regulation of elicitor-induced secondary metabolism in C. roseus.

The Leaf Epidermome ofCatharanthus roseusReveals Its Biochemical Specialization

“…However, this clone (CAC27827) is not likely to catalyze the G10H reaction since it was more similar in sequence to other CYPs, including T16H, than to the functionally characterized G10H clone (CAC80883). In general, the ESTs that encoded MIA biosynthesis enzymes were represented several times compared with those of the three transcription factors (ORCA3, BPF1, and ZCT2) (van der Fits and Memelink, 2000;van der Fits et al, 2000;Pauw et al, 2004) that were only represented once. These relative differences implied that transcription factors were expressed at lower levels than those of the MIA pathway enzymes that they regulate (Table 1) and that the overall profile of mRNA expression in the leaf epidermal cells of Catharanthus was largely maintained in the CROLF1NG data set.…”

The Transcription Factor CrWRKY1 Positively Regulates the Terpenoid Indole Alkaloid Biosynthesis in Catharanthus roseus

“…TIA biosynthesis responds strongly to a group of chemical or fungal elicitors that are known to regulate gene transcription, providing an explanation for why the manipulation of TFs often results in substantial effects to the TIA pathway (El-Sayed and Verpoorte, 2007). Promoter analyses of several structural and TF genes related to the C. roseus TIA pathway have revealed the presence of chemical-and elicitorresponsive cis-elements, leading to the cloning of jasmonate-responsive TFs including the AP2-like ORCA2 and ORCA3 (Menke et al, 1999;Ouwerkerk and Memelink, 1999;, the G box-binding factors CrGBF1 and CrGBF2 (Sibéril et al, 2001), the P box-binding factor CrBPF1 (van der , the zinc-finger repressors ZCT1 (for zinc-finger C. roseus transcription factor 1), ZCT2, and ZCT3 (Pauw et al, 2004), and the basic helix-loop-helix TF CrMYC2 (Zhang et al, 2011).…”

A novel CaAbsi1 gene induced by early-abiotic stresses in pepper

“…These Cys2/His2 zinc finger proteins (also called TFIIIA-type, or classical zinc finger) were located in the nucleus and could bind to DNA. The Cys2/His2 zinc finger protein was known to work as repressors, regulating alkaloid biosynthesis transcripts in Catharanthus roseus (36). The spermine-mediated signal transduction pathway in Nicotinana was indicated by drought, cold and high-salinity stress conditions in Arabidopsis (37).…”