Inducible expression system

B. subtilis is the Bacillus species used most, and also the best characterized host [36,37]. A problem with high proteolysis of secreted proteins was solved by constructing the sacB-sacY sucrose-inducible expression system [38] and developing the six protease-deficient strain WB600 or even the eight protease-deficient strain WB800 [39]. Yields can be up to 3 gL-1 media [40]. 

Herai, S., Hashimoto, Y., Higashibata, H. et al. (2004) Hyper-inducible expression system for streptomy-cetes. Proceedings of the National Academy of Sciences of the United States of America, 101 (39), 14031-14035. 

Since this promoter can be induced by the addition of zinc, it allows for the conditional expression of genes. This induction is especially important if the expression of a particular gene is deleterious to the cell. For example, the adenomatous polyposis coli (APC) tumor suppressor gene was inserted into a vector downstream of the MT II promoter (Morin et al., 1996). Since continuous expression of APC is inhibitory to cell growth, an inducible expression system was necessary to examine the effects of APC expression on cells. This promoter was specifically chosen due to its low basal activity in the absence of zinc The drawbacks to this system are the potential effects that increased zinc concentrations may have in the cell. These effects may include toxicity to the cell or altered gene expression due simply to the presence of zinc. 

An overview of some of the most common vector systems is provided in Table 4.5. All the vectors chosen here are inducible expression systems. Induction can result from a change in temperature, from addition of metabolites, or from removal of a necessary carbon source. 

Takahashi et al.61s further identified the primary structure by preparing a cDNA library from A. fumigatus induced with fructosylpropylamine and isolated a clone using a polyclonal Amadoriase II antibody. The structure comprised 438 amino acid residues, corresponding to 48.798 kDa. The identity of the Amadoriase n cDNA was further confirmed by expression in Escherichia coli cells with an inducible expression system. Northern-blotting analysis showed that Amadoriase II was induced by fructosylpropylamine in a dose-dependent manner. The sequence determined showed the enzyme to represent a new family of mammalian enzymes. The sequence exhibited 82 and 36% identity and 92 and 65% similarity, respectively, with the two sequences determined by Yoshida et al.616 Amadori products have been implicated in the formation of H202, but the in vivo mechanism needs to be elucidated further. 

CHO cells, using an inducible expression system [100], and in HEK cells [97]. While the recombinant channels show the expected pharmacology, some of the biophysical properties differ from native TTX-resistant currents, suggesting the existence of auxiliary subunits. In Xenopus oocytes and in mammalian cells, expression of rNayl.8 was increased substantially by co-expression with Navbl and Navb3, respectively [98,101]. 

Purvis, I.J., D. Chotai, C.W. Dykes, D.B. Lubahn, F.S. French, E.M. Wilson, and A.N. Hobden. 1991. An androgen-inducible expression system for Saccharomyces cerevisiae. Gene 106 35-42. 

Several prokaryotic repressors can also be used in eukaryotes. Most notable is the tetracycline (TET) inducible expression system, which has had a... 

Yasumori, T., N. Murayama, Y. Yamazoe, A. Abe, Y. Nogi, T. Fukasawa et al. (1989). Expression of a human P-45011C gene in yeast cells using galactose-inducible expression system. Mol Pharmacol. 35, 443-449. 

The AhR is a well-researched receptor in a mammalian dioxin-dependent inducible expression system (Figrue 1) [5], Dioxins that are transferred into mammalian cells specihcaUy bind to the AhR complex, which then is transported into the nucleus, where it forms a heterodimer with an AhR nuclear translocator (Arnt). The heterodimer binds to a xenobiotic responsive element (XRE) upstream of the gene for a drug-metabolizing enzyme (GYPlAl). This binding induces the production of CYPlAl mRNA and thus the production of the GYPlAl enzyme, which metabolizes some dioxins. 

Plassmeier, J.K., Busche, T., Molck, S, Persicke, M., Piihler, A., Riickert, C., and Kalinowski, J. (2013) A propionate-inducible expression system based... 

G., Liang, Y, and Wen, T. (2012) Development and application of an arabinose-inducible expression system by facilitating inducer uptake in Corynebacterium glutamicum. 

Horbal, L., Fedorenko, V., and Luzhetskyy, A. (2014) Novel and tightly regulated resorcinol and cumate-inducible expression systems for... 

Beyond constitutive expression systems, several inducible expression systems are also available, yet require addition of an inducer to initiate promoter activity. Unfortunately, most inducible promoters exhibit an all-or-nothing behavior, and thus are not fit for fine-tuning gene expression. Therefore, random mutagenesis... 

The plasmid pSKAVAtG was constructed for dioxin-inducible expression system of GUS(6-glucuronidase) reporter gene and transformed into tobacco plants by Agrobacterium tumefaciens( gMte The... 

Figure 1 The expression plasmid for arylhydrocarbon receptor-dependent inducible expression system for GUS reporter gene m35S-P, T, 35S-P and NPTII represent minimal cauliflower mosaic virus(CaMV) 35S promoter, terminator, CaMV 35S promoter and kanamycin resistance gene, respectively.

Figure 4 Expression plasmids for estrogen receptor-dependent inducible expression system for GFP reporter gene P, NPTII, 8xLexA-46 and T represent promoter, kanamycin resistance gene, 8 copies of LexA binding domain and terminator, respectively.

Expression in E. coli of the cloned polymerase gene, even at the uninduced basal level, is apparently highly toxic to the host. Overexpression ( 150-fold) of the gene is possible only in a tightly controlled inducible expression system consist-... 

Nisin-controlled gene expression (NICE) The NICE system is the most commonly used inducible expression system for heterologous proteins production in LAB. The synthesis. 

Zinc-inducible expression systems (P j ZitR-driven Heterologous Expression and Zirex) ... 

More recently, a new zinc-inducible expression system, called Zirex, was developed for L. Metis (Mu et al. 2013). When triggered by a non-toxic concentration of zinc, the streptococcal promoter PczcD (regulated by the SezA repressor) is activated and leads to elevated expression levels. Moreover, Mu and colleagues have successfully combined both the NICE system and Zirex to produce different proteins at different times in the same microorganism. 

Miyoshi, A., Jamet, E., Commissaire, J., et al. (2004) A xylose-inducible expression system for Lactococcus lactis. FEMS Microbiol Lett 239, 205-212. 

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