Cre-LoxP sites

Gopaul, D. N., Guo, F. and Van Duyne, G. D. (1998). Structure of the Holliday junction intermediate in Cre-loxP site-specific recombination. EMBO J. 17, 4175-4187. 

Van Duyne, G.D. (2001) A structural view of Cre-loxP site-specific recombination. Annu. Rev. Biophys. Biomol Struct. 30, 87-104. 

Other research groups are combining stress inducible promoters with the Cre-LoxP site specific recombination system of PI bacteriophage. Scott et al. (2000) have combined the ionizing radiation inducible EGR-1 promoter with this recombination system to express herpes simplex vims thymidine kinase (HSV-tk). With this combination system, radiation doses relevant for cancer treatment can be used to... 

Removal of the Selection Marker by Cre/loxP Site-Specific Recombination... 

Cre is a bacterial recombinase (cre=causes recombination), which recognizes loxP sites of bacteriophage P. If two loxP (loxP= locus of x-ing over of bacteriophage P) sites have a parallel orientation, the DNA segment between these sites will be deleted by the action of the Cre recombinase. 

An alternative to repeated cloning of PCR products is a recombination-based approach developed by Liu et al. (1998) to permit the cloning of a PCR product into a plasmid and the rapid conversion of the plasmid to a number of different expression systems without the necessity of cloning the PCR product multiple, independent times. The method, termed the univector plasmid-fusion system (UPS), involves the insertion of the PCR product into a particular type of plasmid, called the univector, which can then be placed under the control of a variety of promoters or fused in-frame to various tag sequences. The system is based upon plasmid fusion using the Cre-lox site-specific recombination system of bacteriophage PI (Sternberg et al., 1981). The Cre enzyme is a site-specific recombinase that catalyzes recombination between two 34 base pair (bp) loxP sequences and is involved in the resolution of dimers formed during replication of the... 

Figure 4.3. Univector plasmid fusion system. Cre- loxP mediated site-specific recombination fuses the pUNI and pHOST plasmids at the loxP site. As a result, the gene of interest is placed under the control of the pHOST promoter and fused to any Tag sequences present in the pHOST plasmid.

P = constitutive promoter, tetR = TETrepressor gene,TETR = TET repressor protein, tetO = TET operator sequence, = tetracycline, ere/CRE = Cre recombinase gene/protein, PLEA = late embryogenesis abundant promoter, RIP = gene for ribosome inactivating protein, shaded blocks are loxP sites in orientation shown by solid triangle. After [48]... 

A widely used inducible system in the mouse is the bacteriophage Pl-derived Cre-LoxP system (25). The site-specific Cre recombinase recognizes specifically 34 bp loxP sites. Generating mice that harbor a DNA sequence flanked by two loxP sites and... 

Analogously to the Cre-LoxP system, the 34 bp Flippase recognition target (FRT) sites are recognized by the Flippase recombination enzyme (FLP) derived from Saccharomyccs cerevisiae (28). The FLP-FRT recombination system is also utilized for the inducible genetic manipulation of the mouse genome (29, 30). 

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