FLP-FRT recombination

The FLP / FRT system is a method for the removal or insertion of the genetics of the DNA sequences. The FLP / FRT system is used inter alia in the reverse genetics and in the cartridge exchange process for the production of transgenic organisms.

Properties

The FLP / FRT system is used, the flippase recombinase (FLP ) to exchange DNA sequences site specific. The Flp recombinase binds to FRT sequences and recombining them, for example, in a chromosome or a plasmid. The minimal FRT sequence reads ( 34 base pairs):

The flippase binds to both ends of the FRT sequence, which are palindromic to each other on both DNA strands. In the middle of the FRT sequence, a minimum spacing is eight base pairs ( tctagaaa ). On the plus strand is effected by the hydrolysis of a flippase DNA from the spacer, on the minus strand by the spacer.

Although different FRT sequences are known, recombination will only between two identical sequences. Some FRT sequences have in the 5'- direction, an additional DNA sequence (5'- GAAGTTCCTATTCC -3 '), a base before the FRT sequence:

This segment is not necessary for the removal of a DNA sequence (in the case of a deletion ), but necessary for insertion, for example, when RMCE cartridge exchange process. The insertion is carried out with inversion of the DNA sequences. After recombination remain parts of the FRT sequences ( FRT English - Twins ). The recombination can be limited by tissue-specific promoters to individual organs. By inducible promoters (eg, tamoxifen or mifepristone ) of Rekombinationszeitpunkt can be controlled, for example, in the expression of toxic proteins or lethal factors.

Applications

By the FLP / FRT system is used with deletions or insertions, for example, in gene knock-out, wherein said mosaic generation or for the production of transgenic embryonic stem cells for the generation of mutants. It was used among others in mice, Drosophila spp., Baker's yeast and plants.

An alternative to the FLP / FRT system is the Cre / loxP system.