Minicircle

In the mitochondria-derived kinetoplast of trypanosomes, minicircles encode guide RNAs for RNA editing.

[2][3] Minicircles are small (~4kb) circular plasmid derivatives that have been freed from all prokaryotic vector parts.

They have been applied as transgene carriers for the genetic modification of mammalian cells, with the advantage that, since they contain no bacterial DNA sequences, they are less likely to be perceived as foreign and destroyed.

The smaller size of minicircles also extends their cloning capacity and facilitates their delivery into cells.

Their preparation usually follows a two-step procedure:[4][5] The purified minicircle can be transferred into the recipient cell by transfection or lipofection and into a differentiated tissue by, for instance, jet injection.

Minicircle preparation from a parental plasmid. The parental plasmid contains two recombinase target sites (black half arrows). Recombination between these sites generates the desired minicircle (bottom right) together with the miniplasmid (bottom left). The hook on the red minicircle-insert stands for a scaffold-matrix attachment region ( S/MAR-Element ), which allows for autonomous replication in the recipient cell.