Mobile genetic element · BEGINNER LESSON
PiggyBac
PiggyBac is a DNA transposon system: a movable DNA segment and its matching transposase enzyme that can move the DNA into a new genome site, usually at TTAA sequences. In research cells, it is used to insert genes into chromosomes for longer-lasting expression.
What it is
PiggyBac is a transposon, meaning a DNA segment that can change its position in a cell’s genome. The PiggyBac system has two needed parts: the transposon DNA with terminal inverted repeats, and a transposase enzyme that recognizes those repeats and moves the DNA. The cargo DNA is inserted into chromosomes, so the added sequence becomes part of the genome rather than staying only on a separate vector. [0,1]
[1] Non-codon Optimized PiggyBac Transposase Induces ... - PMC [2] PiggyBac transposon vectors: the tools of the human gene ...
How it works
PiggyBac moves by a cut-and-paste mechanism. The transposase cuts the transposon out, then the cell repairs the DNA ends by ligation, which joins the ends without making a new DNA copy. In mammalian cells, insertion occurs at TTAA target sites, and the process can be seamless, meaning no extra bases are left behind at the junction after excision and insertion. [0,1]
[1] Non-codon Optimized PiggyBac Transposase Induces ... - PMC [2] PiggyBac transposon vectors: the tools of the human gene ...
Why it is useful
Because PiggyBac can integrate into the host genome, it can support long-term expression of genes of interest. The sources also note that it can carry large DNA cargo compared with many other systems, and it has been used as an alternative to viral delivery in mammalian research. [0,1]
[1] Non-codon Optimized PiggyBac Transposase Induces ... - PMC [2] PiggyBac transposon vectors: the tools of the human gene ...
Limitations and cautions
PiggyBac activity depends on the matching transposase and transposon, so the system works best with its cognate, or matching, DNA repeats. Too much transposition activity can disturb normal development in experimental systems, and the sources emphasize that transposase removal after the initial integration step is important to reduce further jumping. The family is also species restricted: PiggyBac-related proteins do not freely mobilize unrelated PiggyBac-like elements in the tested human or mouse systems. [0,2]
[1] Non-codon Optimized PiggyBac Transposase Induces ... - PMC [3] Cognate restriction of transposition by piggyBac-like proteins
SEE THE IDEA
PiggyBac cut-and-paste integration
Cargo gene flanked by terminal inverted repeats that the enzyme recognizes
Enzyme that cuts the transposon and helps move it
Preferred insertion target in the chromosome
Cell ligates the DNA ends, leaving the cargo integrated
The transposase recognizes the transposon repeats, excises the DNA, and the cell rejoins the ends at a TTAA site to place the cargo into the genome.
A matching enzyme and DNA element enable precise cut-and-paste insertion into TTAA target sites.
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Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.