Question

components for conservative site-specific recombination involving Cre recombinase?

Answer 1

Conservative site-specific recombination is a type of DNA recombination that involves the exchange of genetic material between segments of DNA exhibiting some amount of sequence homology. Site-specific recombinases (SSRs) bind to short specific DNA sites where they cleave the DNA backbone and allow the exchange of DNA helices followed by rejoining of DNA strands thus causing DNA segment rearrangements. There are two types of recombinases, tyrosine recombinases, and serine recombinases.

Cre recombinase is a tyrosine recombinase and is obtained from P1 bacteriophage. It plays an important role in its life cycle. DNA recognition site is 34 base pair LoxP sites. Its location and orientation play an important role in recombination. Two DNA species having LoxP sites undergo fusion. DNA between LoxP sites (sequence flanked by 2 LoxP sites is known as a floxed sequence) having the same orientation/direction is excised as a circular loop of DNA while the opposite orientation of 2 LoxP sites causes inversion of floxed sequence. Cre recombinase does not require accessory proteins or cofactors for its function.

Cre-LoxP system is very simple to use and is robust which makes it an important tool for research in molecular biology. It can carry out insertions, deletions, translocations, inversions, etc. at specific sites in DNA.