Topocloning

Topocloning is a faster and more efficient version of  traditional cloning. Cloning is the process by which a DNA sequence of interest is integrated into a vector plasmid. This is done traditionally by cutting the plasmid with a restriction enzyme and then ligating either end of the sequence to the open ends of the plasmid. The ligation step is typically performed by an enzyme called ligase. The use of two different enzymes in two different steps makes the traditional cloning method ineffective. Many errors occur using this method. The advent of topocloning has circumvented the use of two enzymes, by the use of a single enzyme called topoisomerase 1. The vector comes open with two toposiomerase 1 enzymes on either end of the open vector. Once the sequence of interest comes into the gap, the topoisomerase 1 enzymes catalyze the ligation step, closing up the vector and integrating the appropriate sequence into the vector.