Schematic depicting the mechanism of transposition catalyzed by the Tn5 transposase

This schematic diagram illustrates the mechanism of transposition catalyzed by the Tn5 transposase. In the first step, individual molecules of transposase (blue spheres) bind to specific sites at the ends of the transposon DNA (purple). In the next step, looping of the transposon DNA results in formation of a synaptic complex that brings the two ends of the transposable element close together. Once the synaptic complex has been formed, the Tn5 transposase cuts the transposon DNA away from the flanking “donor” DNA (green). After cleavage, the Tn5 transposase/DNA complex can move about freely until it encounters and binds to the “target” DNA (red). Through a process called strand transfer the transposase catalyzes insertion of the transposon DNA into the target DNA, completing the transposition process.