Schematic representation of the cut/ligation reaction for tetramer plasmid construction.

<p>4 selected monomer plasmids at each position (NI-1, HD-2, NG-3 and NN-4 for example in this Figure) are put into a reaction pool containing T4 DNA ligase, <i>Bsa</i>I and ligase buffer. Once the temperature rises to 37°C, the right side of NI-1, both sides of HD-2, NG-3 and the left side of NN-4 are digested by <i>Bsa</i>I. The unique cohesive ends facilitate the positioning of each monomer in the ligation product. T4 DNA ligase joins the fragments together at 16°C. The number of constructed tetramer plasmids increases as the cycles continue.