The Creation of a Size-Modified pUC19

In order to study the exclusion effect observed when Escherichia coli DH5 α cells are cotransformed with pBR322 (4361 bp) and pUC19 (2686 bp), a modified pUC19 plasmid must be constructed to match the size of pBR322 to determine whether or not it is plasmid size and the resulting stress on the cell during replication and transcription/translation that is the cause of the exclusion. The plasmid will be made by removing, through restriction digests, a 1.7 kb fragment of pBR322, was prepared and purified by gel electrophoresis and extraction. This fragment was isolated and ligated into a pUC19 that was linearized by a restriction digest, using an enzyme with a single recognition site on the plasmid. Constructs were selected for by α -complementation and screened using restriction analysis. None of the isolates were the desired construct.