Nucleotide sequence of the partition function of Escherichia coli plasmid ColE1

The DNA nucleotide sequence of a 382-bp Hpa II fragment containing cer (ColE1 resolution) function responsible for ColE1 plasmid stability in dividing Escherichia coli was determined. The partition (par) region of pSC101 and the cer region have similar biological functions, as they both maintain plasmid stability through plasmid monomerization. Both regions contain 40- to 70-bp hairpin-loop structures that resemble bidirectional transcription terminators and share sequence homology with each other. Deletion mapping of the cer fragment shows that sequences extending beyond both sides of the terminator-like structure are also involved in the plasmid partition process.