The nucleotide sequence of the region surrounding the replication origin of an R100 resistance factor derivative

The replication origin of a group of small plasmids derived from R100 was previously determined by electron microscopy (Ohtsubo et al., 1977). This region was subjected to extensive restriction enzyme analysis and the nucleotide sequence of the region containing the replication origin was determined using the Maxam and Gilbert sequencing technique. Various characteristics of this sequence, including a very interesting secondary structure are described and discussed.