Beschreibung:
<jats:p>The origin of replication, oriC, of the Escherichia coli chromosome was mapped within a DNA segment of 422 base pairs. The nucleotide sequence of this segment was determined. The source of DNA for the sequence analysis was a minichromosome constructed in vivo, consisting exclusively of chromosomal DNA and a minichromosome constructed by cloning in vitro. The nucleotide sequence of the replication origin is characterized by a high degree of repetitiveness due to both inverted and direct repeats. Sequence homologies were found between portions of the replication origins of E. coli and phages lambda and G4. This suggests similarities in some steps in the initiation of replication of the different replicons.</jats:p>