The nucleotide sequence surrounding the origin of DNA replication of Col E1.

The DNA of Col E1 replicates from a unique origin located at a distance of 17-19% of the genome length from the single Eco RI clevage site. The nucleotide sequence about this site has been determined by a combination of RNA and DNA sequencing techniques. The principal features of the sequence are two palindromes, one of which resembles a palindrome located in the intercistronic region of 0X174. The sequence also contains stretches of purine and pyrimidine clusters of the following compositions: pAT5G, pC2T5G, pGT5G. The origin sequence demonstrates that initiation of DNA replication takes place in an intercistronic region of Col E1DNA, although the possibility that this region makes small polypeptides 30-40 residues long cannot be strictly eliminated at this time.