Ribonucleotides associated with a gap in newly replicated kinetoplast DNA minicircles from Trypanosoma equiperdum

In Trypanosoma equiperdum, some newly replicated kinetoplast DNA minicircles contain a single gap at a unique location in their newly synthesized strand (Ntambi, J.M., and Englund, P.T. (1985) J. Biol. Chem. 260, 5574-5579). We now report that ribonucleotides are associated with this gap, with one or two covalently attached to the 5' terminus of the newly synthesized strand. There appear to be two possible RNA/DNA junctions at adjacent positions in the sequence. The ribonucleotides may be remnants of a replication primer, and their presence strongly implies that the gap is at the site of a replication origin.