Determination of nucleotide sequences beyond the sites of transcriptional termination

A procedure is described by which a discrete high-molecular-weight RNA transcription product can be used as a primer by DNA polymerase (DNA nucleotidyltransferase; EC 2.7.7.7; deoxynucleoside triphosphate: DNA deoxynucleotidyltransferase) for determining nucleic acid sequence in the template DNA beyond the 3'-terminus of the transcript. This procedure is applied to two lambda phage transcripts, the 4S "oop" RNA [Short l-strand RNA transcript from the region of origin of replication (ori) and the 6S RNA. Sequences of 35 and 19 nucleotides, respectively, following the sites at which these two transcripts terminate, are determined. Little structural homology is apparent in the template DNA beyond the 3'-ends of these two transcripts. The lack of homology suggests that this region might not be important to the termination process.