Single RNA Polymerase Binding Site Isolated

One approach to study the structure of promoter regions^1–3 is to isolate RNA polymerase binding sites. Several attempts have been made to isolate such sites as protected DNA fragments^4–10, but so far the DNA isolated has not definitely shown to be only one or a few specific sites. We report here the isolation of a single RNA polymerase binding site from the replicative form (RF) DNA of bacteriophage fd. The site as isolated is a short double-stranded DNA with a unique nucleotide sequence.