Δ21 can use a 21-nt circular RNA template. (A) The sequence of linear LE21, LE21-L along with the possible dimer formation between two molecules of RNA is shown. The arrows indicate the direction of RNA synthesis. The initiation nucleotide is underlined. (B) A demonstration that the ligated RNAs exist in a covalently closed form. The purified RNAs were treated with poly(A) polymerase and [α-32P]ATP as described in Figure 1. (C) Initiation of RNA synthesis from linear and circular templates. The reactions were performed with 0.2 pmol of linear and 5 pmol of circular template RNA and 0.04 μM Δ21. The two different concentrations of GTP, 2 μM and 200 μM, used are given on the top, and the sizes of RNA products are given at the left of the gel.
