Fig. 5.

Hybrid length determines the ability of Nun to inhibit transcription. TECs were assembled as described in Fig. 1, but with RNA8A, RNA9A, and RNA11A (Table S1). All of the RNA primers shared the 3′ sequence, ending at +11A. RNA11A was fully complementary to TDS65, and RNA11A^M carried a 3-nt 5′-end mismatch. TEC 11A^R₁₁ was assembled with RNA11A^M, TDS65^M, and NDS65^M, restoring the full complementarity of the RNA to the template. The assembled TECs were preincubated with Nun or Nun storage buffer before (A) or after (B) addition of 5 μM CTP for 5 min. NTPs (1 mM) were added in even-numbered lanes for 60 s.