Figure 7.

Crosslinking experiments with the TFB variant F192Bpa and radiolabeled DNAs at position -19 T in complexes stalled at +6 to +20 as indicated. TFB is present at register +6 to +14 and crosslinking signals decrease at register +15 to +20. No crosslinking signal is detectable under run-off conditions. TFB-F192Bpa was crosslinked in initiation complexes (PIC; left lanes for each cassette) and in stalled complexes at the respective site (right lane for each cassette) with gdh-C cassettes containing a radiolabeled nucleotide at position -19 on the T-strand. Crosslinking under run-off conditions was performed on the gdh-C20 cassette. All reactions were performed in triplicates and the signals derived from crosslink experiments in halted complexes were compared to the signals of the respective PIC. The standard deviation (SD) as well as the average (A) was calculated and summarized in the bar diagram.