Figure 6.

In vivo footprinting analysis of the NtE2C promoter during the cell cycle. A, Change in the mitotic index during the synchronized cultures of BY-2 cells. The cells were synchronized by aphidicolin treatment. After release from the aphidicolin block, the cells were sampled at 1-h intervals during the culture period to measure the mitotic index. B, Cells at the indicated times after aphidicolin removal were treated in vivo with DMS, and ligation-mediated PCR amplification was performed as described in “Materials and Methods.” As a control, ligation-mediated PCR was performed on in vitro DMS-treated genomic DNA (lane m). Signals representing G residues are shown by black bars, and the protected G residues are indicated by arrowheads. Asterisks indicate the results of the independent experiment. C, Protected residues in in vivo footprinting. The nucleotide sequences of the NtE2C promoter are shown for both strands. The MSA-like motif is boxed, and the protected G residues are shown with a black background. Positions of the end-labeled primers used for the ligation-mediated PCR are shown by arrows (primers B3 and C3).