Abstract
We have shown previously that a left-handed curved DNA segment of 180 bp (T20) can activate eukaryotic transcription. Here, the local chromatin structure around the promoter was investigated in a HeLa cell line HLB10/T20 harboring the T20-containing reporter and in its control cell line HLB10 in which T20 was deleted from the same reporter locus. An analysis of translational positioning of nucleosomes indicated that the nucleosome density in the region spanning from about -500 to +200 relative to the transcription start site (+1) was lower in HLB10/T20 cells than in HLB10 cells. The results of the chromatin analyses also indicated that the histone core may slide within the T20 region, and the ability of T20 to capture and reposition histones may increase the accessibility of both the TATA box and other cis-DNA elements. These effects seem to be responsible for facilitation of transcription by T20.
