Abstract
To understand the relationships between chromatin condensation and gene expression states, we evaluated the degree of chromatin condensation as DNase I sensitivity at a 500 bp resolution across a 80 kb Arabidopsis genomic region containing variously-expressed 30 protein-coding genes. The general DNase I sensitivity was at a similar level irrespective of gene expression states, suggesting that the chromatin condensation is relatively uniform. However, surprisingly, distinct DNase I hypersensitive sites (DNase I HSs) were found at both sides of most genes. Further analysis of several well-characterized genes showed that the DNase I HSs were present in transcriptionally-competent (expressed or inducible) gene promoters and absent from incompetent (not inducible) gene promoters. These results suggest that the DNase I HSs regulate gene expression potential by modulating the accessibility of the DNA elements to transcription regulators.
