Kodama Yuichi, Nagaya Shingo, Shinmyo Atsuhiko, Kato Ko
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
Plant Cell Physiol. 2007 Mar;48(3):459-70. doi: 10.1093/pcp/pcm017. Epub 2007 Feb 5.
Recent genome-wide analyses of yeast and human chromatin revealed the widespread prevalence of DNase I hypersensitive sites (DNase I HSs) at gene regulatory regions with possible roles in eukaryotic gene regulation. The presence of DNase I HSs in plants has been described for only a few genes, and we analyzed the chromatin structure of an 80 kb genomic region containing 30 variably expressed genes by DNase I sensitivity assay at 500 bp resolution in Arabidopsis. Distinct DNase I HSs were found at the 5' and/or 3' ends of most genes irrespective of their expression levels. Further analysis of well-characterized genes showed that the DNase I HSs occurred near cis-regulatory elements in the promoters of these genes. Upon transcriptional activation of a heat-inducible gene, the DNase I HS was extended into the vicinity of a cis-element and adjacent TATA element in the promoter. Concomitant with this change in DNase I HS, histones were acetylated, removed from the promoter, and a transcription activator bound to this cis-element. These results suggest that the DNase I HSs participate in the transcriptional regulation of Arabidopsis genes by enhancing the access of chromatin remodeling factors and/or transcription factors to their target sites as seen in yeast and human chromatin.
最近对酵母和人类染色质进行的全基因组分析表明，脱氧核糖核酸酶I超敏位点（DNase I HSs）在基因调控区域广泛存在，可能在真核基因调控中发挥作用。植物中仅对少数基因描述了DNase I HSs的存在，我们通过拟南芥中分辨率为500 bp的DNase I敏感性分析，分析了一个包含30个表达水平各异基因的80 kb基因组区域的染色质结构。无论基因表达水平如何，在大多数基因的5'和/或3'端都发现了明显的DNase I HSs。对特征明确的基因进行的进一步分析表明，DNase I HSs出现在这些基因启动子中的顺式调控元件附近。在一个热诱导基因转录激活后，DNase I HS延伸到启动子中一个顺式元件和相邻TATA元件附近。伴随着DNase I HS的这种变化，组蛋白被乙酰化，从启动子上移除，并且一个转录激活因子与这个顺式元件结合。这些结果表明，DNase I HSs通过增强染色质重塑因子和/或转录因子对其靶位点的可及性，参与拟南芥基因的转录调控，这与酵母和人类染色质中的情况类似。
