Toussaint Martin, Levasseur Geneviève, Tremblay Maxime, Paquette Michel, Conconi Antonio
Départment de Microbiologie et Infectiologie, Université de Sherbrooke, QC, Canada.
Biochem Cell Biol. 2005 Aug;83(4):449-59. doi: 10.1139/o05-141.
The chromatin structure of RNA polymerase I--transcribed ribosomal DNA (rDNA) is well characterized. In most organisms, i.e., lower eukaryotes, plants, and animals, only a fraction of ribosomal genes are transcriptionally active. At the chromatin level inactive rDNA is assembled into arrays of nucleosomes, whereas transcriptionally active rDNA does not contain canonical nucleosomes. To separate inactive (nucleosomal) and active (non-nucleosomal) rDNA, the technique of psoralen photocrosslinking has been used successfully both in vitro and in vivo. In Saccharomyces cerevisiae, the structure of rDNA chromatin has been particularly well studied during transcription and during DNA replication. Thus, the yeast rDNA locus has become a good model system to study the interplay of all nuclear DNA processes and chromatin. In this review we focused on the studies of chromatin in ribosomal genes and how these results have helped to address the fundamental question: What is the structure of chromatin in the coding regions of genes?
RNA聚合酶I转录的核糖体DNA（rDNA）的染色质结构已得到充分表征。在大多数生物体中，即低等真核生物、植物和动物，只有一小部分核糖体基因具有转录活性。在染色质水平上，无活性的rDNA组装成核小体阵列，而具有转录活性的rDNA不包含典型的核小体。为了分离无活性（核小体的）和活性（非核小体的）rDNA，补骨脂素光交联技术已在体外和体内成功应用。在酿酒酵母中，rDNA染色质的结构在转录和DNA复制过程中得到了特别深入的研究。因此，酵母rDNA基因座已成为研究所有核DNA过程与染色质相互作用的良好模型系统。在本综述中，我们重点关注了核糖体基因中染色质的研究，以及这些结果如何有助于解决一个基本问题：基因编码区的染色质结构是什么？
