Lucchini R, Sogo J M
Institue of Cell Biology, Swiss Federal Institute of Technology, Zürich.
Nature. 1995 Mar 16;374(6519):276-80. doi: 10.1038/374276a0.
In eukaryotic cells, active genes and their regulatory sequences are organized into open chromatin conformations in which nucleosomes can be modified, disrupted or totally absent. It has been proposed that these characteristic chromatin structures and their associated factors might be directly inherited by the newly synthesized daughter strands during chromosome duplication. Here we show that in the yeast Saccharomyces cerevisiae, replication machinery entering upstream of a transcriptionally active ribosomal RNA gene generates two newly replicated coding regions regularly packaged into nucleosomes, indicating that the active chromatin structure cannot be directly inherited at the replication fork. Whereas the establishment of an exposed chromatin conformation at some newly replicated rRNA gene promoters can occur shortly after the passage of the replication fork, regeneration of the active chromatin structure along the coding region is always a post-replicative process involving disruption of preformed nucleosomes.
在真核细胞中，活跃基因及其调控序列被组织成开放染色质构象，其中核小体可被修饰、破坏或完全缺失。有人提出，这些特征性染色质结构及其相关因子可能在染色体复制过程中由新合成的子链直接继承。在此，我们表明，在酿酒酵母中，进入转录活跃的核糖体RNA基因上游的复制机制会产生两个新复制的编码区域，这些区域被定期包装成核小体，这表明活跃染色质结构在复制叉处不能直接继承。虽然在复制叉通过后不久，一些新复制的rRNA基因启动子处可出现暴露的染色质构象，但沿编码区域的活跃染色质结构的再生始终是一个复制后过程，涉及预先形成的核小体的破坏。
