Kim Hye-Jin, Seol Ja-Hwan, Cho Eun-Jung
College of Pharmacy, Sungkyunkwan University, Suwon 440-746, Korea.
BMB Rep. 2009 Apr 30;42(4):227-31. doi: 10.5483/bmbrep.2009.42.4.227.
The eukaryotic genome forms a chromatin structure that contains repeating nucleosome structures. Nucleosome packaging is regulated by chromatin remodeling factors such as histone chaperones. The Saccharomyces cerevisiae H3/H4 histone chaperones, CAF-1 and Asf1, regulate DNA replication and chromatin assembly. CAF-1 function is largely restricted to non-transcriptional processes in heterochromatin, whereas Asf1 regulates transcription together with another H3/H4 chaperone, HIR. This study examined the role of the yeast H3/H4 histone chaperones, Asf1, HIR, and CAF-1 in chromatin dynamics during transcription. Unexpectedly, CAF-1 was recruited to the actively transcribed region in a similar way to HIR and Asf1. In addition, the three histone chaperones genetically interacted with Set2-dependent H3 K36 methylation. Similar to histone chaperones, Set2 was required for tolerance to excess histone H3 but not to excess H2A, suggesting that CAF-1, Asf1, HIR, and Set2 function in a related pathway and target chromatin during transcription.
真核生物基因组形成一种包含重复核小体结构的染色质结构。核小体包装由诸如组蛋白伴侣等染色质重塑因子调控。酿酒酵母H3/H4组蛋白伴侣CAF-1和Asf1调控DNA复制和染色质组装。CAF-1的功能在很大程度上局限于异染色质中的非转录过程，而Asf1与另一种H3/H4伴侣HIR一起调控转录。本研究考察了酵母H3/H4组蛋白伴侣Asf1、HIR和CAF-1在转录过程中染色质动态变化中的作用。出乎意料的是，CAF-1以与HIR和Asf1相似的方式被招募到活跃转录区域。此外，这三种组蛋白伴侣在基因上与Set2依赖的H3 K36甲基化相互作用。与组蛋白伴侣相似，Set2是耐受过量组蛋白H3所必需的，但对过量H2A则不是必需的，这表明CAF-1、Asf1、HIR和Set2在相关途径中发挥作用，并在转录过程中靶向染色质。
