Eukaryotic genomes are packaged in chromatin. The higher-order organization of nucleosome core particles is controlled by the association of the intervening linker DNA with either the linker histone H1 or high mobility group box (HMGB) proteins. While H1 is thought to stabilize the nucleosome by preventing DNA unwrapping, the DNA bending imposed by HMGB may propagate to the nucleosome to destabilize chromatin. For metazoan H1, chromatin compaction requires its lysine-rich C-terminal domain, a domain that is buried between globular domains in the previously characterized yeast Saccharomyces cerevisiae linker histone Hho1p. Here, we discuss the functions of S. cerevisiae HMO1, an HMGB family protein unique in containing a terminal lysine-rich domain and in stabilizing genomic DNA. On ribosomal DNA (rDNA) and genes encoding ribosomal proteins, HMO1 appears to exert its role primarily by stabilizing nucleosome-free regions or "fragile" nucleosomes. During replication, HMO1 likewise appears to ensure low nucleosome density at DNA junctions associated with the DNA damage response or the need for topoisomerases to resolve catenanes. Notably, HMO1 shares with the mammalian linker histone H1 the ability to stabilize chromatin, as evidenced by the absence of HMO1 creating a more dynamic chromatin environment that is more sensitive to nuclease digestion and in which chromatin-remodeling events associated with DNA double-strand break repair occur faster; such chromatin stabilization requires the lysine-rich extension of HMO1. Thus, HMO1 appears to have evolved a unique linker histone-like function involving the ability to stabilize both conventional nucleosome arrays as well as DNA regions characterized by low nucleosome density or the presence of noncanonical nucleosomes.

中文翻译：

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酵母HMO1：重组连接蛋白组蛋白。

真核生物基因组包装在染色质中。核小体核心颗粒的高级组织受插入的接头DNA与接头组蛋白H1或高迁移率族盒（HMGB）蛋白的结合控制。虽然H1被认为可以通过防止DNA解缠来稳定核小体，但是HMGB施加的DNA弯曲可能会传播到核小体，从而使染色质不稳定。对于后生动物H1，染色质紧实需要其富含赖氨酸的C末端结构域，该结构域埋藏在先前表征的酿酒酵母接头组蛋白Hho1p中的球状结构域之间。在这里，我们讨论酿酒酵母HMO1的功能，这是一种HMGB家族蛋白，其独特之处在于包含富含赖氨酸的末端结构域和稳定基因组DNA。关于核糖体DNA（rDNA）和编码核糖体蛋白的基因，HMO1似乎主要通过稳定无核小体的区域或“易碎”的核小体来发挥其作用。在复制过程中，HMO1同样似乎可以确保与DNA损伤反应或需要拓扑异构酶分解链烯相关的DNA连接处的核小体密度低。值得注意的是，HMO1与哺乳动物接头组蛋白H1拥有稳定染色质的能力，这不存在HMO1，从而创造了对核酸酶消化更敏感的更活跃的染色质环境，并且与DNA双链断裂相关的染色质重塑事件也证明了这一点。修复发生得更快；这种染色质稳定需要HMO1的富含赖氨酸的延伸。因此，