在真核细胞中，承载遗传信息的DNA通常是和组蛋白结合，以高度压缩的染色质形式存在于细胞核内。组蛋白H1是组蛋白家族的重要成员，其功能是稳定核小体及形成染色质高级结构。在酿酒酵母中，Hho1和Hmo1两个蛋白究竟谁在体内行使组蛋白H1的功能一直存在争议。本项目将利用可以模拟细胞核内生理条件的YNPE体系，结合单分子技术，明确Hho1和Hmo1在压缩DNA形成染色质这一生物过程中所起的作用，解析两个蛋白行使各自功能的分子机制，比较分析酿酒酵母组蛋白H1和高等生物H1的进化差异，以期深入理解组蛋白H1如何围绕执行精密复杂的调控功能而进化形成多种亚型。

The DNA in eukaryotic cells is highly packaged into chromatin with histones. The linker histone H1 is a key component of the histone family, and it can stabilize both nucleosome and high-order chromatin architecture. In yeast Saccharomyces cerevisiae, there are two histone H1 candidates, Hho1 and Hmo1. So far, it still remains a matter of debate which one functions as the histone H1 in vivo. In this grant proposal, we will utilize the YNPE system which can mimic the nuclear physiological conditions and the single-molecule techniques to determine whether Hho1 or Hmo1 functions as the histone H1 in vivo. We will explore the molecular mechanisms of how the two proteins interact with DNA and stabilize chromatin. The evolutionary diversity between the yeast histone H1 and the metazoan H1 will be analyzed. It will help us better understand why they have evolved variable subtypes to adopt specific functions in vivo.