Dubocanin Danilo, Hartley Gabrielle A, Sedeño Cortés Adriana E, Mao Yizi, Hedouin Sabrine, Ranchalis Jane, Agarwal Aman, Logsdon Glennis A, Munson Katherine M, Real Taylor, Mallory Benjamin J, Eichler Evan E, Biggins Sue, O'Neill Rachel J, Stergachis Andrew B
Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA 98195, USA.
Institute for Systems Genomics, University of Connecticut, Storrs, CT 06269, USA.
Cell Genom. 2025 Apr 9;5(4):100819. doi: 10.1016/j.xgen.2025.100819. Epub 2025 Mar 26.
The attachment of the kinetochore to the centromere is essential for genome maintenance, yet the highly repetitive nature of satellite regional centromeres limits our understanding of their chromatin organization. We demonstrate that single-molecule chromatin fiber sequencing (Fiber-seq) can uniquely co-resolve kinetochore and surrounding chromatin architectures along point centromeres, revealing largely homogeneous single-molecule kinetochore occupancy. In contrast, the application of Fiber-seq to regional centromeres exposed marked per-molecule heterogeneity in their chromatin organization. Regional centromere cores uniquely contain a dichotomous chromatin organization (dichromatin) composed of compacted nucleosome arrays punctuated with highly accessible chromatin patches. CENP-B occupancy phases dichromatin to the underlying alpha-satellite repeat within centromere cores but is not necessary for dichromatin formation. Centromere core dichromatin is conserved between humans and primates, including along regional centromeres lacking satellite repeats. Overall, the chromatin organization of regional centromeres is defined by marked per-molecule heterogeneity, buffering kinetochore attachment against sequence and structural variability within regional centromeres.
动粒与着丝粒的附着对于基因组维持至关重要，然而卫星区域着丝粒的高度重复性质限制了我们对其染色质组织的理解。我们证明，单分子染色质纤维测序（Fiber-seq）能够独特地共同解析沿点着丝粒的动粒及其周围的染色质结构，揭示出基本上均匀的单分子动粒占据情况。相比之下，将Fiber-seq应用于区域着丝粒时，发现其染色质组织存在明显的分子间异质性。区域着丝粒核心独特地包含一种二分染色质组织（二染色质），它由紧密排列的核小体阵列组成，其间穿插着高度可及的染色质斑块。着丝粒蛋白B（CENP-B）的占据将二染色质定位于着丝粒核心内潜在的α-卫星重复序列，但对于二染色质的形成并非必需。着丝粒核心二染色质在人类和灵长类动物之间是保守的，包括在缺乏卫星重复序列的区域着丝粒中也是如此。总体而言，区域着丝粒的染色质组织由明显的分子间异质性定义，缓冲了动粒附着以应对区域着丝粒内的序列和结构变异性。
