Department of Biological Sciences, 111 Research Drive, Lehigh University, Bethlehem, PA 18015, USA
J Cell Sci. 2019 Feb 7;132(3):jcs220491. doi: 10.1242/jcs.220491.
Condensins and cohesins are highly conserved complexes that tether together DNA loci within a single DNA molecule to produce DNA loops. Condensin and cohesin structures, however, are different, and the DNA loops produced by each underlie distinct cell processes. Condensin rods compact chromosomes during mitosis, with condensin I and II complexes producing spatially defined and nested looping in metazoan cells. Structurally adaptive cohesin rings produce loops, which organize the genome during interphase. Cohesin-mediated loops, termed topologically associating domains or TADs, antagonize the formation of epigenetically defined but untethered DNA volumes, termed compartments. While condensin complexes formed through -interactions must maintain chromatin compaction throughout mitosis, cohesins remain highly dynamic during interphase to allow for transcription-mediated responses to external cues and the execution of developmental programs. Here, I review differences in condensin and cohesin structures, and highlight recent advances regarding the intramolecular or -based tetherings through which condensins compact DNA during mitosis and cohesins organize the genome during interphase.
凝聚素和黏合素是高度保守的复合物，可将单个 DNA 分子内的 DNA 位点连接在一起，形成 DNA 环。然而，凝聚素和黏合素的结构不同，它们各自产生的 DNA 环在不同的细胞过程中发挥作用。在有丝分裂过程中，凝聚素杆状结构使染色体浓缩，其中凝聚素 I 和 II 复合物在后生动物细胞中产生空间限定的嵌套环。结构适应性黏合素环产生的环在有丝分裂间期组织基因组。黏合素介导的环，称为拓扑关联域或 TAD，拮抗由表观遗传定义但未连接的 DNA 体积形成，称为隔室。虽然通过 -相互作用形成的凝聚素复合物在有丝分裂过程中必须维持染色质的浓缩，但黏合素在有丝分裂间期仍保持高度动态，以允许转录介导的对外界信号的反应，并执行发育程序。在这里，我回顾了凝聚素和黏合素结构的差异，并强调了最近在凝聚素通过 -相互作用在有丝分裂期间压缩 DNA 以及黏合素在有丝分裂间期组织基因组方面的进展。
