枯草芽孢杆菌SMC复合物在从染色体起点移动到终点的过程中使染色体臂并列。
Bacillus subtilis SMC complexes juxtapose chromosome arms as they travel from origin to terminus.
作者信息
Wang Xindan, Brandão Hugo B, Le Tung B K, Laub Michael T, Rudner David Z
机构信息
Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
Graduate Program in Biophysics, Harvard University, Cambridge, MA 02138, USA.
出版信息
Science. 2017 Feb 3;355(6324):524-527. doi: 10.1126/science.aai8982.
Structural maintenance of chromosomes (SMC) complexes play critical roles in chromosome dynamics in virtually all organisms, but how they function remains poorly understood. In the bacterium Bacillus subtilis, SMC-condensin complexes are topologically loaded at centromeric sites adjacent to the replication origin. Here we provide evidence that these ring-shaped assemblies tether the left and right chromosome arms together while traveling from the origin to the terminus (>2 megabases) at rates >50 kilobases per minute. Condensin movement scales linearly with time, providing evidence for an active transport mechanism. These data support a model in which SMC complexes function by processively enlarging DNA loops. Loop formation followed by processive enlargement provides a mechanism by which condensin complexes compact and resolve sister chromatids in mitosis and by which cohesin generates topologically associating domains during interphase.
染色体结构维持（SMC）复合物在几乎所有生物体的染色体动态变化中都起着关键作用，但其作用机制仍知之甚少。在枯草芽孢杆菌中，SMC-凝聚素复合物在与复制起点相邻的着丝粒位点进行拓扑加载。在此，我们提供证据表明，这些环状组装体在以每分钟超过50千碱基的速度从起点向终点（超过2兆碱基）移动时，将左右染色体臂拴在一起。凝聚素的移动与时间呈线性关系，这为一种主动运输机制提供了证据。这些数据支持了一个模型，即SMC复合物通过逐步扩大DNA环来发挥作用。环的形成随后进行逐步扩大，提供了一种机制，通过该机制凝聚素复合物在有丝分裂中压缩并分离姐妹染色单体，以及黏连蛋白在间期产生拓扑相关结构域。
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