Structural maintenance of chromosomes protein of Bacillus subtilis affects supercoiling in vivo
Structural maintenance of chromosomes protein of Bacillus subtilis affects supercoiling in vivo
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DOI：
10.1128/jb.184.19.5317-5322.2002
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发表时间：
2002-10-01
影响因子：
3.2
通讯作者：
Grossman, AD
中科院分区：
文献类型：
--
作者：
Lindow, JC;Britton, RA;Grossman, AD
染色体结构维持 (SMC) 蛋白几乎存在于所有生物体中。该蛋白质家族的成员参与染色体凝聚和姐妹染色单体凝聚。枯草芽孢杆菌 SMC 蛋白 (BsSMC) 在染色体组织和分配中发挥作用。为了更好地了解 BsSMC 的功能，我们研究了 smc 无效突变对体内 DNA 超螺旋的影响。我们发现 smc 无效突变体对 DNA 旋转酶抑制剂香豆霉素 A1 和诺氟沙星高度敏感。此外，耗尽拓扑异构酶 I 的细胞显着抑制了 smc 无效突变体的分配缺陷。从 smc 无效突变体中分离的质粒 DNA 比从野生型细胞中分离的质粒 DNA 负超螺旋程度更大。体内交联实验表明 BsSMC 与质粒结合。我们的结果表明，BsSMC 影响体内超螺旋，最有可能是通过限制正超螺旋，这种活性有助于染色体压缩和组织。
Structural maintenance of chromosomes (SMC) proteins are found in nearly all organisms. Members of this protein family are involved in chromosome condensation and sister chromatid cohesion. Bacillus subtilis SMC protein (BsSMC) plays a role in chromosome organization and partitioning. To better understand the function of BsSMC, we studied the effects of an smc null mutation on DNA supercoiling in vivo. We found that an smc null mutant was hypersensitive to the DNA gyrase inhibitors coumermycin A1 and norfloxacin. Furthermore, depleting cells of topoisomerase I substantially suppressed the partitioning defect of an smc null mutant. Plasmid DNA isolated from an smc null mutant was more negatively supercoiled than that from wild-type cells. In vivo cross-linking experiments indicated that BsSMC was bound to the plasmid. Our results indicate that BsSMC affects supercoiling in vivo, most likely by constraining positive supercoils, an activity which contributes to chromosome compaction and organization.