The Caulobacter crescentus smc gene is required for cell cycle progression and chromosome segregation
The Caulobacter crescentus smc gene is required for cell cycle progression and chromosome segregation
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DOI：
10.1073/pnas.96.19.10661
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发表时间：
1999-09-14
影响因子：
11.1
通讯作者：
Shapiro, L
中科院分区：
文献类型：
--
作者：
Jensen, RB;Shapiro, L
高度保守的SMC（染色体结构维持）蛋白在真核生物和原核生物的染色体凝聚、分离和染色体动力学的其他方面起作用。新月柄杆菌sme基因中的突变是条件性致死的，并在分裂前细胞阶段引起细胞周期停滞。通过使用荧光原位杂交监测复制起点和末端的细胞内定位来检查野生型和sme无效突变细胞中的染色体分离。在野生型细胞中，起点位于蜂群细胞的鞭毛极，并且在有柄细胞中DNA复制开始后，起点之一立即移动到相反的极，给出了起源的两极定位。末端从与起点相对的群集细胞的末端移动到中细胞。sme无效突变细胞的亚群具有错误定位的起点或末端，表明sme无效突变导致DNA分离缺陷。类核形态也异常。因此，我们建议，柄杆菌染色体的起源有特定的细胞地址和SMC蛋白在维持染色体结构和分区中起着重要作用。sme无效突变体中的特异性细胞周期停滞表明存在细胞周期检查点，该检查点感知染色体组织或分离的扰动。
The highly conserved SMC (Structural Maintenance of Chromosomes) proteins function in chromosome condensation, segregation, and other aspects of chromosome dynamics in both eukaryotes and prokaryotes. A nun mutation in the Caulobacter crescentus sme gene is conditionally lethal and causes a cell cycle arrest at the predivisional cell stage. Chromosome segregation In wild-type and sme null mutant cells was examined by monitoring the intracellular localization of the replication origin and terminus by using fluorescence in situ hybridization, In wild-type cells, the origin is located at the flagellated pole of swarmer cells and, immediately after the initiation of DNA replication in stalked cells, one of the origins moves to the opposite pole, giving a bipolar localization of the origins. The terminus moves from the end of the swarmer cell opposite the origin to midcell. A subpopulation of the sme null mutant cells had mislocalized origins or termini, showing that the sme null mutation gives DNA segregation defects. Nucleoid morphology was also abnormal. Thus, we propose that the Caulobacter chromosomal origins have specific cellular addresses and that the SMC protein plays important roles in maintaining chromosome structure and in partitioning. The specific cell cycle arrest in the sme null mutant Indicates the presence of a cell cycle checkpoint that senses perturbations in chromosome organization or segregation.