Cell cycle-dependent expression of an essential SMC-like protein and dynamic chromosome localization in the archaeon Halobacterium salinarum
Cell cycle-dependent expression of an essential SMC-like protein and dynamic chromosome localization in the archaeon Halobacterium salinarum
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DOI：
10.1046/j.1365-2958.2002.03181.x
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发表时间：
2002-10-01
影响因子：
3.6
通讯作者：
Soppa, J
中科院分区：
文献类型：
--
作者：
Herrmann, U;Soppa, J
盐生盐杆菌的基因组编码染色体结构维持蛋白超家族的四种蛋白。这两个蛋白形成一个新的亚家族，命名为H. salinarum'（Sph 1和Sph 2）。北方印迹分析显示，在指数生长期，而不是在静止期，细胞中，单独转录，hp 24，相邻的基因。一个同步程序的开发，它利用DNA聚合酶抑制剂阿非迪霉素，并导致高度同步的文化。它使我们第一次能够研究古细菌中细胞周期依赖的转录。研究发现，EST 1转录物受到细胞周期的高度调节，在隔膜形成前后积累最多。Sph 1蛋白水平也在那时升高，但在整个细胞周期中发现了基础蛋白水平。hp 24的转录急剧上调约1小时前，1和已经下降的时间，1诱导。这些和额外的转录模式显示，精确控制的转录调控参与盐古菌细胞周期进程。一个DNA染色协议的开发，这打开了以下的动态细胞内定位的haloarchaeal类核使用同步培养的可能性。在最初的分散定位之后，类核在细胞中部凝聚。随后，DNA被快速转运到1/4和3/4位置。在未处理的指数生长细胞中也观察到所有染色模式，不包括同步伪影。当新染色体的分离接近完成时，Sph 1的浓度升高;因此，它被认为在复制的后期步骤中发挥作用，例如。G. DNA修复，类似于真核生物的Rad 18蛋白。
The genome of Halobacterium salinarum encodes four proteins of the structural maintenance of chromosomes (SMC) protein superfamily. Two proteins form a novel subfamily and are named 'SMC-like proteins of H. salinarum' (Sph1 and Sph2). Northern blot analyses revealed that sph1 and hp24, the adjacent gene, are solely transcribed in exponentially growing, but not in stationary phase, cells. A synchronization procedure was developed, which makes use of the DNA polymerase inhibitor aphidicolin and leads to highly synchronous cultures. It allowed us for the first time to study cell cycle-dependent transcription in an archaeon. The sph1 transcript was found to be highly cell cycle regulated, with its maximal accumulation around the time of septum formation. The Sph1 protein level was also elevated at that time, but a basal protein level was found throughout the cell cycle. The hp24 transcript was sharply upregulated about 1 h before sph1 and had already declined at the time of sph1 induction. These and additional transcript patterns revealed that precisely controlled transcriptional regulation is involved in haloarchaeal cell cycle progression. A DNA staining protocol was developed, which opened the possibility of following the dynamic intracellular localization of haloarchaeal nucleoids using synchronized cultures. After an initial dispersed localization, the nucleoid is condensed at mid-cell. Subsequently, DNA is rapidly transported to the 1/4 and 3/4 positions. All staining patterns were also observed in untreated exponentially growing cells, excluding synchronization artifacts. The Sph1 concentration is elevated when segregation of the new chromosomes is nearly complete; therefore, it is pro-posed to play a role in a late step of replication, e. g. DNA repair, similar to eukaryotic Rad18 proteins.