Determination of the minimum domain II size of Escherichia coli DnaA protein essential for cell viability.
Determination of the minimum domain II size of Escherichia coli DnaA protein essential for cell viability.
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DOI：
10.1099/mic.0.2008/019745-0
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发表时间：
2008-11
期刊：
影响因子：
1.5
通讯作者：
Shingo Nozaki;T. Ogawa
中科院分区：
文献类型：
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作者：
Shingo Nozaki;T. Ogawa
DnaA蛋白是细菌在一个独特的染色体位点oriC上复制的启动子。它存在于所有细菌物种中，具有四个结构域的保守结构。结构域I和III-IV的结构最近已经解决了一些细菌物种，和分子过程导致的起始事件已经详细研究。另一方面，结构域II似乎没有刚性结构，并且被认为是连接N-末端结构域I和C-末端结构域III-IV的柔性接头。它的长度和氨基酸序列在细菌物种之间存在显着差异。结构域II是否具有启动复制的任何功能尚不清楚。其两端的精确边界以及其对细胞活力的重要部分也是未知的。在这项研究中，我们介绍了系统性缺失到结构域II区域的染色体DNA A基因的大肠杆菌，并研究其对细胞生理的影响。在第78位和第136位残基之间的不同部分可以缺失30-36个连续氨基酸残基的延伸，而不影响细胞活力。我们提出E. coliDnaA的第79 ~ 135位残基为间隔区，至少需要21-27个残基作为间隔区，以保持结构域I和III-IV的正确位置。
The DnaA protein is the bacterial initiator of replication at a unique chromosomal site, oriC. It is present in all bacterial species and has a conserved structure with four domains. The structures of domains I and III-IV have been solved recently for some bacterial species, and the molecular process leading to the initiation event has been investigated in detail. On the other hand, domain II appears to have no rigid structure and is assumed to be a flexible linker connecting the N-terminal domain I and the C-terminal domains III-IV. It differs significantly in length and amino acid sequence among bacterial species. Whether or not domain II has any function(s) to initiate replication is unknown. The precise borders at both of its ends as well as its essential portions for cell viability are also unknown. In this study, we introduced systematic deletions into the domain II region on the chromosomal dnaA gene of Escherichia coli and examined their effect on cell physiology. Stretches of 30-36 consecutive amino acid residues could be deleted from various portions between the 78th and the 136th residues without affecting cell viability. We propose that domain II of E. coli DnaA is from the 79th to the 135th residues and at least 21-27 residues are required as a spacer to keep domains I and III-IV in the correct positions.