The Escherichia coli dnaA gene: four functional domains.
The Escherichia coli dnaA gene: four functional domains.
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大肠杆菌 dnaA 基因：四个功能域。
DOI：
10.1006/jmbi.1997.1425
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发表时间：
1997
影响因子：
5.6
通讯作者：
Kaguni,JM
中科院分区：
文献类型：
--
作者：
Sutton,MD;Kaguni,JM
大肠杆菌DNAA蛋白是一种序列特异性DNA结合蛋白，可促进细菌染色体和包括pSC101在内的几种质粒的复制。通过选择当包含在lambda载体中时不能复制pSC101的衍生物，分离出了28个新的E.ColiDNAA基因错义突变。这些突变的特征以及七个新的无义突变和一个框架内缺失突变在这里被描述。结果表明，大肠杆菌DNAA蛋白含有4个功能结构域。影响P-环或Walker A基序中残基的突变被认为与ATP结合有关，它们识别一个结构域。第二个结构域映射到C末端附近的一个区域，参与DNA结合。N末端附近的第三个结构域的功能尚不清楚，但可能与DNAA蛋白的寡聚能力有关。编码不同截短基因产物的两个等位基因保留了促进pSC101起源的复制的能力，但不能促进ORIC的复制，从而识别出第四个结构域，对于复制pSC101是必要的，但对于从细菌染色体起源的ORIC复制是必不可少的。
The Escherichia coli DnaA protein is a sequence-specific DNA binding protein that promotes the initiation of replication of the bacterial chromosome, and of several plasmids including pSC101. Twenty-eight novel missense mutations of the E. coli dnaA gene were isolated by selecting for their inability to replicate a derivative of pSC101 when contained in a lambda vector. Characterization of these as well as seven novel nonsense mutations and one in-frame deletion mutation are described here. Results suggest that E. coli DnaA protein contains four functional domains. Mutations that affect residues in the P-loop or Walker A motif thought to be involved in ATP binding identify one domain. The second domain maps to a region near the C terminus and is involved in DNA binding. The function of the third domain that maps near the N terminus is unknown but may be involved in the ability of DnaA protein to oligomerize. Two alleles encoding different truncated gene products retained the ability to promote replication from the pSC101 origin but not oriC, identifying a fourth domain dispensable for replication of pSC101 but essential for replication from the bacterial chromosomal origin, oriC.