FtsK activities in Xer recombination, DNA mobilization and cell division involve overlapping and separate domains of the protein
FtsK activities in Xer recombination, DNA mobilization and cell division involve overlapping and separate domains of the protein
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DOI：
10.1111/j.1365-2958.2004.04335.x
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发表时间：
2004-11-01
影响因子：
3.6
通讯作者：
Barre, FX
中科院分区：
文献类型：
--
作者：
Bigot, S;Corre, J;Barre, FX
大肠杆菌FtsK是一种多功能蛋白，它将细胞分裂和染色体分离偶联在一起。其N端跨膜结构域（FtsK（N））是隔膜形成所必需的，而其C端结构域（FtsK（C））是通过XerCD-dif位点特异性重组进行染色体二聚体解析所必需的。FtsK（C）是一种ATP依赖性DNA转位酶。体外和体内数据表明，该结构域在染色体二聚体解析中具有双重作用：（i）通过XerCD-dif直接激活重组，（ii）将重组位点聚集在一起和/或从闭合隔膜中清除DNA。FtsK（N）和FtsK（C）被未知功能的长接头区（FtsK（L））分开，该长接头区在细菌物种之间高度不同。在此，我们分析了FtsK（L）和/或FtsK（C）缺失、这些结构域与流感嗜血杆菌对应物交换以及使FtsK（C）的步行者A基序失活的点突变的体内效应。突变体的表型表征表明FtsK（L）在细胞分裂中的作用。更重要的是，尽管Xer重组激活和DNA移动都依赖于FtsK（C）的ATP酶活性，但发现了仅能执行这两种功能中的一种或另一种的突变体，这使得它们首次在体内分离。
Escherichia coli FtsK is a multifunctional protein that couples cell division and chromosome segregation. Its N-terminal transmembrane domain (FtsK(N)) is essential for septum formation, whereas its C-terminal domain (FtsK(C)) is required for chromosome dimer resolution by XerCD-dif site-specific recombination. FtsK(C) is an ATP-dependent DNA translocase. In vitro and in vivo data point to a dual role for this domain in chromosome dimer resolution (i) to directly activate recombination by XerCD-dif and (ii) to bring recombination sites together and/or to clear DNA from the closing septum. FtsK(N) and FtsK(C) are separated by a long linker region (FtsK(L)) of unknown function that is highly divergent between bacterial species. Here, we analysed the in vivo effects of deletions of FtsK(L) and/or of FtsK(C), of swaps of these domains with their Haemophilus influenzae counterparts and of a point mutation that inactivates the walker A motif of FtsK(C). Phenotypic characterization of the mutants indicated a role for FtsK(L) in cell division. More importantly, even though Xer recombination activation and DNA mobilization both rely on the ATPase activity of FtsK(C), mutants were found that can perform only one or the other of these two functions, which allowed their separation in vivo for the first time.