Extent of the activity domain and possible roles of FtsK in the Escherichia coli chromosome terminus
Extent of the activity domain and possible roles of FtsK in the Escherichia coli chromosome terminus
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DOI：
10.1111/j.1365-2958.2005.04633.x
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发表时间：
2005-06-01
影响因子：
3.6
通讯作者：
Louarn, JM
中科院分区：
文献类型：
--
作者：
Corre, J;Louarn, JM
大肠杆菌FtsK蛋白偶联细胞分裂和染色体分离。它是细胞分裂所必需的隔膜的组成部分。它还在染色体二聚体解析过程中通过XerCD特异性重组在difsite发挥作用，具有两种不同的活性：由偏斜序列元件导向的DNA易位和直接激活Xer重组。二聚体分辨率要求偏斜的元素在相反的方向30 - 50 kb的任一侧的dif。这构成了DIF结构域，与复制终止的区域大致一致。利用ftsK 1突变增加dif附近重组的观察结果来确定FtsK作用的染色体区域是否限于DIF结构域。对dif左侧350 kb区域中多个位点的重组活性进行监测，发现（i）与二聚体分辨率无关的不同活性区，以及（ii）ftsK 1突变体中dif附近250 kb区域中重组恒定增加10倍。后一种效应允许定义FTSK结构域，其总大小至少是DIF结构域的四倍。进一步的分析表明，FtsK活性响应于整个FTSK结构域的极化，并且复制终止的区域的位移保留了重组区之间的差异。我们的解释是，FtsK易位主要发生在属于染色体的特定组织结构域的DNA上，当二聚体或仍然连锁的染色体之间的物理连接迫使该DNA在分裂时穿过隔膜时。
Escherichia coli FtsK protein couples cell division and chromosome segregation. It is a component of the septum essential for cell division. It also acts during chromosome dimer resolution by XerCD-specific recombination at the difsite, with two distinct activities: DNA translocation oriented by skewed sequence elements and direct activation of Xer recombination. Dimer resolution requires that the skewed elements polarize in opposite directions 30 50 kb on either side of dif. This constitutes the DIF domain, approximately coincident with the region where replication terminates. The observation that the ftsK1 mutation increases recombination near dif was exploited to determine whether the chromosome region on which FtsK acts is limited to the DIF domain. A monitoring of recombination activity at multiple loci in a 350 kb region to the left of dif revealed (i) zones of differing activities unconnected to dimer resolution and (ii) a constant 10- fold increase of recombination in the 250 kb region adjacent to dif in the ftsK1 mutant. The latter effect allows definition of an FTSK domain whose total size is at least fourfold that of the DIF domain. Additional analyses revealed that FtsK activity responds to polarization in the whole FTSK domain and that displacement of the region where replication terminates preserves differences between recombination zones. Our interpretation is that translocation by FtsK occurs mostly on DNA belonging to a specifically organized domain of the chromosome, when physical links between either dimeric or still intercatenated chromosomes force this DNA to run across the septum at division.