F plasmid partition depends on interaction of SopA with non-specific DNA
F plasmid partition depends on interaction of SopA with non-specific DNA
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DOI：
10.1111/j.1365-2958.2008.06465.x
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发表时间：
2008-11-01
影响因子：
3.6
通讯作者：
Lane, David
中科院分区：
文献类型：
--
作者：
Castaing, Jean-Philippe;Bouet, Jean-Yves;Lane, David
细菌ATPases属于ParA家族，通过形成动态组装体，将复制子拷贝移动到新的细胞半部分，确保复制子的分割。Walker-box类atp酶（包括大多数质粒和所有染色体上的ParAs）的分裂机制尚不清楚。所研究的atp酶以atp依赖的方式与非特异性DNA聚合和相互作用。先前的研究表明，在体外，其中一种atp酶，质粒F的SopA的聚合被DNA抑制，这表明SopA与宿主类核的相互作用可以调节分裂。在试图确定SopA中与非特异性DNA相互作用所需的氨基酸时，我们发现密码子340（赖氨酸到丙氨酸）的突变将ATP依赖的DNA结合降低了100倍，并相应地降低了依赖于它的SopA活性：抑制聚合物的形成和持久性，刺激基础水平ATP水解和在类核上的定位。K340A突变体保留了除质粒稳定外的所有其他SopA特性；突变体SopA对野生型的替代几乎废除了mini-F分区。该突变体的行为表明，与细胞非特异性DNA的相互作用与促进确保F质粒分裂的动态行为之间存在因果关系。
Bacterial ATPases belonging to the ParA family assure partition of their replicons by forming dynamic assemblies which move replicon copies into the new cell-halves. The mechanism underlying partition is not understood for the Walker-box ATPase class, which includes most plasmid and all chromosomal ParAs. The ATPases studied both polymerize and interact with non-specific DNA in an ATP-dependent manner. Previous work showed that in vitro, polymerization of one such ATPase, SopA of plasmid F, is inhibited by DNA, suggesting that interaction of SopA with the host nucleoid could regulate partition. In an attempt to identify amino acids in SopA that are needed for interaction with non-specific DNA, we have found that mutation of codon 340 (lysine to alanine) reduces ATP-dependent DNA binding > 100-fold and correspondingly diminishes SopA activities that depend on it: inhibition of polymer formation and persistence, stimulation of basal-level ATP hydrolysis and localization over the nucleoid. The K340A mutant retained all other SopA properties tested except plasmid stabilization; substitution of the mutant SopA for wild-type nearly abolished mini-F partition. The behaviour of this mutant indicates a causal link between interaction with the cell's non-specific DNA and promotion of the dynamic behaviour that ensures F plasmid partition.