Sequence-specific assembly of FtsK hexamers establishes directional translocation on DNA
Sequence-specific assembly of FtsK hexamers establishes directional translocation on DNA
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DOI：
10.1073/pnas.1007518107
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发表时间：
2010-11-23
影响因子：
11.1
通讯作者：
Szczelkun, Mark D.
中科院分区：
文献类型：
--
作者：
Graham, James E.;Sherratt, David J.;Szczelkun, Mark D.
FtsK 是一种同源六聚体、RecA 样 dsDNA 转位酶，在细菌染色体分离中发挥关键作用。 FtsK 调节伽玛子域通过与特定 8 碱基对染色体序列的相互作用来确定易位的方向性 [(KOPS); FtsK 定向/极化序列]与染色体中的复制方向同向。我们使用毫秒分辨率的整体易位和 ATP 酶测定来分析 FtsK 的组装、起始和易位。我们证明 KOPS 用于启动新的易位事件，而不是重新定位现有的易位事件。通过确定动力学参数，我们显示了易位和 ATP 酶速率对 ATP 浓度的 S 型依赖性，这表明 ATP 水解与 DNA 运动的顺序协同耦合。我们还估计易位的 ATP 偶联效率为 dsDNA 易位/ATP 水解的 1.63-2.11 bp。这些数据用于推导 FtsK 六聚体的组装、起始和易位模型。
FtsK is a homohexameric, RecA-like dsDNA translocase that plays a key role in bacterial chromosome segregation. The FtsK regulatory gamma-subdomain determines directionality of translocation through its interaction with specific 8 base pair chromosomal sequences [(KOPS); FtsK Orienting / Polarizing Sequence(s)] that are cooriented with the direction of replication in the chromosome. We use millisecond-resolution ensemble translocation and ATPase assays to analyze the assembly, initiation, and translocation of FtsK. We show that KOPS are used to initiate new translocation events rather than reorient existing ones. By determining kinetic parameters, we show sigmoidal dependences of translocation and ATPase rates on ATP concentration that indicate sequential cooperative coupling of ATP hydrolysis to DNA motion. We also estimate the ATP coupling efficiency of translocation to be 1.63-2.11 bp of dsDNA translocated/ATP hydrolyzed. The data were used to derive a model for the assembly, initiation, and translocation of FtsK hexamers.