CTP and parS coordinate ParB partition complex dynamics and ParA-ATPase activation for ParABS-mediated DNA partitioning.
CTP and parS coordinate ParB partition complex dynamics and ParA-ATPase activation for ParABS-mediated DNA partitioning.
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DOI：
10.7554/elife.65651
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发表时间：
2021-07-21
期刊：
影响因子：
7.7
通讯作者：
Mizuuchi K
中科院分区：
文献类型：
--
作者：
Taylor JA;Seol Y;Budhathoki J;Neuman KC;Mizuuchi K
ParABS分割系统包括着丝粒样DNA序列parS， parS结合的ParB-CTPase和核结合的ParA-ATPase，确保细菌染色体和低拷贝数质粒的忠实分离。含有ParBF和parSF的f质粒分割复合物通过产生和遵循核苷结合的ParAF的局部浓度梯度而移动。然而，ParBF激活ParAF-ATPase的过程尚未明确。我们研究了CTP和parsf调节的ParAF-ParBF复合物组装，其中dna结合的ParAF-ATP二聚体通过与两个ParBF n端结构域相互作用激活ATP水解。CTP或parSF可提高atp酶速率，但不会显著加速ParAF-ParBF复合物的组装。parSF和CTP共同加速了ParAF-ParBF的组装，而没有进一步显著增加atp酶的速率。磁镊子实验表明，CTP促进多个ParBF加载到含parsf的DNA上，产生凝聚的分割复合物样组装体。我们提出分区复合体中的ParBF采用一种增强ParBF - ParBF和ParAF-ParBF相互作用的构象，以促进有效的分区。
ParABS partition systems, comprising the centromere-like DNA sequence parS, the parS-binding ParB-CTPase, and the nucleoid-binding ParA-ATPase, ensure faithful segregation of bacterial chromosomes and low-copy-number plasmids. F-plasmid partition complexes containing ParBF and parSF move by generating and following a local concentration gradient of nucleoid-bound ParAF. However, the process through which ParBF activates ParAF-ATPase has not been defined. We studied CTP- and parSF-modulated ParAF–ParBF complex assembly, in which DNA-bound ParAF-ATP dimers are activated for ATP hydrolysis by interacting with two ParBF N-terminal domains. CTP or parSF enhances the ATPase rate without significantly accelerating ParAF–ParBF complex assembly. Together, parSF and CTP accelerate ParAF–ParBF assembly without further significant increase in ATPase rate. Magnetic-tweezers experiments showed that CTP promotes multiple ParBF loading onto parSF-containing DNA, generating condensed partition complex-like assemblies. We propose that ParBF in the partition complex adopts a conformation that enhances ParBF–ParBF and ParAF–ParBF interactions promoting efficient partitioning.