Relief of ParB autoinhibition by parS DNA catalysis and recycling of ParB by CTP hydrolysis promote bacterial centromere assembly.
Relief of ParB autoinhibition by parS DNA catalysis and recycling of ParB by CTP hydrolysis promote bacterial centromere assembly.
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DOI：
10.1126/sciadv.abj2854
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发表时间：
2021-10-08
期刊：
影响因子：
13.6
通讯作者：
Gruber S
中科院分区：
文献类型：
--
作者：
Antar H;Soh YM;Zamuner S;Bock FP;Anchimiuk A;Rios PL;Gruber S
CTP结合和水解使ParB在parS着丝粒处浓缩以介导细菌中的忠实染色体分离。三组分ParABS系统是细菌中广泛分布的质粒分配和染色体分离因子。ParB作为16碱基对着丝粒parS DNA序列与DNA分离蛋白帕拉和Smc（染色体的结构维持）之间的衔接蛋白。在三磷酸胞苷（CTP）和parS DNA结合后，ParB二聚体形成DNA夹，其通过滑动扩散到parS侧翼DNA上，从而组装所谓的分区复合物。我们在这里表明，CTP水解是必不可少的有效的染色体分离的ParABS，但在很大程度上是Smc招聘。我们的研究结果表明，CTP水解通过两种机制有助于分区复合物组装。它促进ParB从DNA卸载以限制ParB扩散的程度，并且它消除脱靶ParB夹以允许parS重新靶向，一起使ParB超浓缩在parS附近。我们还提出了一个模型，涉及一个立体碰撞时，绑定ParB的原聚体对parS半位点的钳关闭。
CTP binding and hydrolysis concentrate ParB at parS centromeres to mediate faithful chromosome segregation in bacteria. Three-component ParABS systems are widely distributed factors for plasmid partitioning and chromosome segregation in bacteria. ParB acts as adaptor protein between the 16–base pair centromeric parS DNA sequences and the DNA segregation proteins ParA and Smc (structural maintenance of chromosomes). Upon cytidine triphosphate (CTP) and parS DNA binding, ParB dimers form DNA clamps that spread onto parS-flanking DNA by sliding, thus assembling the so-called partition complex. We show here that CTP hydrolysis is essential for efficient chromosome segregation by ParABS but largely dispensable for Smc recruitment. Our results suggest that CTP hydrolysis contributes to partition complex assembly via two mechanisms. It promotes ParB unloading from DNA to limit the extent of ParB spreading, and it recycles off-target ParB clamps to allow for parS retargeting, together superconcentrating ParB near parS. We also propose a model for clamp closure involving a steric clash when binding ParB protomers to opposing parS half sites.
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