大多数细菌使用ParABS系统来分离其新复制的染色体。来自各种细菌物种的该系统的两个蛋白质成分具有其生化特性:ParB是一种CTPase,可结合特定的着丝粒样parS序列以组装核蛋白复合物,而ParAATP酶形成非特异性结合DNA并与ParB复合物相互作用的二聚体。ParA-ParB相互作用促使ParB复合物向相反的细胞两极运动。然而,除了它们在染色体分离中的功能,这两种ParAB都可能参与与其他蛋白质伴侣的属特异性相互作用。一个这样的例子是放线菌中的极性生长控制蛋白DivIVA,它与分枝杆菌中的ParA结合,而与棒状杆菌中的ParB相互作用。这里,我们使用异源宿主来研究DivIVA和ParA或ParB之间的相互作用是否在系统发育类别中得以维持.具体来说,我们检查了来自四种细菌物种的蛋白质的相互作用,两个属于革兰氏阳性放线菌门,两个属于革兰氏阴性假单胞菌。我们表明,虽然ParA和ParB之间的相互作用保留了密切相关的直系同源物,与极性定位的蛋白质伴侣的相互作用不是由直系同源ParAB赋予的。此外,我们证明异源ParA不能替代内源性ParA,尽管它们的序列相似性很高。因此,我们得出的结论是,ParA直系同源物经过微调,可以与伴侣互动,特别是它们与极性局部化蛋白质的相互作用被调整以适应特定的细菌物种需求。
Most bacteria use the ParABS system to segregate their newly replicated chromosomes. The two protein components of this system from various bacterial species share their biochemical properties: ParB is a CTPase that binds specific centromere-like parS sequences to assemble a nucleoprotein complex, while the
ParA ATPase forms a dimer that binds DNA non-specifically and interacts with ParB complexes. The
ParA-ParB interaction incites the movement of ParB complexes toward the opposite cell poles. However, apart from their function in chromosome segregation, both ParAB may engage in genus-specific interactions with other protein partners. One such example is the polar-growth controlling protein DivIVA in Actinomycetota, which binds
ParA in Mycobacteria while interacts with ParB in Corynebacteria. Here, we used heterologous hosts to investigate whether the interactions between DivIVA and ParA or ParB are maintained across phylogenic classes. Specifically, we examined interactions of proteins from four bacterial species, two belonging to the Gram positive Actinomycetota phylum and two belonging to the Gram-negative Pseudomonadota. We show that while the interactions between
ParA and ParB are preserved for closely related orthologs, the interactions with polarly localised protein partners are not conferred by orthologous ParABs. Moreover, we demonstrate that heterologous
ParA cannot substitute for endogenous
ParA, despite their high sequence similarity. Therefore, we conclude that ParA orthologs are fine-tuned to interact with their partners, especially their interactions with polarly localised proteins are adjusted to particular bacterial species demands.