Promiscuous stimulation of ParF protein polymerization by heterogeneous centromere binding factors
Promiscuous stimulation of ParF protein polymerization by heterogeneous centromere binding factors
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DOI：
10.1016/j.jmb.2007.09.025
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发表时间：
2007-11-16
影响因子：
5.6
通讯作者：
Hayes, Finbarr
中科院分区：
文献类型：
--
作者：
Machon, Cristina;Fothergill, Timothy J. G.;Hayes, Finbarr
核糖体是一种核蛋白复合体，它调节细菌质粒的准确分离。TP228的片段包括PARF和PARG蛋白，它们聚集在PARH着丝粒上。PARF是无处不在的ParA分离蛋白超家族的一个分支，它广泛地聚合以响应ATP结合。聚合受ParG着丝粒结合因子(CBF)的调节。质粒pTAR、pVT745和pB171的脂质体包括PARF亚组的对位同系物，以及不同的同源二聚体CBF，与PARG没有一级序列相似性，或者彼此没有相似性。这些类似物与着丝粒的结合在很大程度上是特异的。在这里，我们建立了pTAR和pB171细丝的PARF同系物与ATP的适度同源，并且这种聚合不需要核苷酸水解，当同源CBF也存在时，这是更大的。相反，pVT745的PARF同源物对ATP单独反应不明显，但在其同源CBF和ATP存在下广泛聚合。辅助因子还刺激同源PARF蛋白的核苷酸非依赖性聚合。此外，除了pTAR的CBF外，不同的ParG类似物还促进了非同源PARF蛋白的聚合，这表明PARF蛋白的丝状化是通过共同的机制促进的。像PARG一样，辅助因子可能是模块化的，具有着丝粒特异的相互作用结构域，连接到包含混合刺激PARF聚合的决定因素的灵活区域。CBF似乎是调节真核细胞骨架动力学的Forn-Dns、微管相关蛋白或相关辅助因子的细菌类似物。(C)2007爱思唯尔有限公司。保留所有权利。
The segrosome is the nucleoprotein complex that mediates accurate segregation of bacterial plasmids. The segrosome of plasmid TP228 comprises ParF and ParG proteins that assemble on the parH centromere. ParF, which exemplifies one clade of the ubiquitous ParA superfamily of segregation proteins, polymerizes extensively in response to ATP binding. Polymerization is modulated by the ParG centromere binding factor (CBF). The segrosomes of plasmids pTAR, pVT745 and pB171 include ParA homologues of the ParF subgroup, as well as diverse homodimeric CBFs with no primary sequence similarity to ParG, or each other. Centromere binding by these analogues is largely specific. Here, we establish that the ParF homologues of pTAR and pB171 filament modestly with ATP, and that nucleotide hydrolysis is not required for this polymerization, which is more prodigious when the cognate CBF is also present. By contrast, the ParF homologue of plasmid pVT745 did not respond appreciably to ATP alone, but polymerized extensively in the presence of both its cognate CBF and ATP. The co-factors also stimulated nucleotide-independent polymerization of cognate ParF proteins. Moreover, apart from the CBF of pTAR, the disparate ParG analogues promoted polymerization of non-cognate ParF proteins suggesting that filamentation of the ParF proteins is enhanced by a common mechanism. Like ParG, the co-factors may be modular, possessing a centromere-specific interaction domain linked to a flexible region containing determinants that promiscuously stimulate ParF polymerization. The CBFs appear to function as bacterial analogues of forn-dns, microtubule-associated proteins or related ancillary factors that regulate eucaryotic cytoskeletal dynamics. (c) 2007 Elsevier Ltd. All rights reserved.