Cross-linking FtsZ polymers into coherent Z rings
Cross-linking FtsZ polymers into coherent Z rings
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DOI：
10.1111/j.1365-2958.2010.07352.x
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发表时间：
2010-11-01
影响因子：
3.6
通讯作者：
Wirtz, Denis
中科院分区：
文献类型：
--
作者：
Dajkovic, Alex;Pichoff, Sebastien;Wirtz, Denis
细菌胞质分裂的一个关键事件是Z环的形成，它作为一个机械支架，招募其他细胞动力学蛋白来建立功能性分裂体。Z环的这种支架功能在整个细胞分裂过程中是必不可少的，但潜在的分子相互作用却知之甚少。在这里，我们报道了一种广泛保守的FtsZ结合蛋白ZapA，它具有细胞学、生化和生物物理特性，这证明了FtsZ聚合物之间的交联相互作用在Z环的相干性中的重要性。大肠杆菌zapA零突变细胞具有结构松散的Z环，并且Z环的许多螺旋前体不能合并成连贯的环。在ZapA存在下，FtsZ的生物物理行为表明，ZapA不仅可以捆绑FtsZ聚合物，还可以交联FtsZ聚合物，这使其成为细菌细胞骨架的第一个交联蛋白。体外交联发生在体内Z环上FtsZ-ZapA相互作用的化学计量学中，其中几乎所有细胞内ZapA都是动态相关的。ZapA还稳定了FtsZ单体之间的纵向键，因为它促进了在聚合界面有损伤的FtsZ突变体的聚合，并且因为它逆转了SulA（一种已知的FtsZ纵向相互作用拮抗剂）的抑制作用。
P>A key event in bacterial cytokinesis is the formation of the Z ring, which serves as a mechanical scaffold that recruits other cytokinetic proteins to establish functional divisomes. This scaffolding function of Z rings is essential throughout cytokinesis, but the underlying molecular interactions are poorly understood. Here we report that a widely conserved FtsZ binding protein, ZapA, has cytological, biochemical and biophysical properties that argue for the importance of cross-linking interactions between FtsZ polymers in the coherence of Z rings. Escherichia coli zapA null mutant cells have Z rings that are structurally looser and many helical precursors of Z rings fail to coalesce into coherent rings. Biophysical behaviour of FtsZ in the presence of ZapA reveals that ZapA not only bundles, but also cross-links FtsZ polymers, which makes it the first cross-linking protein of the bacterial cytoskeleton. Cross-linking in vitro occurs at the stoichiometry of FtsZ-ZapA interaction at the Z rings in vivo, where nearly all intracellular ZapA is dynamically associated. ZapA also stabilizes longitudinal bonds between FtsZ monomers since it promotes the polymerization of FtsZ mutants with lesions at the polymerization interface and since it reverses the inhibitory effects of SulA, a known antagonist of FtsZ longitudinal interactions.