Tetramerization of ZapA is required for FtsZ bundling
Tetramerization of ZapA is required for FtsZ bundling
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DOI：
10.1042/bj20120140
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发表时间：
2013-02-01
影响因子：
4.1
通讯作者：
Dafforn, Timothy R.
中科院分区：
文献类型：
--
作者：
Pacheco-Gomez, Raul;Cheng, Xi;Dafforn, Timothy R.
原核细胞分裂是一个高度协调的过程，需要形成一系列生物分子复合体，其中最重要的可能涉及原核生物微管蛋白同源物FtsZ，一种形成纤维的GTP酶。FtsZ在细胞分裂部位的内膜内表面组装成一个环(Z环)。然后，Z环作为至少10种其他蛋白质的招募部位，这些蛋白质构成了分裂装置。其中一种名为ZapA的蛋白质可以增强FtsZ纤维之间的横向联系，形成束。此前，我们已经表达、纯化和结晶了ZapA，并证明了它以四聚体的形式存在。我们还发现ZapA与FtsZ聚合物结合，强烈促进它们的结合，同时通过诱导结合核苷酸的构象变化抑制FtsZ GTP酶的活性。在本研究中，我们研究了ZapA的四聚化对其功能的重要性。我们产生了一些ZapA的突变形式，目的是破坏二聚体-二聚体的界面。我们发现其中一个突变体I83E完全折叠并与FtsZ结合，但是一个结构性二聚体。使用这个突变体，我们证明了四聚化是FtsZ结合和GTPase调节活动的必需条件。
Prokaryotic cell division is a highly orchestrated process requiring the formation of a wide range of biomolecular complexes, perhaps the most important of these involving the prokaryotic tubulin homologue FtsZ, a fibre-forming GTPase. FtsZ assembles into a ring (the Z-ring) on the inner surface of the inner membrane at the site of cell division. The Z-ring then acts as a recruitment site for at least ten other proteins which form the division apparatus. One of these proteins, ZapA, acts to enhance lateral associations between FtsZ fibres to form bundles. Previously we have expressed, purified and crystallized ZapA and demonstrated that it exists as a tetramer. We also showed that ZapA binds to FtsZ polymers, strongly promoting their bundling, while inhibiting FtsZ GTPase activity by inducing conformational changes in the bound nucleotide. In the present study we investigate the importance of the tetramerization of ZapA on its function. We generated a number of mutant forms of ZapA with the aim of disrupting the dimer-dimer interface. We show that one of these mutants, I83E, is fully folded and binds to FtsZ, but is a constitutive dimer. Using this mutant we show that tetramerization is a requirement for both FtsZ bundling and GTPase modulation activities.