Non-hydrolysable GTP-γ-S stabilizes the FtsZ polymer in a GDP-bound state
Non-hydrolysable GTP-γ-S stabilizes the FtsZ polymer in a GDP-bound state
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DOI：
10.1046/j.1365-2958.2000.01791.x
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发表时间：
2000-03-01
影响因子：
3.6
通讯作者：
Driessen, AJM
中科院分区：
文献类型：
--
作者：
Scheffers, DJ;den Blaauwen, T;Driessen, AJM
FtsZ是一种微管蛋白同源物，在原核生物的细胞分裂位点形成细胞动力学环。该环被认为是由聚合物组成，这些聚合物以严格依赖GTP的方式组装。GTP，而不是鸟苷-5 '-O-（3-硫代三磷酸）（GTP-γ-S），已被证明可诱导FtsZ的聚合，而体外Ca 2+已知可抑制FtsZ的GTP水解活性。我们已经研究了FtsZ动力学在限制GTP浓度在10 mM Ca 2+的存在下。GTP及其不可水解的类似物GTP-γ-S以相似的亲和力结合FtsZ，而不可水解的类似物鸟苷酰-亚氨二磷酸（GMP-PNP）是较差的底物。预形成的FtsZ聚合物可以通过GTP-γ-S稳定，并且通过GDP去稳定。由于超过95%的核苷酸与FtsZ聚合物是在GDP的形式，它的结论是GTP水解本身不触发FtsZ聚合物解体。引人注目的是，GTP-gamma-S仅交换FtsZ聚合物结合的GDP的一小部分。这些数据表明，FtsZ聚合物是稳定的一小部分的GTP含有FtsZ亚基。这些亚基可以位于整个聚合物或聚合物末端，形成类似于微管蛋白的GTP帽。
FtsZ, a tubulin homologue, forms a cytokinetic ring at the site of cell division in prokaryotes. The ring is thought to consist of polymers that assemble in a strictly GTP-dependent way. GTP, but not guanosine-5'-O-(3-thiotriphosphate) (GTP-gamma-S), has been shown to induce polymerization of FtsZ, whereas in vitro Ca2+ is known to inhibit the GTP hydrolysis activity of FtsZ. We have studied FtsZ dynamics at limiting GTP concentrations in the presence of 10 mM Ca2+. GTP and its non-hydrolysable analogue GTP-gamma-S bind FtsZ with similar affinity, whereas the non-hydrolysable analogue guanylyl-imidodiphosphate (GMP-PNP) is a poor substrate. Preformed FtsZ polymers can be stabilized by GTP-gamma-S and are destabilized by GDP. As more than 95% of the nucleotide associated with the FtsZ polymer is in the GDP form, it is concluded that GTP hydrolysis by itself does not trigger FtsZ polymer disassembly. Strikingly, GTP-gamma-S exchanges only a small portion of the FtsZ polymer-bound GDP. These data suggest that FtsZ polymers are stabilized by a small fraction of GTP-containing FtsZ subunits. These subunits may be located either throughout the polymer or at the polymer ends, forming a GTP cap similar to tubulin.