Energetics and geometry of FtsZ polymers: Nucleated self-assembly of single protofilaments
Energetics and geometry of FtsZ polymers: Nucleated self-assembly of single protofilaments
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DOI：
10.1529/biophysj.107.115493
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发表时间：
2008-03-01
影响因子：
3.4
通讯作者：
Andreu, Jose Manuel
中科院分区：
文献类型：
--
作者：
Huecas, Sonia;Llorca, Oscar;Andreu, Jose Manuel
细胞分裂必需蛋白FtsZ是一种组装型GTZ，它指导细菌细胞分裂中细胞动力学环的形成。FtsZ共享真核微管蛋白的结构折叠并组装形成微管蛋白样原丝，但不形成微管。两个令人困惑的问题，在FtsZ大会的性质的原丝协会和一个可能的机制为成核自组装的单链原丝超过一个临界FtsZ浓度。我们组装二维阵列的FtsZ碳支持，研究线性聚合物的FtsZ与玻璃化无支撑的解决方案的冷冻电子显微镜，并制定可能的聚合模型。来自大肠杆菌的FtsZ与GTP和镁的成核自组装产生4-6 nm宽的柔性细丝，仅与单个原丝相容。这同意与以前的扫描透射电子显微镜的结果，并支持最近的冷冻电子断层扫描研究两种细菌细胞。负染色的双链FtsZ纤维的观察结果可能来自碳载体上的原丝增生。优先原丝环化不适用于FtsZ组装。一个单一的原丝与相同的单体间接触的明显的合作聚合的解释是一个非活性单体到下一个协会之前的活性结构的开关，创造一个晚餐核。FtsZ表现为一个合作的线性装配机。
Essential cell division protein FtsZ is an assembling GTPase which directs the cytokinetic ring formation in dividing bacterial cells. FtsZ shares the structural fold of eukaryotic tubulin and assembles forming tubulin-like protofilaments, but does not form microtubules. Two puzzling problems in FtsZ assembly are the nature of protofilament association and a possible mechanism for nucleated self-assembly of single-stranded protofilaments above a critical FtsZ concentration. We assembled two-dimensional arrays of FtsZ on carbon supports, studied linear polymers of FtsZ with cryo-electron microscopy of vitrified unsupported solutions, and formulated possible polymerization models. Nucleated self-assembly of FtsZ from Escherichia coli with GTP and magnesium produces flexible filaments 4-6 nm-wide, only compatible with a single protofilament. This agrees with previous scanning transmission electron microscopy results and is supported by recent cryo-electron tomography studies of two bacterial cells. Observations of double-stranded FtsZ filaments in negative stain may come from protofilament accretion on the carbon support. Preferential protofilament cyclization does not apply to FtsZ assembly. The apparently cooperative polymerization of a single protofilament with identical intermonomer contacts is explained by the switching of one inactive monomer into the active structure preceding association of the next, creating a dinner nucleus. FtsZ behaves as a cooperative linear assembly machine.