The chloroplast division protein ARC6 acts to inhibit disassembly of GDP-bound FtsZ2
The chloroplast division protein ARC6 acts to inhibit disassembly of GDP-bound FtsZ2
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DOI：
10.1074/jbc.ra117.000999
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发表时间：
2018-05
期刊：
影响因子：
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通讯作者：
M. Sung;R. Shaik;Allan D Terbush;K. Osteryoung;S. Vitha;A. Holzenburg
中科院分区：
文献类型：
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作者：
M. Sung;R. Shaik;Allan D Terbush;K. Osteryoung;S. Vitha;A. Holzenburg
叶绿体负责光合作用，并完成其他对植物生命至关重要的代谢功能。它们必须通过二分裂进行分裂，以在整个细胞分裂周期中保持其数量。叶绿体分裂是通过位于叶绿体被膜内侧（基质）和外侧（胞质）的复杂环形分裂机制实现的。内分裂环（称为Z环）由微管蛋白样FtsZ1和FtsZ2蛋白组装而成。ARC 6是一个与Z环相互作用的关键叶绿体分裂蛋白。ARC 6跨越内包膜，已知稳定或维持Z环，并通过与FtsZ 2相互作用将Z环锚定到内膜。Z环稳定化的潜在机制尚未得到充分理解。在这里，ARC 6的生物化学和结构表征进行使用光散射，沉降，光和透射电镜。将重组蛋白纯化为二聚体。结果表明，ARC 6的截短形式（tARC 6），代表ARC 6的基质部分，影响FtsZ 2组装，而不形成高阶结构，并通过FtsZ 2动力学发挥其作用。tARC 6阻止GDP诱导的FtsZ 2分解，并在GDP存在时引起FtsZ 2组装的显著净增加。进行单粒子分析和3D重建以阐明ARC 6活性的结构基础。总之，这些数据揭示了tARC 6的二聚体形式与FtsZ 2细丝结合，并且不增加FtsZ聚合速率，而是抑制GDP相关的FtsZ 2分解。
Chloroplasts host photosynthesis and fulfill other metabolic functions that are essential to plant life. They have to divide by binary fission to maintain their numbers throughout cycles of cell division. Chloroplast division is achieved by a complex ring-shaped division machinery located on both the inner (stromal) and the outer (cytosolic) side of the chloroplast envelope. The inner division ring (termed the Z ring) is formed by the assembly of tubulin-like FtsZ1 and FtsZ2 proteins. ARC6 is a key chloroplast division protein that interacts with the Z ring. ARC6 spans the inner envelope membrane, is known to stabilize or maintain the Z ring, and anchors the Z ring to the inner membrane through interaction with FtsZ2. The underlying mechanism of Z ring stabilization is not well-understood. Here, biochemical and structural characterization of ARC6 was conducted using light scattering, sedimentation, and light and transmission EM. The recombinant protein was purified as a dimer. The results indicated that a truncated form of ARC6 (tARC6), representing the stromal portion of ARC6, affects FtsZ2 assembly without forming higher-order structures and exerts its effect via FtsZ2 dynamics. tARC6 prevented GDP-induced FtsZ2 disassembly and caused a significant net increase in FtsZ2 assembly when GDP was present. Single particle analysis and 3D reconstruction were performed to elucidate the structural basis of ARC6 activity. Together, the data reveal that a dimeric form of tARC6 binds to FtsZ2 filaments and does not increase FtsZ polymerization rates but rather inhibits GDP-associated FtsZ2 disassembly.