Löwe J, Amos L A
MRC Laboratory of Molecular Biology, Cambridge, UK.
Biol Chem. 2000 Sep-Oct;381(9-10):993-9. doi: 10.1515/BC.2000.122.
Bacterial cell division depends on the formation of a cytokinetic ring structure, the Z-ring. The bacterial tubulin homologue FtsZ is required for Z-ring formation. FtsZ assembles into various polymeric forms in vitro, indicating a structural role in the septum of bacteria. We have used recombinant FtsZ1 protein from M. jannaschii to produce helical tubes and sheets with high yield using the GTP analogue GMPCPP [guanylyl-(alpha,beta)-methylene-diphosphate]. The sheets appear identical to the previously reported Ca++-induced sheets of FtsZ from M. jannaschii that were shown to consist of 'thick'-filaments in which two protofilaments run in parallel. Tubes assembled either in Ca++ or in GMPCPP contain filaments whose dimensions indicate that they could be equivalent to the 'thick'-filaments in sheets. Some tubes are hollow but others are filled by additional protein density. Helical FtsZ tubes differ from eukaryotic microtubules in that the filaments curve around the filament axis with a pitch of approximately 430 A for Ca++-induced tubes or 590 - 620 A for GMPCPP. However, their assembly in vitro as well-ordered polymers over distances comparable to the inner circumference of a bacterium may indicate a role in vivo. Their size and stability make them suitable for use in motility assays.
细菌细胞分裂依赖于细胞动力学环结构即Z环的形成。Z环的形成需要细菌微管蛋白同源物FtsZ。FtsZ在体外组装成各种聚合形式，表明其在细菌隔膜中起结构作用。我们利用来自詹氏甲烷球菌的重组FtsZ1蛋白，使用GTP类似物GMPCPP[鸟苷基-(α,β)-亚甲基二磷酸]高产率地生成螺旋管和薄片。这些薄片看起来与先前报道的来自詹氏甲烷球菌的Ca++诱导的FtsZ薄片相同，后者显示由“厚”丝组成，其中两条原丝平行排列。在Ca++或GMPCPP中组装的管含有细丝，其尺寸表明它们可能等同于薄片中的“厚”丝。一些管是中空的，但其他管被额外的蛋白质密度填充。螺旋状FtsZ管与真核微管不同，对于Ca++诱导的管，细丝围绕细丝轴弯曲，螺距约为430埃；对于GMPCPP诱导的管，螺距为590 - 620埃。然而，它们在体外组装成与细菌内周相当距离的有序聚合物可能表明其在体内的作用。它们的大小和稳定性使其适用于运动性测定。
