Filament structure of bacterial tubulin homologue TubZ
Filament structure of bacterial tubulin homologue TubZ
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DOI：
10.1073/pnas.1010176107
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发表时间：
2010-11-16
影响因子：
11.1
通讯作者：
Loewe, Jan
中科院分区：
文献类型：
--
作者：
Aylett, Christopher H. S.;Wang, Qing;Loewe, Jan
低拷贝数的质粒通常依赖于准确的分割系统来持续生存。一般来说，这样的系统由DNA着丝粒样区、DNA结合接头和聚合的细胞动丝组成。这些成分共同将新复制的质粒驱动到分裂细胞的相反两端。苏云金芽孢杆菌质粒pBToxis依赖于微管蛋白/类FtsZ蛋白TubZ的一丝进行分离。通过结晶学和电子显微镜的结合，我们确定了该纤维的结构。我们解释了GTP水解是如何弱化亚单位-亚单位接触的，并揭示了质粒-接头复合体的分配。TubZ细丝的双螺旋超结构在微管蛋白样蛋白中是不寻常的。Parm的细丝也是双螺旋的，Parm是一种肌动蛋白样分割蛋白。我们认为，趋同的进化将这些不同类型的细胞运动细丝塑造成一种通用的质粒分离机制。
Low copy number plasmids often depend on accurate partitioning systems for their continued survival. Generally, such systems consist of a centromere-like region of DNA, a DNA-binding adaptor, and a polymerizing cytomotive filament. Together these components drive newly replicated plasmids to opposite ends of the dividing cell. The Bacillus thuringiensis plasmid pBToxis relies on a filament of the tubulin/FtsZ-like protein TubZ for its segregation. By combining crystallography and electron microscopy, we have determined the structure of this filament. We explain how GTP hydrolysis weakens the subunit-subunit contact and also shed light on the partitioning of the plasmid-adaptor complex. The double helical superstructure of TubZ filaments is unusual for tubulin-like proteins. Filaments of ParM, the actin-like partitioning protein, are also double helical. We suggest that convergent evolution shapes these different types of cytomotive filaments toward a general mechanism for plasmid separation.