The Scc Spirochetal Coiled-Coil Protein Forms Helix-Like Filaments and Binds to Nucleic Acids Generating Nucleoprotein Structures
The Scc Spirochetal Coiled-Coil Protein Forms Helix-Like Filaments and Binds to Nucleic Acids Generating Nucleoprotein Structures
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Scc 螺旋体卷曲螺旋蛋白形成螺旋状细丝并与核酸结合生成核蛋白结构
DOI：
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发表时间：
2006
影响因子：
3.2
通讯作者：
M. Picardeau
中科院分区：
文献类型：
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作者：
Khalil Mazouni;G. Péhau;P. England;P. Bourhy;I. Saint Girons;M. Picardeau
钩端螺旋体是螺旋体纲的一组细菌，具有多种独特的进化和形态特征。通过对钩端螺旋体的基因组分析，鉴定出一种编码卷曲蛋白的基因，称为SCC，它与任何其他真核或原核生物蛋白完全不相关。由于卷曲卷曲蛋白通常是细胞骨架的关键元件，我们分析了SCC蛋白，它是一个24 kDa的蛋白质，由一个N-末端卷曲卷曲结构域、一个富含Pro的中间结构域和一个酸性尾巴组成。SCC基因位于操纵子中，操纵子还包含编码起始因子IF3和两个核糖体蛋白L20和L35的基因。在这项研究中，我们发现螺旋卷曲结构域的存在是导致螺旋状结构中SCC聚合的原因，这种聚合不依赖于ATP，在大肠杆菌活细胞中和体外都是如此。电子显微镜分析表明，SCC聚合物的纤维宽度为6~10 nm，与真核细胞的中间纤维相似。鳞状细胞癌还被发现与RNA和双链DNA结合，而没有检测到序列特异性。在电子显微镜下，我们发现SCC聚合物的组装受到核酸存在的影响，产生了宽度在45-155 nm之间的棒状结构。最后，SCC中的双弯钩端螺旋体细胞枯竭形成小的菌落，但其螺旋状细胞体的形态没有受到影响。这些结果首次揭示了一种独特的DNA结合细丝形成卷曲卷曲蛋白，该蛋白可能在螺旋体微生物的亚细胞结构中发挥重要作用。
ABSTRACT The analysis of the genome of Leptospira spp., a group of bacteria of the phylum of spirochetes with several unique evolutionary and morphological features, has allowed the identification of a gene encoding a coiled-coil protein, called Scc, which is completely unrelated to any other eukaryotic or prokaryotic protein. Since coiled-coil proteins are often key elements of the cytoskeleton, we analyzed the protein Scc, which is a 24-kDa protein composed of a N-terminal coiled-coil domain, a proline-rich intermediate domain, and an acidic tail. The gene scc is located in an operon which also contains the genes encoding the initiation factor IF3 and the two ribosomal proteins L20 and L35. In this study, we showed that the presence of the coiled-coil domain was responsible for the polymerization of Scc in helix-like structures, in an ATP-independent manner, in both Escherichia coli living cells and in vitro. Analysis of the Scc polymers by electron microscopy showed filaments with a width of 6 to 10 nm, similar to that of eukaryotic intermediate filaments. Scc was also found to bind both RNA and double-stranded DNA without detectable sequence specificity. By electron microscopy, we showed that Scc polymer assembly was affected by the presence of nucleic acids, giving rise to rod-shaped structures with a width ranging from 45 to 155 nm. Finally, Leptospira biflexa cells depleted in Scc form small colonies, but the morphology of their helicoidal cell body was not affected. These results provide the first insight into a unique DNA binding filament-forming coiled-coil protein that could play an important role in the subcellular architecture of the spirochetal microorganism.