Spiral Architecture of the Nucleoid in Bdellovibrio bacteriovorus
Spiral Architecture of the Nucleoid in Bdellovibrio bacteriovorus
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DOI：
10.1128/jb.01061-10
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发表时间：
2011-03-01
影响因子：
3.2
通讯作者：
Milne, Jacqueline L. S.
中科院分区：
文献类型：
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作者：
Butan, Carmen;Hartnell, Lisa M.;Milne, Jacqueline L. S.
我们对革兰氏阴性菌噬菌弓形菌菌株的三维结构进行了冷冻电子断层扫描分析，其中内源性 MreB2 被单体青色荧光蛋白 (mTFP) 标记的 MreB2 取代。与主要显示紧凑核区的野生型蛭弧菌细胞相比，表达 mTFP 标记的 MreB2 的细胞显示出扭曲的螺旋状核组织。 MreB2-mTFP 核仁的更开放的结构使得装饰核仁外围的核糖体能够清晰地原位可视化。核糖体还与来自野生型细胞和突变细胞的更紧凑的核仁的边缘接壤。令人惊讶的是，MreB2-mTFP 定位于螺旋核和细胞质之间的界面，表明核结构和 MreB 排列之间存在密切联系。此外，与野生型细胞相反，野生型细胞中单个紧密的化学感受器簇位于靠近单个极鞭毛的位置，MreB2-mTFP细胞通常在一个或两个极处表现出扩展的化学感受器阵列，并表现出多个或位置不准确的鞭毛。我们的研究结果为细菌核的螺旋组织提供了直接的结构证据，并表明 MreB 在核结构的调节和趋化装置的定位中可能发挥作用。
We present a cryo-electron tomographic analysis of the three-dimensional architecture of a strain of the Gram-negative bacterium Bdellovibrio bacteriovorus in which endogenous MreB2 was replaced with monomeric teal fluorescent protein (mTFP)-labeled MreB2. In contrast to wild-type Bdellovibrio cells that predominantly displayed a compact nucleoid region, cells expressing mTFP-labeled MreB2 displayed a twisted spiral organization of the nucleoid. The more open structure of the MreB2-mTFP nucleoids enabled clear in situ visualization of ribosomes decorating the periphery of the nucleoid. Ribosomes also bordered the edges of more compact nucleoids from both wild-type cells and mutant cells. Surprisingly, MreB2-mTFP localized to the interface between the spiral nucleoid and the cytoplasm, suggesting an intimate connection between nucleoid architecture and MreB arrangement. Further, in contrast to wild-type cells, where a single tight chemoreceptor cluster localizes close to the single polar flagellum, MreB2-mTFP cells often displayed extended chemoreceptor arrays present at one or both poles and displayed multiple or inaccurately positioned flagella. Our findings provide direct structural evidence for spiral organization of the bacterial nucleoid and suggest a possible role for MreB in regulation of nucleoid architecture and localization of the chemotaxis apparatus.