Envelope structure of Synechococcus sp. WH8113, a nonflagellated swimming cyanobacterium.
Envelope structure of Synechococcus sp. WH8113, a nonflagellated swimming cyanobacterium.
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DOI：
10.1186/1471-2180-1-4
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发表时间：
2001
期刊：
影响因子：
4.2
通讯作者：
Reese TS
中科院分区：
文献类型：
--
作者：
Samuel AD;Petersen JD;Reese TS
许多细菌靠旋转的螺旋状鞭毛游动。沃特伯里等人发现了一个例外，蓝细菌聚球藻的菌株没有鞭毛或可见的形状变化。其他种类的蓝细菌在表面滑行。聚球藻可能利用行进表面波游泳的假设促使了这项研究。使用快速冷冻电子显微镜，我们已经确定了一个晶体表面层，包围外膜的能动菌株聚球藻。WH8113，其中的组件是安排在一个菱形晶格。针状体从层中大量出现，并延伸到周围流体中长达150 nm。这些针状体也向内延伸到细胞内膜，在那里运动是由离子动力驱动的。聚球藻（Synechococcus sp.）WH8113的外膜结构为其运动机制提供了新的限制。针状体的位置很好，可以将细胞膜上的能量转化为细胞表面的机械功。一种模型是，嵌入细胞膜中的未知马达以纤毛真核生物的方式利用针状体作为桨在表面层外部产生行波。
Many bacteria swim by rotating helical flagellar filaments. Waterbury et al. discovered an exception, strains of the cyanobacterium Synechococcus that swim without flagella or visible changes in shape. Other species of cyanobacteria glide on surfaces. The hypothesis that Synechococcus might swim using traveling surface waves prompted this investigation. Using quick-freeze electron microscopy, we have identified a crystalline surface layer that encloses the outer membrane of the motile strain Synechococcus sp. WH8113, the components of which are arranged in a rhomboid lattice. Spicules emerge in profusion from the layer and extend up to 150 nm into the surrounding fluid. These spicules also send extensions inwards to the inner cell membrane where motility is powered by an ion-motive force. The envelope structure of Synechococcus sp. WH8113 provides new constraints on its motile mechanism. The spicules are well positioned to transduce energy at the cell membrane into mechanical work at the cell surface. One model is that an unidentified motor embedded in the cell membrane utilizes the spicules as oars to generate a traveling wave external to the surface layer in the manner of ciliated eukaryotes.