TssA forms a gp6-like ring attached to the type VI secretion sheath.
TssA forms a gp6-like ring attached to the type VI secretion sheath.
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DOI：
10.15252/embj.201694024
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发表时间：
2016-08-01
期刊：
影响因子：
--
通讯作者：
Filloux A
中科院分区：
文献类型：
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作者：
Planamente S;Salih O;Manoli E;Albesa-Jové D;Freemont PS;Filloux A
VI型分泌系统（T6 SS）是一种超分子细菌复合物，类似于噬菌体尾。它是一种杀伤机器，在其TssBC鞘收缩时将毒素发射到靶细胞中。在这里，我们表明，TssA 1是一个T6 SS组件形成十二聚体环结构，其尺寸匹配的TssBC鞘，可以容纳内HCP管。TssA 1环复合物结合T6 SS鞘并影响其体内行为。在噬菌体中，gp 18鞘的第一圆盘位于基板上，其中gp 6是十二聚体环。我们发现TssA 1和gp 6 C-末端之间存在显著的序列和结构相似性，并提出TssA 1可能是T6 SS的基板组分。此外，我们确定了TssK 1和gp 8之间的相似性，前者与TssA 1相互作用，而后者被发现在gp 6环的外半径。这些观察结果，结合TssF和gp 6 N末端或TssG和gp 53之间的相似性，使我们提出了噬菌体基板和T6 SS之间的比较模型。
The type VI secretion system (T6SS) is a supra‐molecular bacterial complex that resembles phage tails. It is a killing machine which fires toxins into target cells upon contraction of its TssBC sheath. Here, we show that TssA1 is a T6SS component forming dodecameric ring structures whose dimensions match those of the TssBC sheath and which can accommodate the inner Hcp tube. The TssA1 ring complex binds the T6SS sheath and impacts its behaviour in vivo. In the phage, the first disc of the gp18 sheath sits on a baseplate wherein gp6 is a dodecameric ring. We found remarkable sequence and structural similarities between TssA1 and gp6 C‐termini, and propose that TssA1 could be a baseplate component of the T6SS. Furthermore, we identified similarities between TssK1 and gp8, the former interacting with TssA1 while the latter is found in the outer radius of the gp6 ring. These observations, combined with similarities between TssF and gp6N‐terminus or TssG and gp53, lead us to propose a comparative model between the phage baseplate and the T6SS.