The structure of the periplasmic FlaG-FlaF complex and its essential role for archaellar swimming motility.
The structure of the periplasmic FlaG-FlaF complex and its essential role for archaellar swimming motility.
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周质 FlaG-FlaF 复合物的结构及其对古菌游泳运动的重要作用。
DOI：
10.1038/s41564-019-0622-3
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发表时间：
2020
影响因子：
28.3
通讯作者：
Albers,Sonja-Verena
中科院分区：
文献类型：
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作者：
Tsai,Chi-Lin;Tripp,Patrick;Sivabalasarma,Shamphavi;Zhang,Changyi;Rodriguez-Franco,Marta;Wipfler,RebeccaL;Chaudhury,Paushali;Banerjee,Ankan;Beeby,Morgan;Whitaker,RachelJ;Tainer,JohnA;Albers,Sonja-Verena
运动结构在生命的所有三个领域都是至关重要的。在古细菌中，运动是由古细菌介导的，古细菌是一种旋转的IV型菌毛样结构，是自然界中游泳运动的独特纳米机器。而周质FlaF结合的表面层（S-层），其他周质组件的结构，组装和作用仍然是谜，限制了我们的知识古菌的功能相互作用。在这里，我们发现，周质蛋白FlaG和协会与它的parastrophic FlaF是必不可少的archaellation和运动。因此，我们确定了酸热硫化叶菌可溶性FlaG（sFlaG）的晶体结构，其显示类似于S层相互作用FlaF可溶性结构域（sFlaF）的β-夹心折叠。此外，我们解决了sFlaG 2-sFlaF 2共晶体结构，通过小角X射线散射确定其在溶液中的异源四聚体复合物，并发现破坏复合物的突变废除运动性。有趣的是，Pyrococcus furiosus的sFlaF和sFlaG形成球状复合物，而sFlaG单独形成细丝，表明FlaF可以调节FlaG细丝组装。引人注目的是，缺乏FlaF结合的S层成分的硫化叶杆菌组装古细菌，但不能游泳。这些集体的结果支持了一个模型，其中一个FlaG丝加盖的FlaG-FlaF复合物锚定的S-层，使运动的古菌。
Motility structures are vital in all three domains of life. In Archaea, motility is mediated by the archaellum, a rotating type IV pilus-like structure that is a unique nanomachine for swimming motility in nature. Whereas periplasmic FlaF binds the surface layer (S-layer), the structure, assembly and roles of other periplasmic components remain enigmatic, limiting our knowledge of the archaellum’s functional interactions. Here, we find that the periplasmic protein FlaG and the association with its paralogue FlaF are essential for archaellation and motility. Therefore, we determine the crystal structure ofSulfolobus acidocaldariussoluble FlaG (sFlaG), which reveals a β-sandwich fold resembling the S-layer-interacting FlaF soluble domain (sFlaF). Furthermore, we solve the sFlaG2–sFlaF2co-crystal structure, define its heterotetrameric complex in solution by small-angle X-ray scattering and find that mutations that disrupt the complex abolish motility. Interestingly, the sFlaF and sFlaG ofPyrococcus furiosusform a globular complex, whereas sFlaG alone forms a filament, indicating that FlaF can regulate FlaG filament assembly. Strikingly,Sulfolobuscells that lack the S-layer component bound by FlaF assemble archaella but cannot swim. These collective results support a model where a FlaG filament capped by a FlaG–FlaF complex anchors the archaellum to the S-layer to allow motility.