Herrou Julien, My Laetitia, Monteil Caroline L, Bergot Marine, Jain Rikesh, Martinez Emmanuelle, Mignot Tâm
Aix Marseille Univ, CNRS, LCB, Marseille, France.
Aix-Marseille Univ, CEA, CNRS, BIAM, Saint-Paul-lez-Durance, France.
Nat Commun. 2025 May 13;16(1):4425. doi: 10.1038/s41467-025-58967-0.
The predatory bacterium, Myxococcus xanthus, kills its prey by contact, using a putative Tight Adherence pilus, known as the Kil system, along with a protein complex resembling the basal body a type-III secretion system, named the "needleless" T3SS*. In this work, we provide direct evidence that Myxococcus polymerizes a Kil pilus at the prey contact site, which is constituted by the major pilin KilP. We also genetically demonstrate that the predation function of this pilus is linked to four different minor pilin complexes, which work in specific combinations to detect and kill phylogenetically diverse bacterial species. Structural models of the Kil pilus suggest that these minor pilin complexes form interchangeable "Tips", exposing variable domains at the extremity of the pilus to interact with prey cells. Remarkably, the activity of these Tips also depends on the T3SS*, revealing a tight functional connection between the Kil system and the T3SS*. While these Tips are mostly restricted to predatory bacteria, genomic and structural analyses suggest that in other bacteria, including pathogens, Tad pili are also customized and functionalized by similar minor pilin complexes exposing variable domains.
掠食性细菌黄色粘球菌通过接触杀死猎物，它利用一种被认为是紧密粘附菌毛的Kil系统，以及一种类似于III型分泌系统基体的蛋白质复合物（称为“无针”T3SS*）。在这项研究中，我们提供了直接证据，证明黄色粘球菌在猎物接触部位聚合形成由主要菌毛蛋白KilP构成的Kil菌毛。我们还通过遗传学方法证明，这种菌毛的捕食功能与四种不同的次要菌毛复合物相关，它们以特定组合发挥作用，以检测和杀死系统发育上不同的细菌物种。Kil菌毛的结构模型表明，这些次要菌毛复合物形成可互换的“尖端”，在菌毛末端暴露可变结构域以与猎物细胞相互作用。值得注意的是，这些尖端的活性也依赖于T3SS*，揭示了Kil系统与T3SS*之间紧密的功能联系。虽然这些尖端大多局限于掠食性细菌，但基因组和结构分析表明，在包括病原体在内的其他细菌中，Tad菌毛也通过类似的暴露可变结构域的次要菌毛复合物进行定制和功能化。
