Structural basis of host recognition and biofilm formation by Salmonella Saf pili.
Structural basis of host recognition and biofilm formation by Salmonella Saf pili.
复制标题
沙门氏菌菌毛沙门氏菌宿主识别和生物膜形成的结构基础
作者：
Zeng L;Zhang L;Wang P;Meng G
在细菌感染过程中，皮利在宿主识别、定殖和生物膜形成中起关键作用。在这里，我们报告的晶体结构的SafD-dsc和SafD-SafA-SafA（SafDAA-dsc）的SAF皮利。细胞粘附试验表明，SafD和SafA都是宿主识别所必需的，表明Saf皮利的多粘附机制。此外，SafDAA-dsc结构，以及SAXS表征，揭示了一个意想不到的分子间的寡聚化，促使调查的SAF驱动的自缔合在生物膜形成。珠/细胞聚集和生物膜形成测定用于证明Saf皮利的新功能。靶向SafDAA-dsc二聚体中分子间氢键和互补结构/表面的基于结构的突变体显著损害了Saf自缔合活性和生物膜形成。总之，我们的研究结果确定了两个新的功能的Saf皮利：多粘附和自缔合活动。更重要的是，Saf-Saf结构和功能表征有助于定义用于细菌聚集、定殖和最终生物膜形成的菌毛介导的细胞间寡聚化机制。
Pili are critical in host recognition, colonization and biofilm formation during bacterial infection. Here, we report the crystal structures of SafD-dsc and SafD-SafA-SafA (SafDAA-dsc) in Saf pili. Cell adherence assays show that SafD and SafA are both required for host recognition, suggesting a poly-adhesive mechanism for Saf pili. Moreover, the SafDAA-dsc structure, as well as SAXS characterization, reveals an unexpected inter-molecular oligomerization, prompting the investigation of Saf-driven self-association in biofilm formation. The bead/cell aggregation and biofilm formation assays are used to demonstrate the novel function of Saf pili. Structure-based mutants targeting the inter-molecular hydrogen bonds and complementary architecture/surfaces in SafDAA-dsc dimers significantly impaired the Saf self-association activity and biofilm formation. In summary, our results identify two novel functions of Saf pili: the poly-adhesive and self-associating activities. More importantly, Saf-Saf structures and functional characterizations help to define a pili-mediated inter-cellular oligomerizaiton mechanism for bacterial aggregation, colonization and ultimate biofilm formation.