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Structural basis of host recognition and biofilm formation by Salmonella Saf pili
eLife ( IF 7.7 ) Pub Date : 2017-11-10 , DOI: 10.7554/elife.28619
Longhui Zeng 1 , Li Zhang 1 , Pengran Wang 1 , Guoyu Meng 1
Affiliation  

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.

中文翻译:

沙门氏菌 Saf pili 宿主识别和生物膜形成的结构基础

菌毛在细菌感染期间对宿主识别、定植和生物膜形成至关重要。在这里,我们报告了 Saf 菌毛中 SafD-dsc 和 SafD-SafA-SafA (SafDAA-dsc) 的晶体结构。细胞粘附测定表明 SafD 和 SafA 都是宿主识别所必需的,这表明 Saf 菌毛的多粘附机制。此外,SafDAA-dsc 结构以及 SAXS 表征揭示了意外的分子间寡聚化,促使对生物膜形成中 Saf 驱动的自缔合进行研究。珠/细胞聚集和生物膜形成试验用于证明 Saf pili 的新功能。针对 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着损害了 Saf 自缔合活性和生物膜形成。总而言之,我们的结果确定了 Saf pili 的两个新功能:多粘和自结合活动。更重要的是,Saf-Saf 结构和功能表征有助于定义菌毛介导的细胞间寡聚化机制,用于细菌聚集、定植和最终生物膜形成。
更新日期:2017-11-10
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