Curli play critical roles in biofilm formation, host cell adhesion, and colonization of inert surfaces in many Enterobacteriaceae. In Escherichia coli, curli biogenesis requires 7 curli-specific gene (csg) products—CsgA through G—working in concert. Of them, CsgG and CsgF are 2 outer membrane (OM)-localized components that consists of the core apparatus for secretion and assembly of curli structural subunits, CsgB and CsgA. Here, we report the cryogenic electron microscopy (cryo-EM) structure of CsgG in complex with CsgF from E. coli. The structure reveals that CsgF forms a stable complex with CsgG via a 1:1 stoichiometry by lining the upper lumen of the nonameric CsgG channel via its N-terminal 27 residues, forming a funnel-like entity plugged in the CsgG channel and creating a unique secretion channel with 2 constriction regions, consistent with the recently reported structure of the CsgG-CsgF complex. Functional studies indicate that export of CsgF to the cell surface requires the CsgG channel, and CsgF not only functions as an adaptor that bridges CsgB with CsgG but also may play important roles in controlling the rates of translocation and/or polymerization for curli structural subunits. Importantly, we found that a series of CsgF-derived peptides are able to efficiently inhibit curli production to E. coli when administrated exogenously, highlighting a potential strategy to interfere biofilm formation in E. coli strains.

Curli在许多肠杆菌科的生物膜形成，宿主细胞粘附以及惰性表面定殖中起着关键作用。在大肠杆菌中，卷曲的生物发生需要7个卷曲特定的基因（csg）产物-CsgA到G-协同工作。其中，CsgG和CsgF是2个外膜（OM）定位的组件，由用于分泌和组装curli结构亚基CsgB和CsgA的核心设备组成。在这里，我们报道了CsgG与E中CsgF的复合体的低温电子显微镜（cryo-EM）结构。大肠杆菌。该结构表明，CsgF通过1：1的化学计量比与CsgG形成稳定的复合物，方法是通过其N末端27个残基衬里非异构CsgG通道的上腔，形成插入CsgG通道的漏斗状实体，并形成独特的分泌通道具有2个收缩区，与最近报道的CsgG-CsgF复合体结构一致。功能研究表明，将CsgF输出到细胞表面需要CsgG通道，并且CsgF不仅充当衔接CsgB与CsgG的衔接子，而且在控制curli结构亚基的转运和/或聚合速率中可能起重要作用。重要的是，我们发现一系列CsgF衍生的肽能够有效地抑制curli向E的产生。大肠杆菌外用时，强调了干扰E中生物膜形成的潜在策略。大肠杆菌菌株。