Structural insights into the secretin complex of a type IVb pilus system.

ABSTRACT: The bundle-forming pilus (BFP) system in enteropathogenic Escherichia coli (EPEC) produces type IVb pili that enable bacterial auto-aggregation, facilitating bacterial adhesion, colonization, and virulence. One of its components, lipoprotein BfpB, interacts with BfpG to form a secretin channel complex that enables pilus translocation across the outer membrane. Here, we report a high-resolution cryo-EM structure of the BfpB-BfpG complex, revealing a 17:17 stoichiometry with stable zigzag-like interactions between BfpG and BfpB near the N3 ring. Secretin BfpB consists of three β-barrels, including an additional N3 barrel that is crucial for BFP biogenesis. As a lipoprotein-type secretin, BfpB possesses an N-terminal LG domain that bridges the N0 domain and the outer membrane, ensuring its co

SUBMITTER: Pei C 

PROVIDER: S-EPMC12531336 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature