Fiber Formation across the Bacterial Outer Membrane by the Chaperone/Usher Pathway

Han Remaut, Chunyan Tang, Nadine S. Henderson, Jerome S. Pinkner, Tao Wang, Scott J. Hultgren, David G. Thanassi, Gabriel Waksman, Huilin Li

Research output: Contribution to journalArticlepeer-review

180 Scopus citations


Gram-negative pathogens commonly exhibit adhesive pili on their surfaces that mediate specific attachment to the host. A major class of pili is assembled via the chaperone/usher pathway. Here, the structural basis for pilus fiber assembly and secretion performed by the outer membrane assembly platform-the usher-is revealed by the crystal structure of the translocation domain of the P pilus usher PapC and single particle cryo-electron microscopy imaging of the FimD usher bound to a translocating type 1 pilus assembly intermediate. These structures provide molecular snapshots of a twinned-pore translocation machinery in action. Unexpectedly, only one pore is used for secretion, while both usher protomers are used for chaperone-subunit complex recruitment. The translocating pore itself comprises 24 β strands and is occluded by a folded plug domain, likely gated by a conformationally constrained β-hairpin. These structures capture the secretion of a virulence factor across the outer membrane of Gram-negative bacteria.

Original languageEnglish
Pages (from-to)640-652
Number of pages13
Issue number4
StatePublished - May 16 2008




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