The pilus usher controls protein interactions via domain masking and is functional as an oligomer

Glenn T. Werneburg, Nadine S. Henderson, Erica B. Portnoy, Samema Sarowar, Scott J. Hultgren, Huilin Li, David G. Thanassi

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

The chaperone-usher (CU) pathway assembles organelles termed pili or fimbriae in Gram-negative bacteria. Type 1 pili expressed by uropathogenic Escherichia coli are prototypical structures assembled by the CU pathway. Biogenesis of pili by the CU pathway requires a periplasmic chaperone and an outer-membrane protein termed the usher (FimD). We show that the FimD C-terminal domains provide the high-affinity substrate-binding site but that these domains are masked in the resting usher. Domain masking requires the FimD plug domain, which serves as a switch controlling usher activation. We demonstrate that usher molecules can act in trans for pilus biogenesis, providing conclusive evidence for a functional usher oligomer. These results reveal mechanisms by which molecular machines such as the usher regulate and harness protein-protein interactions and suggest that ushers may interact in a cooperative manner during pilus assembly in bacteria.

Original languageEnglish
Pages (from-to)540-546
Number of pages7
JournalNature Structural and Molecular Biology
Volume22
Issue number7
DOIs
StatePublished - Jul 9 2015

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