Donor-Strand Exchange in Chaperone-Assisted Pilus Assembly Proceeds through a Concerted β Strand Displacement Mechanism

Han Remaut, Rebecca J. Rose, Thomas J. Hannan, Scott J. Hultgren, Sheena E. Radford, Alison E. Ashcroft, Gabriel Waksman

Research output: Contribution to journalArticle

128 Scopus citations

Abstract

Gram-negative pathogens commonly use the chaperone-usher pathway to assemble adhesive multisubunit fibers on their surface. In the periplasm, subunits are stabilized by a chaperone that donates a β strand to complement the subunits' truncated immunoglobulin-like fold. Pilus assembly proceeds through a "donor-strand exchange" (DSE) mechanism whereby this complementary β strand is replaced by the N-terminal extension (Nte) of an incoming pilus subunit. Using X-ray crystallography and real-time electrospray ionization mass spectrometry (ESI-MS), we demonstrate that DSE requires the formation of a transient ternary complex between the chaperone-subunit complex and the Nte of the next subunit to be assembled. The process is crucially dependent on an initiation site (the P5 pocket) needed to recruit the incoming Nte. The data also suggest a capping reaction displacing DSE toward product formation. These results support a zip-in-zip-out mechanism for DSE and a catalytic role for the usher, the molecular platform at which pili are assembled.

Original languageEnglish
Pages (from-to)831-842
Number of pages12
JournalMolecular cell
Volume22
Issue number6
DOIs
StatePublished - Jun 23 2006

Keywords

  • MIRCOBIO
  • PROTEINS

Fingerprint Dive into the research topics of 'Donor-Strand Exchange in Chaperone-Assisted Pilus Assembly Proceeds through a Concerted β Strand Displacement Mechanism'. Together they form a unique fingerprint.

  • Cite this