The molecular basis of functional bacterial amyloid polymerization and nucleation

Xuan Wang, Neal D. Hammer, Matthew R. Chapman

Research output: Contribution to journalArticlepeer-review

95 Scopus citations

Abstract

Amyloid fibers are filamentous proteinaceous structures commonly associated with mammalian neurodegenerative diseases. Nucleation is the rate-limiting step of amyloid propagation, and its nature remains poorly understood. Escherichia coli assembles functional amyloid fibers called curli on the cell surface using an evolved biogenesis machine. In vivo, amyloidogenesis of the major curli subunit protein, CsgA, is dependent on the minor curli subunit protein, CsgB. Here, we directly demonstrated that CsgB+ cells efficiently nucleated purified soluble CsgA into amyloid fibers on the cell surface. CsgA contains five imperfect repeating units that fulfill specific roles in directing amyloid formation. Deletion analysis revealed that the N- and C-terminal most repeating units were required for in vivo amyloid formation. We found that CsgA nucleation specificity is encoded by the N- and C-terminal most repeating units using a blend of genetic, biochemical, and electron microscopic analyses. In addition, we found that the C-terminal most repeat was most aggregation-prone and dramatically contributed to CsgA polymerization in vitro. This work defines the elegant molecular signatures of bacterial amyloid nucleation and polymerization, thereby revealing how nature directs amyloid formation to occur at the correct time and location.

Original languageEnglish (US)
Pages (from-to)21530-21539
Number of pages10
JournalJournal of Biological Chemistry
Volume283
Issue number31
DOIs
StatePublished - Aug 1 2008
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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