The mechanical properties of E. coli type 1 pili measured by atomic force microscopy techniques

Eric Miller, Tzintzuni Garcia, Scott Hultgren, Andres F. Oberhauser

Research output: Contribution to journalArticlepeer-review

132 Scopus citations


The first step in the encounter between a host and a pathogen is attachment to the host epithelium. For uropathogenic Escherichia coli, these interactions are mediated by type 1 and P adhesive pili, which are long (∼1 μm) rods composed of more than 1000 protein subunits arranged in a helical structure. Here we used single-molecule atomic force microscopy to study the mechanical properties of type 1 pili. We found that type 1 pili readily extend under an applied force and that this extensibility is the result of unwinding the pilus rod's helical quaternary structure. The forced unraveling is also reversible, with helical rewinding taking place under considerable forces (∼60 pN). These data are similar to those obtained on P pili using optical tweezers, indicating that these are conserved properties of uropathogenic E. coli pili. We also show that our data can readily be reproduced using Monte Carlo simulation techniques based on a two-state kinetic model. This model provides a simple way to extrapolate the mechanical behavior of pili under a wide range of forces. We propose that type 1 pilus unraveling is an essential mechanism for absorbing physiological shear forces encountered during urinary tract infections and probably essential for adhesion and colonization of the bladder epithelium.

Original languageEnglish (US)
Pages (from-to)3848-3856
Number of pages9
JournalBiophysical journal
Issue number10
StatePublished - Nov 2006

ASJC Scopus subject areas

  • Biophysics


Dive into the research topics of 'The mechanical properties of E. coli type 1 pili measured by atomic force microscopy techniques'. Together they form a unique fingerprint.

Cite this