Fig. 3
From: Mechanical architecture and folding of E. coli type 1 pilus domains
Mechanical stability of the FimF-FimG-FimH array. a Force-ramp experimental trace of the polyprotein (I91)2-FimF-FimG-FimH-(I91)2 at 10 pN s−1 pulling speed showing the gradual unfolding of Fim domains, starting with the weaker FimHL. The four I91 domains follow the unfolding of FimHL that occurs before the unfolding of FimG and FimF. Small steps of about 6 nm, as depicted in the inset, are observed in about 50% of the traces. b Histogram of step size vs unfolding force where the different domains can be distinguished by the color code given their step size. The average step size (mean ± SD) and unfolding forces (mean ± SEM) are: 62 ± 4 pN and 33 ± 1 nm for FimHL (n = 23); 238 ± 7 pN and 32 ± 1 nm for FimHP (n = 15); 261 ± 9 pN and 33 ± 1 nm for FimG (n = 16) and 281 ± 8 pN and 37 ± 1 nm for FimF(n = 15). The small steps show unfolding force of 82 ± 7 pN and length increments of 6 ± 1 nm (n = 11)
