Fig. 1. Cpe0147 is highly resistant to mechanical forces.
a Cpe0147 links the tip adhesion domain and bacteria to establish invasion and colonization and experiences considerable mechanical forces in the biological settings. b Structure of the C1 domain from PDB (4MKM). The ester bond is highlighted in magenta and the two calcium ions are shown as orange spheres. c Topology of C1WT domain. The ester bond is formed between Thr-11 and Gln-141. d Schematic of the AFM-based single-molecule force spectroscopy experiments. Fgβ-(GB1)2-C1WT-(GB1)2-cys was covalently anchored to a glass surface through a polyethylene glycol (PEG) linker via thiol–maleimide chemistry and picked up using a SdrG-cys modified cantilever. e Mechanical extension of C1WT from its N- and C-termini is blocked by the ester bond as the ester bond is located right at the force concentration point. f A representative single-molecule force–extension trace at 1.6 μm s−1 showing the unfolding of the four GB1 domains (black arrow) at ~200 pN but no unfolding peak of C1WT up to the rupture forces of Fgβ-SdrG complexes (red arrow). This experiment was repeated more than six times independently with similar results. Source data are provided as a Source Data file.