CnaA domains in bacterial pili are efficient dissipaters of large mechanical shocks
Proceeding of the National Academy of Sciences
Bacteria colonizing the oropharynx must adhere despite mechanical challenges from coughing, sneezing, and chewing; however, little is known about how Gram-positive organisms achieve this feat. We studied the pilus adhesive proteins from two Gram-positive organisms and report a conserved mechanism for dissipating the energy of a mechanical perturbation. The two proteins are stable up to forces of 525 pN and 690 pN, respectively, making these proteins the most mechanically stable proteins known. After a perturbation, the proteins refold rapidly at low force, resulting in a large hysteresis with most of the unfolding energy lost as heat. The work presents an initial model whereby transient unfolding at forces of 500–700 pN dissipates mechanical energy and protects covalent bonds from cleavage.